Display apparatus

Abstract

To provide a highly reliable display apparatus.SOLUTION: There is provided a display apparatus that includes a pixel including a first subpixel and a second subpixel. The area of the first subpixel is smaller than the area of the second subpixel. The first subpixel includes a first tandem light-emitting device, and the second subpixel includes a second tandem light-emitting device. Light-emitting layers included in the first light-emitting device each include an emission center substance, a first organic compound including a π-electron deficient heteroaromatic ring, and a second organic compound including an electron-rich heteroaromatic ring or an aromatic amine skeleton. At least one of the first organic compound and the second organic compound includes deuterium. Each of the light-emitting layers included in the second light-emitting device emits light with a hue different from a hue of light emitted from each of the light-emitting layers included in the first light-emitting device.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] One embodiment of the present invention relates to an organic compound, an organic semiconductor element, a light-emitting device, a photodiode sensor, a display module, a lighting module, a display device, an electronic device, a lighting device, and an electronic device. Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification etc. relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Therefore, more specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, lighting devices, power storage devices, memory devices, imaging devices, driving methods thereof, and manufacturing methods thereof. [Background technology]

[0002] Light-emitting devices (also called organic EL elements) that utilize electroluminescence (EL) using organic compounds are becoming more and more common. The basic structure of these light-emitting devices is a pair of electrodes sandwiching an organic compound layer containing a luminescent center substance between them. By applying a voltage to this device, carriers are injected, and the recombination energy of these carriers is utilized to emit light from the luminescent center substance.

[0003] Since light-emitting devices are self-luminous, display devices using these light-emitting devices as pixels have higher visibility than liquid crystal display devices and do not require backlighting. Another major advantage of display devices using such light-emitting devices is that they can be fabricated to be thin and lightweight. Another feature is their extremely fast response speed.

[0004] Furthermore, these light-emitting devices can emit light in a planar, continuous pattern because the light-emitting layer can be formed continuously in a planar pattern. This is a feature that is difficult to obtain with point light sources such as incandescent bulbs and LEDs, or linear light sources such as fluorescent lamps, making them highly useful as surface light sources for lighting applications.

[0005] Display devices and lighting devices using such light-emitting devices are suitable for a variety of electronic devices, but research and development is ongoing to find light-emitting devices with even better characteristics.

[0006] Tandem light-emitting devices in particular have attracted attention because they achieve high current efficiency.

[0007] Patent Documents 1 and 2 disclose tandem light-emitting devices using a separate coating method. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-317548 [Patent Document 2] Japanese Patent Publication No. 2023-161850 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of one embodiment of the present invention is to provide a light-emitting device with good characteristics.An object of one embodiment of the present invention is to provide a light-emitting device with good emission efficiency.An object of one embodiment of the present invention is to provide a light-emitting device with good reliability.An object of one embodiment of the present invention is to provide a light-emitting device with low driving voltage.An object of one embodiment of the present invention is to provide a light-emitting device with good reliability and low driving voltage.

[0010] Another object of one embodiment of the present invention is to provide a light-emitting device that can provide a display device with good characteristics. Another object of one embodiment of the present invention is to provide a light-emitting device that can provide a display device with good emission efficiency. Another object of one embodiment of the present invention is to provide a light-emitting device that can provide a display device with good reliability. Another object of one embodiment of the present invention is to provide a display device with low driving voltage. Another object of one embodiment of the present invention is to provide a light-emitting device that can provide a display device with low driving voltage and good reliability.

[0011] Another object is to provide any one of an organic semiconductor device, a light-emitting device, a light-receiving device, a display device, an electronic device, and a lighting device that consumes low power, or to provide any one of an electronic device and a lighting device that is highly reliable, or to provide any one of a novel organic semiconductor device, a light-emitting device, a light-receiving device, a display device, an electronic device, and a lighting device.

[0012] The present invention is intended to solve any one of the above-mentioned problems. Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other problems from the description in the specification, drawings, claims, etc. [Means for solving the problem]

[0013] One embodiment of the present invention is a display device including a pixel having a first subpixel and a second subpixel, wherein the area of ​​the first subpixel is smaller than the area of ​​the second subpixel, the first subpixel has a first light-emitting device, and the second subpixel has a second light-emitting device. The first light-emitting device has a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, and a second light-emitting layer, the first intermediate layer being located between the first electrode and the second electrode, the first light-emitting layer being located between the first electrode and the first intermediate layer, and the second light-emitting layer being located between the first intermediate layer and the second electrode, the first light-emitting layer having a first light-emitting center substance, a first organic compound, and a second organic compound, the second light-emitting layer having the second light-emitting center substance, a third organic compound, and a fourth organic compound, and the first organic compound and the third organic compound have π-electron-deficient heteroaromatic rings. the second organic compound and the fourth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; at least one of the first organic compound, the second organic compound, the third organic compound, and the fourth organic compound contains deuterium; a difference between a maximum peak wavelength in an emission spectrum of the first luminescent center substance and a maximum peak wavelength in an emission spectrum of the second luminescent center substance is 30 nm or less; the second light-emitting device has a third electrode, a fourth electrode, a second intermediate layer, a third light-emitting layer, and a fourth light-emitting layer, the second intermediate layer being located between the third electrode and the fourth electrode, the third light-emitting layer being located between the third electrode and the second intermediate layer, and the fourth light-emitting layer being located between the second intermediate layer and the fourth electrode, and the third light-emitting layer and the fourth light-emitting layer exhibiting light of a different hue from the first light-emitting layer and the second light-emitting layer.

[0014] Another embodiment of the present invention is a display device having the above structure, wherein the third light-emitting layer includes a third light-emitting center substance, a fifth organic compound, and a sixth organic compound; the fourth light-emitting layer includes a fourth light-emitting center substance, a seventh organic compound, and an eighth organic compound; the fifth organic compound and the seventh organic compound each have a π-electron-deficient heteroaromatic ring; and the sixth organic compound and the eighth organic compound each have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; and the difference between the maximum peak wavelength in the emission spectrum of the third light-emitting center substance and the maximum peak wavelength in the emission spectrum of the fourth light-emitting center substance is 30 nm or less.

[0015] Alternatively, one embodiment of the present invention is a display device having the above structure, wherein the third light-emitting layer includes a third light-emitting center substance and a fifth organic compound, the fourth light-emitting layer includes a fourth light-emitting center substance and a seventh organic compound, the third light-emitting center substance and the fourth light-emitting center substance are each fluorescent substances, and the difference between the maximum peak wavelength in the emission spectrum of the third light-emitting center substance and the maximum peak wavelength in the emission spectrum of the fourth light-emitting center substance is 30 nm or less.

[0016] Another embodiment of the present invention is a display device including a pixel having a first subpixel, a second subpixel, and a third subpixel, wherein the area of ​​the first subpixel is smaller than that of the second subpixel, and the area of ​​the second subpixel is smaller than that of the third subpixel, the first subpixel has a first light-emitting device, the second subpixel has a second light-emitting device, and the third subpixel has a third light-emitting device, the first light-emitting device has a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, and a second light-emitting layer, the first intermediate layer is located between the first electrode and the second electrode, and the first light-emitting layer The light-emitting layer is located between the first electrode and the first intermediate layer, and the second light-emitting layer is located between the first intermediate layer and the second electrode. The first light-emitting layer has a first light-emitting center substance, a first organic compound, and a second organic compound. The second light-emitting layer has a second light-emitting center substance, a third organic compound, and a fourth organic compound. The first organic compound and the third organic compound have a π-electron-deficient heteroaromatic ring, and the second organic compound and the fourth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton. at least one of the first luminescent center substance and the second luminescent center substance contains deuterium, and a difference between a maximum peak wavelength in an emission spectrum of the first luminescent center substance and a maximum peak wavelength in an emission spectrum of the second luminescent center substance is 30 nm or less; the second light-emitting device has a third electrode, a fourth electrode, a second intermediate layer, a third luminescent layer, and a fourth luminescent layer, the second intermediate layer being located between the third electrode and the fourth electrode, the third luminescent layer being located between the third electrode and the second intermediate layer, and the fourth luminescent layer being located between the second intermediate layer and the fourth electrode, and the third luminescent layer being composed of the third luminescent center substance and a fifth organic compound and a sixth organic compound; the fourth light-emitting layer comprises a fourth light-emitting center substance, a seventh organic compound, and an eighth organic compound; the fifth organic compound and the seventh organic compound have a π-electron-deficient heteroaromatic ring; and the sixth organic compound and the eighth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; the difference between the maximum peak wavelength in the emission spectrum of the third light-emitting center substance and the maximum peak wavelength in the emission spectrum of the fourth light-emitting center substance is 30 nm or less; and the third light-emitting layer and the fourth light-emitting layer exhibit light of a different hue from the first light-emitting layer and the second light-emitting layer;The third light-emitting device is a display device having a fifth electrode, a sixth electrode, a third intermediate layer, a fifth light-emitting layer, and a sixth light-emitting layer, wherein the third intermediate layer is located between the fifth electrode and the sixth electrode, the fifth light-emitting layer is located between the fifth electrode and the third intermediate layer, and the sixth light-emitting layer is located between the third intermediate layer and the sixth electrode, and the fifth light-emitting layer and the sixth light-emitting layer emit light of a different hue from the first light-emitting layer, the second light-emitting layer, the third light-emitting layer, and the fourth light-emitting layer.

[0017] Another embodiment of the present invention is a display device including a pixel having a first subpixel, a second subpixel, and a third subpixel, wherein the area of ​​the first subpixel and the area of ​​the second subpixel are each smaller than the area of ​​the third subpixel, the first subpixel has a first light-emitting device, the second subpixel has a second light-emitting device, and the third subpixel has a third light-emitting device, the first light-emitting device has a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, and a second light-emitting layer, the first intermediate layer is located between the first electrode and the second electrode, and the first light-emitting layer is located between the first electrode and the second electrode. the first light-emitting layer is located between the first intermediate layer and the second electrode, the first light-emitting layer has a first light-emitting center substance, a first organic compound, and a second organic compound, the second light-emitting layer has the second light-emitting center substance, a third organic compound, and a fourth organic compound, the first organic compound and the third organic compound have a π-electron-deficient heteroaromatic ring, the second organic compound and the fourth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, and at least one of the first organic compound, the second organic compound, the third organic compound, and the fourth organic compound is The first luminescent center substance contains deuterium, and a difference between a maximum peak wavelength in an emission spectrum of the first luminescent center substance and a maximum peak wavelength in an emission spectrum of the second luminescent center substance is 30 nm or less. The second light-emitting device has a third electrode, a fourth electrode, a second intermediate layer, a third luminescent layer, and a fourth luminescent layer, wherein the second intermediate layer is located between the third electrode and the fourth electrode, the third luminescent layer is located between the third electrode and the second intermediate layer, and the fourth luminescent layer is located between the second intermediate layer and the fourth electrode, and the third luminescent layer comprises a third luminescent center substance, a fifth organic compound, and a sixth organic compound. the fourth light-emitting layer comprises a fourth luminescence center substance, a seventh organic compound, and an eighth organic compound, the fifth organic compound and the seventh organic compound have a π-electron-deficient heteroaromatic ring, the sixth organic compound and the eighth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, at least one of the fifth organic compound, the sixth organic compound, the seventh organic compound, and the eighth organic compound contains deuterium, and a difference between a maximum peak wavelength in an emission spectrum of the third luminescence center substance and a maximum peak wavelength in an emission spectrum of the fourth luminescence center substance is 30 nm or less,The third light-emitting layer and the fourth light-emitting layer emit light of a different hue from the first light-emitting layer and the second light-emitting layer. The third light-emitting device has a fifth electrode, a sixth electrode, a third intermediate layer, a fifth light-emitting layer, and a sixth light-emitting layer, the third intermediate layer being located between the fifth electrode and the sixth electrode, the fifth light-emitting layer being located between the fifth electrode and the third intermediate layer, and the sixth light-emitting layer being located between the third intermediate layer and the sixth electrode, and the fifth light-emitting layer and the sixth light-emitting layer emit light of a different hue from the first light-emitting layer, the second light-emitting layer, the third light-emitting layer, and the fourth light-emitting layer.

[0018] In one embodiment of the present invention, in the display device having each of the above structures, it is more preferable that the first organic compound and the second organic compound form a first exciplex, and the third organic compound and the fourth organic compound form a second exciplex.

[0019] In one embodiment of the present invention, in the display device having each of the above structures, when the first organic compound and the second organic compound form a first exciplex and the third organic compound and the fourth organic compound form a second exciplex, it is more preferable that the difference between the lowest triplet excitation level of the first organic compound and the lowest triplet excitation level of the second organic compound is 0.30 eV or less, and that the difference between the lowest triplet excitation level of the third organic compound and the lowest triplet excitation level of the fourth organic compound is 0.30 eV or less.

[0020] In one embodiment of the present invention, in the display device having any of the above structures, when the first organic compound and the second organic compound are combined to form a first exciplex and the third organic compound and the fourth organic compound are combined to form a second exciplex, it is more preferable that the emission edge on the short-wavelength side of the first exciplex is positioned at a wavelength shorter than the absorption edge on the long-wavelength side of the first luminescence center substance and the emission edge on the short-wavelength side of the second exciplex is positioned at a wavelength shorter than the absorption edge on the long-wavelength side of the second luminescence center substance.

[0021] In one embodiment of the present invention, in the display device having any of the above structures, when the first organic compound and the second organic compound are combined to form a first exciplex and the third organic compound and the fourth organic compound are combined to form a second exciplex, it is more preferable that the peak energy of the emission spectrum of the first exciplex is higher than the peak energy of the emission spectrum of the first luminescence center substance and the difference between the peak energy of the emission spectrum of the first exciplex and the peak energy of the emission spectrum of the first luminescence center substance is 0.35 eV or less, and the peak energy of the emission spectrum of the second exciplex is higher than the peak energy of the emission spectrum of the second luminescence center substance and the difference between the peak energy of the emission spectrum of the second exciplex and the peak energy of the emission spectrum of the second luminescence center substance is 0.35 eV or less.

[0022] In one embodiment of the present invention, in the display devices having the above structures, it is more preferable that the fifth organic compound and the sixth organic compound form a third exciplex, and the seventh organic compound and the eighth organic compound form a fourth exciplex.

[0023] In one embodiment of the present invention, in the display device having each of the above structures, when the fifth organic compound and the sixth organic compound form a third exciplex and the seventh organic compound and the eighth organic compound form a fourth exciplex, it is more preferable that the difference between the lowest triplet excitation level of the fifth organic compound and the lowest triplet excitation level of the sixth organic compound is 0.20 eV or less, and that the difference between the lowest triplet excitation level of the seventh organic compound and the lowest triplet excitation level of the eighth organic compound is 0.20 eV or less.

[0024] In addition, in one embodiment of the present invention, in the display device having each of the above structures, when the fifth organic compound and the sixth organic compound are combined to form a third exciplex and the seventh organic compound and the eighth organic compound are combined to form a fourth exciplex, it is more preferable that the emission edge on the short-wavelength side of the third exciplex is positioned at a wavelength shorter than the absorption edge on the long-wavelength side of the third luminescence center substance and the emission edge on the short-wavelength side of the fourth exciplex is positioned at a wavelength shorter than the absorption edge on the long-wavelength side of the fourth luminescence center substance.

[0025] In one embodiment of the present invention, in the display device having any of the above structures, when the fifth organic compound and the sixth organic compound form a third exciplex and the seventh organic compound and the eighth organic compound form a fourth exciplex, it is more preferable that the peak energy of the emission spectrum of the third exciplex is higher than the peak energy of the emission spectrum of the third luminescence center substance and the difference between the peak energies of the emission spectrum of the third exciplex and the third luminescence center substance is 0.20 eV or less, and the peak energy of the emission spectrum of the fourth exciplex is higher than the peak energy of the emission spectrum of the fourth luminescence center substance and the difference between the peak energies of the emission spectrum of the fourth exciplex and the fourth luminescence center substance is 0.20 eV or less.

[0026] Another embodiment of the present invention is a display device having any of the above structures, wherein the fifth light-emitting layer includes a fifth light-emitting center substance and a ninth organic compound, the sixth light-emitting layer includes a sixth light-emitting center substance and a tenth organic compound, the fifth light-emitting center substance and the sixth light-emitting center substance are each fluorescent light-emitting substances, and the difference between the maximum peak wavelength in the emission spectrum of the fifth light-emitting center substance and the maximum peak wavelength in the emission spectrum of the sixth light-emitting center substance is 30 nm or less.

[0027] In one embodiment of the present invention, in the display device having each of the above structures, at least one of the first intermediate layer and the second intermediate layer preferably includes a mixed layer of the 11th organic compound and lithium or a lithium compound, and the 11th organic compound preferably has a phenanthroline skeleton.

[0028] Another embodiment of the present invention is that, in the display device having each of the above structures, the first light-emitting device has a first electron-transport layer between the first light-emitting layer and the first intermediate layer and a second electron-transport layer between the second light-emitting layer and the second electrode; the second light-emitting device has a third electron-transport layer between the third light-emitting layer and the second intermediate layer and a fourth electron-transport layer between the fourth light-emitting layer and the fourth electrode; and at least one of the second electron-transport layer and the fourth electron-transport layer contains a twelfth organic compound, and the twelfth organic compound more preferably has a triazine skeleton.

[0029] The above is one embodiment of the present invention, and the present invention is not limited to the above configuration. [Effects of the Invention]

[0030] According to one embodiment of the present invention, a light-emitting device with favorable characteristics can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting device with favorable emission efficiency can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting device with favorable reliability can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting device with low driving voltage can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting device with favorable reliability and low driving voltage can be provided.

[0031] Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with good characteristics. Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with good emission efficiency. Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with good reliability. Alternatively, one embodiment of the present invention can provide a display device with low driving voltage. Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with low driving voltage and good reliability.

[0032] Alternatively, it is possible to provide any one of an organic semiconductor device, a light-emitting device, a light-receiving device, a display device, an electronic device, and a lighting device with low power consumption, or any one of an electronic device and a lighting device with high reliability. [Brief explanation of the drawings]

[0033] [Figure 1] 1A and 1B illustrate a display device according to one embodiment of the present invention. [Figure 2] 2A to 2G are top views showing examples of pixel configurations. [Figure 3] 3A to 3F are top views showing examples of pixel configurations. [Figure 4] 4A to 4C are top views showing examples of pixel configurations. [Figure 5] 5A to 5C are schematic diagrams of a light-emitting device that can be used in a display device of one embodiment of the present invention. [Figure 6] 6A and 6B are schematic diagrams of a light-emitting device that can be used in a display device of one embodiment of the present invention. [Figure 7] 7A and 7B illustrate a display device according to one embodiment of the present invention. [Figure 8] 8A to 8E are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 9]9A and 9B are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 10] 10A to 10D are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 11] 11A to 11C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 12] 12A to 12C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 13] 13A to 13C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 14] 14(A) and 14(B) are perspective views showing configuration examples of a display module. [Figure 15] 15(A) and 15(B) are cross-sectional views showing examples of the configuration of a display device. [Figure 16] FIG. 16 is a perspective view showing an example of the configuration of a display device. [Figure 17] FIG. 17 is a cross-sectional view showing an example of the configuration of a display device. [Figure 18] FIG. 18 is a cross-sectional view showing an example of the configuration of a display device. [Figure 19] 19A to 19C are cross-sectional views and top views showing a structural example of a display device. [Figure 20] FIG. 20 is a cross-sectional view showing an example of the configuration of a display device. [Figure 21] 21A to 21C are cross-sectional views and top views showing a structural example of a display device. [Figure 22] 22(A) to 22(D) are diagrams illustrating an example of a wearable device. [Figure 23] 23A to 23F are diagrams showing examples of electronic devices. [Figure 24] 24A to 24G are diagrams showing examples of electronic devices. [Figure 25] FIG. 25 is a diagram illustrating a method for calculating the luminescence lifetime. [Figure 26]FIG. 26 is a graph showing the luminance-current density characteristics of the light-emitting devices R1-a to R1-c and the comparative light-emitting device R1. [Figure 27] FIG. 27 is a graph showing the current efficiency-luminance characteristics of the light-emitting devices R1-a to R1-c and the comparative light-emitting device R1. [Figure 28] FIG. 28 is a graph showing the current density-voltage characteristics of the light-emitting devices R1-a to R1-c and the comparative light-emitting device R1. [Figure 29] FIG. 29 is a graph showing the power efficiency-luminance characteristics of the light-emitting devices R1-a to R1-c and the comparative light-emitting device R1. [Figure 30] FIG. 30 shows electroluminescence spectra of light-emitting devices R1-a to R1-c and comparative light-emitting device R1. [Figure 31] FIG. 31 is a graph showing the luminance-current density characteristics of the light-emitting device G1 and the comparative light-emitting device G1. [Figure 32] FIG. 32 is a graph showing the current efficiency-luminance characteristics of the light-emitting device G1 and the comparative light-emitting device G1. [Figure 33] FIG. 33 is a graph showing the current density-voltage characteristics of the light-emitting device G1 and the comparative light-emitting device G1. [Figure 34] FIG. 34 is a graph showing the power efficiency-luminance characteristics of the light-emitting device G1 and the comparative light-emitting device G1. [Figure 35] FIG. 35 shows electroluminescence spectra of the light-emitting device G1 and the comparative light-emitting device G1. [Figure 36] FIG. 36 is a graph showing the luminance-current density characteristics of the light-emitting device B1 and the comparative light-emitting device B1. [Figure 37] FIG. 37 is a graph showing the current efficiency-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1. [Figure 38] FIG. 38 is a graph showing the current density-voltage characteristics of the light-emitting device B1 and the comparative light-emitting device B1. [Figure 39]FIG. 39 is a graph showing the power efficiency-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1. [Figure 40] FIG. 40 is a graph showing the blue index-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1. [Figure 41] FIG. 41 shows electroluminescence spectra of light-emitting device B1 and comparative light-emitting device B1. [Figure 42] FIG. 42 shows the emission spectra of 8mpTP-4mDBtPBfpm-d13, βNCCP-d26, and the exciplex of 8mpTP-4mDBtPBfpm-d13 and βNCCP-d26. [Figure 43] FIG. 43 shows the PL spectra of the exciplex of 8mpTP-4mDBtPBfpm-d13 and βNCCP-d26, and the absorption spectrum and PL spectrum of OCPG-006. [Figure 44] FIG. 44 is a diagram showing an example of determining the absorption edge on the long wavelength side of the absorption spectrum. [Figure 45] FIG. 45 is a diagram showing a method for measuring the T1 level of 8mpTP-4mDBtPBfpm-d13. [Figure 46] FIG. 46 is a diagram showing a method for measuring the T1 level of 8mpTP-4mDBtPBfpm. [Figure 47] FIG. 47 shows a method for measuring the T1 level of βNCCP-d26. [Figure 48] FIG. 48 is a diagram showing a method for measuring the T1 level of βNCCP. [Figure 49] FIG. 49 is a graph showing the normalized luminance time change characteristics of the light-emitting devices R1-a to R1-c and the comparative light-emitting device R1. [Figure 50] FIG. 50 shows the emission spectra of 8mpTP-4mDBtPBfpm, βNCCP, and an exciplex of 8mpTP-4mDBtPBfpm and βNCCP. [Figure 51]FIG. 51 shows the PL spectrum of the exciplex of 8mpTP-4mDBtPBfpm and βNCCP, and the absorption spectrum and PL spectrum of Ir(5mppy-d3)2(mbfpypy-d3). [Figure 52] FIG. 52 is a diagram showing an example of determining the absorption edge on the long wavelength side of the absorption spectrum. [Figure 53] FIG. 53 is a graph showing the luminance-current density characteristics of the light-emitting device G2 and the comparative light-emitting device G2. [Figure 54] FIG. 54 is a graph showing the current efficiency-luminance characteristics of the light-emitting device G2 and the comparative light-emitting device G2. [Figure 55] FIG. 55 is a graph showing the current density-voltage characteristics of the light-emitting device G2 and the comparative light-emitting device G2. [Figure 56] FIG. 56 is a graph showing the power efficiency-luminance characteristics of the light-emitting device G2 and the comparative light-emitting device G2. [Figure 57] FIG. 57 shows electroluminescence spectra of light-emitting device G2 and comparative light-emitting device G2. [Figure 58] FIG. 58 shows the PL spectra of the exciplexes of 8mpTP-4mDBtPBfpm-d13 and βNCCP-d26, and the absorption spectrum and PL spectrum of Ir(5mppy-d3)2(mbfpypy-d3). [Figure 59] FIG. 59 is a graph showing the normalized luminance time change characteristics of the light-emitting device G2 and the comparative light-emitting device G2. [Figure 60] FIG. 60 is a graph showing the luminance-current density characteristics of light-emitting device R3-a, light-emitting device R3-b, comparative light-emitting device R3-a, and comparative light-emitting device R3-b. [Figure 61] FIG. 61 is a graph showing the current efficiency-luminance characteristics of the light-emitting device R3-a, the light-emitting device R3-b, the comparative light-emitting device R3-a, and the comparative light-emitting device R3-b. [Figure 62] FIG. 62 is a graph showing the current density-voltage characteristics of the light-emitting device R3-a, the light-emitting device R3-b, the comparative light-emitting device R3-a, and the comparative light-emitting device R3-b. [Figure 63] FIG. 63 is a graph showing the power efficiency-luminance characteristics of the light-emitting device R3-a, the light-emitting device R3-b, the comparative light-emitting device R3-a, and the comparative light-emitting device R3-b. [Figure 64] FIG. 64 shows electroluminescence spectra of light-emitting device R3-a, light-emitting device R3-b, comparative light-emitting device R3-a, and comparative light-emitting device R3-b. [Figure 65] FIG. 65 is a diagram showing a method for measuring the T1 level of PCBBiF. [Figure 66] FIG. 66 is a graph showing the normalized luminance time change characteristics of the light-emitting device R3-a and the comparative light-emitting device R3-a. [Figure 67] FIG. 67 shows the emission spectra of 11mDBtBPPnfpr, βNCCP-d26, and the exciplex of 11mDBtBPPnfpr and βNCCP-d26. [Figure 68] FIG. 68 shows the PL spectrum of the exciplex of 11mDBtBPPnfpr and βNCCP-d26, and the absorption spectrum and PL spectrum of OCPG-006. [Figure 69] FIG. 69 shows the emission spectra of 8mpTP-4mDBtPBfpm-d13, PCBBiF, and the exciplex of 8mpTP-4mDBtPBfpm-d13 and PCBBiF. [Figure 70] FIG. 70 shows the PL spectra of the exciplex of 8mpTP-4mDBtPBfpm-d13 and PCBBiF, and the absorption spectrum and PL spectrum of OCPG-006. [Figure 71] FIG. 71 is a graph showing the luminance-current density characteristics of light-emitting device R5, light-emitting device G5, comparative light-emitting device G5, and light-emitting device B5. [Figure 72] FIG. 72 is a graph showing the current efficiency-luminance characteristics of light-emitting device R5, light-emitting device G5, comparative light-emitting device G5, and light-emitting device B5. [Figure 73]FIG. 73 is a graph showing the current density-voltage characteristics of light-emitting device R5, light-emitting device G5, comparative light-emitting device G5, and light-emitting device B5. [Figure 74] FIG. 74 is a graph showing the power efficiency-luminance characteristics of the light-emitting device R5, the light-emitting device G5, the comparative light-emitting device G5, and the light-emitting device B5. [Figure 75] FIG. 75 is a graph showing the blue index-luminance characteristics of the light-emitting device B5. [Figure 76] FIG. 76 shows electroluminescence spectra of light-emitting device R5, light-emitting device G5, comparative light-emitting device G5, and light-emitting device B5. [Figure 77] FIG. 77 shows the PL spectra of the exciplex of 8mpTP-4mDBtPBfpm-d13 and βNCCP-d26, and the absorption spectrum and PL spectrum of Pt(tBudppymmtBubiz-tBubp). [Figure 78] FIG. 78 is a graph showing the normalized luminance time change characteristics of the light-emitting device G5 and the comparative light-emitting device G5. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0035] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. In addition, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0036] Furthermore, in this specification, "organic compound having deuterium" and "deuterated organic compound" refer to an organic compound in which, when focusing on hydrogen (including deuterium) present at a specific position in the organic compound, the proportion of the hydrogen (including deuterium) that is deuterium is greater than the natural abundance of deuterium. This proportion is preferably sufficiently greater than the natural abundance. In this case, "sufficiently" refers to, for example, 7.5% or more being deuterated. The deuteration of an organic compound can be confirmed by methods such as NMR and mass spectrometry.

[0037] In this specification, the light-emitting area of ​​a sub-pixel having a light-emitting device may be referred to as the area of ​​the sub-pixel. In this specification, the aperture ratio of a sub-pixel refers to the ratio of the area of ​​the sub-pixel to the unit area of ​​the display region (which may also be referred to as the pixel area).

[0038] (Embodiment 1) In this embodiment, a display device according to one embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1A is a top view of the display device, and FIG. 1B is a cross-sectional view of FIG. 1A taken along lines AB and CD. This display device includes a driver circuit portion (source line driver circuit) 601, a pixel portion 602, and a driver circuit portion (gate line driver circuit) 603, each indicated by a dotted line, for controlling light emission from a light-emitting device. Also, 604 denotes a sealing substrate, 605 denotes a sealant, and the inside surrounded by the sealant 605 forms a space 607.

[0039] The routing wiring 608 is wiring for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and receives video signals, clock signals, start signals, reset signals, etc. from an FPC (flexible print circuit) 609, which serves as an external input terminal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to this FPC. In this specification, the display device includes not only the display device itself, but also a state in which an FPC or PWB is attached to it.

[0040] Next, the cross-sectional structure will be described with reference to Fig. 1B. A driver circuit portion and a pixel portion are formed on an element substrate 610, and here, a source line driver circuit 601, which is the driver circuit portion, and one pixel in the pixel portion 602 are shown.

[0041] The element substrate 610 can be fabricated using a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, etc., as well as a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, etc.

[0042] The structure of the transistors used in the pixels and the driver circuits is not particularly limited. For example, they may be inverted staggered transistors or staggered transistors. Furthermore, they may be top-gate or bottom-gate transistors. The semiconductor material used for the transistors is not particularly limited, and examples thereof include silicon, germanium, silicon carbide, and gallium nitride. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In-Ga-Zn-based metal oxide, may be used.

[0043] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0044] Here, it is preferable to use an oxide semiconductor for the transistors provided in the pixel and the driver circuit, as well as for semiconductor devices such as transistors used in touch sensors, which will be described later. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor having a wider band gap than silicon, the current in the off state of the transistor can be reduced.

[0045] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn), and more preferably contains an oxide represented by In-M-Zn oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0046] In particular, it is preferable to use, as the semiconductor layer, an oxide semiconductor film having a plurality of crystal parts whose c-axes are oriented perpendicular to the surface on which the semiconductor layer is formed or the top surface of the semiconductor layer and which does not have grain boundaries between adjacent crystal parts.

[0047] By using such a material for the semiconductor layer, fluctuations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0048] Furthermore, a transistor having the above-described semiconductor layer can retain charge stored in a capacitor through the transistor for a long period of time due to its low off-state current. By applying such a transistor to a pixel, it is possible to stop the driver circuit while maintaining the gray level of an image displayed in each display region. As a result, an electronic device with extremely low power consumption can be realized.

[0049] To stabilize the characteristics of the transistor, it is preferable to provide an underlayer film. The underlayer film can be formed as a single layer or a multilayer using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film. The underlayer film can be formed by a sputtering method, a CVD (Chemical Vapor Deposition) method (such as a plasma CVD method, a thermal CVD method, or a MOCVD (Metal Organic CVD) method), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, or the like. Note that the underlayer film need not be provided if it is not necessary.

[0050] Note that FET 623 represents one of the transistors formed in the drive circuit section 601. The drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, although this embodiment shows a driver-integrated type in which the drive circuit is formed on a substrate, this is not necessarily required, and the drive circuit may also be formed externally rather than on the substrate.

[0051] Furthermore, the pixel portion 602 is formed by a plurality of pixels each including a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to the drain of the FET, but is not limited to this, and the pixel portion may be formed by combining three or more FETs and a capacitive element.

[0052] An insulator 614 is formed to cover an end portion of the first electrode 613. Here, the insulator 614 can be formed using a positive photosensitive acrylic resin film.

[0053] Furthermore, in order to improve the coverage of an organic compound layer or the like to be formed later, a curved surface having a curvature is formed at the upper or lower end of the insulator 614. For example, when a positive photosensitive acrylic resin is used as the material for the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface having a curvature radius (0.2 μm to 3 μm). Furthermore, either a negative photosensitive resin or a positive photosensitive resin can be used as the insulator 614.

[0054] An organic compound layer 616 and a second electrode 617 are formed on the first electrode 613, and a light-emitting device is formed by the first electrode 613, the organic compound layer 616, and the second electrode 617. A structure of a light-emitting device preferable for use as the light-emitting device will be described later in the embodiment mode. Note that a pixel portion is formed with a plurality of light-emitting devices, but the display device in this embodiment mode may include both the light-emitting devices described later in this specification and light-emitting devices having other structures.

[0055] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealant 605, a structure is formed in which a light-emitting device 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. The space 607 is filled with a filler, which may be filled with an inert gas (nitrogen, argon, etc.) or a sealant. A recess is formed in the sealing substrate and a desiccant is provided therein, which is a preferable configuration because it can suppress deterioration due to the influence of moisture.

[0056] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is also desirable that these materials are as moisture and oxygen impermeable as possible. In addition, materials that can be used for the sealing substrate 604 include glass substrates, quartz substrates, and plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, etc.

[0057] Although not shown in FIG. 1, a protective film may be provided on the second electrode. The protective film may be formed of an organic resin film or an inorganic insulating film. The protective film may also be formed so as to cover the exposed portion of the sealing material 605. The protective film may also be provided so as to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, etc.

[0058] The protective film can be made of a material that is impermeable to impurities such as water, and therefore can effectively prevent impurities such as water from diffusing from the outside to the inside.

[0059] The protective film may be made of an oxide, nitride, fluoride, sulfide, ternary compound, metal, polymer, or the like. For example, a material containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide, or the like; a material containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, or the like; a nitride containing titanium and aluminum, an oxide containing titanium and aluminum, an oxide containing aluminum and zinc, a sulfide containing manganese and zinc, a sulfide containing cerium and strontium, an oxide containing erbium and aluminum, or an oxide containing yttrium and zirconium, or the like.

[0060] The protective film is preferably formed using a film formation method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material that can be formed using ALD for the protective film. By using ALD, it is possible to form a dense protective film with reduced defects such as cracks and pinholes, or with a uniform thickness. In addition, it is possible to reduce damage to the workpiece when forming the protective film.

[0061] For example, by forming a protective film using the ALD method, it is possible to form a uniform protective film with few defects on surfaces with complex uneven shapes, including the top, side, and back surfaces of a touch panel.

[0062] The display device of one embodiment of the present invention can be a top-emission type in which light is emitted toward the sealing substrate 604, which is opposite to the element substrate 610 on which the light-emitting device is formed. Note that the display device of one embodiment of the present invention may be a bottom-emission type.

[0063] When the display device of one embodiment of the present invention is a top-emission type, the sealing substrate 604 has a display region in which light from each pixel provided in the pixel portion 602 can be viewed. Figure 1A shows a part of the display region surrounded by an encircling line 630, and Figure 2A shows an enlarged view of the region surrounded by the encircling line 630.

[0064] 2A, pixels 178 are arranged in a matrix in the pixel section 602. The pixels 178 are arranged periodically. Each pixel 178 includes a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0065] In this specification and the like, when describing matters common to, for example, the subpixels 110R, 110G, and 110B, they may be referred to as the subpixels 110. When describing matters common to other components distinguished by alphabets, they may also be described using symbols without the alphabets.

[0066] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. This allows an image to be displayed in the pixel unit 602. In this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are described as an example, but combinations of sub-pixels of other colors may also be used. The number of sub-pixels is not limited to three, and may be four or more. Examples of four sub-pixels include sub-pixels of four colors: R, G, B, and white (W); sub-pixels of four colors: R, G, B, and yellow (Y); and sub-pixels of R, G, B, and infrared (IR).

[0067] In the display device according to one embodiment of the present invention, it is preferable that one of the subpixels 110R, 110G, and 110B has a different area from the other two. Furthermore, in the display device according to one embodiment of the present invention, it is preferable that the subpixels 110R, 110G, and 110B have different areas. By reducing the area of ​​the subpixel having a more reliable light-emitting device and increasing the areas of the subpixels having the other light-emitting colors, it is possible to improve the reliability of the entire pixel 178.

[0068] In particular, in a display device according to one embodiment of the present invention, it is preferable to use a highly reliable light-emitting device, which will be described later in this embodiment and Embodiment 2, for at least one of the subpixels 110R, 110G, and 110B. In this embodiment, Configuration Example 1, which is a highly reliable light-emitting device, will be described, and in Embodiment 2, it is preferable to use a highly reliable light-emitting device. Furthermore, in a display device according to one embodiment of the present invention, Configuration Example 3, which will be described later in Embodiment 3, can be used for another of the subpixels 110R, 110G, and 110B. Note that, as will be described in detail later, Configuration Example 1 uses an organic compound containing deuterium, and therefore, Configuration Example 1 is a light-emitting device with higher reliability than Configuration Example 2. Therefore, for example, it is preferable to use Configuration Example 1 for one of the subpixels 110R, 110G, and 110B, and Configuration Example 2 for the other. Alternatively, it is preferable to use Configuration Example 1 for two of the subpixels 110R, 110G, and 110B. Alternatively, it is preferable to use the configuration example 2 for any two of the subpixels 110R, 110G, and 110B.

[0069] In the present embodiment, the relationship in size between the areas of the subpixels for each emitted color will be described using an example in which highly reliable light-emitting devices, as described later in this embodiment and embodiment 2, are used for the subpixels 110R and 110G, and configuration example 3 is used for the subpixel 110B. For example, when configuration example 1 is used for the subpixel 110R, configuration example 2 is used for the subpixel 110G, and configuration example 3 is used for the subpixel 110B, it is preferable that the area of ​​the subpixel 110R is smaller than that of the subpixel 110G, and that the area of ​​the subpixel 110G is smaller than that of the subpixel 110B. Furthermore, when configuration example 2 is used for the subpixel 110R, configuration example 1 is used for the subpixel 110G, and configuration example 3 is used for the subpixel 110B, it is preferable that the area of ​​the subpixel 110G is smaller than that of the subpixel 110R, and that the area of ​​the subpixel 110R is smaller than that of the subpixel 110B. Furthermore, when Configuration Example 1 is used for both the subpixel 110R and the subpixel 110G and Configuration Example 3 is used for the subpixel 110B, it is preferable that the area of ​​the subpixel 110R and the area of ​​the subpixel 110G are each smaller than the area of ​​the subpixel 110B. Furthermore, when Configuration Example 2 is used for both the subpixel 110R and the subpixel 110G and Configuration Example 3 is used for the subpixel 110B, it is preferable that the area of ​​the subpixel 110R and the area of ​​the subpixel 110G are each smaller than the area of ​​the subpixel 110B. These configurations enable the area of ​​the subpixel 110B to be increased, thereby improving the reliability of the subpixel 110B and the reliability of the pixel 178 as a whole.

[0070] In this specification and the like, the aperture ratio of a subpixel is the ratio of the area of ​​the subpixel to a unit area of ​​the display region (which can also be referred to as pixel area), and therefore, the fact that the area of ​​subpixel 110R is smaller than the area of ​​subpixel 110G and the area of ​​subpixel 110G is smaller than the area of ​​subpixel 110B can be rephrased as the aperture ratio of subpixel 110R is smaller than the aperture ratio of subpixel 110G and the aperture ratio of subpixel 110G is smaller than the aperture ratio of subpixel 110B. Furthermore, the fact that the area of ​​subpixel 110G is smaller than the area of ​​subpixel 110R and the area of ​​subpixel 110R is smaller than the area of ​​subpixel 110B can be rephrased as the aperture ratio of subpixel 110G is smaller than the aperture ratio of subpixel 110R and the aperture ratio of subpixel 110R is smaller than the aperture ratio of subpixel 110B. Furthermore, the fact that the areas of the subpixels 110R and 110G are each smaller than the area of ​​the subpixel 110B can be rephrased as the aperture ratios of the subpixels 110R and 110G being each smaller than the aperture ratio of the subpixel 110B.

[0071] In a display device according to one embodiment of the present invention, the arrangement of subpixels is not particularly limited, and various methods can be applied. Examples of the arrangement of subpixels include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a pentile arrangement. Examples of the top surface shape of a subpixel include a triangle, a quadrangle (including a rectangle and a square), a polygon such as a pentagon, a polygon with rounded corners, an ellipse, or a circle. Furthermore, the circuit layout constituting the subpixel is not limited to the range of the subpixel shown in the figure, and may be arranged outside the range.

[0072] 2B to 2G, a structural example of the pixel 178 will be described. Note that the top surface shape of the sub-pixels shown in the drawings in this embodiment mode corresponds to the top surface shape of the light-emitting region.

[0073] The pixel 178 shown in Figures 2(B) to 2(D) has an S-stripe arrangement and is composed of three subpixels: subpixel 110R, subpixel 110G, and subpixel 110B. The pixel 178 shown in Figures 2(E) to 2(G) has a stripe arrangement and is composed of three subpixels: subpixel 110R, subpixel 110G, and subpixel 110B. In Figures 2(B) and 2(E), the area of ​​the subpixel 110R is smaller than the area of ​​the subpixel 110G, which is smaller than the area of ​​the subpixel 110B. In Figures 2(C) and 2(F), the area of ​​the subpixel 110G is smaller than the area of ​​the subpixel 110R, which is smaller than the area of ​​the subpixel 110B. In addition, in FIGS. 2(D) and 2(G), the area of ​​the subpixel 110R and the area of ​​the subpixel 110G are approximately equal to each other and are smaller than the area of ​​the subpixel 110B.

[0074] 3A includes a subpixel 110R having a generally trapezoidal or triangular top surface shape with rounded corners, a subpixel 110G having a generally trapezoidal or triangular top surface shape with rounded corners, and a subpixel 110B having a generally rectangular or hexagonal top surface shape with rounded corners. The area of ​​the subpixel 110G is smaller than the area of ​​the subpixel 110R, which is smaller than the area of ​​the subpixel 110B. In this way, the shapes of the subpixels can be determined independently.

[0075] The pixels 124a and 124b shown in FIG. 3B are arranged in a Pentile array. FIG. 3B illustrates an example in which the pixel 124a, which includes the subpixels 110R and 110G, and the pixel 124b, which includes the subpixels 110G and 110B, are alternately arranged. When multiple types of pixels with different layouts are provided in a pixel section, the area of ​​each subpixel for each emitted light color can be calculated by adding up the areas of the subpixels in each pixel. For example, in the configuration shown in FIG. 3B, the area of ​​the green subpixel can be calculated by adding up the area of ​​the subpixel 110G in the pixel 124a and the area of ​​the subpixel 110G in the pixel 124b. In the configuration shown in FIG. 3B, the area of ​​the green subpixel is larger than the areas of the subpixels 110R and 110B.

[0076] A delta arrangement is applied to the pixels 124a and 124b shown in Figures 3(C) to 3(E). The pixel 124a has two subpixels (subpixel 110R and subpixel 110G) in the upper row (first row) and one subpixel (subpixel 110B) in the lower row (second row). The pixel 124b has one subpixel (subpixel 110B) in the upper row (first row) and two subpixels (subpixel 110R and subpixel 110G) in the lower row (second row). In this way, even when multiple types of pixels are provided in the pixel section, as long as the areas of the subpixels for each luminescent color are the same among the multiple types of pixels, the area of ​​the subpixel for each luminescent color can be calculated from the area of ​​any of the subpixels in the multiple types of pixels.

[0077] FIG. 3(C) shows an example in which each subpixel has a substantially rectangular top surface shape with rounded corners, FIG. 3(D) shows an example in which each subpixel has a circular top surface shape, and FIG. 3(E) shows an example in which each subpixel has a substantially hexagonal top surface shape with rounded corners. In FIG. 3(C), the area of ​​subpixel 110R is smaller than the areas of subpixel 110G and subpixel 110B. In FIG. 3(D), the area of ​​subpixel 110R is smaller than the area of ​​subpixel 110G, which is smaller than the area of ​​subpixel 110B. In FIG. 3(E), the area of ​​subpixel 110G is smaller than the area of ​​subpixel 110R, which is smaller than the area of ​​subpixel 110B.

[0078] In FIG. 3(E), each subpixel is arranged inside a densely arranged hexagonal region. Each subpixel is arranged so that it is surrounded by six other subpixels. Furthermore, subpixels that emit light of the same color are not adjacent to each other. For example, when focusing on subpixel 110R, three subpixels 110G and three subpixels 110B are arranged alternately to surround it.

[0079] 3(F) shows an example in which subpixels of each color are arranged in a zigzag pattern. Specifically, when viewed from above, the positions of the upper edges of two subpixels arranged in the row direction (for example, subpixels 110R and 110G, or subpixels 110G and 110B) are misaligned. In FIG. 3(F), the area of ​​subpixel 110R is smaller than the area of ​​subpixel 110G, which is smaller than the area of ​​subpixel 110B.

[0080] In each of the pixels shown in FIGS. 3A to 3F, the subpixel 110R and the subpixel 110G may be interchanged.

[0081] As shown in FIGS. 4A to 4C, a pixel can have four types of subpixels.

[0082] FIG. 4A shows an example in which one pixel 178 is configured in three rows and two columns.

[0083] 4(A) has subpixel 110R in the top row (first row), subpixel 110G in the middle row (second row), subpixel 110B across the first and second rows, and one subpixel (subpixel 110W) in the bottom row (third row). In other words, pixel 178 has subpixel 110R and subpixel 110G in the left column (first column), subpixel 110B in the right column (second column), and subpixel 110W across these two columns.

[0084] 4(B) and 4(C) show an example in which one pixel 178 is configured in two rows and three columns.

[0085] 4(B) has three subpixels (subpixel 110R, subpixel 110G, and subpixel 110B) in the top row (first row) and one subpixel (subpixel 110W) in the bottom row (second row). In other words, pixel 178 has subpixel 110R in the left column (first column), subpixel 110G in the center column (second column), subpixel 110B in the right column (third column), and subpixel 110W across these three columns.

[0086] The pixel 178 shown in FIG. 4C has three subpixels (subpixels 110R, 110G, and 110B) in the top row (first row) and three subpixels 110W in the bottom row (second row). In other words, the pixel 178 has subpixels 110R and 110W in the left column (first column), subpixels 110G and 110W in the center column (second column), and subpixels 110B and 110W in the right column (third column). By aligning the subpixels in the top and bottom rows as shown in FIG. 4C, it becomes possible to efficiently remove dust that may occur during the manufacturing process. Therefore, a display device with high display quality can be provided.

[0087] In the pixel 178 shown in FIGS. 4B and 4C, the subpixels 110R, 110G, and 110B are laid out in a stripe arrangement, which can improve the display quality.

[0088] In the above manner, a display device according to one embodiment of the present invention can be obtained.

[0089] The display device in this embodiment can have good characteristics by using a light-emitting device described later in this embodiment. Specifically, the light-emitting device described later in this embodiment has high luminous efficiency, and therefore can have low power consumption. Furthermore, the light-emitting device described later in this embodiment has good reliability, and therefore can have a good reliability. Furthermore, by configuring a sub-pixel using the light-emitting device described later in this embodiment so that the area of ​​the sub-pixel is smaller than the area of ​​the other sub-pixels, the reliability of the entire pixel can be improved. Furthermore, the light-emitting device described later in this embodiment can have good chromaticity and color purity, and therefore can have a good display quality.

[0090] Next, a first structural example of a light-emitting device that can be used in a display device of one embodiment of the present invention will be described.

[0091] <Configuration example 1> A tandem light-emitting device has a structure in which multiple light-emitting units are stacked between a pair of electrodes with an intermediate layer (charge-generating layer) sandwiched between them. Each of the multiple light-emitting units has a light-emitting layer, and light can be emitted from any of the light-emitting layers by passing a current through them. A tandem light-emitting device having such a configuration has significantly higher current efficiency than a non-tandem light-emitting device, and is therefore suitable for use in display devices that require high brightness or high reliability.

[0092] Since tandem light-emitting devices have multiple light-emitting layers, it is easy to obtain white light, and so a white color filter system is often adopted for full-color display systems using tandem light-emitting devices. Color conversion systems using a stacked light-emitting layer that emits blue light and a color conversion layer, typically a quantum dot, have also been put to practical use.

[0093] On the other hand, some display devices using tandem light-emitting devices that employ a color-coded method for full color have also been put to practical use. Color-coded light-emitting devices have little or no energy loss in the color filters or color conversion layers, making them more efficient than the two methods mentioned above.

[0094] At least one of the light-emitting layers of a tandem light-emitting device has a light-emitting center material, a first host material, and a second host material. The light-emitting center material is preferably a phosphorescent material. In a current-excited light-emitting device, a light-emitting device with high luminous efficiency can be obtained by using a material that can convert triplet energy into light emission (a phosphorescent material, a material that exhibits thermally activated delayed fluorescence) as a light-emitting material (guest material).

[0095] Also known is a structure in which two different organic compounds (specifically, an organic compound having electron transport properties and an organic compound having hole transport properties) are used as host materials for the light-emitting layer together with a light-emitting substance (guest material).

[0096] Among these, the so-called ExTET (Exciplex-Triplet Energy Transfer) structure, which uses an exciplex formed by two different organic compounds in the light-emitting layer as the energy donor and a substance that can convert triplet energy into light (a phosphorescent substance or a substance that exhibits thermally activated delayed fluorescence) as the energy acceptor, is an excellent technology that can simultaneously achieve high efficiency, low driving voltage, and long life.

[0097] That is, a light-emitting device having an emitting layer including an exciplex as an energy donor and an energy acceptor, i.e., a substance capable of converting triplet energy into luminescence as an emitting substance, can be a light-emitting device having very good characteristics.

[0098] Here, when one or both of the two substances functioning as host materials (the first host material and the second host material) contain deuterium, a light-emitting device with even better reliability can be obtained.

[0099] In particular, as described below, when the difference between the lowest triplet excitation level (T1 level) of the first host material and the T1 level of the second host material is small, i.e., they are close to each other, triplet excitation energy is unlikely to be concentrated in one of the organic compounds, and energy transfer from the triplet excited state of each compound to a substance that can convert triplet energy into luminescence can occur. The efficiency of energy transfer from each compound is improved by the influence of deuterium, making it possible to suppress deterioration of the first host material and the second host material, one or both of which contain deuterium.

[0100] This is particularly effective when the two substances form an exciplex. The singlet excitation energy of the exciplex transfers from the exciplex to the luminescent material. However, the triplet excitation energy of the exciplex can transfer indirectly via the triplet excited state of the first or second host material, in addition to direct energy transfer to the luminescent material. In particular, as described below, when the difference between the lowest triplet excitation level (T1 level) of the first host material and the T1 level of the second host material is small, i.e., close to each other, energy transfer to a substance capable of converting triplet energy into luminescence can occur via the triplet excited state of each compound. This is because the excitation energy is unlikely to be biased toward one of the organic compounds. The efficiency of energy transfer from the triplet excited state of each compound is improved by the influence of deuterium, which can prevent the first and second host materials from deteriorating. Specifically, the difference between the T1 level of the first host material and the T1 level of the second host material is preferably 0.30 eV or less, more preferably 0.20 eV or less, and further preferably 0.10 eV or less.

[0101] As a result, a light-emitting device that uses an exciplex formed containing a deuterated organic compound as an energy donor is less susceptible to deterioration than a light-emitting device that uses an exciplex formed only from a non-deuterated organic compound as an energy donor, and can be a light-emitting device with good reliability.

[0102] In addition, the entire molecule of one or both of the first host material and the second host material may be deuterated, but it is sufficient that at least the group or skeleton where the lowest triplet excitation level is localized is deuterated, and it is preferable that the hydrogen atoms in the other groups or skeletons are protons. This allows the first host material or the second host material to be obtained more cheaply than when the entire molecule is deuterated.

[0103] The first host material is an organic compound having an electron-transporting property and preferably contains a π-electron-deficient heteroaromatic ring, and the second host material is an organic compound having a hole-transporting property and preferably contains a π-electron-rich heteroaromatic ring or an aromatic amine skeleton.

[0104] When the first host material is an organic compound having electron transport properties and the second host material is an organic compound having hole transport properties, the HOMO level of the organic compound having hole transport properties is preferably equal to or higher than the HOMO level of the organic compound having electron transport properties.Furthermore, it is preferable that the LUMO level of the organic compound having hole transport properties is equal to or higher than the LUMO level of the organic compound having electron transport properties, since an exciplex can be formed more efficiently.

[0105] The values ​​of the HOMO level and the LUMO level can be determined by cyclic voltammetry (CV) measurement.

[0106] In cyclic voltammetry (CV) measurements, the HOMO and LUMO levels (E) can be calculated based on the oxidation peak potential (Epa) and reduction peak potential (Epc) obtained by varying the potential of the working electrode relative to the reference electrode. In the measurements, the HOMO level can be determined from a potential scan in the positive direction, and the LUMO level can be determined from a potential scan in the negative direction. The scan rate in the measurements should be 0.1 V / s.

[0107] Specifically, the standard redox potential (Eo) (= (Epa + Epc) / 2) is calculated from the oxidation peak potential (Epa) and reduction peak potential (Epc) obtained from the cyclic voltammogram of the material, and by subtracting this from the potential energy (Ex) relative to the vacuum level of the reference electrode, the HOMO level and LUMO level values ​​(E) (= Ex - Eo) can be calculated, respectively.

[0108] While the above example shows the case where a reversible redox wave is obtained, when an irreversible redox wave is obtained, the HOMO level is calculated by subtracting a fixed value (0.1 eV) from the oxidation peak potential (Epa) and assuming this to be the reduction peak potential (Epc), and the standard redox potential (Eo) is calculated to one decimal place. The LUMO level is calculated by adding a fixed value (0.1 eV) to the reduction peak potential (Epc), and assuming this to be the oxidation peak potential (Epa), and the standard redox potential (Eo) is calculated to one decimal place.

[0109] In the light-emitting device described in this embodiment, the energy transfer efficiency is improved by including deuterium in one or both of the first host material and the second host material because the phosphorescence lifetime or delayed fluorescence lifetime of the deuterated organic compound is longer than the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated organic compound. This is because the intramolecular vibration in the lowest triplet excited state (T1 state) of the deuterated organic compound is more suppressed than the intramolecular vibration of the non-deuterated organic compound, thereby suppressing the non-radiative transition from the T1 state to a more stable state.

[0110] Energy transfer efficiency φ from an energy donor (in one embodiment of the present invention, an exciplex) to an energy acceptor (in one embodiment of the present invention, a substance capable of converting triplet excitation energy into luminescence) ET is expressed by the following formula (1): From this formula, the energy transfer efficiency φ ET To increase the energy transfer rate constant k h*→g becomes large, and other competing rate constants k r +k nr It turns out that it is good if (=1 / τ) becomes relatively small.

[0111] In addition, in formula (1), k r represents the rate constant of the luminescence process of the energy donor (fluorescence when discussing energy transfer from a singlet excited state, phosphorescence or delayed fluorescence when discussing energy transfer from a triplet excited state), and k nrrepresents the rate constant of the non-radiative process of the energy donor (thermal deactivation and intersystem crossing), and τ represents the measured lifetime of the excited state of the energy donor. h*→g represents the rate constant for energy transfer (Förster or Dexter mechanism).

[0112]

number

[0113] Energy transfer rate constant k h*→g The energy transfer rate constant k is almost the same between deuterated and non-deuterated organic compounds because the atomic arrangement of the molecules and the spectral shape are almost the same (see formula (2) or (3) below). Therefore, when comparing deuterated and non-deuterated organic compounds, the energy transfer rate constant k h*→g is significantly affected by the luminescence lifetime (phosphorescence lifetime or delayed fluorescence lifetime) τ. In other words, the energy transfer efficiency improves as the luminescence lifetime (phosphorescence lifetime or delayed fluorescence lifetime) increases.

[0114]

number

[0115]

number

[0116] Equation (2) is the rate constant k for the Förster mechanism, and equation (3) is the rate constant k for the Dexter mechanism. h*→g This is the formula.

[0117] In equation (2), ν represents the frequency, and f′ h (ν) represents the normalized emission spectrum of the host material (fluorescence spectrum when discussing energy transfer from a singlet excited state, and phosphorescence spectrum when discussing energy transfer from a triplet excited state), and ε g(ν) represents the molar absorption coefficient of the guest material, N represents Avogadro's number, n represents the refractive index of the medium, R represents the intermolecular distance between the host material and the guest material, τ represents the measured lifetime of the excited state (fluorescence lifetime, phosphorescence lifetime), φ represents the luminescence quantum yield (fluorescence quantum yield when discussing energy transfer from a singlet excited state, and phosphorescence quantum yield when discussing energy transfer from a triplet excited state), and K 2 is a coefficient (0 to 4) that represents the orientation of the transition dipole moments of the host material and guest material. In the case of random orientation, K 2 =2 / 3.

[0118] In equation (3), h is Planck's constant, K is a constant with the dimension of energy, ν is the frequency, and f′ h (ν) represents the normalized emission spectrum of the host material (fluorescence spectrum when discussing energy transfer from a singlet excited state, and phosphorescence spectrum when discussing energy transfer from a triplet excited state), and ε′ g (ν) represents the normalized absorption spectrum of the guest material, L represents the effective molecular radius, and R represents the intermolecular distance between the host material and the guest material.

[0119] As described above, in the energy transfer from the first host material and the second host material, the efficiency of energy transfer from each triplet excited state is important, and therefore the lifetime of the triplet excited state is important. That is, by deuterating one or both of the first host material and the second host material, the phosphorescence lifetime or delayed fluorescence lifetime is extended, thereby improving the energy transfer efficiency and suppressing deterioration of the deuterated organic compound. As a result, a light-emitting device having an energy donor using a deuterated organic compound can be made to have more suppressed deterioration of the organic compound than a light-emitting device using an energy donor that does not use a deuterated organic compound, resulting in a light-emitting device with good reliability.

[0120] The phosphorescence lifetime and delayed fluorescence lifetime are calculated by measuring transient PL through time-resolved measurements, in which the intensity of the decaying emission is measured at regular intervals after the excitation light is blocked with a shutter. In this case, fluorescent components may be mixed in at the beginning of the decay, and the graph may not form a straight line. In such cases, the starting point can be determined at the linear portion of the graph, and the time it takes for the intensity at the starting point to decay to 1 / e can be used as the phosphorescence lifetime or delayed fluorescence lifetime.

[0121] In the light-emitting device described in this embodiment, an exciplex formed from a first host material and a second host material preferably serves as an energy donor. However, as described above, with regard to the triplet excited state, there may be a pathway for energy transfer from the triplet excited state of the exciplex via the triplet excited states of the first host material and the second host material. Therefore, the phosphorescence lifetime or delayed fluorescence lifetime of the first host material and the second host material constituting the exciplex is important. Here, in the light-emitting device described in this embodiment, it has been found that the phosphorescence lifetime or delayed fluorescence lifetime is increased to a certain extent or more due to the presence of deuterium in one or preferably both of the first host material and the second host material, thereby significantly improving the reliability of the light-emitting device using the exciplex as an energy donor.

[0122] That is, the first host material is preferably an organic compound whose phosphorescence lifetime or delayed fluorescence lifetime is 1.50 times or more that of a first material obtained by substituting protons for deuterium in the first host material. Furthermore, the second host material is preferably an organic compound whose phosphorescence lifetime or delayed fluorescence lifetime is 3.00 times or more that of a second material obtained by substituting protons for deuterium in the second host material. In this case, it is preferable that the light emitted by the substance capable of converting triplet excitation energy into luminescence (the luminescent substance contained in the luminescent layer) is in the green region, i.e., its peak wavelength is typically 500 nm or more and 600 nm or less. Alternatively, it is preferable that the light emitted by the substance capable of converting triplet excitation energy into luminescence (the luminescent substance contained in the luminescent layer) is in the red region, i.e., its peak wavelength is typically 600 nm or more and 700 nm or less.

[0123] As shown in Figure 25, the starting point was set to t = 0 within the range where the graph is a straight line from the measurement data (left panel of Figure 25) (here, t = 0 was set to the time when the light intensity reached 50% of the intensity at the start of measurement) (right panel of Figure 25). The time from there until the light intensity decays to 1 / e times the value at t = 0 is the phosphorescence lifetime or delayed fluorescence lifetime. In Figure 25, the graph was created with the time when the measurement data reached 50% of the intensity at the start of measurement as time 0 s, and when the light intensity at 0 s is set to 1, the time when the light intensity reaches 1 / e is the phosphorescence lifetime or delayed fluorescence lifetime. Note that while it is easy to use an intensity of 50% of the intensity at the start of measurement as the starting point, other values ​​are also acceptable.

[0124] The phosphorescence lifetime can be measured at the liquid nitrogen temperature (77 K) by installing a liquid nitrogen cooling unit in a fluorometer such as the FP-8600 manufactured by JASCO Corporation. The material solution is prepared in a glove box, and the sample is dissolved in deoxygenated 2-MeTHF and stirred with a stirrer at room temperature for about 30 minutes (heating may also be used for materials that are difficult to dissolve). -4 A solution with a concentration of about M can be prepared and used.

[0125] Time-resolved measurements can be performed by irradiating the sample cell with excitation light for approximately 30 seconds, shutting off the excitation light with a shutter, and then measuring the decaying emission intensity at 10-ms intervals. The wavelength for phosphorescence lifetime measurements is preferably the peak wavelength of the phosphorescence spectrum. If there are multiple peaks in the phosphorescence spectrum, it is preferable to select the wavelength with the highest peak intensity. Accurate measurements may be hindered by the presence of fluorescence spectra at certain wavelengths. In such cases, it is preferable to compare the emission spectrum measured at low temperatures (e.g., 77 K) (including phosphorescence) with the emission spectrum measured at room temperature (fluorescence only, without phosphorescence) and select a wavelength with as little fluorescence as possible. Alternatively, the longest-wavelength peak wavelength of the phosphorescence spectrum can be selected. In the case of frozen solutions, emission from states other than the lowest triplet excited state may also be observed. In such cases, the longest-wavelength peak should be selected.

[0126] The excitation wavelength can be selected appropriately within a wavelength range that is not affected by the solvent. If the material can be sufficiently excited, it is preferable to measure at 330 nm, as this will not be affected by the solvent. The bandwidth of the excitation light and measurement light should be approximately 10 nm. Ideally, the emission decays according to a single exponential function, so the starting point can be determined in the linear portion of the graph, and the time it takes for the intensity at the starting point to decay to 1 / e can be defined as the phosphorescence lifetime or delayed fluorescence lifetime.

[0127] Fluorescence lifetime, phosphorescence lifetime, and delayed fluorescence lifetime can be distinguished by their lifetimes in time-resolved measurements. An emission lifetime of around n seconds is a fluorescence lifetime, while emission lifetimes of μs to msec or longer are phosphorescence lifetimes and delayed fluorescence lifetimes.

[0128] In the light-emitting device described in this embodiment, reliability is improved by extending the phosphorescence lifetime of the first and second host materials, i.e., the lifetime of triplet excitons. The extended lifetime of triplet excitons is due to the suppression of non-radiative deactivation of triplet excitation energy, which is caused by the suppression of vibrations by deuteration. In this case, a small difference between the lowest triplet excitation level (T1 level) of the first host material and the T1 level of the second host material makes it difficult for excitation energy to be biased toward one of the organic compounds, preventing significant degradation of either of them, and thus improving the reliability of the light-emitting device. Specifically, the difference between the T1 levels of the first host material and the second host material is preferably 0.30 eV or less, preferably 0.20 eV or less, more preferably 0.15 eV or less, and even more preferably 0.10 eV or less.

[0129] The lowest triplet excitation energy level (T1 level) can be calculated by measuring the emission spectrum (phosphorescence spectrum) at a temperature of 10 K using a 50 nm thin film of the sample deposited on a quartz substrate. Measurements can be performed using a microphotoluminescence microscope, LabRAM HR-PL (Horiba, Ltd.), with a He-Cd laser (325 nm) as the excitation light. The emission edge can be calculated by drawing a tangent at the value where the slope on the short-wavelength side of the peak (or shoulder peak) observed at the shortest wavelength in the emission spectrum (phosphorescence spectrum) is maximum, and then calculating the tangent from the intersection point of the tangent with the horizontal axis (wavelength) or the baseline.

[0130] Alternatively, in one embodiment of the present invention, the sublimation temperatures of the first host material and the second host material are preferably close to each other. For example, the difference between the 5% weight loss temperature measured by thermogravimetry of the first host material and the 5% weight loss temperature measured by thermogravimetry of the second host material is preferably 60°C or less. It is more preferably 45°C or less, more preferably 20°C or less, and even more preferably 10°C or less. This allows vapor deposition to be performed using a mixture of the first host material and the second host material, thereby reducing the number of vapor deposition sources and enabling the provision of a light-emitting device with excellent characteristics at low cost.

[0131] The 5% weight loss temperature can be determined from the relationship between weight and temperature (thermogravimetry) by thermogravimetry-differential thermal analysis (TG-DTA). If the pressure at which vapor deposition is performed is predetermined, it is preferable to use the value measured under that pressure.

[0132] Note that a light-emitting device with better characteristics can be realized by combining the extension rates of the phosphorescence lifetime or delayed fluorescence lifetime due to deuteration of the first host material and the second host material, their product, the difference in T1 level, and the difference in sublimation temperature.

[0133] Furthermore, it is preferable that the photoluminescence (PL) spectrum of the exciplex formed from the first host material and the second host material overlap with the PL spectrum of the light-emitting material (a material capable of converting triplet energy into light emission). This is because the excitation energy of the energy donor and the light-emitting material are close to each other, thereby reducing the driving voltage of the light-emitting device. Therefore, the difference in energy between the maximum peak wavelengths is preferably 0.35 eV or less, more preferably 0.30 eV or less, even more preferably 0.25 eV or less, even more preferably 0.20 eV or less, and most preferably 0.15 eV or less. Alternatively, a light-emitting device having a configuration in which the difference between the energy of the maximum peak in the PL spectrum of the exciplex and the energy of the wavelength at the long-wavelength absorption edge in the absorption spectrum of the light-emitting material is 0.35 eV or less, more preferably 0.30 eV or less, even more preferably 0.25 eV or less, even more preferably 0.20 eV or less, and most preferably 0.15 eV or less is preferable because it can reduce the driving voltage.

[0134] The PL spectrum of an exciplex is preferably measured using a co-evaporated film of a first host material and a second host material. When measuring the PL spectrum of a light-emitting substance (a substance capable of converting triplet energy into luminescence), the sample may be in the form of a thin film or a solution, but a solution is preferred from the perspective of examining the state of isolated molecules. The solvent for the solution is not particularly limited as long as the same solvent is used for comparison, but a solvent with relatively low polarity, such as toluene or chloroform, is preferred. Furthermore, measurements can be performed using a thin film in which the ratio of the first host material to the second host material is 1:1 by weight or volume.

[0135] When the light emitted by the substance capable of converting triplet excitation energy into light (the light-emitting substance contained in the light-emitting layer) is in the blue region, that is, when the peak wavelength is typically 450 nm or more and less than 500 nm, the first host material is preferably an organic compound having a triazine skeleton or a diazine skeleton, and the second host material is preferably a material having a carbazole skeleton. Specifically, the first host material is 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole-1,2,3,4,5,6,7,8,1',2',3',4',5',6',7',8'-d 16 )(Abbreviation: SiTrzCz2-d 16 ), and 9-[3-(triphenylsilyl)phenyl]-3,9'-(bi-9H-carbazole-d) as the second host material. 15 ) (Abbreviation: PSiCzCz-d 15 ), 9'-(phenyl-d5)-9'H-9,3':6',9''-tercarbazole-1,1',1'',2,2',2'',3,3'',4,4',4'',5,5',5'',6,6'',7,7',7'',8,8',8''-d 22 (Abbreviation: PhCzGI-d 27 ), 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9''-tercarbazole-1,1',1'',2,2',2'',3,3'',4,4',4'',5,5',5'',6,6'',7,7',7'',8,8',8''-d22 (Abbreviation: PSiCzGI-d 22 ) can be mentioned.

[0136] Furthermore, when the light emitted by the substance capable of converting triplet excitation energy into light (the light-emitting substance contained in the light-emitting layer) is in the green or red region, i.e., when the peak wavelength is typically 500 nm or more and 700 nm or less, the first host material is preferably an organic compound having a diazine skeleton or a triazine skeleton, and the second host material is preferably a material having a carbazole skeleton. Specifically, the first host material is 8-(1,1':4',1''-terphenyl-3-yl-2,4,5,6,2',3',5',6',2'',3'',4'',5'',6''-d 13 )-4-[3-(dibenzothiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d 23 ), 8-(1,1':4',1''-terphenyl-3-yl-2,4,5,6,2',3',5',6',2'',3'',4'',5'',6''-d 13 )-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d 13 ), 11-[4-(biphenyl-4-yl-2,2′,3,3′,4′,5,5′,6,6′-d9)-6-(phenyl-2,3,4,5,6-d5)-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole-1,2,3,4,5,6,7,8,9,10-d 10 Examples of the second host material include 9-(2-naphthyl-1,3,4,5,6,7,8-d7)-9'-(phenyl-2,3,4,5,6-d5)-3,3'-bi-9H-carbazole-1,1',2,2',4,4',5,5',6,6',7,7',8,8'-d 14 (Abbreviation: βNCCP-d 26), 9-phenyl-9'-(phenyl-2,3,4,5,6-d5)-3,3'-bis(9H-carbazole) (abbreviation: PCCP-d5), and the like.

[0137] The light-emitting device described in this embodiment is a tandem light-emitting device and therefore has multiple light-emitting layers. The configuration of the light-emitting layers described above may be applied to only some of the light-emitting layers, but it is more preferable that all of the light-emitting layers have the same configuration.

[0138] For example, in the case of a tandem light-emitting device having two light-emitting layers, a first light-emitting layer and a second light-emitting layer, the first light-emitting layer preferably contains a first light-emitting center substance, a first organic compound, and a second organic compound, and the second light-emitting layer preferably contains a third organic compound and a fourth organic compound, one or both of the first organic compound and the second organic compound being deuterated, and one or both of the third organic compound and the fourth organic compound being deuterated. The first organic compound and the third organic compound correspond to a first host material, and the second organic compound and the fourth organic compound correspond to a second host material, respectively. The first light-emitting layer and the second light-emitting layer preferably have the above-described light-emitting layer configuration.

[0139] Specifically, the first organic compound and the third organic compound are organic compounds having electron transport properties and preferably contain a π-electron-deficient heteroaromatic ring. The second organic compound and the fourth organic compound are organic compounds having hole transport properties and preferably contain a π-electron-rich heteroaromatic ring or an aromatic amine skeleton. The first organic compound and the second organic compound, and the third organic compound and the fourth organic compound, are preferably combined to form exciplexes. The difference between the T1 level of the first organic compound and the T1 level of the second organic compound, and the difference between the T1 level of the third organic compound and the T1 level of the fourth organic compound, are preferably 0.30 eV or less, preferably 0.20 eV or less, more preferably 0.15 eV or less, and more preferably 0.10 eV or less. The other structures described above can also be applied to each light-emitting layer by replacing the first host material with a "first organic compound" or a "third organic compound" and the second host material with a "second organic compound" or a "fourth organic compound."

[0140] Note that the name of the first host material is not limited to "first organic compound" or "third organic compound." Similarly, the name of the second host material is not limited to "second organic compound" or "fourth organic compound." For example, when Configuration Example 1 is used for any two of the subpixels 110R, 110G, and 110B shown in FIG. 2(B), in order to distinguish the first host material and the second host material contained in the two light-emitting devices, the first host material contained in the first light-emitting device may be referred to as the "first organic compound" and the "third organic compound," the second host material contained in the first light-emitting device may be referred to as the "second organic compound" and the "fourth organic compound," the first host material contained in the second light-emitting device may be referred to as the "fifth organic compound" and the "seventh organic compound," and the second host material contained in the second light-emitting device may be referred to as the "sixth organic compound" and the "eighth organic compound."

[0141] The formation of exciplexes can be confirmed by, for example, comparing the emission spectra of organic compounds with hole-transporting properties, organic compounds with electron-transporting properties, and a mixed film of these organic compounds, and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of the individual organic compounds (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of organic compounds with hole-transporting properties, organic compounds with electron-transporting properties, and a mixed film of these materials, and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL can also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of organic compounds with hole-transporting properties, organic compounds with electron-transporting properties, and a mixed film of these organic compounds, and observing differences in transient response.

[0142] In this case, it is preferable that the short-wavelength emission edge of the PL spectrum of the exciplex formed by the first host material and the second host material is positioned at a wavelength shorter than the long-wavelength absorption edge of the absorption spectrum of the luminescent center substance. Such a positional relationship between the PL spectrum of the exciplex and the absorption edge of the luminescent center substance enables efficient energy transfer.

[0143] Alternatively, the peak wavelength of the PL spectrum of the exciplex formed by the first host material and the second host material is preferably shorter than the peak wavelength of the PL spectrum of the luminescent center substance. Furthermore, the difference in energy between the peak wavelength of the PL spectrum of the exciplex and the peak wavelength of the PL spectrum of the luminescent center substance is preferably 0.35 eV or less, more preferably 0.30 eV or less, even more preferably 0.25 eV or less, even more preferably 0.20 eV or less, and most preferably 0.15 eV or less. Such a relationship between the peak wavelength of the PL spectrum of the exciplex and the peak wavelength of the PL spectrum of the luminescent center substance enables efficient energy transfer.

[0144] Alternatively, the difference between the energy at the peak wavelength of the PL spectrum of the exciplex formed by the first host material and the second host material and the energy at the wavelength of the absorption edge on the longer wavelength side in the absorption spectrum of the luminescent center substance is preferably 0.35 eV or less, more preferably 0.30 eV or less, even more preferably 0.25 eV or less, even more preferably 0.20 eV or less, and most preferably 0.15 eV or less. Such a relationship between the energy at the peak wavelength of the PL spectrum of the exciplex and the energy at the wavelength of the absorption edge on the longer wavelength side in the absorption spectrum of the luminescent center substance enables efficient energy transfer.

[0145] The PL spectrum of the exciplex is preferably measured using a co-evaporated film of the first host material and the second host material. On the other hand, the sample form for measuring the PL spectrum or absorption spectrum of the luminescent center substance may be a thin film or a solution, but a solution is preferred from the viewpoint of examining the state of isolated molecules. The solvent for the solution is preferably a solvent with relatively low polarity, such as toluene or chloroform.

[0146] The absorption edge of the absorption spectrum can be calculated by drawing a tangent at the point where the absolute value of the slope on the long-wavelength side of the peak (or shoulder peak) observed at the longest wavelength in the absorption spectrum is maximum, and then calculating from the intersection of the tangent with the horizontal axis or the baseline. The emission edge on the short-wavelength side of the PL spectrum can be calculated by drawing a tangent at the point where the slope on the short-wavelength side of the peak (or shoulder peak) observed at the shortest wavelength in the PL spectrum is maximum, and then calculating from the intersection of the tangent with the horizontal axis or the baseline.

[0147] As described above, in one embodiment of the present invention, the first host material is preferably an organic compound having an electron-transport property, and the second host material is preferably an organic compound having a hole-transport property.

[0148] The organic compound having electron transport properties as the first host material has an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 Organic compounds having a .DELTA. / Vs or higher are preferred.

[0149] The organic compound having electron transport properties is preferably an organic compound having a π-electron-deficient heteroaromatic ring, such as an organic compound having an azole skeleton, an organic compound having a pyridine skeleton, an organic compound having a diazine skeleton, or an organic compound having a triazine skeleton.

[0150] Among these, organic compounds containing a heteroaromatic ring having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reduced driving voltage. In addition, benzofuropyrimidine skeletons, benzothienopyrimidine skeletons, benzofuropyrazine skeletons, and benzothienopyrazine skeletons are preferred because of their high acceptor properties and high reliability.

[0151] As organic compounds having a π-electron-deficient heteroaromatic ring that can be used as organic compounds having electron transport properties, for example, the following organic compounds are preferred: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), and other organic compounds with an azole skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35 DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10-phenanthroline Organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl 1-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated as 9mDBtBPN fpr), 9-[3'-dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated as 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviated as 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviated as 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviated as 4,6mCzP2Pm), 9,9'-[pyrimidinyl]pyrimidine benzofuro[3,2-d]pyrimidine (abbreviated as 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviated as 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazo phosphorus) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[ 3,5-Bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPB fpm), 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl -1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz) , 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpB PTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviated as PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviated as mBP-TPDBfTzn), 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-Triazine (abbreviation: βNP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviation: SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviation: BP-mBPIcz(II)Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl ]phenyl}-9-phenyl-9H-carbazole (abbreviation: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3''-diyl]bis(9H-carbazole) (abbreviation: Cz-pmCzBPTzn), 3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole (abbreviation: PDBf-PCzTzn), and 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviation: PCzDBtTzn) are examples of organic compounds containing a heteroaromatic ring with a triazine skeleton. When the first host material is an organic compound containing deuterium, the organic compound described above may be partially or entirely deuterated. In particular, an organic compound in which a group or skeleton in which a triplet excitation level is localized is deuterated is preferred.

[0152] The organic compound having hole transport properties is preferably an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring containing at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton, and more specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is fused to one of these rings.

[0153] Such organic compounds having hole-transporting properties preferably have a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. It is preferable that these hole-transporting substances are organic compounds having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of light-emitting devices with long lifetimes.

[0154] As such an organic compound, for example, the following organic compounds are preferable: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3 ... mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), )triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), compounds with an aromatic amine skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl ( abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 3,9-bis(9-phenyl-9H-carbazole-3-yl)-9H-carbazole (abbreviation: PCCzPC), 9-(biphenyl-4-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzBP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-Bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3, 3'-Bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-5'-yl-3,3'-9H ,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-Bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 9-[3-(triphenylsilyl)phenyl]-3,Compounds with a carbazole skeleton, such as 9'-bi-9H-carbazole (abbreviation: PSiCzCz) and 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9''-tercarbazole (abbreviation: PSiCzGI), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), and 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-I) Examples of suitable organic compounds include compounds having a thiophene skeleton, such as 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reduced driving voltage. When the second host material is an organic compound containing deuterium, organic compounds in which some or all of the above organic compounds are deuterated can be used. In particular, organic compounds in which a group or skeleton in which a triplet excitation level is localized is deuterated are preferred.

[0155] As described above, it is preferable that the first host material be an organic compound having electron transport properties, and the second host material be an organic compound having hole transport properties. Furthermore, as a combination thereof, it is preferable that the first host material be an organic compound having a π-electron-deficient heteroaromatic ring, and the second host material be an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring, because these materials have excellent carrier transport properties and efficiently form exciplexes. Alternatively, it is more preferable that the first host material be an organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton, or an organic compound having a heteroaromatic ring with a triazine skeleton, and the second host material be an organic compound having any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton, because these materials have high triplet excitation energy. Furthermore, it is preferable that the first host material be an organic compound having a triazine skeleton or a pyrimidine skeleton, and the second host material be an organic compound having a carbazole skeleton, because these materials are stable and reliable. As the organic compound having a carbazole skeleton, an organic compound having a 3,3′-bicarbazole skeleton is particularly preferred because it has high donor properties and high heat resistance. It is also very preferred that the second host material is an organic compound having a 3,3′-bicarbazole skeleton and the first host material is an organic compound having a triazine skeleton because it has high triplet excitation energy, stability, and good reliability.

[0156] By mixing an organic compound having electron transport properties with an organic compound having hole transport properties, the transport properties of the light-emitting layer can be easily adjusted and the recombination region can be easily controlled. The weight ratio of the organic compound having hole transport properties to the organic compound having electron transport properties may be 1:19 to 19:1, preferably 3:7 to 7:3.

[0157] Furthermore, it is preferable that the light-emitting layer of the tandem light-emitting device having such a light-emitting layer and described in this embodiment is separated from the light-emitting layer of at least one of the other adjacent light-emitting devices, or that the light-emitting layer of the tandem light-emitting device is different from the light-emitting layer of at least one of the other adjacent light-emitting devices, or that the color of light emitted by the tandem light-emitting device is different from the color of light emitted by at least one of the other adjacent light-emitting devices, or that the light-emitting center substance of the light-emitting layer of the tandem light-emitting device has a different structure from the light-emitting center substance of the light-emitting layer of at least one of the other adjacent light-emitting devices.

[0158] In the tandem light-emitting device described in this embodiment, the electron-transporting layer of the cathode-side light-emitting unit preferably contains an eleventh organic compound having a triazine skeleton, and the intermediate layer preferably contains a twelfth organic compound having a phenanthroline skeleton. By including the eleventh organic compound in the electron-transporting layer of the cathode-side light-emitting unit and the twelfth organic compound in the intermediate layer, a tandem light-emitting device with low driving voltage can be obtained. Furthermore, by including the eleventh organic compound in the electron-transporting layer of the cathode-side light-emitting unit and the twelfth organic compound in the intermediate layer, and by including a light-emitting center substance and a first host material and a second host material, one or both of which are deuterated, a tandem light-emitting device with lower driving voltage can be obtained. Furthermore, the luminous efficiency can be improved, resulting in a light-emitting device with good power efficiency and energy efficiency.

[0159] Furthermore, as described above, the light-emitting layer of the tandem light-emitting device is separated from the light-emitting layer of at least one of the other adjacent light-emitting devices, or the light-emitting layer of the tandem light-emitting device is a light-emitting layer different from the light-emitting layer of at least one of the other adjacent light-emitting devices, or the color of light emitted by the tandem light-emitting device is different from the color of light emitted by at least one of the other adjacent light-emitting devices, or the light-emitting center substance of the light-emitting layer of the tandem light-emitting device has a different composition from the light-emitting center substance of the light-emitting layer of at least one of the other adjacent light-emitting devices, thereby making it possible to make a light-emitting device with very good current efficiency, and therefore better power efficiency and energy efficiency.

[0160] As a result, a display device according to one embodiment of the present invention using such a light-emitting device can be a display device with low power consumption, high reliability, and high luminance, and can provide good visibility and display quality.

[0161] The eleventh organic compound containing the triazine skeleton has an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 It is preferable that the material has an electron transporting property of electron mobility of 1 / Vs or more. Note that, other materials can be used as long as they have a higher electron transporting property than holes.

[0162] The eleventh organic compound containing a triazine skeleton is preferably a compound containing a triazine skeleton and an aromatic ring. The aromatic ring may be a monocyclic aromatic ring, a polycyclic aromatic ring, an aromatic ring having an alkyl group as a substituent, an aromatic ring having a fluoro group as a substituent, or an aromatic ring having a cyano group as a substituent. The triazine skeleton may have a substituent other than the aromatic ring, and the aromatic ring may have a substituent other than the fluoro group, cyano group, or alkyl group. The triazine skeleton is also called a triazine ring, and the skeleton of other skeletons can also be referred to as a ring.

[0163] Examples of the monocyclic aromatic ring include aromatic hydrocarbon rings such as a benzene ring, and heteroaromatic rings such as a pyrrole ring, a pyridine ring, a pyrimidine ring, a triazine ring, etc. Having an aromatic ring as a substituent improves heat resistance, specifically, has the effect of improving the glass transition temperature (Tg) and the effect of improving electron transport properties.

[0164] Examples of polycyclic aromatic rings include aromatic hydrocarbon rings such as naphthalene rings, phenanthrene rings, chrysene rings, triphenylene rings, fluorene rings, and spirobifluorene rings, as well as heteroaromatic rings such as carbazole rings, dibenzofuran rings, dibenzothiophene rings, xanthene rings, indolocarbazole rings, and indenocarbazole rings. Compounds having polycyclic aromatic rings as substituents are preferred because they can improve heat resistance compared to compounds having monocyclic aromatic rings such as benzene rings. Furthermore, compounds having a ring in which an aromatic ring (such as a benzene ring, naphthalene ring, or pyridine ring) is fused to these polycyclic aromatic rings as a substituent can further improve heat resistance. Examples of rings in which an aromatic ring is fused to a polycyclic aromatic ring include a benzofluorene ring, a benzonaphthofuran ring, a benzoxanthene ring, and a benzonaphthothiophene ring. By providing a layer containing a highly heat-resistant compound near the cathode, damage to the element due to heat can be suppressed when high-temperature treatment such as a patterning step is performed after the layer or the cathode is formed.

[0165] Examples of alkyl groups include methyl, ethyl, propyl, tertiary butyl, cyclohexyl, and adamantyl groups. A layer using a compound having an alkyl group as a substituent can lower the refractive index. This reduces total reflection at the interface between the layer and other layers, improving light extraction efficiency. The use of a compound having these substituents in the hole transport layer can also reduce the refractive index. In particular, using a compound having a triazine skeleton and an alkyl group in the electron transport layer and a compound having an aromatic amine skeleton and an alkyl group in the hole transport layer can synergistically enhance the light extraction efficiency improvement effect. The alkyl group having multiple carbon atoms, preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more, can enhance the effect. A layer using a compound having a fluoro group as a substituent is also preferred because it can lower the refractive index. In particular, having multiple fluoro groups can reduce the refractive index and thereby enhance the light extraction efficiency improvement effect. It is also effective to use a compound having a fluoro group in both the electron transport layer and the hole transport layer. A compound having a structure in which multiple alkyl groups are bonded to one aromatic ring can further lower the refractive index of the layer. For example, a structure in which two or more tertiary butyl groups are bonded as substituents to one benzene ring is exemplified. A structure in which multiple alkyl groups are bonded to a monocyclic aromatic ring such as a pyridine ring or a polycyclic aromatic ring such as a fluorene ring is also suitable, in addition to the benzene ring. Furthermore, a structure in which multiple alkyl groups are bonded to some of the rings constituting a polycyclic aromatic ring (such as a naphthalene ring, a fluorene ring, a carbazole ring, a quinoline ring, or a xanthene ring) is also suitable. For example, a structure in which multiple tertiary butyl groups are bonded to one benzene ring constituting a fluorene ring is exemplified. A structure in which multiple fluoro groups are bonded to one aromatic ring or a structure in which multiple fluoro groups are bonded to some of the rings of a polycyclic aromatic ring is also preferred, in addition to alkyl groups.

[0166] In addition, a compound having a cyano group as a substituent is preferable because it can improve the electron transport property.

[0167] It is also preferable to combine a polycyclic aromatic ring, an alkyl group, a fluoro group, or a cyano group as a substituent. For example, when a polycyclic aromatic ring and a cyano group are used as a substituent, both heat resistance and electron transport properties can be improved. Furthermore, when a polycyclic aromatic ring and an alkyl group are used as a substituent, both heat resistance and light extraction efficiency can be improved. In this way, a combination of substituents can be used depending on the desired function.

[0168] Furthermore, the heat resistance can be further improved by including a plurality of polycyclic aromatic rings as substituents. In this case, it is preferable that the aromatic hydrocarbon ring and the heteroaromatic ring are included.

[0169] Specific examples of the eleventh organic compound containing a triazine skeleton include 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5 -triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3, 5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2, 6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-triazine (abbreviation: β NP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviated as SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviated as mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviated as BP-mBPIc z(II)Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviated as mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3''-diyl]bis(9H-carbazole) (abbreviated as Cz-pmCzBPTzn), 3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole (abbreviated as Cz-pmCzBPTzn), abbreviation: PDBf-PCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviation: PCzDBtTzn), 2,4-diphenyl-6-[3'-(spiro[7H-benzo[c]fluorene-7,9'-[9H]xanthene]-2'-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: mSbfxBPTzn), 3'-[4-phenyl-6-(spiro[9H-fluorene-9,9'-[9H]xanthene]-2'-yl)-1,3,Organic compounds containing a heteroaromatic ring with a triazine skeleton, such as 5-triazin-2-yl]biphenyl-4-carbonitrile (abbreviation: mpCNBP-SFxTzn) and 2,2'-[1,2-naphthalenediyldi(4,1-phenylene)]bis(4,6-diphenyl-1,3,5-triazine) (abbreviation: TznP2N), can be used. However, TznP2N (100), mSbfxBPTzn (101), mpCNBP-SFxTzn (102), CNBPNPTzn (103), βNP-SFx (4)Tzn (104), mmtBuBP-mDMePyPTzn (105), mBnfBPTzn (106), and the like, represented by the following structural formulas (100) to (106), are particularly preferred.

[0170] [ka]

[0171] The electron transport layer included in the light-emitting unit on the anode side may be a layer containing an organic compound having a triazine skeleton, or may be a layer containing an organic compound not having a triazine skeleton, similar to the electron transport layer included in the light-emitting unit on the cathode side.

[0172] The electron transport layer included in the light-emitting unit on the anode side preferably contains an organic compound containing a triazine skeleton to reduce power consumption. In particular, it is preferable that this layer contains the same organic compound as the eleventh organic compound, because this prevents the manufacturing equipment from becoming complicated and is advantageous in terms of raw material procurement costs.

[0173] Furthermore, the electron transport layer included in the light-emitting unit on the anode side contains an organic compound that does not contain a triazine skeleton, which makes it easier to control the carrier transport property and allows for the provision of a light-emitting device with better characteristics. Organic compounds that do not contain a triazine skeleton are preferably organic compounds that contain a heteroaromatic ring having a pyridine skeleton or a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton. It should be noted that organic compounds obtained by appropriately deuterating the above-listed organic compounds can also be used.

[0174] The twelfth organic compound containing the phenanthroline skeleton contained in the intermediate layer has an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 It is preferable that the value is / Vs or more. Note that, other substances can be used as long as they have a higher electron transporting property than a hole transporting property.

[0175] The twelfth organic compound containing a phenanthroline skeleton is preferably a compound containing a phenanthroline skeleton and an aromatic ring, which may be a monocyclic aromatic ring or a polycyclic aromatic ring.

[0176] Examples of the monocyclic aromatic ring include a benzene ring, a pyrrole ring, a pyridine ring, and a pyrimidine ring. Furthermore, examples of the polycyclic aromatic ring include aromatic hydrocarbon rings such as a naphthalene ring, a phenanthrene ring, a chrysene ring, a triphenylene ring, and a fluorene ring, and heteroaromatic rings such as a phenanthroline ring and a pyrrole ring. In particular, the inclusion of a plurality of these polycyclic aromatic rings is preferred because it can improve heat resistance or electron transport properties.

[0177] Examples of the twelfth organic compound containing a phenanthroline skeleton include bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: mTpPPhen), and 2-phenyl-9-(2-triphenylenyl)phenyl. Organic compounds containing a heteroaromatic ring having a phenanthroline skeleton, such as 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: PnNPhen), and 2-[4-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen), can be used. However, PnNPhen(200) and mPPhen2P(201), represented by the following structural formula (200) or (201), are particularly preferred.

[0178] [ka]

[0179] In the light-emitting device described in this embodiment, the intermediate layer may have any configuration as long as it contains a twelfth organic compound having a phenanthroline skeleton and is a layer that can inject electrons into the light-emitting unit on the anode side and holes into the light-emitting unit on the cathode side in contact with the intermediate layer when a voltage is applied between the first electrode and the second electrode. However, the intermediate layer preferably has a stacked structure including a first layer containing the twelfth organic compound and a second layer located closer to the cathode than the first layer.

[0180] The first layer preferably contains a metal or a metal compound in addition to the organic compound 12. The metal or the metal in the metal compound is preferably an alkali metal (Group 1 element) such as Li, an alkaline earth metal (Group 2 element) such as Mg or Ca, a Group 3 element including a lanthanide such as Y, Eu, or Yb, a Group 11 element such as Cu, Ag, or Au, a Group 12 element such as Zn, or an earth metal (Group 13 element) such as Al or In.

[0181] The first layer may have a stacked structure of a layer containing an organic compound and a layer having a metal or metal compound located closer to the cathode than the layer containing the organic compound, or may be a mixed layer of an organic compound and a metal or metal compound. A mixed layer is preferable because it can reduce the number of required film formation chambers, thereby reducing manufacturing costs, and also contributes to improving the stability of the light-emitting device.

[0182] When an organic compound and a metal or metal compound are mixed, the distribution of the organic compound and the distribution of the metal or metal compound show roughly the same tendency when the first layer is analyzed in the film thickness direction. That is, when the distribution of the organic compound is constant, the distribution of the metal or metal compound is also roughly constant. In the case of a layered structure of an organic compound and a metal or metal compound, the metal or metal compound may be detected in areas other than the layer made of the metal or metal compound due to diffusion from the layer made of the metal or metal compound, but since the distribution shows a different distribution from the distribution of the organic compound, the analysis results can be distinguished between diffusion and mixing.

[0183] Furthermore, when the first layer is analyzed in the film thickness direction, if there is a region in which a metal or metal compound is detected that is 10 nm or more, preferably 15 nm or more, and more preferably 20 nm or more, the first layer can be considered to have a mixed layer in which an organic compound and a metal or metal compound are mixed.

[0184] In particular, the metal in the metal or metal compound is preferably a substance that exhibits donor properties to the twelfth organic compound. Examples of substances that exhibit donor properties to the twelfth organic compound include metals of Group 1 and Group 2, with lithium or lithium compounds being particularly preferred. Specifically, Li, lithium fluoride (LiF), lithium oxide (LiO), and 8-hydroxyquinolinato-lithium (abbreviated as Liq) are preferred. When the first layer contains the twelfth organic compound and a substance that exhibits donor properties to the twelfth organic compound, electrons are generated by charge separation. When a voltage is applied between the first electrode and the second electrode, the electrons are injected into the light-emitting unit on the anode side via the twelfth organic compound. This allows the light-emitting device described in this embodiment to operate at a low driving voltage.

[0185] In addition to the organic compounds described above, the twelfth organic compound is preferably an organic compound containing a phenanthroline skeleton with an electron-donating substituent. The phenanthroline skeleton is a skeleton that easily interacts with metals, etc., and when the twelfth organic compound containing such a phenanthroline skeleton further contains an electron-donating group, the electron density of the phenanthroline skeleton increases, making it more likely to interact with metals or metal compounds. In particular, when a metal of Group 3, 11, 12, or 13 is used as the metal or the metal in the metal compound, an increase in driving voltage can be suppressed, and a tandem light-emitting device with excellent characteristics can be provided.

[0186] Specific examples of the electron-donating group include an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group. However, the electron-donating group that is preferably introduced into the phenanthroline ring is not limited to these. Any group that can increase the electron density of the phenanthroline ring by introducing it into the phenanthroline ring can be used as the electron-donating group. In addition, the electron-donating group may be introduced into the phenanthroline ring via an arylene group such as a phenylene group, and the arylene group is preferably a p-phenylene group.

[0187] Specific examples of organic compounds containing a phenanthroline skeleton with an electron-donating substituent are shown in structural formulas (300) to (311).

[0188] [ka]

[0189] Note that a configuration in which the first layer contains a Group 1 or Group 2 element, particularly lithium or a lithium compound, and a 12th organic compound having a phenanthroline skeleton with an electron-donating substituent is preferable because it can provide a tandem light-emitting device with lower driving voltage and better reliability. Furthermore, a configuration in which the first layer contains a Group 1 or Group 2 element, particularly lithium or a lithium compound, and a 12th organic compound having a phenanthroline skeleton with an electron-donating substituent is preferable because it can suppress an increase in driving voltage when processing the organic compound of the light-emitting device by photolithography.

[0190] In an intermediate layer having the above-described configuration, the twelfth organic compound is preferably an organic compound having a phenanthroline skeleton, particularly an organic compound having a 1,10-phenanthroline skeleton, because the two nitrogen atoms contained therein can coordinate to a metal, and therefore interaction with a metal or metal compound is likely to occur.

[0191] When an electron-donating group is introduced into the 1,10-phenanthroline skeleton, the electron-donating group is preferably substituted at positions 4 and 7 of the 1,10-phenanthroline skeleton. By introducing the electron-donating group into positions 4 and 7 of the 1,10-phenanthroline skeleton, the electron density of the nitrogen atoms at positions 1 and 10 can be increased, making it easier for the 1,10-phenanthroline skeleton to interact with a metal or metal compound.

[0192] The first layer may further contain an organic compound different from the twelfth organic compound. The organic compound is preferably an organic compound having electron transport properties. In particular, the organic compound preferably has two or more heteroaromatic rings bonded or condensed to each other, and the two or more heteroaromatic rings preferably have a total of three or more heteroatoms. By including such an organic compound in the first layer, improvements in heat resistance and electron transport properties can be achieved.

[0193] The second layer preferably contains a thirteenth organic compound having hole-transporting properties. The second layer preferably further contains a substance exhibiting acceptor properties, and the substance exhibiting acceptor properties is preferably an organic compound exhibiting acceptor properties to the thirteenth organic compound. As the substance exhibiting acceptor properties, an organic compound having at least one of a halogen group and a cyano group is particularly preferred, and an organic compound having at least one of a fluorine group and a cyano group is more preferred. It is more preferred that the organic compound contains four or more halogen groups (fluorine) and cyano groups in total.

[0194] When the second layer contains the thirteenth organic compound and a substance that exhibits acceptor properties for the thirteenth organic compound, holes are generated by charge separation, and when a voltage is applied between the first electrode and the second electrode, the holes are injected into the light-emitting unit on the cathode side via the thirteenth organic compound. This allows the light-emitting device described in this embodiment to be a light-emitting device with a low driving voltage.

[0195] The intermediate layer may have a third layer between the first and second layers.

[0196] The third layer contains a substance with electron transport properties and has functions such as smoothing the transfer of electrons between the first and second layers to reduce the driving voltage, and reducing the interaction between the first and second layers to improve reliability.

[0197] The thickness of the third layer is preferably 1 nm or more and 10 nm or less, more preferably 2 nm or more and 5 nm or less, in order to suppress an increase in driving voltage.

[0198] The light-emitting device having the above structure described in this embodiment can be a light-emitting device with high current efficiency, low energy loss, and favorable characteristics. In addition, a display device according to one embodiment of the present invention using such a light-emitting device can be a display device with low power consumption, high reliability, and high luminance and thus favorable visibility.

[0199] Next, the light-emitting device described in this embodiment will be described in detail with reference to the drawings. FIG. 5A shows a light-emitting device 130 described in this embodiment. The light-emitting device described in this embodiment is a tandem light-emitting device including a first electrode 101 including an anode and a second electrode 102 including a cathode, and an organic compound layer 103 (also referred to as an EL layer) including a first light-emitting unit 501 including a first light-emitting layer 113_1, a second light-emitting unit 502 including a second light-emitting layer 113_2 and a second electron-transporting layer 114_2, and an intermediate layer 116. Note that the first light-emitting unit may include a first electron-transporting layer 114_1 between the first light-emitting layer 113_1 and the intermediate layer 116.

[0200] In the light-emitting device 130, the second electron-transporting layer 114_2 contains an eleventh organic compound having a triazine skeleton, and the intermediate layer 116 contains a twelfth organic compound having a phenanthroline skeleton. In addition, the second electron-transporting layer 114_2 containing the eleventh organic compound having a triazine skeleton is preferably in contact with the second electrode 102 in order to reduce power consumption.

[0201] Although the present embodiment will be described taking as an example a light-emitting device having one intermediate layer 116 and two light-emitting units, the light-emitting device may have n (n is an integer of 1 or more) intermediate layers and n+1 light-emitting units. For example, the light-emitting device 130 shown in Fig. 5(B) is an example of a tandem light-emitting device in which n is 2 and the light-emitting device has a first light-emitting unit 501, a first intermediate layer 116_1, a second light-emitting unit 502, a second intermediate layer 116_2, and a third light-emitting unit 503.

[0202] The first light-emitting unit 501 and the second light-emitting unit 502 may include other functional layers in addition to the above-described light-emitting layer, electron-transport layer, and the like. In FIG. 5A, the first light-emitting unit 501 includes the hole-injection layer 111 and the first hole-transport layer 112_1 in addition to the first light-emitting layer 113_1 and the first electron-transport layer 113_1, and the second light-emitting unit 502 includes the second hole-transport layer 112_2 in addition to the second light-emitting layer 113_2 and the second electron-transport layer 114_2. However, the structure of the organic compound layer 103 in one embodiment of the present invention is not limited thereto. Any of these layers may be omitted, or other layers may be included. Typical examples of such other layers include a carrier block layer and an exciton block layer.

[0203] The first electrode 101 is an electrode including an anode. The first electrode 101 may have a stacked structure, in which case the layer in contact with the organic compound layer 103 functions as the anode. The anode is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or more). Specific examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are usually formed by sputtering, but may also be formed by applying a sol-gel method or the like. For example, indium zinc oxide may be formed by sputtering using a target in which 1 to 20 wt % of zinc oxide is added to indium oxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) can also be formed by sputtering using a target containing 0.5 to 5 wt % tungsten oxide and 0.1 to 1 wt % zinc oxide relative to indium oxide. Other materials that can be used for the anode include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and nitrides of metal materials (e.g., titanium nitride). Graphene can also be used for the anode. Using the composite material constituting the second layer 117 of the intermediate layer 116 as a layer in contact with the anode (typically a hole injection layer) allows for the selection of an electrode material regardless of the work function.

[0204] The hole injection layer 111 is provided in contact with the anode and has the function of facilitating injection of holes into the organic compound layer 103 (first light-emitting unit 501). The hole injection layer 111 can be formed of a phthalocyanine-based compound or complex compound such as phthalocyanine (abbreviation: HPc) or copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene) / polystyrenesulfonic acid (abbreviation: PEDOT / PSS).

[0205] Alternatively, the hole injection layer 111 may be formed of a substance having electron acceptor properties. Examples of the substance having acceptor properties include organic compounds having an electron-withdrawing group (such as a halogen group or a cyano group), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are preferred because of their thermal stability. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups, cyano groups, etc.) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. As the substance having acceptor properties, in addition to the organic compounds described above, transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide can be used.Alternatively, the hole injection layer 111 can be formed using a phthalocyanine compound or complex compound such as phthalocyanine (abbreviation: HPc) or copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (abbreviation: PEDOT / PSS). Acceptor materials can extract electrons from an adjacent hole transport layer (or hole transport material) when an electric field is applied.

[0206] The hole-injecting layer 111 is preferably formed using a composite material containing the above-mentioned material having an acceptor property and a substance having a hole-transport property.

[0207] As a substance having hole transport properties used in a composite material, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that as a substance having hole transport properties used in a composite material, a 1×10 -6 cm 2 Preferably, the compound has a hole mobility of 1 / Vs or more. The hole-transporting substance used in the composite material is preferably a compound having a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the fused aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. As the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferred. Specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to the above ring is preferred.

[0208] Such a substance having hole-transporting properties preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, the substance may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen atom of the amine via an arylene group. It is preferable that the substance having hole-transporting properties has an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of a light-emitting device with a long lifetime.

[0209] Specific examples of the substance having the hole transporting property as described above include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-yl, [b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]- N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβN B-03), 4,4'-diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviated as BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviated as BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviated as BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviated as BBAβNαNB), 4,4'-Diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl] 4'-[4'-(3-phenyl-9H-carbazol-9-yl)biphenyl-4-yl]-4''-phenyltriphenylamine (abbreviated as TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviated as αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviated as αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviated as YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)furan N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N- Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)triphenylamine] 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine Triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis( 9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz), 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',Examples include 9''-terecarbazole (abbreviation: PSiCzGI).

[0210] Other aromatic amine compounds that can be used as hole-transporting substances include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0211] By forming the hole injection layer 111, the hole injection property becomes good, and a light emitting device with a low driving voltage can be obtained.

[0212] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film.

[0213] The hole transport layers (the first hole transport layer 112_1 and the second hole transport layer 112_2) are formed by containing an organic compound having a hole transport property. -6 cm 2 It is preferable that the hole mobility is / Vs or more.

[0214] Examples of the hole-transporting substance include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3-methylphenyl-4,4'-diaminobiphenyl (abbreviation: 4,4'-bis(9H-fluoren-2-yl)triphenylamine) ... '-(9-Phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl) Compounds with an aromatic amine skeleton, such as 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di( N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-Bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1' :4',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3' ,1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, Compounds with a carbazole skeleton such as N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, and 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable compounds include compounds having a thiophene skeleton, such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. The organic compounds listed as the substances having hole transport properties used in the composite material of the hole injection layer 111 can also be suitably used as materials for the hole transport layer 112. Note that organic compounds obtained by appropriately deuterating the above-listed organic compounds can also be used in the same way.

[0215] The first hole-transport layer 112_1 and the second hole-transport layer 112_2 preferably contain an organic compound having the same skeleton, and more preferably contain the same compound. One or both of the first hole-transport layer 112_1 and the second hole-transport layer 112_2 may have a stacked structure. By forming the hole-transport layer 112 into a stacked structure and using an organic compound with high electron resistance and / or an organic compound with electron blocking properties in the layer closer to the light-emitting layer 113, a highly reliable light-emitting device can be obtained. When the hole-transport layer 112 has a stacked structure, the layer closer to the light-emitting layer 113 is preferably made of a material with excellent hole-transport properties, low electron-transport properties, and a high LUMO level. The LUMO level of this material is preferably higher than that of the material with the highest composition ratio among the materials constituting the light-emitting layer or the material with the highest LUMO level among the materials constituting the light-emitting layer, preferably by 0.30 eV or more. The material is preferably an organic compound having an amine skeleton and a polycyclic heteroaromatic ring, and more preferably an organic compound having an amine skeleton and a furan skeleton or a dibenzofuran skeleton. When the hole-transport layer 112 has a stacked structure, using such a material for the layer closer to the light-emitting layer 113 can prevent electrons from passing through from the light-emitting layer 113 to the first electrode 101, thereby enabling the manufacture of a highly efficient display device with a long lifetime. Note that in the hole-transport layer 112 having a stacked structure, an organic compound having an amine skeleton and a polycyclic hydrocarbon is preferably used for the layer closer to the first electrode 101, and an organic compound having an amine skeleton and a fluorene skeleton is more preferably used. Organic compounds having an amine skeleton and a fluorene skeleton are preferred because they have good reliability and high hole-transport properties, thereby reducing the power consumption of the light-emitting device.

[0216] The light-emitting layers (the first light-emitting layer 113_1 and the second light-emitting layer 113_2) preferably contain a light-emitting center substance and a host material. At least one of the light-emitting layers contains a light-emitting center substance, a first host material, and a second host material, both of which are organic compounds, and one or both of the first host material and the second host material are deuterated. The first host material and the second host material preferably form an exciplex. Both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 preferably have this structure. The light-emitting layer may also contain other materials.

[0217] Furthermore, the first light-emitting layer 113_1 and the second light-emitting layer 113_2 are preferably light-emitting layers that emit light of similar colors. For example, red, green, and blue pixels are often used in display devices to express full colors. In a light-emitting device used for a red pixel, both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 are light-emitting layers that emit red light. In a light-emitting device used for a green pixel, both the two light-emitting layers are light-emitting layers that emit green light. In a light-emitting device used for a blue pixel, both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 emit blue light. In this case, the light-emitting center substance contained in the first light-emitting layer 113_1 and the light-emitting center substance contained in the second light-emitting layer 113_2 are preferably compounds whose difference in maximum peak wavelength in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. It is more preferable that the light-emitting center substance contained in the first light-emitting layer 113_1 and the light-emitting center substance contained in the second light-emitting layer 113_2 are the same. It is more preferable that the first light-emitting layer 113_1 and the second light-emitting layer 113_2 are made of the same material.

[0218] The luminescent center substance may be a fluorescent substance, a phosphorescent substance, a substance exhibiting thermally activated delayed fluorescence (TADF), or any other luminescent substance.

[0219] Examples of fluorescent substances that can be used as the luminescent center substance in the light-emitting layer include the following: In addition, fluorescent substances other than these can also be used.

[0220] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N,N',N'-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviated as DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA) , 9,10-bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyra N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), Name: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB),6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b]naphtho]] Examples include N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviated as 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds, such as pyrenediamine compounds 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred due to their high hole-trapping properties and excellent luminous efficiency and reliability.

[0221] Examples of phosphorescent materials that can be used as the luminescent center material in the light-emitting layer include the following:

[0222] Organometallic iridium complexes with a 4H-triazole skeleton, such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]) and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]). , organometallic iridium complexes with a 1H-triazole skeleton, such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), fac-tris[1-(2,6-di [Ir(iPrpim)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazol-2-yl-κN3}-4-cyano organometallic iridium complexes with an imidazole skeleton such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium(III) (abbreviation: CNImIr), organometallic complexes with a benzimidazolidene skeleton such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]), and organometallic complexes with a benzimidazolidene skeleton such as bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ Examples include organometallic iridium complexes with phenylpyridine derivatives containing electron-withdrawing groups, such as ]iridium(III) acetylacetonate (abbreviated as FIracac), and platinum complexes such as (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC2]phenoxy-κC2}-9-(4-tert-butyl-2-pyridinyl-κN)carbazole-2,1-diyl-κC1)platinum(II) (abbreviated as PtON-TBBI). These compounds exhibit blue phosphorescence, with peak emission wavelengths in the 450-520 nm range. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium can also be used.

[0223] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6- Organometallic iridium complexes with a pyrimidine skeleton, such as (2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and tris(2-phenylpyridinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’) iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), {2- (Methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl Ir(ppy)2(mbfpypy-d3) and Ir(ppy)2(mbfpypy-d3) are bis[2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]iridium(III) compounds. ) (abbreviation: Ir(ppy)2(mdppy)), [2-(4-d3-methyl-5-phenyl-2-pyridinyl-κN2)phenyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mdppy-d3)]), [2-methyl-(2-pyridinyl-κN)benzofuro[2,Organometallic iridium complexes with a pyridine skeleton, such as [2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy)]), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium (abbreviation: [Ir(ppy)2(mdppy)]), and tris{2-[5-(methyl-d3)-4-phenyl-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5m4dppy-d3)3), and (2-{1-(5-tert-butylbiphenyl-2-yl)-4-[3-tert-butyl-5-(4-phenyl-2-pyridinyl-κN)phenyl-κC]iridium(III). Examples of such complexes include organometallic platinum complexes such as [2-(4-(3,5-di-tert-butylphenyl)-6-{3-[4-(5'-tert-butyl[1,1':3',1''-terphenyl]-2'-yl)-2-pyridinyl-κN]phenyl-κC2}-2-pyridinyl-κN)phenolato-κO]platinum(II) (abbreviation: Pt(4tButpppypyp-mmtBup)), as well as rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These compounds exhibit phosphorescence with a predominantly green hue, with emission peaks in the wavelength range of 500 nm to 600 nm. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred because they are remarkably reliable and offer excellent luminous efficiency. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0224] and organometallic iridium complexes having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]). Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’) iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III), and (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III). In addition to iridium complexes, platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP) and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]) are examples of iridium complexes. These compounds exhibit red phosphorescence with peak emission in the wavelength range from 600 nm to 700 nm. Organometallic iridium complexes with a pyrazine skeleton also exhibit excellent red chromaticity. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0225] In one embodiment of the present invention, the use of a deuterated compound as the luminescent center substance improves luminous efficiency, and therefore the luminescent center substance is preferably a deuterated material.

[0226] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0227] TADF materials include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also available are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), all of which are shown in the following structural formulas.

[0228] [ka]

[0229] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), and Heterocyclic compounds having one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the electron-donating ability of the π-electron-rich heteroaromatic ring and the electron-accepting ability of the π-electron-deficient heteroaromatic ring are both enhanced, thereby reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0230] [ka]

[0231] In addition, TADF materials that are in thermal equilibrium between the singlet excited state and the triplet excited state may also be used. Such TADF materials have a shorter emission lifetime (excitation lifetime), which can suppress efficiency decline in the high brightness range of light-emitting devices. Specific examples include materials with the molecular structure shown below.

[0232] [ka]

[0233] TADF materials are materials with a small difference between the S1 and T1 levels, and have the ability to convert triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) using a small amount of thermal energy, allowing for efficient generation of a singlet excited state. Triplet excitation energy can also be converted into light emission.

[0234] Furthermore, exciplexes (also known as exciplexes), which form an excited state with two types of substances, have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0235] Note that a phosphorescence spectrum observed at low temperatures (for example, 77 K to 10 K) can be used as an indicator of the T1 level. For a TADF material, when a tangent line is drawn at the base of the short wavelength side of the fluorescence spectrum and the energy of the wavelength of the extrapolated line is defined as the S1 level, and a tangent line is drawn at the base of the short wavelength side of the phosphorescence spectrum and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between the S1 level and the T1 level is preferably 0.30 eV or less, and more preferably 0.20 eV or less.

[0236] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0237] The host material for the light-emitting layer has been described in detail above when the light-emitting layer has a structure according to one embodiment of the present invention, and therefore, a repetitive description will be omitted. The light-emitting device described in this embodiment is a tandem light-emitting device and therefore has multiple light-emitting layers. Therefore, some of the light-emitting layers may not have the above-described structure. When the light-emitting layer does not have the above-described structure, various carrier transport materials such as organic compounds having electron-transporting properties and / or organic compounds having hole-transporting properties can be used as the host material.

[0238] The organic compound having hole transport properties is preferably an organic compound having an amine skeleton, a π-electron-rich heteroaromatic ring, etc. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring containing at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton, and specifically preferably a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to one of these rings.

[0239] Such a substance having hole-transporting properties preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, the substance may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. It is preferable that the substance having hole-transporting properties is an organic compound having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of a light-emitting device with a long lifetime.

[0240] As such an organic compound, for example, the following organic compounds are preferable: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3 ... mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), )triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), compounds with an aromatic amine skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl ( abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 3,9-bis(9-phenyl-9H-carbazole-3-yl)-9H-carbazole (abbreviation: PCCzPC), 9-(biphenyl-4-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzBP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-Bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3, 3'-Bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-5'-yl-3,3'-9H ,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-Bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 9-[3-(triphenylsilyl)phenyl]-3,Compounds with a carbazole skeleton, such as 9'-bi-9H-carbazole (abbreviation: PSiCzCz) and 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9''-tercarbazole (abbreviation: PSiCzGI), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), and 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-I) Examples of suitable compounds include compounds having a thiophene skeleton, such as 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. The organic compounds listed as examples of materials having hole transport properties for the hole transport layer can also be used.

[0241] The organic compound having electron transport properties is preferably an organic compound having a π-electron-deficient heteroaromatic ring. Examples of the organic compound having a π-electron-deficient heteroaromatic ring include an organic compound having an azole skeleton, an organic compound having a pyridine skeleton, an organic compound having a diazine skeleton, and an organic compound having a triazine skeleton.

[0242] Among these, organic compounds containing a heteroaromatic ring having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reduced driving voltage. In addition, benzofuropyrimidine skeletons, benzothienopyrimidine skeletons, benzofuropyrazine skeletons, and benzothienopyrazine skeletons are preferred because of their high acceptor properties and high reliability.

[0243] As the organic compound having a π-electron-deficient heteroaromatic ring, for example, the following organic compounds are preferable: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), and other organic compounds with an azole skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35 DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10-phenanthroline Organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9 H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3 '-(Dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis (Biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6( P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviated as 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm), 4-[3,5-bis( 9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviated as 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviated as PC-cgDBCzQz), 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as 8mpTP-4mDBtPBfpm) organic compounds with a diazine skeleton, such as 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl -1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz) , 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpB PTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviated as PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviated as mBP-TPDBfTzn), 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-Triazine (abbreviation: βNP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviation: SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviation: BP-mBPIcz(II)Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl ]phenyl}-9-phenyl-9H-carbazole (abbreviation: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3''-diyl]bis(9H-carbazole) (abbreviation: Cz-pmCzBPTzn), 3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole (abbreviation: PDBf-PCzTzn), and 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviation: PCzDBtTzn) are examples of organic compounds containing a heteroaromatic ring with a triazine skeleton. In addition, organic compounds containing a heteroaromatic ring having a diazine skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0244] TADF materials that can be used as host materials can be the same as those listed above as TADF materials that can be used as emissive center materials. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted to singlet excitation energy through reverse intersystem crossing, and the energy is then transferred to the emissive material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the emissive material functions as an energy acceptor.

[0245] This is very effective when the luminescent material is a fluorescent luminescent material. In this case, in order to obtain high luminous efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. In addition, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent luminescent material.

[0246] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, as this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0247] Furthermore, to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, carrier recombination is preferred in the TADF material. Furthermore, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to triplet excitation energy in the fluorescent material. To achieve this, the fluorescent material preferably has a protecting group around the luminophore (the skeleton responsible for light emission) of the fluorescent material. The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples include alkyl groups with 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups with 3 to 10 carbon atoms, and trialkylsilyl groups with 3 to 10 carbon atoms. Multiple protecting groups are even more preferred. Substituents without a π bond have poor carrier transport properties, allowing for increased distance between the TADF material and the luminophore of the fluorescent material without significantly affecting carrier transport or carrier recombination. Here, the term "luminophore" refers to the atomic group (skeleton) responsible for light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of such luminophores include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton. In particular, fluorescent materials having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0248] When a fluorescent material is used as the emission center, a material having an anthracene skeleton is suitable as the host material. Using a material having an anthracene skeleton as a host material for a fluorescent material makes it possible to realize an emission layer with both excellent luminous efficiency and durability. As a material having an anthracene skeleton to be used as a host material, a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferred due to its chemical stability. Furthermore, host materials having a carbazole skeleton are preferred because of their enhanced hole injection and transport properties. However, host materials containing a benzocarbazole skeleton, in which a benzene ring is further condensed to a carbazole skeleton, are even more preferred because their HOMO level is approximately 0.1 eV higher than that of host materials having a carbazole skeleton, making it easier for holes to enter. In particular, host materials containing a dibenzocarbazole skeleton are preferred because their HOMO level is approximately 0.1 eV higher than that of host materials having a carbazole skeleton, making it easier for holes to enter, as well as providing excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that, from the viewpoint of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'- 9-(1-naphthyl)-10-(4-(2-naphthyl)phenyl)anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)benzo Examples include zo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0249] The host material may be a mixture of multiple substances, and when a mixture of host materials is used, it is preferable to mix a material having electron-transporting properties with a material having hole-transporting properties. By mixing a material having electron-transporting properties with a material having hole-transporting properties, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole-transporting properties to the material having electron-transporting properties may be 1:19 to 19:1 (material having hole-transporting properties:material having electron-transporting properties).

[0250] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0251] Furthermore, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, using this structure is also preferable because it reduces the driving voltage.

[0252] The first electron-transporting layer 114_1 is a layer containing a substance having an electron-transporting property. The material having an electron-transporting property is a material having an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can be used as long as they have a higher electron transport property than holes. Note that the organic compound is preferably an organic compound having a π-electron-deficient heteroaromatic ring. As the organic compound having a π-electron-deficient heteroaromatic ring, for example, one or more of an organic compound having a heteroaromatic ring with an azole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton are preferred, and an organic compound having a heteroaromatic ring with a triazine skeleton is particularly preferred.

[0253] The organic compounds having electron transport properties that can be used in the first electron-transport layer 114_1 can be the same as the organic compounds that can be used as the organic compounds having electron transport properties of the host materials in the first light-emitting layer 113_1 and the second light-emitting layer 113_2. Among them, organic compounds containing a heteroaromatic ring with a diazine skeleton, an organic compound containing a heteroaromatic ring with a pyridine skeleton, and an organic compound containing a heteroaromatic ring with a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and an organic compound containing a heteroaromatic ring with a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0254] As described above, the second electron-transporting layer 114_2 is a layer including the eleventh organic compound having a triazine skeleton. Details thereof have already been described, and therefore will not be repeated.

[0255] Note that the first electron-transport layer 114_1 preferably contains an organic compound having a triazine skeleton to reduce power consumption. In particular, it is preferable that the first electron-transport layer 114_1 contains the same organic compound having a triazine skeleton as the eleventh organic compound having a triazine skeleton contained in the second electron-transport layer 114_2, because this prevents the manufacturing equipment from becoming complicated and is advantageous in terms of raw material procurement costs.

[0256] Alternatively, the first electron-transporting layer 114_1 may contain an organic compound that does not contain a triazine skeleton, which facilitates control of carrier transport properties and enables provision of a light-emitting device with better characteristics. The organic compound that does not contain a triazine skeleton is preferably an organic compound that contains a heteroaromatic ring having a pyridine skeleton or an organic compound that contains a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton.

[0257] The intermediate layer 116 is a layer including a twelfth organic compound having a phenanthroline skeleton. As shown in FIG. 5A, the intermediate layer 116 preferably includes a first layer 119 including the twelfth organic compound having a phenanthroline skeleton. The intermediate layer 116 also preferably includes a second layer 117 including a thirteenth organic compound having hole-transporting properties and a substance having acceptor properties. The second layer 117 is located closer to the second electrode 102 than the first layer 119. The intermediate layer 116 may also include a third layer 118 between the first layer 119 and the second layer 117.

[0258] The details of the first layer have been described above, so a repeated description will be omitted.

[0259] The first layer 119 may further include an organic compound having electron-transporting properties. Examples of organic compounds having electron-transporting properties that can be used for the organic compound include those that can be used as the organic compounds having electron-transporting properties of the host materials in the first light-emitting layer 113_1 and the second light-emitting layer 113_2. Furthermore, it is preferable to use an organic compound having two or more heteroaromatic rings bonded to or condensed with each other, and the two or more heteroaromatic rings having three or more heteroatoms in total, because this improves the resistance to photolithography and suppresses an increase in driving voltage.

[0260] The first layer 119 may have a stacked structure of a layer containing an organic compound and a layer having a metal or a metal compound located closer to the cathode than the layer containing the organic compound, or may be a mixed layer of an organic compound and a metal or a metal compound. A mixed layer is preferable because it requires fewer deposition chambers and reduces manufacturing costs, and also contributes to improving the stability of the light-emitting device.

[0261] When an organic compound and a metal or metal compound are mixed, the distribution of the organic compound and the distribution of the metal or metal compound show roughly the same tendency when the first layer 119 is analyzed in the film thickness direction. That is, when the distribution of the organic compound is constant, the distribution of the metal or metal compound is also roughly constant. In the case of a laminated structure of an organic compound and a layer containing a metal or metal compound, the metal or metal compound may be detected in regions other than the layer containing the metal or metal compound due to diffusion from the layer containing the metal or metal compound, but since the distribution shows a different distribution from the distribution of the organic compound, the analysis results can be distinguished between diffusion and mixing.

[0262] The second layer 117 preferably contains a thirteenth organic compound having a hole-transporting property. The second layer 117 preferably further contains a substance exhibiting an acceptor property, and the substance exhibiting an acceptor property is preferably an organic compound exhibiting an acceptor property to the thirteenth organic compound.

[0263] When the second layer 117 is a layer containing a thirteenth organic compound and a substance that exhibits acceptor properties for the thirteenth organic compound, holes are generated by charge separation, and when a voltage is applied between the first electrode 101 and the second electrode 102, the holes are injected into the second light-emitting unit 502 on the cathode side via the thirteenth organic compound. This allows the light-emitting device 130 described in this embodiment to be a light-emitting device with a low driving voltage.

[0264] As the thirteenth organic compound having hole transport properties, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymeric compounds (oligomers, dendrimers, polymers, etc.) can be used. -6 cm 2The thirteenth organic compound is preferably an organic compound having a hole mobility of 1 / Vs or more. The thirteenth organic compound is preferably a compound having a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. The fused aromatic hydrocarbon ring is preferably an anthracene ring, a naphthalene ring, or the like. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton, and more preferably a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to the carbazole ring, a dibenzothiophene ring, or the like.

[0265] Such organic compounds having hole-transporting properties preferably have a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. It is preferable that these organic compounds having hole-transporting properties are substances having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of light-emitting devices with long lifetimes.

[0266] Specifically, as the organic compound having the hole-transporting property as described above, the organic compounds listed as the organic compounds having the hole-transporting property that can be used in the hole injection layer 111 can be similarly used.

[0267] As the substance having acceptor properties, for example, the substances exemplified as organic compounds having acceptor properties that can be used in the hole-injection layer 111 can be similarly used. In particular, organic compounds having at least one of a halogen group and a cyano group are preferred, and organic compounds having at least one of a fluorine group and a cyano group are more preferred. It is more preferred that the organic compound contains four or more halogen groups (fluorine) and cyano groups in total. Examples of organic compounds having at least one of a halogen group and a cyano group include α,α',α''-1,2,3-cyclopropane triylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropane triylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0268] The material having acceptor properties preferably has electron-accepting properties for the thirteenth organic compound having hole-transporting properties. When the material having acceptor properties has electron-accepting properties for the thirteenth organic compound, charge separation occurs, and the second layer 117 can function as a charge-generating layer and as a tandem intermediate layer. In addition, the second layer 117 preferably exhibits a signal observed by electron spin resonance. For example, the spin density resulting from a signal observed around a g-value of 2.00 is 1×10 17 spins / cm 3 More than 1×10 is preferable. 18 spins / cm 3 More than 1×10 is preferable. 19 spins / cm 3 The above is even more preferable.

[0269] The third layer 118 contains a substance having an electron transporting property, and has functions such as preventing interaction between the first layer 119 and the second layer 117, smoothing the transfer of electrons to reduce the driving voltage, and reducing the interaction between the first layer 119 and the second layer 117 to improve reliability.

[0270] The LUMO level of the substance having electron-transporting properties contained in the third layer 118 is preferably between the LUMO level of the substance having acceptor properties in the second layer 117 and the LUMO level of the organic compound contained in the layer in contact with the first layer 119 in the light-emitting unit on the anode side (the first electron-transporting layer 114_1 in the first light-emitting unit 501 in Figure 5(A)).

[0271] The specific energy level of the LUMO level of the substance having an electron-transporting property used in the third layer 118 is preferably −5.0 eV or higher, preferably −5.0 eV or higher to −3.0 eV or lower, more preferably −4.30 eV or higher to −3.00 eV or lower, and still more preferably −4.30 eV or higher to −3.30 eV or lower, in order to suppress an increase in driving voltage. Note that the substance having an electron-transporting property used in the third layer 118 is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0272] Specific examples of the substance having an electron transport property that can be used for the third layer 118 include diquinoxalino[2,3-a:2′,3′-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2′,3′-c]phenazine (abbreviation: HATNA-F6), perylene tetracarboxylic acid derivatives such as 3,4,9,10-perylene tetracarboxylic diimide (abbreviation: PTCDI) and 3,4,9,10-perylene tetracarboxylic-bis-benzimidazole (abbreviation: PTCBI), (C60-Ih)[5,6]fullerene (abbreviation: C60), and (C70-D5h)[5,6]fullerene (abbreviation: C70). Compounds having a heterophane skeleton, which is a cyclophane skeleton containing a heterocycle, can also be used, including phthalocyanine compounds such as phthalocyanine (abbreviated as HPc). Metal phthalocyanines containing copper, zinc, cobalt, iron, chromium, nickel, etc., such as copper phthalocyanine (abbreviated as CuPc), zinc phthalocyanine (abbreviated as ZnPc), cobalt phthalocyanine (abbreviated as CoPc), iron phthalocyanine (abbreviated as FePc), tin phthalocyanine (abbreviated as SnPc), tin oxide phthalocyanine (abbreviated as SnOPc), titanium oxide phthalocyanine (abbreviated as TiOPc), and vanadium oxide phthalocyanine (abbreviated as VOPc), as well as derivatives thereof, can also be used. Also preferred are metal complexes of the phthalocyanine series, such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine.

[0273] The thickness of the third layer 118 is preferably 1 nm or more and 10 nm or less, and more preferably 2 nm or more and 5 nm or less.

[0274] Since the second layer 117 in the intermediate layer 116 functions as a hole injection layer, the second light-emitting unit 502 does not have a hole injection layer, but the second light-emitting unit 502 may have a hole injection layer.

[0275] The second electrode 102 is an electrode including a cathode. The second electrode 102 may have a laminated structure, in which case the layer in contact with the organic compound layer 103 functions as the cathode. Materials that form the cathode include metals, alloys, electrically conductive compounds, and mixtures thereof, each having a low work function (specifically, 3.8 eV or less). Specific examples of such cathode materials include alkali metals such as lithium (Li) or cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing these elements (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these elements. Specific examples include alkali metals, alkaline earth metals, rare earth metals, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-hydroxyquinolinato-lithium (abbreviated as Liq), and Yb, as well as compounds or complexes thereof, and electrides. Examples of electrides include a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. Two or more of these may be mixed and used. When the second electrode 102 has a laminated structure, materials with good conductivity can be used for the components other than the cathode, regardless of their work function.

[0276] Note that the second electron-transport layer 114_2 is preferably in contact with the second electrode 102. When the second electron-transport layer 114_2 is in contact with the second electrode 102, a light-emitting device having excellent electron injection and electron transport properties, low driving voltage, and low power consumption can be provided.

[0277] When the second electrode 102 is formed using a material that is transparent to visible light, a light-emitting device that emits light from the second electrode 102 side can be obtained.

[0278] These conductive materials can be formed into films by dry methods such as vacuum deposition or sputtering, inkjet methods, spin coating, etc. Alternatively, they may be formed by wet methods using a sol-gel method, or by wet methods using a paste of a metal material.

[0279] In addition, various methods, whether dry or wet, can be used to form the organic compound layer 103. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, spin coating, or the like may be used.

[0280] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0281] 5C shows two adjacent light-emitting devices (a light-emitting device 130a and a light-emitting device 130b) included in a display device of one embodiment of the present invention. At least one of the light-emitting device 130a and the light-emitting device 130b preferably uses the structure example 1.

[0282] The light-emitting device 130a includes an organic compound layer 103a between a first electrode 101a and a second electrode 102 on an insulating layer 175. The organic compound layer 103a includes a first light-emitting unit 501a and a second light-emitting unit 502a stacked with an intermediate layer 116a sandwiched therebetween. While FIG. 5C shows an example in which two light-emitting units are stacked, a configuration in which three or more light-emitting units are stacked may also be used. The first light-emitting unit 501a includes a hole-injection layer 111a, a first hole-transport layer 112a_1, a first light-emitting layer 113a_1, and a first electron-transport layer 114a_1. The intermediate layer 116a includes a second layer 117a, a third layer 118a, and a first layer 119a. The third layer 118a is optional. The second light-emitting unit 502a includes a second hole-transporting layer 112a_2, a second light-emitting layer 113a_2, and a second electron-transporting layer 114a_2.

[0283] The light-emitting device 130b includes an organic compound layer 103b between a first electrode 101b and a second electrode 102 on an insulating layer 175. The organic compound layer 103b includes a first light-emitting unit 501b and a second light-emitting unit 502b stacked with an intermediate layer 116b sandwiched therebetween. While FIG. 5C shows an example in which two light-emitting units are stacked, a configuration in which three or more light-emitting units are stacked may also be used. The first light-emitting unit 501b includes a hole injection layer 111b, a first hole transport layer 112b_1, a first light-emitting layer 113b_1, and a first electron transport layer 114b_1. The intermediate layer 116b includes a second layer 117b, a third layer 118b, and a first layer 119b. The third layer 118b is optional. The second light-emitting unit 502b includes a second hole-transporting layer 112b_2, a second light-emitting layer 113b_2, and a second electron-transporting layer 114b_2.

[0284] The second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 are layers containing an eleventh organic compound having a triazine skeleton. The first layer 119a and the first layer 119b are layers containing a twelfth organic compound having a phenanthroline skeleton.

[0285] The first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are preferably light-emitting layers that emit light of similar colors. Furthermore, the luminescent center substances contained in each layer are preferably compounds whose difference in maximum peak wavelength in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less, and it is even more preferable that the luminescent center substances contained therein are the same. Furthermore, the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are preferably made of the same material. Preferably, one or, preferably both, of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 has the light-emitting layer configuration of one embodiment of the present invention described above.

[0286] The first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are preferably light-emitting layers that emit light of similar colors. Furthermore, the luminescent center substances contained in each layer are preferably compounds whose difference in maximum peak wavelength in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less, and it is even more preferable that the luminescent center substances contained in each layer are the same. Furthermore, the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are preferably made of the same material. Preferably, one or both of the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 have the structure of the light-emitting layer according to one embodiment of the present invention described above.

[0287] Preferably, the first light-emitting layer 113a_1 and the first light-emitting layer 113b_1 are separated, and the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 are separated. Preferably, the emission colors of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are different from the emission colors of the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2. Preferably, the luminescent center substance contained in the first light-emitting layer 113a_1 is different from the luminescent center substance contained in the first light-emitting layer 113b_1, and the luminescent center substance contained in the second light-emitting layer 113a_2 is different from the luminescent center substance contained in the second light-emitting layer 113b_2.

[0288] The hole injection layer 111a and the hole injection layer 111b, the first hole transport layer 112a_1 and the first hole transport layer 112b_1, the first electron transport layer 114a_1 and the first electron transport layer 114b_1, the intermediate layer 116a and the intermediate layer 116b (the second layer 117a and the second layer 117b, the third layer 118a and the third layer 118b, and the first layer 119a and the first layer 119b), the second hole transport layer 112a_2 and the second hole transport layer 112b_2, and the second electron transport layer 114a_2 and the second electron transport layer 114b_2 may be continuous layers or may be separate layers in the light-emitting device 130a and the light-emitting device 130b. Being continuous layers improves productivity and enables light-emitting devices to be produced inexpensively. The separate layers for each light-emitting device allow the use of materials suited to the emission color, thereby enabling the manufacture of light-emitting devices or display devices with excellent characteristics. In particular, the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 are preferably continuous layers, since this allows both the light-emitting device 130a and the light-emitting device 130b to have excellent characteristics.

[0289] Being a continuous layer means that the second electron transport layer 114a_2 and the second electron transport layer 114b_2 are layers made of the same material. That is, when the second electron transport layer 114a_2 and the second electron transport layer 114b_2 are layers made of the same material, both the light-emitting device 130a and the light-emitting device 130b can be light-emitting devices with excellent characteristics. Furthermore, it is more preferable that the second electron transport layer 114a_2 and the second electron transport layer 114b_2 are layers having similar structures, and it is even more preferable that they are layers having the same structure.

[0290] Furthermore, when the luminescent center substance contained in the first light-emitting layer 113a_1 is a different substance from the luminescent center substance contained in the first light-emitting layer 113b_1, and when the luminescent center substance contained in the second light-emitting layer 113a_2 is a different substance from the luminescent center substance contained in the second light-emitting layer 113b_2 (for example, when the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are blue fluorescent light-emitting layers and the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are green phosphorescent light-emitting layers, or When the first and second light-emitting layers 113a_1 and 113a_2 are blue fluorescent light-emitting layers and the first and second light-emitting layers 113b_1 and 113b_2 are red phosphorescent light-emitting layers, or when the first and second light-emitting layers 113a_1 and 113a_2 are green phosphorescent light-emitting layers and the first and second light-emitting layers 113b_1 and 113b_2 are red phosphorescent light-emitting layers, the carrier balances of the light-emitting layers of the light-emitting devices 130a and 130b are different. Therefore, to maximize the performance of each of the light-emitting devices 130a and 130b, appropriate intermediate layers and electron-transporting layers must be selected and changed. However, by applying a layer containing an eleventh organic compound having a triazine skeleton to the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 and applying a layer containing a twelfth organic compound having a phenanthroline skeleton to the first layer 119a and the first layer 119b, it is possible to obtain the performance of both the light-emitting device 130a and the light-emitting device 130b even if the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 have the same structure. In other words, it is possible to achieve both improved productivity and improved performance. Note that the first layer 119a and the first layer 119b may have the same structure.

[0291] The continuous layer is a so-called common layer that is formed across both the light-emitting device 130a and the light-emitting device 130b.

[0292] FIG. 6(A) is a modified example of FIG. 5(C). Light-emitting device 130a and light-emitting device 130b emit light of different colors, and therefore have different optical path lengths between electrodes that can amplify light emission using microcavities. Therefore, in light-emitting device 130b1, the distance between the electrodes can be adjusted by increasing the thickness of light-emitting layers such as light-emitting layer 113b_11 and light-emitting layer 113b_21. Alternatively, the optical path length can be changed by thickening or adding a functional layer, such as hole-transport layer 112b_21.

[0293] FIG. 6B illustrates three adjacent light-emitting devices (light-emitting device 130a, light-emitting device 130b1, and light-emitting device 130c) included in a display device of one embodiment of the present invention.

[0294] The light-emitting device 130c includes an organic compound layer 103c between a first electrode 101c and a second electrode 102 on an insulating layer 175. The organic compound layer 103c includes a first light-emitting unit 501c and a second light-emitting unit 502c stacked with an intermediate layer 116c sandwiched therebetween. While FIG. 6B shows an example in which two light-emitting units are stacked, a stack of three or more light-emitting units may also be used. The first light-emitting unit 501c includes a hole-injection layer 111c, a first hole-transport layer 112c_1, a first light-emitting layer 113c_1, and a first electron-transport layer 114c_1. The intermediate layer 116c includes a second layer 117c, a third layer 118c, and a first layer 119c. The third layer 118c is optional. The second light-emitting unit 502c includes a second hole-transporting layer 112c_2, a second light-emitting layer 113c_2, and a second electron-transporting layer 114c_2.

[0295] The light emitted from the light-emitting device 130c is assumed to have a shorter wavelength than the light-emitting devices 130a and 130b1. The distance between the electrodes of the light-emitting device 130c is adjusted by making the film thicknesses of the light-emitting layers 113c_1 and 113c_2 thinner than those of the other two light-emitting devices.

[0296] The second electron-transporting layer 114c_2 is a layer including an eleventh organic compound having a triazine skeleton, and the first layer 119c is a layer including a twelfth organic compound having a phenanthroline skeleton.

[0297] The first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 are preferably light-emitting layers that emit light of similar colors. Furthermore, the luminescent center substances contained in each layer are preferably compounds whose difference in maximum peak wavelength in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less, and it is even more preferable that the luminescent center substances contained in each layer are the same. Furthermore, the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 are preferably made of the same material. Preferably, one or both of the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 have the light-emitting layer configuration of one embodiment of the present invention described above.

[0298] Preferably, the first light-emitting layer 113a_1 and the first light-emitting layer 113c_1 are separated, and the second light-emitting layer 113a_2 and the second light-emitting layer 113c_2 are separated. Preferably, the emission colors of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are different from the emission colors of the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2. Preferably, the luminescent center substance contained in the first light-emitting layer 113a_1 is different from the luminescent center substance contained in the first light-emitting layer 113c_1, and the luminescent center substance contained in the second light-emitting layer 113a_2 is different from the luminescent center substance contained in the second light-emitting layer 113c_2.

[0299] In this example, the hole injection layer 111a and the hole injection layer 111c, the first hole transport layer 112a_1 and the first hole transport layer 112c_1, the first electron transport layer 114a_1 and the first electron transport layer 114c_1, the intermediate layer 116a and the intermediate layer 116c (the second layer 117a and the second layer 117c, the third layer 118a and the third layer 118c, and the first layer 119a and the first layer 119c), and the second hole transport layer 112a_2 and the second hole transport layer 112c_2 are each independently separated in the light-emitting device 130a and the light-emitting device 130c, while the second electron transport layer 114a_2 and the second electron transport layer 114c_2 are a continuous layer. In this way, a single light-emitting device may include both continuous and separated layers. This allows a light-emitting device or display device with a good balance between productivity and performance to be manufactured. In particular, the second electron-transporting layer 114a_2 and the second electron-transporting layer 114c_2 are preferably formed as a continuous layer, which allows both the light-emitting device 130a and the light-emitting device 130c to have good performance.

[0300] For example, in a three-color light-emitting device having two light-emitting devices with fluorescent luminescent center substances and one light-emitting device with phosphorescent luminescent center substances, it is preferable that the carrier transport layer in the light-emitting device with fluorescent luminescent center substances be formed as a continuous layer, and that the carrier transport layer in the light-emitting device with phosphorescent luminescent center substances be formed as a layer separated from the light-emitting devices emitting other luminescent colors. Alternatively, in a three-color light-emitting device having two light-emitting devices with phosphorescent luminescent center substances and one light-emitting device with fluorescent luminescent center substances, it is preferable that the carrier transport layer in the light-emitting device with phosphorescent luminescent center substances be formed as a continuous layer, and that the carrier transport layer in the light-emitting device with fluorescent luminescent center substances be formed as a layer separated from the light-emitting devices emitting other luminescent colors.

[0301] The light-emitting device described in this embodiment having such a structure can be a light-emitting device with high current efficiency, low energy loss, and favorable characteristics. A display device according to one embodiment of the present invention using such a light-emitting device can be a display device with low power consumption, high reliability, and high luminance, and thus has favorable visibility. This embodiment can be freely combined with other embodiments or examples.

[0302] (Embodiment 2) In this embodiment, a second structural example of a light-emitting device that can be used for a display device according to one embodiment of the present invention will be described.

[0303] <Configuration example 2> Structure Example 2 is different from Structure Example 1 described in Embodiment 1 in that two substances (the first host material and the second host material) that function as host materials in Structure Example 1 do not contain deuterium. The light-emitting device in Structure Example 2 is otherwise the same as Structure Example 1. As described above, Structure Example 1 further improves reliability by using an organic compound containing deuterium as one or both of the first host material and the second host material. Therefore, when Structure Example 2 is used in a display device of one embodiment of the present invention, it is more preferable to use Structure Example 1 in combination. For example, it is preferable to use Structure Example 1 for any one of the subpixels 110R, 110G, and 110B shown in FIG. 2B and to use Structure Example 2 for any of the others. In the display device of one embodiment of the present invention, the area of ​​the subpixel using Structure Example 2 can be larger than the area of ​​the subpixel using Structure Example 1, which has higher reliability. This can further improve the reliability of the pixel using Structure Example 2 and the reliability of the entire pixel.

[0304] For example, in the case of a tandem light-emitting device having two light-emitting layers, a third light-emitting layer and a fourth light-emitting layer, the third light-emitting layer preferably contains a third light-emitting center substance, a fifth organic compound, and a sixth organic compound, and the fourth light-emitting layer preferably contains a seventh organic compound and an eighth organic compound. The fifth organic compound and the seventh organic compound correspond to the first host material, and the sixth organic compound and the eighth organic compound correspond to the second host material, respectively. The third light-emitting layer and the fourth light-emitting layer preferably have the above-described light-emitting layer configuration.

[0305] Specifically, the fifth organic compound and the seventh organic compound are organic compounds having electron transport properties and preferably contain a π-electron-deficient heteroaromatic ring. The sixth organic compound and the eighth organic compound are organic compounds having hole transport properties and preferably contain a π-electron-rich heteroaromatic ring or an aromatic amine skeleton. The fifth organic compound and the sixth organic compound, and the seventh organic compound and the eighth organic compound, are preferably combined to form exciplexes. The difference between the T1 level of the fifth organic compound and the sixth organic compound, and the difference between the T1 level of the seventh organic compound and the eighth organic compound, are preferably 0.20 eV or less, preferably 0.15 eV or less, and more preferably 0.10 eV or less. The other structures described above can also be applied to each light-emitting layer by replacing the first host material with a "fifth organic compound" or a "seventh organic compound" and the second host material with a "sixth organic compound" or an "eighth organic compound."

[0306] In this specification, terms such as "fifth organic compound," "sixth organic compound," "seventh organic compound," and "eighth organic compound" can also be used to explain Configuration Example 1.

[0307] In Configuration Example 2, for organic compounds that can be used as the first host material and the second host material, reference can be made to the examples of the organic compound having an electron-transport property and the organic compound having a hole-transport property described in Configuration Example 1.

[0308] The light-emitting device described in this embodiment having such a structure can be a light-emitting device with high current efficiency, low energy loss, and favorable characteristics. A display device according to one embodiment of the present invention using such a light-emitting device can be a display device with low power consumption, high reliability, and high luminance, and thus has favorable visibility. This embodiment can be freely combined with other embodiments or examples.

[0309] (Embodiment 3) In this embodiment, a third structural example of a light-emitting device that can be used for a display device according to one embodiment of the present invention will be described.

[0310] <Configuration example 3> Structure Example 3 differs from Structure Examples 1 and 2 in that the light-emitting device includes an emitting substance and one substance functioning as a host material in the light-emitting layer. However, the structures other than the light-emitting layer are the same as those of Structure Examples 1 and 2. As described above, Structure Examples 1 and 2 use two substances (a first host material and a second host material) functioning as host materials to improve the emission efficiency. Therefore, when Structure Example 3 is used in a display device of one embodiment of the present invention, it is more preferable to use it in combination with Structure Example 1. For example, it is preferable to use Structure Example 1 for one of the subpixels 110R, 110G, and 110B shown in FIG. 2B, use Structure Example 2 for another one, and use Structure Example 3 for still another one. In the display device of one embodiment of the present invention, the area of ​​the subpixel using Structure Example 3 can be larger than the areas of the subpixels using Structure Examples 1 and 2, which have higher reliability. Therefore, the luminance of the pixel using Structure Example 3 can be increased, thereby improving the reliability of the entire pixel.

[0311] For example, in the case of a tandem light-emitting device having two light-emitting layers, a fifth light-emitting layer and a sixth light-emitting layer, the fifth light-emitting layer contains a fifth light-emitting center substance and a ninth organic compound, and the sixth light-emitting layer contains a tenth organic compound. The ninth organic compound and the tenth organic compound each correspond to a host material.

[0312] In Configuration Example 3, the luminescent center substance is more preferably a fluorescent substance. When the luminescent center substance is a fluorescent substance, the luminous efficiency is less likely to decrease even when only one host material is used, compared to when the luminescent center substance is a phosphorescent material. In Configuration Example 3, the examples of organic compounds in Configuration Example 1 can be referred to for fluorescent substances and host materials that can be used as the luminescent center substance.

[0313] This embodiment mode can be freely combined with other embodiment modes or examples.

[0314] (Fourth embodiment) 7A and 7B, a display device is formed by forming a plurality of light-emitting devices 130 over an insulating layer 175. In this embodiment, a display device according to another embodiment of the present invention will be described in detail.

[0315] The display device 100 has a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 has a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0316] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. This allows an image to be displayed in the pixel section 177. Note that, in this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are described as an example, but combinations of sub-pixels of other colors may also be used. Furthermore, the number of sub-pixels is not limited to three, and may be four or more.

[0317] In this specification, the row direction may be referred to as the X direction, and the column direction may be referred to as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly.

[0318] 7A shows an example in which sub-pixels of different colors are arranged side by side in the X direction, and sub-pixels of the same color are arranged side by side in the Y direction. Note that sub-pixels of different colors may also be arranged side by side in the Y direction, and sub-pixels of the same color may also be arranged side by side in the X direction.

[0319] A connection section 140 may be provided outside the pixel section 177, and a region 141 may also be provided. When the region 141 is provided, the region 141 is provided between the pixel section 177 and the connection section 140. When the region 141 is provided, an organic compound layer is provided in the region 141. Furthermore, a conductive layer 151C is provided in the connection section 140.

[0320] 7A shows an example in which the region 141 and the connection portion 140 are located on the right side of the pixel portion 177, but the positions of the region 141 and the connection portion 140 are not particularly limited. The region 141 and the connection portion 140 may be singular or plural.

[0321] Fig. 7(B) is an example of a cross-sectional view taken along dashed line A1-A2 in Fig. 7(A). As shown in Fig. 7(B), the display device 100 includes an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and on the conductive layer 172, an insulating layer 174 on the insulating layer 173, and an insulating layer 175 on the insulating layer 174. The insulating layer 171 is provided on a substrate (not shown). The insulating layers 175, 174, and 173 have openings that reach the conductive layer 172, and plugs 176 are provided to fill the openings.

[0322] In the pixel section 177, the light-emitting device 130 is provided on the insulating layer 175 and the plug 176. A protective layer 131 is provided to cover the light-emitting device 130. The substrate 120 is bonded to the protective layer 131 by a resin layer 122. Preferably, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are provided between adjacent light-emitting devices 130.

[0323] Although multiple cross sections of the inorganic insulating layer 125 and the insulating layer 127 are shown in FIG. 7B, when the display device 100 is viewed from above, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are each connected into one.

[0324] 7(B) shows light emitting device 130R, light emitting device 130G, and light emitting device 130B. Light emitting device 130R, light emitting device 130G, and light emitting device 130B emit light of different colors. For example, light emitting device 130R can emit red light, light emitting device 130G can emit green light, and light emitting device 130B can emit blue light. Light emitting device 130R, light emitting device 130G, or light emitting device 130B may also emit other visible light or infrared light.

[0325] The display device of one embodiment of the present invention can be, for example, a top-emission type that emits light in the direction opposite to the substrate on which the light-emitting device is formed. Note that the display device of one embodiment of the present invention may also be a bottom-emission type.

[0326] The light-emitting device 130R has a first electrode 101R (pixel electrode) composed of a conductive layer 151R and a conductive layer 152R, an organic compound layer 103R on the first electrode, a common layer 104 on the organic compound layer 103R, and a second electrode (common electrode) 102 on the common layer. Note that the common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103R during processing.

[0327] The light-emitting device 130G has a first electrode 101G (pixel electrode) composed of a conductive layer 151G and a conductive layer 152G, an organic compound layer 103G on the first electrode, a common layer 104 on the organic compound layer 103G, and a second electrode (common electrode) 102 on the common layer 104. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103G during processing.

[0328] The light-emitting device 130B has the same configuration as that described in Embodiment 2. It includes a first electrode 101B (pixel electrode) composed of a conductive layer 151B and a conductive layer 152B, an organic compound layer 103B on the first electrode, a common layer 104 on the organic compound layer 103B, and a second electrode (common electrode) 102 on the common layer. The common layer 104 may or may not be provided, but is preferably provided because it reduces damage to the organic compound layer 103B during processing. When the common layer 104 is provided, the stacked structure of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103 in Embodiment 2. When the common layer 104 is not provided, the organic compound layer 103B corresponds to the organic compound layer 103 in Embodiment 2.

[0329] The common layer 104 is preferably an electron transport layer. When the common layer 104 is an electron transport layer, the electron transport layer preferably has a laminated structure, and it is more preferable that the layer on the second electrode side is the common layer 104 and the layer on the light-emitting layer side is the organic compound layer 103.

[0330] The light emitting devices 130R and 130G are also light emitting devices fabricated through a photolithography process.

[0331] One of the pixel electrode and the common electrode of the light-emitting device 130 functions as an anode, and the other functions as a cathode. In the following description, unless otherwise specified, the pixel electrode functions as an anode and the common electrode functions as a cathode.

[0332] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independent and island-shaped for each light-emitting device. By providing the organic compound layer 103 in an island shape for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in a high-resolution display device. This makes it possible to prevent crosstalk and realize a display device with extremely high contrast. In particular, a display device with high current efficiency at low brightness can be realized.

[0333] The island-shaped organic compound layer 103 is formed by depositing an organic compound film and processing the organic compound film using a photolithography method.

[0334] The organic compound layer 103 is preferably provided so as to cover the top and side surfaces of the first electrode (pixel electrode) of the light-emitting device 130. This makes it easier to increase the aperture ratio of the display device 100 compared to a configuration in which the end of the organic compound layer 103 is located inside the end of the pixel electrode. Furthermore, covering the side surfaces of the pixel electrode of the light-emitting device 130 with the organic compound layer 103 prevents the pixel electrode from coming into contact with the second electrode 102, thereby preventing short circuits in the light-emitting device 130.

[0335] In the display device of one embodiment of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a stacked-layer structure. For example, in the example shown in FIG. 7B, the first electrode of the light-emitting device 130 has a stacked-layer structure of a conductive layer 151 and a conductive layer 152.

[0336] For example, a metal material can be used for the conductive layer 151. Specifically, metals such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), neodymium (Nd), etc., and alloys containing appropriate combinations of these metals can also be used.

[0337] The conductive layer 152 can be formed using an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, it is preferable to use a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. In particular, indium tin oxide containing silicon has a large work function, for example, a work function of 4.0 eV or more, and therefore can be suitably used for the conductive layer 152.

[0338] The conductive layer 151 may have a stacked structure of multiple layers containing different materials, and the conductive layer 152 may have a stacked structure of multiple layers containing different materials. In this case, the conductive layer 151 may include a layer containing a material that can be used for the conductive layer 152, such as a conductive oxide, or the conductive layer 152 may include a layer containing a material that can be used for the conductive layer 151, such as a metal material. For example, when the conductive layer 151 has a stacked structure of two or more layers, a layer in contact with the conductive layer 152 can be a layer containing a material that can be used for the conductive layer 152.

[0339] Next, an example of a method for manufacturing the display device 100 having the configuration shown in FIG. 7A will be described with reference to FIGS.

[0340] [Production method example 1] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum deposition method, a pulsed laser deposition (PLD) method, an ALD method, etc.

[0341] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by wet film formation methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0342] Furthermore, when processing the thin films that constitute the display device, they can be processed using, for example, photolithography.

[0343] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, and ArF laser light. Exposure may also be performed using immersion exposure techniques. Extreme ultraviolet (EUV) light or X-rays may also be used as light for exposure. An electron beam may also be used instead of light for exposure.

[0344] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0345] In addition, in the process of creating light-emitting devices, organic compounds that absorb light and become excited are handled. Excited organic compounds may be highly likely to react with oxygen in the atmosphere or water. In other words, when light with a wavelength that the organic compound absorbs is irradiated in the presence of oxygen, degradation products may be generated in the organic compound.

[0346] Therefore, when processing a substrate on which an organic compound is formed by photolithography, if the processing involves exposure to the atmosphere, it is advisable to carry out the processing in an environment where the lighting is appropriately controlled. Ideally, the processing should be carried out under lighting with a wavelength that does not excite the organic compound that absorbs and becomes excited by light. However, in order to ensure illuminance or color rendering properties that do not reduce work efficiency, it is advisable to use lighting with an emission edge at the shortest wavelength of 600 nm or less, preferably 580 nm or less, in the emission edge of the light source's emission spectrum.

[0347] For example, it is preferable to use yellow light (fluorescent lamp or light-emitting diode (LED)) that does not emit light with a wavelength shorter than 500 nm for illumination. It is also preferable to use orange light (fluorescent lamp or light-emitting diode (LED)) that does not emit light with a wavelength shorter than 530 nm. A low-pressure sodium lamp can also be used. Lighting using an optical filter that can block light in the short wavelength range can also be used, and for example, incandescent lamps, fluorescent lamps, light-emitting diodes (LED), halogen lamps, and sunlight can be used. Examples of optical filters that can block light in the short wavelength range include band-pass filters and long-pass filters (short-wavelength cut filters). Furthermore, by using the above-mentioned lighting, the illuminance of the illumination light can be reduced.

[0348] 8(A), an insulating layer 171 is formed on a substrate (not shown). Subsequently, conductive layers 172 and 179 are formed on the insulating layer 171, and an insulating layer 173 is formed on the insulating layer 171 so as to cover the conductive layers 172 and 179. Subsequently, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

[0349] The substrate may be a substrate having heat resistance at least sufficient to withstand subsequent heat treatment, such as a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, a single crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate made of silicon germanium, or an SOI substrate.

[0350] 8A, openings are formed in the insulating layers 175, 174, and 173, reaching the conductive layer 172. Then, plugs 176 are formed to fill the openings.

[0351] 8A, a conductive film 151f, which will later become the conductive layers 151R, 151G, 151B, and 151C, and a conductive film 152f, which will later become the conductive layers 152R, 152G, 152B, and 152C, are formed on the plug 176 and the insulating layer 175. The conductive film 151f can be formed of, for example, a metal material. The conductive film 152f can be formed of, for example, an oxide containing one or more elements selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon.

[0352] 8A, a resist mask 191 is formed over the conductive film 152f. The resist mask 191 can be formed by applying a photosensitive material (photoresist), exposing it to light, and developing it.

[0353] 8B, for example, the conductive film 151f and the conductive film 152f are removed from regions that do not overlap with the resist mask 191. As a result, the conductive layer 151 and the conductive layer 152 are formed.

[0354] 8(C), the resist mask 191 is removed. The resist mask 191 can be removed by ashing using oxygen plasma, for example.

[0355] Next, as shown in FIG. 8(D), an insulating film 156f, which will later become insulating layers 156R, 156G, 156B, and 156C, is formed on conductive layer 152R, conductive layer 152G, conductive layer 152B, conductive layer 152C, and insulating layer 175.

[0356] The insulating film 156f can be an inorganic insulating film such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, or an insulating nitride oxide film, for example, a silicon oxynitride film.

[0357] Subsequently, as shown in FIG. 8(E), the insulating film 156f is processed to form insulating layers 156R, 156G, 156B, and 156C.

[0358] 9(A), the organic compound film 103Rf is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the insulating layer 175. Note that, as shown in FIG. 9(A), the organic compound film 103Rf is not formed on the conductive layer 152C.

[0359] Subsequently, as shown in FIG. 9(A), a sacrificial film 158Rf and a mask film 159Rf are formed.

[0360] By providing the sacrificial film 158Rf on the organic compound film 103Rf, damage to the organic compound film 103Rf during the manufacturing process of the display device can be reduced, and the reliability of the light-emitting device can be improved.

[0361] The sacrificial film 158Rf is made of a film that is highly resistant to the processing conditions of the organic compound film 103Rf, specifically, a film that has a large etching selectivity with respect to the organic compound film 103Rf.The mask film 159Rf is made of a film that has a large etching selectivity with respect to the sacrificial film 158Rf.

[0362] The sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the heat-resistant temperature of the organic compound film 103Rf. The substrate temperature during the formation of the sacrificial film 158Rf and the mask film 159Rf is typically 100° C. to 200° C., preferably 100° C. to 150° C., and more preferably 100° C. to 120° C. The light-emitting device used in the display device of one embodiment of the present invention includes the first compound, and therefore a display device with good display quality can be provided even after a heating step at a higher temperature.

[0363] It is preferable to use films that can be removed by wet etching or dry etching for the sacrificial film 158Rf and the mask film 159Rf.

[0364] The sacrificial film 158Rf formed on and in contact with the organic compound film 103Rf is preferably formed using a method that causes less damage to the organic compound film 103Rf than the mask film 159Rf. For example, the ALD method or the vacuum deposition method is more preferable than the sputtering method.

[0365] The sacrificial film 158Rf and the mask film 159Rf may each be made of one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, an inorganic insulating film, or the like.

[0366] The sacrificial film 158Rf and the mask film 159Rf can be made of metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metal materials. It is particularly preferable to use a low-melting-point material such as aluminum or silver. Using a metal material capable of blocking ultraviolet rays for one or both of the sacrificial film 158Rf and the mask film 159Rf is preferable because it can prevent the organic compound film 103Rf from being irradiated with ultraviolet rays during pattern exposure, thereby suppressing deterioration of the organic compound film 103Rf.

[0367] Furthermore, for the sacrificial film 158Rf and the mask film 159Rf, metal oxides such as In-Ga-Zn oxide, indium oxide, In-Zn oxide, In-Sn oxide, indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), and indium tin oxide containing silicon can be used, respectively.

[0368] In addition, in the above metal oxide, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used instead of gallium.

[0369] For the sacrificial film 158Rf and the mask film 159Rf, it is preferable to use a semiconductor material such as silicon or germanium, which has a high affinity with the semiconductor manufacturing process, or a compound containing the semiconductor material.

[0370] Moreover, various inorganic insulating films can be used for the sacrificial film 158Rf and the mask film 159Rf, respectively. In particular, an oxide insulating film is preferable because it has higher adhesion to the organic compound film 103Rf than a nitride insulating film.

[0371] 9(A), a resist mask 190R is formed. The resist mask 190R can be formed by applying a photosensitive material (photoresist) and then performing exposure and development.

[0372] The resist mask 190R is provided in a position overlapping with the conductive layer 152R. The resist mask 190R is preferably provided also in a position overlapping with the conductive layer 152C, which can prevent the conductive layer 152C from being damaged during the manufacturing process of the display device.

[0373] 9(B), a resist mask 190R is used to remove a portion of the mask film 159Rf to form a mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. The resist mask 190R is then removed. The mask layer 159R is used as a mask (also referred to as a hard mask) to remove a portion of the sacrificial film 158Rf to form a sacrificial layer 158R.

[0374] By using the wet etching method, damage to the organic compound film 103Rf during processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced compared to when using the dry etching method. When using the wet etching method, it is preferable to use an acid aqueous solution such as a developing solution, an alkaline aqueous solution such as a tetramethylammonium hydroxide (TMAH) aqueous solution, or a chemical solution using dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture of these.

[0375] Furthermore, when dry etching is used to process the sacrificial film 158Rf, deterioration of the organic compound film 103Rf can be suppressed by not using a gas containing oxygen as the etching gas.

[0376] The resist mask 190R can be removed in the same manner as the resist mask 191.

[0377] 9(B), the organic compound film 103Rf is processed to form the organic compound layer 103R. For example, the mask layer 159R and the sacrificial layer 158R are used as a hard mask to remove a part of the organic compound film 103Rf, thereby forming the organic compound layer 103R.

[0378] 9B, a stacked structure of the organic compound layer 103R, the sacrificial layer 158R, and the mask layer 159R remains on the conductive layer 152R. Also, the conductive layers 152G and 152B are exposed.

[0379] The organic compound film 103Rf is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0380] When dry etching is used, deterioration of the organic compound film 103Rf can be suppressed by not using an oxygen-containing gas as the etching gas.

[0381] Alternatively, an etching gas containing oxygen may be used. The etching rate can be increased by using an etching gas containing oxygen. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate. This can reduce damage to the organic compound film 103Rf. Furthermore, problems such as adhesion of reaction products generated during etching can be reduced.

[0382] When dry etching is used, it is preferable to use a gas containing one or more of H, CF, C, F, SF, CHF, Cl, H, O, BCl, or Group 18 elements such as He and Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of these elements and oxygen as the etching gas. Alternatively, oxygen gas may be used as the etching gas.

[0383] Subsequently, as shown in FIG. 10(A), an organic compound film 103Gf, which will later become the organic compound layer 103G, is formed.

[0384] The organic compound film 103Gf can be formed by the same method as that used to form the organic compound film 103Rf, and can have the same structure as the organic compound film 103Rf.

[0385] Next, as shown in FIG. 10A, a sacrificial film 158Gf and a mask film 159Gf are formed in this order. Then, a resist mask 190G is formed. The materials and forming methods of the sacrificial film 158Gf and the mask film 159Gf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and forming methods of the resist mask 190G are the same as those applicable to the resist mask 190R.

[0386] The resist mask 190G is provided in a position overlapping with the conductive layer 152G.

[0387] 10(B), a resist mask 190G is used to remove a portion of the mask film 159Gf to form a mask layer 159G. The mask layer 159G remains on the conductive layer 152G. The resist mask 190G is then removed. Next, using the mask layer 159G as a mask, a portion of the sacrificial film 158Gf is removed to form a sacrificial layer 158G. Next, the organic compound film 103Gf is processed to form an organic compound layer 103G.

[0388] Subsequently, as shown in FIG. 10(C), an organic compound film 103Bf is formed.

[0389] The organic compound film 103Bf can be formed by the same method as that used to form the organic compound film 103Rf, and can have the same structure as the organic compound film 103Rf.

[0390] 10(C), a sacrificial film 158Bf and a mask film 159Bf are formed in this order. Then, a resist mask 190B is formed. The materials and forming methods of the sacrificial film 158Bf and the mask film 159Bf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and forming methods of the resist mask 190B are the same as those applicable to the resist mask 190R.

[0391] The resist mask 190B is provided in a position overlapping with the conductive layer 152B.

[0392] 10(D), a resist mask 190B is used to remove a portion of the mask film 159Bf to form a mask layer 159B. The mask layer 159B remains on the conductive layer 152B. The resist mask 190B is then removed. The mask layer 159B is used as a mask to remove a portion of the sacrificial film 158Bf to form a sacrificial layer 158B. The organic compound film 103Bf is then processed to form the organic compound layer 103B. For example, the mask layer 159B and the sacrificial layer 158B are used as hard masks to remove a portion of the organic compound film 103Bf to form the organic compound layer 103B.

[0393] 10D, a stacked structure of the organic compound layer 103B, the sacrificial layer 158B, and the mask layer 159B remains on the conductive layer 152B, and the mask layers 159R and 159G are exposed.

[0394] It is preferable that the side surfaces of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are perpendicular or approximately perpendicular to the surface on which they are formed. For example, it is preferable that the angle formed between the surface on which they are formed and these side surfaces is 60 degrees or more and 90 degrees or less.

[0395] As described above, the distance between adjacent pairs of the organic compound layers 103R, 103G, and 103B formed using photolithography can be narrowed to 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. Here, the distance can be defined, for example, as the distance between the opposing ends of adjacent pairs of the organic compound layers 103R, 103G, and 103B. By narrowing the distance between the island-shaped organic compound layers in this manner, a display device with high definition and a large aperture ratio can be provided. Furthermore, the distance between the first electrodes of adjacent light-emitting devices can also be narrowed, for example, to 10 μm or less, 8 μm or less, 5 μm or less, 3 μm or less, or 2 μm or less. The distance between the first electrodes of adjacent light-emitting devices is preferably 2 μm or more and 5 μm or less.

[0396] Subsequently, as shown in FIG. 11(A), it is preferable to remove the mask layers 159R, 159G, and 159B.

[0397] The mask layer removal process can be performed using the same method as the mask film processing process. In particular, by using a wet etching method, damage to the organic compound layer 103 during the mask layer removal can be reduced compared to when a dry etching method is used.

[0398] The mask layer may also be removed by dissolving it in a polar solvent such as water or alcohol, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0399] After removing the mask layer, a drying treatment may be performed to remove water adsorbed on the surface. For example, a heat treatment can be performed in an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced pressure atmosphere is preferred because it allows drying at a lower temperature.

[0400] Subsequently, as shown in FIG. 11(B), an inorganic insulating film 125f is formed.

[0401] Subsequently, as shown in FIG. 11(C), an insulating film 127f, which will later become the insulating layer 127, is formed on the inorganic insulating film 125f.

[0402] The substrate temperature when forming the inorganic insulating film 125f and the insulating film 127f is preferably 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher, and 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower, respectively.

[0403] As the inorganic insulating film 125f, it is preferable to form an insulating film having a thickness of 3 nm or more, 5 nm or more, or 10 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less within the above substrate temperature range.

[0404] The inorganic insulating film 125f is preferably formed by, for example, the ALD method. The ALD method is preferable because it can reduce film formation damage and also allows for the formation of a film with high coverage. The inorganic insulating film 125f is preferably formed as an aluminum oxide film by, for example, the ALD method.

[0405] The insulating film 127f is preferably formed by the wet film formation method described above. The insulating film 127f is preferably formed by, for example, spin coating using a photosensitive material, more specifically, using a photosensitive resin composition containing an acrylic resin.

[0406] Subsequently, exposure is performed to expose a part of the insulating film 127f to visible light or ultraviolet light. The insulating layer 127 is formed in a region sandwiched between any two of the conductive layers 152R, 152G, and 152B, and around the conductive layer 152C.

[0407] The exposed region of the insulating film 127f can control the width of the insulating layer 127 to be formed later. In this embodiment, the insulating layer 127 is processed so as to have a portion overlapping the upper surface of the conductive layer 151.

[0408] The light used for exposure preferably contains i-line (wavelength 365 nm), and may contain at least one of g-line (wavelength 436 nm) and h-line (wavelength 405 nm).

[0409] Subsequently, as shown in FIG. 12(A), development is carried out to remove the exposed area of ​​the insulating film 127f, thereby forming an insulating layer 127a.

[0410] 12(B), an etching process is performed using the insulating layer 127a as a mask to remove a portion of the inorganic insulating film 125f and reduce the thickness of a portion of the sacrificial layers 158R, 158G, and 158B. As a result, the inorganic insulating layer 125 is formed below the insulating layer 127a. Furthermore, the surfaces of the thin portions of the sacrificial layers 158R, 158G, and 158B are exposed. Note that, hereinafter, the etching process using the insulating layer 127a as a mask may be referred to as the first etching process.

[0411] The first etching process can be performed by dry etching or wet etching. Note that, when the inorganic insulating film 125f is formed using the same material as the sacrificial layers 158R, 158G, and 158B, the first etching process can be performed all at once, which is preferable.

[0412] When dry etching is performed, it is preferable to use a chlorine-based gas. Examples of chlorine-based gases that can be used include Cl2, BCl3, SiCl4, and CCl4, either singly or in combination. Furthermore, oxygen gas, hydrogen gas, helium gas, and argon gas can be added to the chlorine-based gas, either singly or in combination. By using dry etching, thin-film regions of the sacrificial layers 158R, 158G, and 158B can be formed with good in-plane uniformity.

[0413] The dry etching apparatus may be a dry etching apparatus having a high-density plasma source, such as an inductively coupled plasma (ICP) etching apparatus, or a capacitively coupled plasma (CCP) etching apparatus having parallel plate electrodes.

[0414] Furthermore, it is preferable to perform the first etching process by wet etching. Using wet etching can reduce damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B compared to using dry etching. For example, wet etching can be performed using an alkaline solution. For example, TMAH, which is an alkaline solution, can be used for wet etching of an aluminum oxide film. Alternatively, an acid solution containing fluoride can also be used. In this case, wet etching can be performed by a puddle method. Note that, if the inorganic insulating film 125f is formed using the same material as the sacrificial layers 158R, 158G, and 158B, the above-mentioned etching processes can be performed simultaneously, which is preferable.

[0415] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, and the etching process is stopped when the film thicknesses of the sacrificial layers 158R, 158G, and 158B are reduced. In this manner, by leaving the sacrificial layers 158R, 158G, and 158B on the organic compound layers 103R, 103G, and 103B, respectively, it is possible to prevent the organic compound layers 103R, 103G, and 103B from being damaged in subsequent processes.

[0416] Next, the entire substrate is exposed to visible light or ultraviolet light, and the insulating layer 127a is preferably irradiated with the energy density of 0 mJ / cm. 2 Larger, 800mJ / cm 2 It is preferable that the dose is 0 mJ / cm or less, and 2 Larger, 500mJ / cm 2 It is more preferable to perform the following. By performing such exposure after development, the transparency of the insulating layer 127a can be improved in some cases. Furthermore, the substrate temperature required for heat treatment to transform the insulating layer 127a into a tapered shape in a later step can be reduced in some cases.

[0417] Here, the presence of a barrier insulating layer against oxygen (e.g., an aluminum oxide film, etc.) as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B can reduce the diffusion of oxygen into the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B.

[0418] Next, heat treatment (also referred to as post-baking) is performed. By performing the heat treatment, the insulating layer 127a can be transformed into the insulating layer 127 having tapered side surfaces (FIG. 12C). The heat treatment is performed at a temperature lower than the upper temperature limit of the organic compound layer. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., more preferably 70° C. to 130° C. The heating atmosphere may be an air atmosphere or an inert gas atmosphere. The heating atmosphere may be an atmospheric pressure atmosphere or a reduced-pressure atmosphere. This can improve adhesion between the insulating layer 127 and the inorganic insulating layer 125 and also improve corrosion resistance of the insulating layer 127.

[0419] By not completely removing the sacrificial layers 158R, 158G, and 158B in the first etching process and leaving the sacrificial layers 158R, 158G, and 158B in a thinner state, the organic compound layers 103R, 103G, and 103B can be prevented from being damaged and deteriorated in the heat treatment, thereby improving the reliability of the light-emitting device.

[0420] 13(A), an etching process is performed using the insulating layer 127 as a mask to remove portions of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B. As a result, openings are formed in the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, respectively, and the upper surfaces of the organic compound layer 103R, the organic compound layer 103G, the organic compound layer 103B, and the conductive layer 152C are exposed. Note that, hereinafter, this etching process may be referred to as a second etching process.

[0421] The end of the inorganic insulating layer 125 is covered with the insulating layer 127. Also, Fig. 13(A) shows an example in which part of the end of the sacrificial layer 158G (specifically, the tapered portion formed by the first etching process) is covered with the insulating layer 127, and the tapered portion formed by the second etching process is exposed.

[0422] The second etching process is performed by wet etching. By using wet etching, damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be reduced compared to when dry etching is used. Wet etching can be performed using, for example, an alkaline solution or an acidic solution. It is preferable to use an aqueous solution so that the organic compound layer 103 does not dissolve.

[0423] 13(B), a common electrode 155 is formed on the organic compound layer 103R, the organic compound layer 103G, the organic compound layer 103B, the conductive layer 152C, and the insulating layer 127. The common electrode 155 can be formed by a method such as sputtering or vacuum deposition.

[0424] 13(C), a protective layer 131 is formed on the common electrode 155. The protective layer 131 can be formed by a method such as vacuum deposition, sputtering, CVD, or ALD. The protective layer 131 may also function as a cap layer. For example, by using a material having an ordinary refractive index (no) of 1.90 or more at a wavelength of 450 nm, an ordinary refractive index (no) of 1.80 or more at a wavelength of 520 nm, or an ordinary refractive index (no) of 1.75 or more at a wavelength of 630 nm, it is possible to prevent light from the organic compound layer 103 from being totally reflected by the cap layer, thereby improving the light extraction efficiency.

[0425] Furthermore, to prevent the light-emitting device from being exposed to the atmosphere before being incorporated into a display device, a sealing film may be provided on the protective layer 131. A material that is impermeable to impurities such as oxygen and water can be used for the sealing film. Specifically, an alumina oxide film may be provided by the ALD method. After the protective layer 131 is formed, the light-emitting device may be transported into the ALD apparatus in a glove box with a nitrogen atmosphere in order to prevent the light-emitting device from being exposed to the atmosphere until the sealing film is provided. At this time, the oxygen concentration in the glove box is preferably 100 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less.

[0426] Subsequently, the substrate 120 is attached to the protective layer 131 or the sealing film using the resin layer 122, whereby a display device can be manufactured. As described above, in the method for manufacturing a display device of one embodiment of the present invention, the insulating layer 156 is provided so as to have a region overlapping with a side surface of the conductive layer 151, and the conductive layer 152 is formed so as to cover the conductive layer 151 and the insulating layer 156. This can increase the yield of the display device and suppress the occurrence of defects. Note that a display device having a microlens array can also be manufactured by providing a microlens array on the protective layer 131 or the sealing film before attaching the substrate 120, and then attaching the substrate 120.

[0427] As described above, in the manufacturing method of a display device according to one embodiment of the present invention, the island-shaped organic compound layers 103R, 103G, and 103B are formed by forming films over the entire surface and then processing them, rather than using a fine metal mask. This allows the island-shaped layers to be formed with uniform thicknesses. This allows a high-resolution display device or a display device with a high aperture ratio to be realized. Furthermore, even when the resolution or aperture ratio is high and the distance between subpixels is extremely short, the organic compound layers 103R, 103G, and 103B can be prevented from contacting each other in adjacent subpixels. Therefore, leakage current between subpixels can be suppressed. This prevents crosstalk and realizes a display device with extremely high contrast. Furthermore, even in a display device including tandem light-emitting devices fabricated by photolithography, a display device with excellent characteristics can be provided.

[0428] (Embodiment 5) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0429] The display device of the present embodiment can be a high-definition display device, and can therefore be used as a display unit for information terminals (wearable devices) such as wristwatches and bracelets, as well as for wearable devices that can be worn on the head, such as VR devices such as head-mounted displays (HMDs) and AR devices such as glasses.

[0430] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproducing devices.

[0431] [Display module] 14A shows a perspective view of a display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A, and may be any of display devices 100B to 100G described below.

[0432] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel unit 284 (described later) can be viewed.

[0433] 14(B) is a perspective view schematically showing the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0434] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of Fig. 14(B). The various configurations described in the previous embodiments can be applied to the pixel 284a.

[0435] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0436] One pixel circuit 283a is a circuit that controls the driving of a plurality of elements included in one pixel 284a.

[0437] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a gate line driver circuit and a source line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0438] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may be mounted on the FPC 290.

[0439] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby making it possible to extremely increase the aperture ratio (effective display area ratio) of the display unit 281.

[0440] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as HMDs or glasses-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so that even if the display unit is enlarged with the lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this and can be suitably used in electronic devices having relatively small display units.

[0441] [Display device 100A] The display device 100A shown in FIG. 15A includes a substrate 301, a light-emitting device 130R, a light-emitting device 130G, a light-emitting device 130B, a capacitor 240, and a transistor 310.

[0442] The substrate 301 corresponds to the substrate 291 in FIGS. 14A and 14B. The transistor 310 is a transistor having a channel formation region in the substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities and functions as a source or drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0443] Furthermore, an eleme...

Claims

1. A display device provided with a pixel having a first sub-pixel and a second sub-pixel, the area of ​​the first subpixel is smaller than the area of ​​the second subpixel; the first subpixel includes a first light-emitting device; the second subpixel includes a second light-emitting device; the first light-emitting device includes a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, and a second light-emitting layer; the first intermediate layer is located between the first electrode and the second electrode; the first light-emitting layer is located between the first electrode and the first intermediate layer, the second light-emitting layer is located between the first intermediate layer and the second electrode; the first light-emitting layer includes a first luminescence center substance, a first organic compound, and a second organic compound; the second light-emitting layer includes a second luminescent center substance, a third organic compound, and a fourth organic compound; the first organic compound and the third organic compound each have a π-electron-deficient heteroaromatic ring; the second organic compound and the fourth organic compound each have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; at least one of the first organic compound, the second organic compound, the third organic compound, and the fourth organic compound contains deuterium; a difference between a maximum peak wavelength in an emission spectrum of the first luminescence center substance and a maximum peak wavelength in an emission spectrum of the second luminescence center substance is 30 nm or less; the second light-emitting device includes a third electrode, a fourth electrode, a second intermediate layer, a third light-emitting layer, and a fourth light-emitting layer; the second intermediate layer is located between the third electrode and the fourth electrode; the third light-emitting layer is located between the third electrode and the second intermediate layer, the fourth light-emitting layer is located between the second intermediate layer and the fourth electrode, The display device, wherein the third light-emitting layer and the fourth light-emitting layer emit light of a different hue from the first light-emitting layer and the second light-emitting layer.

2. In claim 1, the third light-emitting layer includes a third light-emitting center substance, a fifth organic compound, and a sixth organic compound; the fourth light-emitting layer includes a fourth light-emitting center substance, a seventh organic compound, and an eighth organic compound; the fifth organic compound and the seventh organic compound each have a π-electron-deficient heteroaromatic ring, the sixth organic compound and the eighth organic compound each have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, a difference between a maximum peak wavelength in the emission spectrum of the third luminescence center substance and a maximum peak wavelength in the emission spectrum of the fourth luminescence center substance is 30 nm or less.

3. A display device provided with a pixel having a first sub-pixel, a second sub-pixel, and a third sub-pixel, the area of ​​the first subpixel is smaller than the area of ​​the second subpixel; the area of ​​the second subpixel is smaller than the area of ​​the third subpixel; the first subpixel includes a first light-emitting device; the second subpixel includes a second light-emitting device; the third subpixel includes a third light-emitting device; the first light-emitting device includes a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, and a second light-emitting layer; the first intermediate layer is located between the first electrode and the second electrode; the first light-emitting layer is located between the first electrode and the first intermediate layer, the second light-emitting layer is located between the first intermediate layer and the second electrode; the first light-emitting layer includes a first luminescence center substance, a first organic compound, and a second organic compound; the second light-emitting layer includes a second luminescent center substance, a third organic compound, and a fourth organic compound; the first organic compound and the third organic compound each have a π-electron-deficient heteroaromatic ring; the second organic compound and the fourth organic compound each have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; at least one of the first organic compound, the second organic compound, the third organic compound, and the fourth organic compound contains deuterium; a difference between a maximum peak wavelength in an emission spectrum of the first luminescence center substance and a maximum peak wavelength in an emission spectrum of the second luminescence center substance is 30 nm or less; the second light-emitting device includes a third electrode, a fourth electrode, a second intermediate layer, a third light-emitting layer, and a fourth light-emitting layer; the second intermediate layer is located between the third electrode and the fourth electrode; the third light-emitting layer is located between the third electrode and the second intermediate layer, the fourth light-emitting layer is located between the second intermediate layer and the fourth electrode, the third light-emitting layer includes a third light-emitting center substance, a fifth organic compound, and a sixth organic compound; the fourth light-emitting layer includes a fourth light-emitting center substance, a seventh organic compound, and an eighth organic compound; the fifth organic compound and the seventh organic compound each have a π-electron-deficient heteroaromatic ring, the sixth organic compound and the eighth organic compound each have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, a difference between a maximum peak wavelength in the emission spectrum of the third luminescent center substance and a maximum peak wavelength in the emission spectrum of the fourth luminescent center substance is 30 nm or less; the third light-emitting layer and the fourth light-emitting layer emit light of a different hue from the first light-emitting layer and the second light-emitting layer; the third light-emitting device has a fifth electrode, a sixth electrode, a third intermediate layer, a fifth light-emitting layer, and a sixth light-emitting layer; the third intermediate layer is located between the fifth electrode and the sixth electrode; the fifth light-emitting layer is located between the fifth electrode and the third intermediate layer, the sixth light-emitting layer is located between the third intermediate layer and the sixth electrode, a fifth light-emitting layer and a sixth light-emitting layer that emit light of a different hue from the first light-emitting layer, the second light-emitting layer, the third light-emitting layer, and the fourth light-emitting layer;

4. A display device provided with a pixel having a first sub-pixel, a second sub-pixel, and a third sub-pixel, an area of ​​the first subpixel and an area of ​​the second subpixel are each smaller than an area of ​​the third subpixel; the first subpixel includes a first light-emitting device; the second subpixel includes a second light-emitting device; the third subpixel includes a third light-emitting device; the first light-emitting device includes a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, and a second light-emitting layer; the first intermediate layer is located between the first electrode and the second electrode; the first light-emitting layer is located between the first electrode and the first intermediate layer, the second light-emitting layer is located between the first intermediate layer and the second electrode; the first light-emitting layer includes a first luminescence center substance, a first organic compound, and a second organic compound; the second light-emitting layer includes a second luminescent center substance, a third organic compound, and a fourth organic compound; the first organic compound and the third organic compound each have a π-electron-deficient heteroaromatic ring; the second organic compound and the fourth organic compound each have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; at least one of the first organic compound, the second organic compound, the third organic compound, and the fourth organic compound contains deuterium; a difference between a maximum peak wavelength in an emission spectrum of the first luminescence center substance and a maximum peak wavelength in an emission spectrum of the second luminescence center substance is 30 nm or less; the second light-emitting device includes a third electrode, a fourth electrode, a second intermediate layer, a third light-emitting layer, and a fourth light-emitting layer; the second intermediate layer is located between the third electrode and the fourth electrode; the third light-emitting layer is located between the third electrode and the second intermediate layer, the fourth light-emitting layer is located between the second intermediate layer and the fourth electrode, the third light-emitting layer includes a third light-emitting center substance, a fifth organic compound, and a sixth organic compound; the fourth light-emitting layer includes a fourth light-emitting center substance, a seventh organic compound, and an eighth organic compound; the fifth organic compound and the seventh organic compound each have a π-electron-deficient heteroaromatic ring, the sixth organic compound and the eighth organic compound each have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, at least one of the fifth organic compound, the sixth organic compound, the seventh organic compound, and the eighth organic compound contains deuterium; a difference between a maximum peak wavelength in the emission spectrum of the third luminescent center substance and a maximum peak wavelength in the emission spectrum of the fourth luminescent center substance is 30 nm or less; the third light-emitting layer and the fourth light-emitting layer emit light of a different hue from the first light-emitting layer and the second light-emitting layer; the third light-emitting device has a fifth electrode, a sixth electrode, a third intermediate layer, a fifth light-emitting layer, and a sixth light-emitting layer; the third intermediate layer is located between the fifth electrode and the sixth electrode; the fifth light-emitting layer is located between the fifth electrode and the third intermediate layer, the sixth light-emitting layer is located between the third intermediate layer and the sixth electrode, a fifth light-emitting layer and a sixth light-emitting layer that emit light of a different hue from the first light-emitting layer, the second light-emitting layer, the third light-emitting layer, and the fourth light-emitting layer;

5. In any one of claims 1 to 4, the first organic compound and the second organic compound are a combination that forms a first exciplex, The display device, wherein the third organic compound and the fourth organic compound are a combination that forms a second exciplex.

6. In claim 5, a difference between the lowest triplet excitation level of the first organic compound and the lowest triplet excitation level of the second organic compound is 0.30 eV or less; a difference between the lowest triplet excitation level of the third organic compound and the lowest triplet excitation level of the fourth organic compound being 0.30 eV or less;

7. In claim 5, an emission edge on a short wavelength side of the first exciplex is positioned at a wavelength shorter than an absorption edge on a long wavelength side of the first luminescence center substance, A display device, wherein the emission edge on the short wavelength side of the second exciplex is positioned at a wavelength shorter than the absorption edge on the long wavelength side of the second luminescence center substance.

8. In claim 5, The peak energy of the emission spectrum of the first exciplex is higher than the peak energy of the emission spectrum of the first luminescence center substance; and a difference between the peak energy of the emission spectrum of the first exciplex and the peak energy of the emission spectrum of the first luminescence center substance is 0.35 eV or less; The peak energy of the emission spectrum of the second exciplex is higher than the peak energy of the emission spectrum of the second luminescence center substance; and a difference in peak energy of the emission spectrum of the second exciplex and a peak energy of the emission spectrum of the second luminescence center substance being 0.35 eV or less;

9. In any one of claims 2 to 4, the fifth organic compound and the sixth organic compound are a combination that forms a third exciplex, The seventh organic compound and the eighth organic compound are a combination that forms a fourth exciplex.

10. In claim 9, a difference between the lowest triplet excitation level of the fifth organic compound and the lowest triplet excitation level of the sixth organic compound is 0.20 eV or less; a difference between the lowest triplet excitation level of the seventh organic compound and the lowest triplet excitation level of the eighth organic compound being 0.20 eV or less;

11. In claim 9, an emission edge on a short wavelength side of the third exciplex is positioned at a wavelength shorter than an absorption edge on a long wavelength side of the third luminescence center substance; a light emitting edge on the short wavelength side of the fourth exciplex positioned at a wavelength shorter than an absorption edge on the long wavelength side of the fourth luminescence center substance;

12. In claim 9, The peak energy of the emission spectrum of the third exciplex is higher than the peak energy of the emission spectrum of the third luminescence center substance; and a difference between the peak energy of the emission spectrum of the third exciplex and the peak energy of the emission spectrum of the third luminescence center substance is 0.20 eV or less; The peak energy of the emission spectrum of the fourth exciplex is higher than the peak energy of the emission spectrum of the fourth luminescence center substance; and a difference in peak energy of the emission spectrum of the fourth exciplex and a peak energy of the emission spectrum of the fourth luminescence center substance being 0.20 eV or less;

13. In any one of claims 1 to 4, At least one of the first intermediate layer and the second intermediate layer has a mixed layer of an eleventh organic compound and lithium or a lithium compound, The display device, wherein the eleventh organic compound has a phenanthroline skeleton.

14. In any one of claims 1 to 4, the first light-emitting device has a first electron transport layer between the first light-emitting layer and the first intermediate layer, and a second electron transport layer between the second light-emitting layer and the second electrode; the second light-emitting device has a third electron transport layer between the third light-emitting layer and the second intermediate layer, and a fourth electron transport layer between the fourth light-emitting layer and the fourth electrode; at least one of the second electron transport layer and the fourth electron transport layer contains a twelfth organic compound; The display device, wherein the twelfth organic compound has a triazine skeleton.

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