Light emitting device and display apparatus

Abstract

A light-emitting device with favorable characteristics is provided.SOLUTION: A tandem light-emitting device includes a first light-emitting layer containing a first light-emitting substance, a second light-emitting layer containing a second light-emitting substance, each of the first light-emitting substance and the second light-emitting substance being a TADF material, and at least one of a first hole-transport layer and a second hole-transport layer containing an organic compound having a π - electron rich heteroaromatic ring and not having a triarylamine skeleton. The difference between the maximum peak wavelengths of the emission spectra of the first and second light-emitting substances is less than or equal to 30nm, and the first and second light-emitting layers include a light-emitting layer that emits light with a hue different from that of a light-emitting layer included in at least one of a plurality of light-emitting devices adjacent to the light-emitting devices.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a light-emitting device. Note that this 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, a manufacture, or a composition of matter. Therefore, more specific 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, light-emitting devices, lighting devices, power storage devices, memory devices, imaging devices, electronic devices, driving methods thereof, and manufacturing methods thereof. [Background technology]

[0002] In recent years, display devices are expected to be used in a variety of applications. For example, applications of large display devices include home television devices (also called televisions or television receivers), digital signage, and public information displays (PIDs). In addition, development of mobile information terminals such as smartphones and tablet terminals equipped with touch panels is progressing.

[0003] There is also a demand for higher resolution display devices. Devices requiring high resolution display devices, such as those for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR), are being actively developed.

[0004] As a display device, for example, a light-emitting device having a light-emitting device (also called a light-emitting element) has been developed. A light-emitting device (also called an EL device or an EL element) utilizing the electroluminescence (hereinafter referred to as EL) phenomenon has features such as being easily thin and lightweight, being capable of high-speed response to input signals, and being capable of being driven by a DC constant voltage power supply, and is therefore applied to a display device.

[0005] Tandem light-emitting devices in particular have attracted attention because they achieve high current efficiency, and Patent Documents 1 and 2 disclose tandem light-emitting devices using a separate coloring method. [Prior art documents] [Patent documents]

[0006] [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]

[0007] 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.

[0008] 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 light-emitting device that can 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.

[0009] 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.

[0010] 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 of the specification, drawings, claims, etc., and it is possible to extract other problems from the description of the specification, drawings, claims, etc. [Means for solving the problem]

[0011] In view of this, one embodiment of the present invention uses a substance capable of exhibiting thermally activated delayed fluorescence (TADF) as a light-emitting substance for each light-emitting layer of a tandem light-emitting device using a color-coded method, and uses an organic compound that does not have a triarylamine skeleton for a layer in contact with one of the light-emitting layers.

[0012] A light-emitting device according to one embodiment of the present invention has a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first hole-transporting layer, and a second hole-transporting layer, in which the 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 intermediate layer, the second light-emitting layer is located between the intermediate layer and the second electrode, the first hole-transporting layer is located between the first electrode and the first light-emitting layer, and the second hole-transporting layer is located between the intermediate layer and the second light-emitting layer, the first light-emitting layer contains a first light-emitting substance, the second light-emitting layer contains a second light-emitting substance, and the second light-emitting substance is a TADF material, at least one of the first hole transport layer and the second hole transport layer contains an organic compound having a π-electron-rich heteroaromatic ring and not having a triarylamine skeleton, the difference between the maximum peak wavelength in the emission spectrum of the first light-emitting substance and the maximum peak wavelength in the emission spectrum of the second light-emitting substance is 30 nm or less, and the first light-emitting layer and the second light-emitting layer are light-emitting layers that emit light of a different hue from the light-emitting layer of at least one light-emitting device among a plurality of other light-emitting devices adjacent to the light-emitting device.

[0013] One embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first hole-transporting layer, and a second hole-transporting layer, wherein the 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 intermediate layer, the second light-emitting layer is located between the intermediate layer and the second electrode, the first hole-transporting layer is located between the first electrode and the first light-emitting layer, the second hole-transporting layer is located between the intermediate layer and the second light-emitting layer, and the first hole-transporting layer is located between the intermediate layer and the second light-emitting layer. The light-emitting layer has a first layer and a second layer, the first layer being in contact with the first light-emitting layer, the first light-emitting layer having a first light-emitting material and a first organic compound, a difference between an emission edge on the short wavelength side in the fluorescence spectrum of the first light-emitting material and an emission edge on the short wavelength side in the phosphorescence spectrum of the first light-emitting material being 30 nm or less, the emission edge on the short wavelength side in the phosphorescence spectrum of the first organic compound being at a wavelength shorter than the emission edge on the short wavelength side in the phosphorescence spectrum of the first light-emitting material, and the second light-emitting layer having a a second light-emitting material and a second organic compound, wherein the difference between the short-wavelength emission edge in the fluorescence spectrum of the second light-emitting material and the short-wavelength emission edge in the phosphorescence spectrum of the second light-emitting material is 30 nm or less, and the short-wavelength emission edge in the phosphorescence spectrum of the second organic compound is shorter than the short-wavelength emission edge in the phosphorescence spectrum of the second light-emitting material; the first layer comprises a third organic compound, which has a π-electron-rich heteroaromatic ring and does not have a triarylamine skeleton; the second layer comprises a fourth organic compound, which has a triarylamine skeleton; the difference between the maximum peak wavelength in the fluorescence spectrum of the first light-emitting material and the maximum peak wavelength in the fluorescence spectrum of the second light-emitting material is 30 nm or less; and the first and second light-emitting layers have light-emitting layers that emit light of a different hue from that of at least one light-emitting device among a plurality of other light-emitting devices adjacent to the light-emitting device.

[0014] Another embodiment of the present invention is a light-emitting device having the above structure, wherein a difference between a singlet excitation energy level (S1 level) of the first light-emitting substance and a triplet excitation energy level (T1 level) of the first light-emitting substance is greater than 0 eV and less than or equal to 0.20 eV, and a difference between a singlet excitation energy level (S1 level) of the second light-emitting substance and a triplet excitation energy level (T1 level) of the second light-emitting substance is greater than 0 eV and less than or equal to 0.20 eV.

[0015] One embodiment of the present invention is a light-emitting device having the above structure, wherein an emission edge on the short wavelength side in the fluorescence spectrum of the first organic compound is shorter than an absorption edge on the long wavelength side in the absorption spectrum of the first light-emitting substance, and an emission edge on the short wavelength side in the fluorescence spectrum of the second organic compound is shorter than an absorption edge on the long wavelength side in the absorption spectrum of the second light-emitting substance.

[0016] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first light-emitting substance and the second light-emitting substance are substances capable of exhibiting thermally activated delayed fluorescence.

[0017] Another embodiment of the present invention is a light-emitting device having the above structure, in which the fourth organic compound includes a polycyclic aromatic ring.

[0018] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first light-emitting substance and the second light-emitting substance are the same substance.

[0019] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the light-emitting device includes a first electron-transport layer located between the first light-emitting layer and the intermediate layer, and the first electron-transport layer includes an organic compound including any one of a triazine ring, a pyrimidine ring, an imidazole ring, and an anthracene ring.

[0020] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein a second electron-transport layer is provided between the second light-emitting layer and the second electrode, the second electron-transport layer includes a layer including an organic compound having a triazine ring, and the intermediate layer includes a first mixed layer of an organic compound having a phenanthroline ring and lithium or a lithium compound.

[0021] Another embodiment of the present invention is a light-emitting device having the above structure, in which the second electron-transport layer includes a second mixed layer of an organic compound having a triazine ring and lithium or a lithium compound, and the second mixed layer is located between the layer including the organic compound having a triazine ring and the second electrode.

[0022] Another embodiment of the present invention is a display device including a light-emitting device A and a light-emitting device B. The light-emitting device B emits light of a different color from the light-emitting device A. The light-emitting device A includes a first electrode A, a second electrode A, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first hole-transport layer A, and a second hole-transport layer A. The intermediate layer A is located between the first electrode A and the second electrode A. The first light-emitting layer A is located between the first electrode A and the intermediate layer A. The second light-emitting layer A is located between the intermediate layer A and the second electrode A. The first hole-transport layer A is located between the first electrode A and the first light-emitting layer A. the second hole transport layer A is located between the intermediate layer A and the second light-emitting layer A; the first light-emitting layer A contains a first light-emitting substance; the second light-emitting layer A contains a second light-emitting substance; the first light-emitting substance is a substance capable of exhibiting thermally activated delayed fluorescence; the second light-emitting substance is a substance capable of exhibiting thermally activated delayed fluorescence; at least one of the first hole transport layer A and the second hole transport layer A contains an organic compound A having a π-electron-rich heteroaromatic ring and not having a triarylamine skeleton; and the maximum peak wavelength in the emission spectrum of the first light-emitting substance and the second light-emitting substance are The difference between the maximum peak wavelengths in the emission spectra of the two light-emitting substances is 30 nm or less. The light-emitting device B has a first electrode B, a second electrode B, an intermediate layer B, a first light-emitting layer B, a second light-emitting layer B, a first hole transport layer B, and a second hole transport layer B, the intermediate layer B being located between the first electrode B and the second electrode B, the first light-emitting layer B being located between the first electrode B and the intermediate layer B, the second light-emitting layer B being located between the intermediate layer B and the second electrode B, the first hole transport layer B being located between the first electrode B and the first light-emitting layer B, and the second hole transport layer B being located between the intermediate layer B and the second light-emitting layer B. a first light-emitting layer B containing a first phosphorescent light-emitting material, a second light-emitting layer B containing a second phosphorescent light-emitting material, at least one of the first hole-transporting layer B and the second hole-transporting layer B containing an organic compound B having a triarylamine skeleton, a difference between a maximum peak wavelength in the emission spectrum of the first phosphorescent light-emitting material and a maximum peak wavelength in the emission spectrum of the second phosphorescent light-emitting material being 30 nm or less, and the first light-emitting layer A and the second light-emitting layer A having light-emitting layers that emit light of a different hue from the first light-emitting layer B and the second light-emitting layer B.

[0023] Another embodiment of the present invention is a display device including a light-emitting device A and a light-emitting device B. The light-emitting device B emits light of a different color from the light-emitting device A. The light-emitting device A includes a first electrode A, a second electrode A, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first hole-transport layer A, and a second hole-transport layer A. The intermediate layer A is located between the first electrode A and the second electrode A. The first light-emitting layer A is located between the first electrode A and the intermediate layer A. The second light-emitting layer A is located between the intermediate layer A and the second electrode A. The first hole-transport layer A is located between the first electrode A and the first light-emitting layer A. A second hole transport layer A is located between the intermediate layer A and the second light-emitting layer A, the first light-emitting layer A contains a first light-emitting substance, and the second light-emitting layer A contains a second light-emitting substance, the first light-emitting substance is a substance capable of exhibiting thermally activated delayed fluorescence, and the second light-emitting substance is a substance capable of exhibiting thermally activated delayed fluorescence, and at least one of the first hole transport layer A and the second hole transport layer A contains an organic compound A that does not have a triarylamine skeleton, and the maximum peak wavelength in the emission spectrum of the first light-emitting substance and the emission spectrum of the second light-emitting substance are The difference in maximum peak wavelengths in the optical spectra is 30 nm or less. The light-emitting device B has a first electrode B, a second electrode B, an intermediate layer B, a first light-emitting layer B, a second light-emitting layer B, a first hole transport layer B, and a second hole transport layer B, wherein the intermediate layer B is located between the first electrode B and the second electrode B, the first light-emitting layer B is located between the first electrode B and the intermediate layer B, the second light-emitting layer B is located between the intermediate layer B and the second electrode B, the first hole transport layer B is located between the first electrode B and the first light-emitting layer B, and the second hole transport layer B is located between the intermediate layer B and the second light-emitting layer B. the first light-emitting layer B contains a first fluorescent light-emitting substance, the second light-emitting layer B contains a second fluorescent light-emitting substance, at least one of the first hole-transporting layer B and the second hole-transporting layer B contains an organic compound B having a triarylamine skeleton, the difference between the maximum peak wavelength in the emission spectrum of the first fluorescent light-emitting substance and the maximum peak wavelength in the emission spectrum of the second fluorescent light-emitting substance is 30 nm or less, and the first light-emitting layer A and the second light-emitting layer A have light-emitting layers that emit light of a different hue from the first light-emitting layer B and the second light-emitting layer B.

[0024] Another embodiment of the present invention is a light-emitting device including the light-emitting device having any of the above structures and a transistor or a substrate.

[0025] Another embodiment of the present invention is an electronic device including a light-emitting device having any of the above structures and a detection unit, an input unit, or a communication unit. [Effects of the Invention]

[0026] 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.

[0027] 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 light-emitting device that 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.

[0028] Alternatively, 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 can be provided. Alternatively, any one of an electronic device and a lighting device with high reliability can be provided. Alternatively, 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 can be provided.

[0029] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief explanation of the drawings]

[0030] [Figure 1] 1(A) and 1(B) are diagrams showing a light-emitting device. [Figure 2] FIG. 2 is a diagram illustrating a light-emitting device. [Figure 3] 3(A) and 3(B) are diagrams showing a light-emitting device. [Figure 4] FIG. 4 is a diagram illustrating a light-emitting device. [Figure 5] 5A and 5B illustrate a display device according to one embodiment of the present invention. [Figure 6] 6(A) and 6(B) are a top view and a cross-sectional view of the light emitting device. [Figure 7] 7A to 7G are top views showing examples of pixel configurations. [Figure 8] 8A to 8I are top views showing examples of pixel configurations. [Figure 9] 9(A) and 9(B) are perspective views showing configuration examples of a display module. [Figure 10] 10(A) and 10(B) are cross-sectional views showing configuration examples of a display device. [Figure 11] FIG. 11 is a perspective view showing an example of the configuration of a display device. [Figure 12] FIG. 12 is a cross-sectional view showing an example of the configuration of a display device. [Figure 13] FIG. 13 is a cross-sectional view showing an example of the configuration of a display device. [Figure 14] 14A to 14C are cross-sectional views and top views showing structural examples of a display device. [Figure 15] FIG. 15 is a cross-sectional view showing an example of the configuration of a display device. [Figure 16] 16A to 16C are cross-sectional views and top views showing structural examples of a display device. [Figure 17] 17A to 17D are diagrams showing examples of electronic devices. [Figure 18] 18A to 18F are diagrams showing examples of electronic devices. [Figure 19] 19A to 19G are diagrams showing examples of electronic devices. [Figure 20] FIG. 20 is a diagram illustrating the structure of a light-emitting device. [Figure 21] FIG. 21 is a diagram illustrating the structure of a light-emitting device. [Figure 22] FIG. 22 is a graph showing the luminance-current density characteristics of light-emitting devices B-1 to B-3. [Figure 23] FIG. 23 is a graph showing the luminance-voltage characteristics of light-emitting devices B-1 to B-3. [Figure 24] FIG. 24 is a graph showing the current efficiency-luminance characteristics of light-emitting devices B-1 to B-3. [Figure 25] FIG. 25 is a graph showing the current density-voltage characteristics of light-emitting devices B-1 to B-3. [Figure 26] FIG. 26 is a graph showing the blue index (BI)-current density characteristics of light-emitting devices B-1 to B-3. [Figure 27] FIG. 27 is a graph showing electroluminescence spectra of light-emitting devices B-1 to B-3. [Figure 28] FIG. 28 is a graph showing the luminance-current density characteristics of light-emitting devices G-1, G-2, and G-3. [Figure 29] FIG. 29 is a graph showing the luminance-voltage characteristics of light-emitting device G-1, light-emitting device G-2, and light-emitting device G-3. [Figure 30] FIG. 30 is a graph showing the current efficiency-luminance characteristics of light-emitting devices G-1, G-2, and G-3. [Figure 31] FIG. 31 is a graph showing the current density-voltage characteristics of light-emitting device G-1, light-emitting device G-2, and light-emitting device G-3. [Figure 32] FIG. 32 shows electroluminescence spectra of light-emitting devices G-1, G-2, and G-3. [Figure 33] FIG. 33 is a graph showing the luminance-current density characteristics of the light-emitting devices R-1 and R-2. [Figure 34] FIG. 34 is a diagram showing the luminance-voltage characteristics of the light-emitting device R-1 and the light-emitting device R-2. [Figure 35] FIG. 35 is a graph showing the current efficiency-luminance characteristics of the light-emitting devices R-1 and R-2. [Figure 36] FIG. 36 is a graph showing the current density-voltage characteristics of the light-emitting device R-1 and the light-emitting device R-2. [Figure 37] FIG. 37 shows the electroluminescence spectra of light-emitting devices R-1 and R-2. [Figure 38] 38(A) and 38(B) are diagrams illustrating the emission spectrum of v-DABNA. [Figure 39] 39(A) and 39(B) are diagrams illustrating the emission spectrum of DACT-II. [Figure 40] 40(A) and 40(B) are diagrams illustrating the emission spectrum of TDBA-Si. [Figure 41] 41(A) and 41(B) are diagrams illustrating the emission spectrum of 4,6mCzP2Pm. [Figure 42] 42(A) and 42(B) are diagrams illustrating the emission spectrum of 3,10PCA2Nbf(IV)-02. [Figure 43] 43(A) to 43(C) are diagrams illustrating the emission spectrum of αN-βNPAnth. [Figure 44] FIG. 44 is a diagram illustrating the emission spectrum of 2PCAPA. [Figure 45]FIG. 45 is a diagram illustrating the emission spectrum of cgDBCzPA. [Figure 46] FIG. 46 is a diagram illustrating the absorption spectrum and emission spectrum of TDBA-Si. [Figure 47] FIG. 47 is a diagram illustrating the absorption spectrum and emission spectrum of v-DABNA. [Figure 48] FIG. 48 is a diagram illustrating the absorption spectrum and emission spectrum of 4,6mCzP2Pm. [Figure 49] FIG. 49 is a diagram illustrating the absorption spectrum and emission spectrum of DACT-II. [Figure 50] FIG. 50 is a diagram illustrating the emission spectrum of oFBiSF(2). [Figure 51] FIG. 51 is a diagram illustrating the emission spectrum of PSiCzCz. [Figure 52] FIG. 52 is a diagram illustrating the emission spectrum of mPCCzPTzn-02. [Figure 53] FIG. 53 is a diagram illustrating the emission spectrum of mFBPTzn. [Figure 54] FIG. 54 is a diagram illustrating the emission spectrum of DBfBB1TP. [Figure 55] FIG. 55 is a diagram illustrating the emission spectrum of PCCP. [Figure 56] FIG. 56 is a diagram illustrating the emission spectrum of 11mDBtBPPnfpr. [Figure 57] FIG. 57 is a diagram illustrating the emission spectrum of PCBBiF. [Figure 58] FIG. 58 is a graph showing the luminance-current density characteristics of light-emitting devices B-4, G-4, and R-3. [Figure 59] FIG. 59 is a graph showing the luminance-voltage characteristics of light-emitting devices B-4, G-4, and R-3. [Figure 60] FIG. 60 is a graph showing the current efficiency-luminance characteristics of light-emitting devices B-4, G-4, and R-3. [Figure 61] FIG. 61 is a graph showing the current density-voltage characteristics of light-emitting device B-4, light-emitting device G-4, and light-emitting device R-3. [Figure 62] FIG. 62 is a graph showing the blue index (BI)-current density characteristics of light-emitting device B-4. [Figure 63] FIG. 63 shows electroluminescence spectra of light-emitting devices B-4, G-4, and R-3. [Figure 64] Figures 64(A) and 64(B) are diagrams illustrating the emission spectrum of 3Ph2CzCzBN. [Figure 65] 65(A) and 65(B) are diagrams illustrating the emission spectrum of SiTrzCz2. [Figure 66] 66(A) and 66(B) are diagrams illustrating the emission spectrum of PSiCzCz. [Figure 67] FIG. 67 is a diagram illustrating the absorption spectrum and emission spectrum of 3Ph2CzCzBN. [Figure 68] FIG. 68 is a diagram illustrating the absorption spectrum and emission spectrum of SiTrzCz2. [Figure 69] FIG. 69 is a diagram illustrating the absorption spectrum and emission spectrum of PSiCzCz. [Figure 70] FIG. 70 shows the emission spectra of a single film of SiTrzCz2, a single film of PSiCzCz, and a mixed film. DETAILED DESCRIPTION OF THE INVENTION

[0031] The embodiments 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 can be made in form and detail 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.

[0032] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0033] Furthermore, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0034] The terms "film" and "layer" can be interchangeable depending on the circumstances. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[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] In this specification and the like, holes or electrons may be referred to as "carriers." Specifically, a hole injection layer or electron injection layer may be referred to as a "carrier injection layer," a hole transport layer or electron transport layer may be referred to as a "carrier transport layer," and a hole block layer or electron block layer may be referred to as a "carrier block layer." Note that the above-mentioned carrier injection layer, carrier transport layer, and carrier block layer may not be clearly distinguishable. Furthermore, one layer may have two or three functions among the carrier injection layer, carrier transport layer, and carrier block layer. Furthermore, the terms "injection layer," "transport layer," and "block layer" may be simply referred to as "layer." Similarly, other layers such as "light-emitting layer" and "intermediate layer" may also be referred to as "layer."

[0037] In this specification and the like, a light-emitting device (also referred to as a light-emitting element) has an EL layer between a pair of electrodes. The EL layer has at least a light-emitting layer. In this specification and the like, a light-receiving device (also referred to as a light-receiving element) has at least an active layer that functions as a photoelectric conversion layer between a pair of electrodes. In this specification and the like, one of the pair of electrodes may be referred to as a pixel electrode, and the other as a common electrode.

[0038] In this specification, a tapered shape refers to a shape in which at least a portion of the side surface of the structure is inclined with respect to the substrate surface. For example, it is preferable to have a region in which the angle (also called the taper angle) between the inclined side surface and the substrate surface is less than 90°. The side surface of the structure and the substrate surface do not necessarily need to be completely flat, and may be approximately planar with a slight curvature or approximately planar with minute irregularities.

[0039] In this specification, the term "light-emitting device" includes an image display device using an organic EL device. The term "light-emitting device" may also include a module in which a connector, such as an anisotropic conductive film or TCP (Tape Carrier Package), is attached to an organic EL device, a module in which a printed wiring board is provided at the end of the TCP, or a module in which an IC (integrated circuit) is directly mounted on an organic EL device using a COG (Chip On Glass) method. Furthermore, lighting fixtures and the like may include a light-emitting device.

[0040] In this specification and the like, a photoluminescence (PL) spectrum refers to a spectrum obtained in fluorometry by fixing the excitation wavelength of excitation light and scanning the emission wavelength. It may also be referred to as an emission spectrum. An emission spectrum may include a fluorescent component and a phosphorescent component. In this specification and the like, an emission spectrum consisting of a fluorescent component may be particularly referred to as a fluorescence spectrum, and an emission spectrum consisting of a phosphorescent component may be particularly referred to as a phosphorescent spectrum. Furthermore, since phosphorescent materials do not exhibit fluorescence, the emission spectrum of phosphorescent materials is a phosphorescent spectrum. Furthermore, since TADF materials exhibit fluorescence by converting triplet excitation energy to singlet excitation energy at room temperature, the emission spectrum of TADF materials at room temperature is a fluorescence spectrum.

[0041] (Embodiment 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.

[0042] Tandem light-emitting devices have multiple light-emitting layers, making it easy to produce white light. Therefore, full-color display devices using tandem light-emitting devices often use a white color filter system. Color conversion systems using a blue-emitting light-emitting layer and a color conversion layer, typically a quantum dot, have also been put to practical use.

[0043] 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.

[0044] Furthermore, it is preferable that 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 that the light-emitting layer of the tandem light-emitting device has a light-emitting layer 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 material in the light-emitting layer of the tandem light-emitting device has a different composition from the light-emitting material in the light-emitting layer of at least one of the other adjacent light-emitting devices.

[0045] The light-emitting device of the present invention having the above 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 favorable visibility.

[0046] Next, a light-emitting device of one embodiment of the present invention will be described in detail with reference to the drawings. Figure 1A shows a light-emitting device 130 of one embodiment of the present invention. The light-emitting device of one embodiment of the present invention 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 an intermediate layer 160.

[0047] Although the present embodiment describes an example of a light-emitting device having one intermediate layer 160 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. 1(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 160_1, a second light-emitting unit 502, a second intermediate layer 160_2, and a third light-emitting unit 503.

[0048] <Light-emitting layer> In one embodiment of the present invention, a material capable of emitting thermally activated delayed fluorescence (TADF material) is used as the light-emitting substance contained in the first light-emitting layer 113_1 or the second light-emitting layer 113_2. Note that the TADF material has a function of converting both singlet excitation energy and triplet excitation energy into light emission. Use of a TADF material in the light-emitting layer is preferable because it can increase the emission efficiency of the light-emitting device. In particular, use of a TADF material is preferable for a light-emitting device that emits green light and a light-emitting device that emits blue light.

[0049] TADF materials have a small difference between the triplet excited energy level (T1 level) and the singlet excited energy level (S1 level), and are capable of converting energy from the triplet excited state to the singlet excited state through reverse intersystem crossing. Therefore, the triplet excited state can be upconverted to the singlet excited state with a small amount of thermal energy (reverse intersystem crossing), allowing efficient emission (fluorescence) from the singlet excited state. Furthermore, conditions for efficient thermally activated delayed fluorescence include a difference of 30 nm or less between the short-wavelength emission edge of the fluorescence spectrum and the short-wavelength emission edge of the phosphorescence spectrum. Alternatively, the energy difference between the T1 level and the S1 level is preferably greater than 0 eV and less than 0.20 eV, more preferably greater than 0 eV and less than 0.10 eV.

[0050] The T1 level can be determined by measuring the phosphorescence component (phosphorescence spectrum) in a photoluminescence (PL) spectrum at a low temperature (e.g., a temperature between 4 and 80 K). For example, a PL spectrum (phosphorescence spectrum) can be measured at 10 K, and the energy at the short-wavelength emission edge can be considered the T1 level. The S1 level can be determined by measuring a PL spectrum at a low temperature (e.g., a temperature between 4 and 80 K) or at room temperature. For example, a PL spectrum can be measured at room temperature, and the energy at the short-wavelength emission edge can be considered the S1 level. When a fluorescence spectrum and a phosphorescence spectrum are observed in a PL spectrum measured at a low temperature, the energy at the shortest-wavelength emission edge of the PL spectrum (fluorescence spectrum) can be considered the S1 level. The short-wavelength emission edge of the PL spectrum can be determined by drawing a tangent at the point where the absolute value of the slope on the short-wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the PL spectrum is maximized, and then calculating the intersection of the tangent with the horizontal axis (wavelength) or the baseline. The method for calculating the short wavelength emission edge of the fluorescent spectrum and the short wavelength emission edge of the phosphorescent spectrum is similar.

[0051] As a TADF material, for example, an organic compound having a nitrogen-containing fused heteroaromatic ring is preferred, and an organic compound having a diazaboranaphthoanthracene ring or an indolocarbazole ring is more preferred. The nitrogen-containing fused heteroaromatic ring preferably contains, in addition to boron and the above ring, at least one of an aromatic ring (monocyclic or polycyclic aromatic ring) and an alkyl group. Examples of the aromatic ring include a benzene ring, a fluorene ring, a carbazole ring, and a dibenzofuran ring. Examples of the alkyl group include a methyl group, an ethyl group, a cyclohexyl group, a propyl group, and a tert-butyl group. A structure in which an alkyl group is bonded to an aromatic ring is preferred, and a structure in which multiple alkyl groups are bonded to one benzene ring is particularly suitable. A structure in which multiple alkyl groups are bonded to one benzene ring constituting a fused ring (such as a carbazole ring, a fluorene ring, or a dibenzofuran ring) is also desirable. The inclusion of a structure in which an alkyl group is bonded to an aromatic ring makes it possible to suppress concentration quenching and to suppress aggregation or crystallization due to stacking interactions between molecules, thereby improving device characteristics (efficiency, reliability, etc.). Note that the above examples of aromatic rings and alkyl groups are preferred examples, and other aromatic rings and alkyl groups described in this specification can also be used.

[0052] Specific examples of organic compounds having a condensed heteroaromatic ring containing nitrogen include 5,9-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: DABNA-1) represented by structural formula (400), 2,12-di-tert-butyl-5,9-bis(4-tert-butylphenyl)-5,9-dihydro-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (abbreviation: t-DABNA) represented by structural formula (401), and 2,12 -di(tert-butyl)-5,9-di(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: Me-tBu4DABNA), 7-(9H-carbazol-9-yl)-5,9-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: Cz-DABNA) represented by structural formula (403), N,N,5,9-tetraphenyl-5H,9H-[1,4 ]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: DPhA-DABNA), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: DPhA-tBu4DABNA) represented by structural formula (405), 2,12-di(tert-butyl)-N,N,5,9-tetra(4-tert-butylphenyl) represented by structural formula (406), N-(4-(tert-butyl)phenyl)-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-di-tert-butyl-5,9-bis(4-(tert-butyl)phenyl)-7-(3,6-di-tert-butyl-9H-carbazol-9-yl)-5,9-dihydro-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (abbreviation: TBN-TPA) represented by structural formula (407), N-(4-(tert-butyl)phenyl)-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: tBuDPhA-tBu4DABNA) represented by structural formula (408), 7 ,N 7 ,N 13 ,N 13,5,9,11,15-Octaphenyl-5H,9H,11H,15H-[1,4]benzazaborino[2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[3,2-b]phenazaborine-7,13-diamine (abbreviation: ν-DABNA), N represented by structural formula (409) 7 ,N 7 ,N 13 ,N 13,5,15-hexaphenyl-9,11-bis(4-(tert-butyl)phenyl)-5,9,11,15-tetrahydro-5,9,11,15-tetraaza-19b,20b-diborazinenaphtho[3,2,1-de:1',2',3'-jk]pentacene-7,13-diamine (abbreviated as t-Bu-ν-DABNA), 3,11-bis(2,7-di-tert-butyl-9H-carbazol-9-yl)-7-[2,7-di(3,5-di-tert-butyl)- 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: mmtBuP2Cz-(2,7tBuCz)2DABNA), 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborine-3-amine (abbreviation: DABNA-2) represented by structural formula (411), N-( [1,1'-biphenyl]-3-yl)-N,5,9-tris(2,6-dimethylphenyl)-3,11-diphenyl-5,9-dihydro-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracen-7-amine (abbreviation: mBP-DABNA-Me), N-([1,1'-biphenyl]-4-yl)-N,5,9-tris(2,6-dimethylphenyl)-2,12-diphenyl-5,9-dihydro-5,9-diaza-13b-boranaphtho represented by structural formula (413) [3,2,1-de]anthracene-7-amine (abbreviation: pBP-DABNA-Me), 2-(4-tert-butylphenyl)benz[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc) represented by structural formula (414), benz[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: Bibc) represented by structural formula (415), and compounds represented by structural formulas (416) to (421) can be suitably used.

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] TADF materials that can be used 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), palladium (Pd), etc. Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (SnF2(Proto IX)) represented by structural formula (422), a mesoporphyrin-tin fluoride complex (SnF2(Meso IX)) represented by structural formula (423), a hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)) represented by structural formula (424), a coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)) represented by structural formula (425), an octaethylporphyrin-tin fluoride complex (SnF2(OEP)) represented by structural formula (426), and an etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP) represented by structural formula (428).

[0057] [ka]

[0058] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ) represented by structural formula (429), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCC) represented by structural formula (430), zTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzPTzn) represented by structural formula (431), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ) represented by structural formula (432), 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) represented by structural formula (433), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN) represented by structural formula (434), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS) represented by structural formula (435), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA) represented by structural formula (436), can also be used. The heterocyclic compound has one or both of 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 π-electron-deficient heteroaromatic rings, pyridine rings, diazine rings (pyrimidine rings, pyrazine rings, pyridazine rings), and triazine rings are preferred because they are stable and reliable. In particular, benzofuropyrimidine rings, benzothienopyrimidine rings, benzofuropyrazine rings, and benzothienopyrazine rings have high acceptor properties and high reliability, and therefore it is preferred to use a compound having at least one of these rings or a fused ring containing at least one of these rings.Among π-electron-rich heteroaromatic rings, acridine rings, phenoxazine rings, phenothiazine rings, furan rings, thiophene rings, and pyrrole rings are stable and reliable, and therefore it is preferable to use a compound having at least one of these rings or a fused ring containing at least one of these rings. The fused ring containing a furan ring is preferably a dibenzofuran ring, and the fused ring containing a thiophene ring is preferably a dibenzothiophene ring. The fused ring containing a pyrrole ring is particularly preferably an indole ring, a carbazole ring, an indolocarbazole ring, a bicarbazole ring, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole ring. Compounds 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 property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring are both enhanced, thereby reducing the energy difference between the S1 level and the T1 level, and 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. Examples of π-electron-rich skeletons that can be used include triarylamine skeletons and phenazine skeletons. Examples of π-electron-deficient skeletons that can be used include boron-containing skeletons such as xanthene rings, thioxanthene dioxide rings, oxadiazole rings, triazole rings, imidazole rings, anthraquinone rings, phenylboranes, and boranthrene rings; aromatic rings bonded to nitrile groups or cyano groups such as benzonitrile or cyanobenzene; carbonyl skeletons such as benzophenone; phosphine oxide skeletons; and sulfone skeletons. 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.

[0059] [ka]

[0060] Alternatively, a TADF material in thermal equilibrium between the singlet excited state and the triplet excited state may be used. Such a TADF material has a shorter emission lifetime (excitation lifetime), which can suppress efficiency loss in the high-brightness region of light-emitting devices. Specifically, an organic compound represented by structural formula (437) can be used. Another TADF material is 3,6-bis(diphenylamino)-9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9H-carbazole (abbreviated as DACT-II), represented by structural formula (438).

[0061] [ka]

[0062] By using the above TADF material, it is possible to provide a light-emitting device with high luminous efficiency.

[0063] At least one of the light-emitting layers included in the tandem light-emitting device of one embodiment of the present invention preferably contains a TADF material and at least one host material, and the tandem light-emitting device of one embodiment of the present invention has a configuration in which the TADF material emits light by energy transfer from the at least one host material to the TADF material.

[0064] In the light-emitting layer of the tandem light-emitting device according to one embodiment of the present invention, the short-wavelength emission edge of the phosphorescent component of the PL spectrum (phosphorescence spectrum) observed at low temperatures (e.g., any temperature in the range of 4 K to 80 K) of the host material is preferably shorter in wavelength than the short-wavelength emission edge of the phosphorescent component of the PL spectrum (phosphorescence spectrum) observed at low temperatures of the TADF material. That is, the T1 level of the host material is preferably higher than the T1 level of the TADF material. This relationship allows efficient excitation energy transfer from the host material to the TADF material, enabling the TADF material to emit light efficiently.

[0065] As described above, the TADF material can upconvert a triplet excited state to a singlet excited state with a small amount of thermal energy (reverse intersystem crossing). Therefore, in the light-emitting layer of the tandem light-emitting device of one embodiment of the present invention, when the TADF material receives energy from the host material and becomes a triplet excited state, it can be upconverted to a singlet state, and thus light emission (fluorescence) from the singlet excited state can be efficiently exhibited.

[0066] In addition, in the light-emitting layer of the tandem light-emitting device according to one embodiment of the present invention, the emission edge on the short wavelength side of the fluorescent component (fluorescence spectrum) of the PL spectrum observed at room temperature of the host material is preferably shorter in wavelength than the absorption edge on the long wavelength side of the absorption spectrum measured at room temperature of the TADF material. This relationship allows efficient transfer of excitation energy from the host material to the TADF material, enabling the TADF material to emit light efficiently. The absorption edge on the long wavelength side of the absorption spectrum can be calculated by drawing a tangent at the value where the slope on the long wavelength side of the peak (or shoulder peak) observed at the longest wavelength of the absorption spectrum is minimum (maximum in absolute value), and then calculating the intersection of the tangent with the horizontal axis (wavelength) or the baseline.

[0067] Note that when at least one of the light-emitting layers of the tandem light-emitting device of one embodiment of the present invention includes a TADF material and two host materials (a first host material and a second host material), the two host materials may form an exciplex (also referred to as an exciplex). In this case, the first host material, the second host material, and the exciplex formed by the first host material and the second host material can function as energy donors. The exciplex is easily formed by using a material having electron-transporting properties and a material having hole-transporting properties in combination as the first host material and the second host material. The structure in which a TADF material and an exciplex are contained in the light-emitting layer allows efficient ExTET (Exciplex-Triplet Energy Transfer), which is energy transfer from the exciplex to the TADF material, and therefore, can improve emission efficiency. Furthermore, this structure simultaneously enables high efficiency, low-voltage operation, and a long lifetime of a light-emitting device.

[0068] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO (Highest Occupied Molecular Orbital) level of the material having hole transport properties is equal to or higher than the HOMO level of the material having electron transport properties. It is also preferable that the LUMO (Lowest Unoccupied Molecular Orbital) level of the material having hole transport properties is equal to or higher than the LUMO level of the material having electron transport properties. It is also preferable that the difference between the HOMO level of the material having hole transport properties and the HOMO level of the material having electron transport properties is 0.2 eV or more. It is also preferable that the difference between the LUMO level of the material having hole transport properties and the LUMO level of the material having electron transport properties is 0.2 eV or more. Such a configuration is suitable because holes are easily injected into the material having hole transport properties and electrons are easily injected into the material having electron transport properties. The LUMO and HOMO levels of a material can be derived from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV) measurements, and can also be derived by photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, etc. When comparing values ​​between different compounds, it is preferable to use values ​​estimated by the same measurement.

[0069] Furthermore, it is preferable that the HOMO level of the phosphorescent material is lower than that of the material having hole-transporting properties, and that the LUMO level of the phosphorescent material is higher than that of the material having electron-transporting properties. That is, it is preferable that the energy difference between the LUMO level and the HOMO level of the phosphorescent material is larger than the energy difference between the LUMO level of the material having electron-transporting properties and the HOMO level of the material having hole-transporting properties. This can suppress the reaction that forms an exciplex between the phosphorescent material and the material having hole-transporting properties or the material having electron-transporting properties, thereby providing a light-emitting device that emits light efficiently.

[0070] The formation of exciplexes can be confirmed by, for example, comparing the emission spectra of a hole-transporting material, an electron-transporting material, and a mixed film of these materials and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, 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 a hole-transporting material, the transient EL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response.

[0071] As the host material, it is preferable to use at least one of a compound having a π-electron-deficient heteroaromatic ring and a compound having a π-electron-rich heteroaromatic ring. The compound having a π-electron-deficient heteroaromatic ring functions as a material having electron transport properties, and the compound having a π-electron-rich heteroaromatic ring functions as a material having hole transport properties. It is more preferable to use an organic compound not having a triarylamine skeleton as the host material. Organic compounds not having a triarylamine skeleton are preferred because they tend to have a high T1 level, which is higher than the T1 level of the above-mentioned TADF materials.

[0072] In this specification and the like, a triarylamine skeleton refers to a skeleton in which three aryl groups are bonded to a nitrogen atom, and the three aryl groups are not bonded to each other. A specific example of an organic compound having a triarylamine skeleton is triphenylamine.

[0073] Compounds having a π-electron-deficient heteroaromatic ring that can be used as a host material are preferably compounds having an azine ring. Examples of azine rings include pyridine rings, pyrimidine rings, and triazine rings. These can improve electron transport properties. It is also preferable to use a compound in which a carbazole ring is bonded to the azine ring directly or via an arylene group, and it is preferable to have multiple carbazole rings. Thus, the presence of a carbazole ring can adjust carrier transport properties. Furthermore, compounds having a heteroaromatic ring may contain one or more elements such as silicon, boron, oxygen, and sulfur.

[0074] Furthermore, compounds having a π-electron-rich heteroaromatic ring that can be used as a host material are preferably compounds having a carbazole ring. These compounds can improve hole transport properties. The compound having a carbazole ring preferably has multiple carbazole rings. It is preferable that the compound has at least one of the following structures: a structure in which the 3-position of one carbazole ring is bonded to the 9-position of another carbazole ring; a structure in which the 2-position of one carbazole ring is bonded to the 9-position of another carbazole ring; a structure in which the 4-position of one carbazole ring is bonded to the 9-position of another carbazole ring; a structure in which the 1-position of one carbazole ring is bonded to the 9-position of another carbazole ring; or a structure in which the 3-position of one carbazole ring is bonded to the 3-position of another carbazole ring. It is more preferable that the compound has multiple of these structures. Furthermore, the compound having a carbazole ring may contain one or more elements such as silicon, boron, oxygen, or sulfur.

[0075] Furthermore, when the compound having a π-electron-deficient heteroaromatic ring or the compound having a π-electron-rich heteroaromatic ring has a group having silicon, such as a triphenylsilyl group, the intermolecular distance can be increased and the thermal stability of the light-emitting layer can be improved, which is preferable.

[0076] Specific examples of organic compounds that can be used as the host material include 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviation: SiTrzCz2) represented by structural formula (450) and 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz) represented by structural formula (451). 9-{4-phenyl-6-[3-(triphenylsilyl)phenyl]-1,3,5-triazin-2-yl}-9H-carbazole (abbreviation: SiCzTrz) represented by structural formula (452), 9-{4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazin-2-yl}-9H-carbazole (abbreviation: DSiCzTrz) represented by structural formula (453), 9-(biphenyl) represented by structural formula (454), 3-{6-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]dibenzothiophen-4-yl}-9-phenyl-9H-carbazole (abbreviation: m) represented by structural formula (455). PCDBtPTzn), 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz) represented by structural formula (456), and [4-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)phenyl]triphenylsilane (abbreviation: TDBA-Si) represented by structural formula (457). Organic compounds represented by structural formulas (458), (459), and (460) can also be used. The organic compounds represented by structural formulas (450) to (460) can be used, for example, as host materials for the light-emitting layer of a blue light-emitting device.

[0077] [ka]

[0078] [ka]

[0079] Specific examples of organic compounds that can be used for the host material include 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) represented by structural formula (461), 4-(9'-phenyl-[3,3'-bi-9H-carbazol]-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm) represented by structural formula (462), Examples of the organic compounds include 9-(4,6-diphenylpyrimidin-2-yl)-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: 2PCCzPm) represented by structural formula (463) and 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn) represented by structural formula (464). The organic compounds represented by structural formulas (461) to (464) can be used, for example, as a host material for an emitting layer of a green light-emitting device.

[0080] [ka]

[0081] Specific examples of organic compounds that can be used as the host material include 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)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), )-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-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)phenyl]dibenzo[f,h]quinoxaline 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-(phenanthren-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 (abbreviated as 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviated as 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} (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) Examples of suitable organic compounds include those having heteroaromatic rings containing diazine rings, such as 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz) and 8-(p-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm).

[0082] In this specification and the like, a "heteroaromatic ring containing ring A" includes a fused ring containing ring A and ring A itself. Ring A is a heteroaromatic ring. For example, in the case of a diazine ring, a "heteroaromatic ring containing a diazine ring" includes a fused ring containing the diazine ring and the diazine ring itself.

[0083] Specific examples of organic compounds that can be used as the host material include PIC-TRZ, PCCzTzn, PCCzPTzn, PXZ-TRZ, PPZ-3TPT, ACRXTN, DMAC-DPS, and ACRSA, which are mentioned above as TADF materials.

[0084] By using the above host material for the phosphorescent material, a light-emitting device with high luminous efficiency can be provided.

[0085] Further, the first light-emitting unit 501 and the second light-emitting unit 502 may include other functional layers in addition to the light-emitting layers described above. In FIG. 1A, the first light-emitting unit 501 includes a first hole-transport layer 112_1, a hole-injection layer 111, and a first electron-transport layer 114_1 in addition to the first light-emitting layer 113_1, and the second light-emitting unit 502 includes a second hole-transport layer 112_2, a second electron-transport layer 114_2, and an electron-injection layer 115 in addition to the second light-emitting layer 113_2. However, the structure of the organic compound layer 103 in one embodiment of the present invention is not limited thereto, and any of the layers may be omitted, or other layers may be provided.

[0086] <Hole transport layer> 1A, the first hole-transport layer 112_1 and the second hole-transport layer 112_2 are illustrated as single layers, but the first hole-transport layer 112_1 and the second hole-transport layer 112_2 may be single layers or may have a stacked structure. The first hole-transport layer 112_1 and the second hole-transport layer 112_2 do not necessarily have the same structure. For example, the first hole-transport layer 112_1 may be a single layer, and the second hole-transport layer 112_2 may have a stacked structure.

[0087] In one embodiment of the present invention, the first hole-transport layer 112_1 and the second hole-transport layer 112_2 are preferably made of a material that has excellent hole-transport properties, poor electron-transport properties, and a higher T1 level than the TADF material used in the light-emitting layer. In particular, the first hole-transport layer 112_1, which is in contact with the first light-emitting layer 113_1, preferably has a higher T1 level than the TADF material used in the first light-emitting layer 113_1, and the second hole-transport layer 112_2, which is in contact with the second light-emitting layer 113_2, preferably has a higher T1 level than the TADF material used in the second light-emitting layer 113_2. This prevents the excitation energy of excitons generated by carrier recombination in the light-emitting layer from diffusing to a layer in contact with the light-emitting layer, resulting in a light-emitting device with high luminous efficiency. Organic compounds having a π-electron-rich heteroaromatic ring such as a carbazole ring and not having a triarylamine skeleton have excellent hole transport properties and many of them have a high T1 level, and are therefore suitable for the first hole transport layer 112_1 and the second hole transport layer 112_2.

[0088] Furthermore, by forming the first hole-transport layer 112_1 as a stacked structure and using a material having a LUMO level higher than that of the material constituting the light-emitting layer for a layer in contact with the first light-emitting layer 113_1, it is possible to prevent electrons from penetrating from the first light-emitting layer 113_1 to the first electrode 101. Similarly, by forming the second hole-transport layer 112_2 as a stacked structure and using a material having a LUMO level higher than that of the material constituting the light-emitting layer for a layer in contact with the second light-emitting layer 113_2, it is possible to prevent electrons from penetrating from the second light-emitting layer 113_2 to the intermediate layer 160, and therefore a highly efficient and long-life display device can be manufactured.

[0089] Specific examples of organic compounds that can be used in the first hole transport layer 112_1 and the second hole transport layer 112_2, which are in contact with the light-emitting layer, include 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz) represented by structural formula (350), 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9''-terecarbazole (abbreviation: PSiCzGI) represented by structural formula (351), and 9,9''-(1,3-phenylene)bis(3,9'-bi-9H-carbazole) represented by structural formula (352). 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP) represented by structural formula (353), 9,9''-[3,3'-(diphenylsilyl)diphenyl]bis(3,9'-bi-9H-carbazole) (abbreviation: mCzCz2PSi) represented by structural formula (354), 3,3'-9H-carbazol-9-yl-biphenyl (abbreviation: mCBP) represented by structural formula (359), 9'-phenyl-9'H-9,3':6',9''-tercarbazole (abbreviation: PhCzGI) represented by structural formula (360), 12-[3 -(9H-carbazol-9-yl)phenyl]-5,12-dihydro-5-phenyl-indolo[3,2-a]carbazole (abbreviation: mCzPICz), 5,12-bis[3-(9H-carbazol-9-yl)phenyl]-5,12-dihydro-indolo[3,2-a]carbazole (abbreviation: mCzP2ICz) represented by structural formula (362), 5-[3-(9H-carbazol-9-yl)phenyl]-5,12-dihydro-12-phenyl-indolo[3,2-a]carbazole (abbreviation: mCzPICz-02) represented by structural formula (363), Examples include 12,12'-(1,4-phenylene)bis(5,12-dihydro-5-phenyl-indolo[3,2-a]carbazole) (abbreviation: ICz2P) represented by (364), 12,12'-(1,3-phenylene)bis(5,12-dihydro-5-phenyl-indolo[3,2-a]carbazole) (abbreviation: mICz2P) represented by structural formula (365), and 5,5'-(1,3-phenylene)bis(5,12-dihydro-12-phenyl-indolo[3,2-a]carbazole) (abbreviation: mICz2P-02) represented by structural formula (366).Further, organic compounds represented by structural formulas (355) to (358) can be used. When the organic compounds represented by structural formulas (350) to (366) are used in a blue light-emitting device, for example, they can be used in the first hole-transport layer 112_1 and the second hole-transport layer 112_2, which are in contact with the light-emitting layer. Further, the organic compounds represented by structural formulas (350) to (366) can also be used as host materials for the light-emitting layer of a blue light-emitting device, for example.

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[0092] Specific examples of organic compounds that can be used for the layer in contact with the light-emitting layer in the first hole-transporting layer 112_1 and the second hole-transporting layer 112_2 include 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP) represented by structural formula (367), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP) represented by structural formula (368), and 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBP) represented by structural formula (369). CCBP), 9-(biphenyl-4-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzBP) represented by structural formula (370), 9-phenyl-9'-(triphenylen-2-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTp) represented by structural formula (371), 3,9-bis(9-phenyl-9H-carbazol-3-yl)-9H-carbazole (abbreviation: PCCzPC) represented by structural formula (372), PCCzPC-02 represented by structural formula (373), 9,9'-bis(biphenyl-4- 9-[(4-phenyl)dibenzothiophen-2-yl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PDBtCPC) represented by structural formula (375), 5,9-bis(biphenyl-3-yl)-7,9-dihydro-7,7-dimethyl-5H-cyclopenta[1,2-b:4,3-b']dicarbazole (abbreviation: mBPCdcz) represented by structural formula (376), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz) represented by structural formula (377), Examples of suitable carbazoles include 9-(9,9-dimethyl-9H-fluoren-2-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzF) represented by structural formula (378), 9,9'-di(2-naphthyl)-9H,9'H-3,3'-bicarbazole (abbreviation: BisβNCz) represented by structural formula (379), 9-(biphenyl-3-yl)-9'-phenyl-3,3'-bi(9H-carbazole) (abbreviation: PCCzmBP) represented by structural formula (380), and BisDBtCz represented by structural formula (381).The organic compounds represented by the structural formulas (367) to (381) can be used, for example, in the first hole-transporting layer 112_1 and the second hole-transporting layer 112_2 in a green light-emitting device, which are in contact with the light-emitting layer. The organic compounds represented by the structural formulas (367) to (381) can also be used, for example, as a host material for the light-emitting layer of a green light-emitting device.

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[0096] Furthermore, it is preferable to use an organic compound containing a triarylamine skeleton for the layer not in contact with the light-emitting layer out of the first hole-transporting layer 112_1 and the second hole-transporting layer 112_2. Examples of aromatic rings contained in organic compounds containing a triarylamine skeleton include monocyclic aromatic rings and polycyclic aromatic rings, with polycyclic aromatic rings being preferred due to their high heat resistance and stability. Furthermore, organic compounds containing a triarylamine skeleton and also having a fluorene ring are preferred due to their high reliability, high hole-transporting properties, and reduced power consumption. Furthermore, these aromatic rings may have an alkyl group as a substituent.

[0097] Examples of monocyclic aromatic rings include aromatic hydrocarbon rings such as benzene rings, and heteroaromatic rings such as pyrrole rings and furan rings. Having an aromatic ring as a substituent improves heat resistance, specifically, the glass transition temperature (T g ) is improved. In addition, by having an aromatic ring as a substituent, it is possible to adjust the transportability of carriers such as holes or electrons. In addition, by having a plurality of these monocyclic aromatic rings, it is possible to further improve T gThe refractive index can be improved, and for example, it is preferable that the compound has a biphenyl structure or a terphenyl structure. The compound may have a paraphenylene structure, a metaphenylene structure, or an orthophenylene structure. By having at least one of a metaphenylene structure or an orthophenylene structure, the solubility of the compound can be improved, production can be facilitated, and the refractive index can also be reduced. Furthermore, in the case of a compound having three or more benzene rings, such as a terphenyl structure, it is preferable to have an aromatic ring containing at least two of a paraphenylene structure, a metaphenylene structure, and an orthophenylene structure, because this allows adjustment of the solubility and refractive index as well as carrier transportability.

[0098] Examples of polycyclic aromatic rings include aromatic hydrocarbon rings such as naphthalene ring, phenanthrene ring, chrysene ring, triphenylene ring, fluorene ring, and spirobifluorene ring, as well as heteroaromatic rings such as carbazole ring, dibenzofuran ring, dibenzothiophene ring, and xanthene ring. Compounds having polycyclic aromatic rings as substituents are preferred because they can improve heat resistance compared to compounds having monocyclic aromatic rings. It is also preferred to have multiple of these polycyclic aromatic rings. When multiple polycyclic aromatic rings are present, they may be the same or different. When the same ring is present, examples include a structure having multiple aromatic hydrocarbon rings, a structure having multiple heteroaromatic rings, and a structure having one or more aromatic hydrocarbon rings and one or more heteroaromatic rings. When the same aromatic ring is used, reduction in raw material costs and simplification of the synthesis process can be expected. When different aromatic rings are used, the transport properties of carriers such as holes or electrons can be adjusted depending on the type of aromatic ring used, or T g Examples of the structure having a plurality of polycyclic aromatic rings include a structure having a carbazole ring and a dibenzofuran ring, a structure having two, three, or four or more carbazole rings, and a structure having two, three, or four or more fluorene rings.

[0099] Furthermore, in the case of a compound having a ring in which an aromatic ring (such as the monocyclic aromatic ring described above) is further fused to the polycyclic aromatic ring as a substituent, the heat resistance can be further improved. Examples of the ring in which an aromatic ring is further fused to the polycyclic aromatic ring include a benzofluorene ring, a benzonaphthofuran ring, a benzoxanthene ring, and a benzonaphthothiophene ring.

[0100] In addition, the above-mentioned monocyclic aromatic ring and the above-mentioned polycyclic aromatic ring can be used as a substituent. Examples include a structure in which a monocyclic aromatic ring is used as a linking group between the nitrogen of the amine skeleton and the polycyclic aromatic ring. For example, a structure in which a phenylene group is used between the nitrogen and the fluorene ring, a structure in which a phenylene group is used between the nitrogen and the carbazole ring, or a structure in which a phenylene group is used between the nitrogen and the dibenzofluorene ring. In addition, a structure in which multiple polycyclic aromatic rings are bonded to one phenylene group used as a linking group is also effective. The multiple polycyclic aromatic rings may be the same aromatic ring or different aromatic rings. For example, a compound in which both a carbazole ring and a dibenzofluorene ring are bonded to one phenylene group is T g The functionalities of both the carbazole ring and the dibenzofluorene ring can be obtained while improving the functionalities of both the carbazole ring and the dibenzofluorene ring.

[0101] 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. Therefore, total reflection at the interface between the layer and other layers can be reduced, improving light extraction efficiency. Furthermore, using a compound having such a substituent in the hole transport layer can also reduce the refractive index. In particular, using a compound having a triarylamine skeleton and an alkyl group in the hole transport layer can synergistically enhance the effect of improving light extraction efficiency. Furthermore, the effect can be enhanced when the alkyl group has multiple carbon atoms, preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. Furthermore, multiple alkyl groups bonded to one aromatic ring are preferred because they can further reduce the refractive index. In this case, the multiple alkyl groups may be the same or different. For example, two or three tertiary butyl groups may be bonded to one benzene ring. Furthermore, when multiple aromatic rings are present, alkyl groups bonded to two or more aromatic rings can reduce the refractive index. Furthermore, the refractive index can be adjusted by including alkyl groups on some of the multiple aromatic rings. For example, when there are three aromatic rings, there may be a structure in which two of the aromatic rings have alkyl groups and the remaining aromatic ring does not have an alkyl group.

[0102] Specific examples of organic compounds containing a triarylamine skeleton are shown as the following structural formulas (300) to (330). In particular, BBASF (4) shown in structural formula (300), oBBASF shown in structural formula (301), BBAFLP (4) shown in structural formula (302), oFBiSF (2) shown in structural formula (303), FBiSF (4) shown in structural formula (304), oFBiSF shown in structural formula (305), FBimFLP shown in structural formula (306), and FBimMemFL shown in structural formula (307). P, SF(4)FAF represented by structural formula (308), FrBBiFLP represented by structural formula (309), tBu-oFBiSF(2) represented by structural formula (310), FBiFLPB represented by structural formula (311), DBfBBFLP(2) represented by structural formula (312), FLP2oBP represented by structural formula (313), PCAFLP(2)-02 represented by structural formula (314), and tBu2FoFBi represented by structural formula (316), oFrTPPnox represented by structural formula (317), mPDBfBNBN represented by structural formula (317), BBAaBnf(7) represented by structural formula (318), DBfBB1TP represented by structural formula (319), BOx3Am represented by structural formula (320), BBA2BP represented by structural formula (321), PCBBi1BP represented by structural formula (322), structural formula (323) YGBBiBP-02 represented by the structural formula (324), YGBBiBP represented by the structural formula (324), PCBBiTP represented by the structural formula (325), YGBBiPDBf represented by the structural formula (326), BPPCA represented by the structural formula (327), PCBBiF represented by the structural formula (328), DBf-YGBBiBP represented by the structural formula (329), and YGTPDBfB represented by the structural formula (330) are preferred.

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[0107] For example, among the organic compounds represented by structural formulas (300) to (330), the first hole-transport layer 112_1 and the second hole-transport layer 112_2 preferably use an organic compound having an amine skeleton and a polycyclic heteroaromatic ring, and more preferably use an organic compound having an amine skeleton and a furan ring or a dibenzofuran ring. In particular, when the first hole-transport layer 112_1 and the second hole-transport layer 112_2 have a stacked structure, the layer in contact with the light-emitting layer may be appropriately selected from an organic compound having a higher LUMO level than the material constituting the light-emitting layer (at least the host material, preferably the material constituting the light-emitting layer).

[0108] <Electron transport layer> 1A, the first electron-transporting layer 114_1 and the second electron-transporting layer 114_2 are illustrated as single layers, but the first electron-transporting layer 114_1 and the second electron-transporting layer 114_2 may have a single layer or a stacked structure. In addition, the first electron-transporting layer 114_1 and the second electron-transporting layer 114_2 do not necessarily have the same structure.

[0109] For example, the first electron transport layer 114_1 may be a single layer, and the second electron transport layer 114_2 may be a laminated layer. Specifically, the electron transport layer included in the cathode-side light-emitting unit (for example, the second electron transport layer 114_2 in FIG. 1A) may be a laminated layer, and the electron transport layers included in the other light-emitting units (for example, the first electron transport layer 114_1 in FIG. 1A) may be a single layer.

[0110] In one embodiment of the present invention, the electron-transporting layer included in the cathode-side light-emitting unit preferably includes at least one layer of an organic compound having a triazine ring. Alternatively, the electron-transporting layer may have a stacked structure using organic compounds having different triazine rings. In particular, the cathode-side layer of the stacked layers preferably includes an organic compound having a triazine ring and an alkali metal such as Li. This structure can improve electron injection properties.

[0111] The electron transport layer included in the light-emitting unit located closer to the anode than the light-emitting unit on the cathode side (hereinafter also referred to as the anode-side light-emitting unit) may use the same organic compound as that used in the electron transport layer included in the cathode-side light-emitting unit, or a different organic compound. For example, an organic compound having a triazine ring, a pyrimidine ring, an imidazole ring, or an anthracene ring may be used. Furthermore, for example, an organic compound having a triazine ring different from the organic compound having a triazine ring used in the electron transport layer included in the cathode-side light-emitting unit may be used.

[0112] In order to reduce power consumption, it is preferable that the electron transport layer included in the light-emitting unit on the anode side also contains an organic compound having a triazine ring. In particular, using the same organic compound as that of the electron transport layer included in the light-emitting unit on the cathode side is preferable because it prevents the manufacturing equipment from becoming complicated and is advantageous in terms of raw material procurement costs.

[0113] 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 ring, which makes it easier to control the carrier transport property and enables the provision of a light-emitting device with better characteristics. As the organic compound that does not contain a triazine ring, an organic compound that has a heteroaromatic ring containing a pyridine ring, or an organic compound that has a heteroaromatic ring containing a diazine (pyrimidine or pyrazine) ring is preferred.

[0114] The electron transport layer included in the light-emitting unit on the anode side may have either a laminated structure or a single-layer structure, but the laminated structure provides high current efficiency, lower power consumption, and a light-emitting device with excellent characteristics. A single-layer structure is advantageous in terms of manufacturing costs because fewer film-forming chambers are required.

[0115] The organic compound having a triazine ring that can be used in the electron transport layer included in the light-emitting unit on the anode side and the electron transport layer included in the light-emitting unit on the cathode side 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 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.

[0116] The organic compound having a triazine ring is preferably a compound containing a triazine ring 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 containing a cyano group as a substituent. The triazine ring 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.

[0117] 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, and a triazine ring. The presence of an aromatic ring as a substituent improves heat resistance, specifically, T g and the electron transport property.

[0118] 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 benzene rings. Furthermore, compounds having a ring in which an aromatic ring (such as a benzene ring, a naphthalene ring, or a 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 device 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.

[0119] 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. Therefore, total reflection at the interface between the layer and other layers can be reduced, improving light extraction efficiency. Furthermore, using a compound having these substituents in the hole transport layer can also lower the refractive index. In particular, using a compound having a triazine ring and an alkyl group in the electron transport layer and a compound having a triarylamine skeleton and an alkyl group in the hole transport layer can synergistically enhance the light extraction efficiency improvement effect. Furthermore, the alkyl group can be made to have multiple carbon atoms, preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more, to 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 enhance the refractive index 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.

[0120] In addition, a compound having a cyano group as a substituent is preferable because it can improve the electron transport property.

[0121] 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.

[0122] 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.

[0123] Specific examples of organic compounds having a triazine ring 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), and 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn). azine (abbreviation: mBnfBPTzn-02), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (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: mF BPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviated as mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)biphenyl]- nyl)-5-(9-phenanthryl)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-naphthyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-triazine (abbreviation: βNP-SFx(4)T zn), 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-mBPIcz(II)Tz n), 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), 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)-1,3,5-triazin-2-yl]biphenyl-4-carbonitrile (abbreviation: mpCNBP-SFxTzn), 2,2'-(1,2-naphthalenediyldi-4,1-phenylene)bis[4,6-diphenyl-1,3,5-triazine] (abbreviation: TznP2N), etc. Particularly preferred are TznP2N represented by structural formula (500), mSbfxBPTzn represented by structural formula (501), mpCNBP-SFxTzn represented by structural formula (502), CNBPNPTzn represented by structural formula (503), βNP-SFx(4)Tzn represented by structural formula (504), mmtBuBP-mDMePyPTzn represented by structural formula (505), and mBnfBPTzn represented by structural formula (506). These organic compounds can also be used as host materials for the emitting layer.

[0124] [ka]

[0125] In addition, materials that can be used for the electron transport layer included in the light-emitting unit on the anode side are those that have an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600 or less. -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 transporting 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 containing an azole ring, an organic compound having a heteroaromatic ring containing a pyridine ring, an organic compound having a heteroaromatic ring containing a diazine ring, and an organic compound having a triazine ring are preferred, and an organic compound having a triazine ring is particularly preferred.

[0126] As an organic compound having electron transport properties that can be used in the electron transport layer included in the light-emitting unit on the anode side, the electron transport materials described below can be used. In particular, organic compounds having a heteroaromatic ring containing a diazine ring, organic compounds having a heteroaromatic ring containing a pyridine ring, and organic compounds having a triazine ring are preferred because of their high reliability. In particular, organic compounds having a heteroaromatic ring containing a diazine (pyrimidine or pyrazine) ring and organic compounds having a triazine ring have high electron transport properties and can reduce driving voltage.

[0127] <Middle class> In addition, in one embodiment of the present invention, in the tandem light-emitting device, the intermediate layer 160 preferably contains an organic compound having a phenanthroline ring.

[0128] The organic compound having the above phenanthroline ring 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 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.

[0129] The organic compound having a phenanthroline ring is preferably a compound containing a phenanthroline ring and an aromatic ring, and the aromatic ring may be a monocyclic aromatic ring or a polycyclic aromatic ring.

[0130] Examples of the monocyclic aromatic ring include a benzene ring, a pyrrole ring, a pyridine ring, and a pyrimidine ring. Furthermore, the polycyclic aromatic ring preferably includes an aromatic hydrocarbon ring such as a naphthalene ring, a phenanthrene ring, a chrysene ring, a triphenylene ring, and a fluorene ring, and a heteroaromatic ring 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.

[0131] Examples of organic compounds having a phenanthroline ring 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

[0043] Organic compounds having a heteroaromatic ring containing a phenanthroline ring, such as 2-[4-(9-phenanthryl)-1-naphthyl]-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthryl)-1-naphthyl]-1,10-phenanthroline (abbreviation: PnNPhen), and 2-[4-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen), can be used. However, PnNPhen shown in the following structural formula (200) or mPPhen2P shown in structural formula (201) is particularly preferred.

[0132] [ka]

[0133] In the light-emitting device of one embodiment of the present invention, the intermediate layer may have any structure as long as it contains an organic compound having a phenanthroline ring and can inject electrons into the light-emitting unit on the anode side and holes into the light-emitting unit on the cathode side, both of which are in contact with the intermediate layer, by applying a voltage between the first electrode and the second electrode. However, as shown in Figure 1(A), the intermediate layer 160 preferably has a stacked structure including a first layer 161 containing an organic compound and a second layer 162 located closer to the cathode than the first layer.

[0134] The first layer preferably contains a metal or a metal compound in addition to an organic compound. The metal or 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.

[0135] The first layer may have a stacked structure of a layer containing an organic compound and a layer containing a metal or metal compound located closer to the cathode than the layer containing the organic compound. Alternatively, the first layer may be a mixed layer of an organic compound and a metal or metal compound. The mixed layer is preferable for the first layer because it requires fewer deposition chambers, reduces manufacturing costs, and also contributes to improving the stability of the light-emitting device.

[0136] 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 laminated structure of a layer containing an organic compound and a layer having a metal or metal compound, the metal or metal compound may be detected in areas other than the layer having the metal or metal compound due to diffusion from the layer having 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.

[0137] 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.

[0138] In particular, the metal in the metal or metal compound is preferably a substance that exhibits donor properties to an organic compound having a phenanthroline ring. Examples of substances that exhibit donor properties to an organic compound having a phenanthroline ring include metals of Group 1 and Group 2, with lithium or a lithium compound being particularly preferred. Specifically, Li, lithium fluoride (LiF), lithium oxide (LiO), and 8-quinolinolato-lithium (abbreviated as Liq) are preferred. When the first layer contains an organic compound having a phenanthroline ring and a substance that exhibits donor properties to the organic compound having a phenanthroline ring, 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 organic compound having a phenanthroline ring. This allows the light-emitting device of one embodiment of the present invention to have a low driving voltage.

[0139] In addition to the organic compounds having a phenanthroline ring, organic compounds having a phenanthroline ring with an electron-donating substituent are preferred. The phenanthroline ring has a skeleton that easily interacts with metals, etc., and when such an organic compound having a phenanthroline ring further includes an electron-donating group, the electron density of the phenanthroline ring increases, making it more likely to interact with the metal or metal compound. In particular, when a metal belonging to Groups 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.

[0140] 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.

[0141] Specific examples of organic compounds having a phenanthroline ring with an electron-donating substituent are shown in structural formulas (203) to (210). Specific examples of organic compounds that are not phenanthroline ring-containing organic compounds but can be used in the intermediate layer are shown in structural formulas (211) to (213).

[0142] [ka]

[0143] A configuration in which the first layer contains an element of Group 1 or Group 2, particularly lithium or a lithium compound, and an organic compound having a phenanthroline ring with an electron-donating substituent is preferable because it can provide a tandem light-emitting device with lower drive voltage and better reliability.Furthermore, a configuration in which the first layer contains an element of Group 1 or Group 2, particularly lithium or a lithium compound, and an organic compound having a phenanthroline ring with an electron-donating substituent is preferable because it can suppress an increase in drive voltage when processing the organic compound layer of the light-emitting device by photolithography.

[0144] In an intermediate layer having the above-described configuration, organic compounds having a phenanthroline ring, particularly organic compounds having a 1,10-phenanthroline ring, are preferred because the two nitrogen atoms contained therein can coordinate to a metal, and therefore interaction with the metal or metal compound is likely to occur.

[0145] When an electron-donating group is introduced into the 1,10-phenanthroline ring, the electron-donating group is preferably substituted at positions 4 and 7 of the 1,10-phenanthroline ring. By introducing the electron-donating group into positions 4 and 7 of the 1,10-phenanthroline ring, the electron density of the nitrogen atoms at positions 1 and 10 can be increased, making it easier for the ring to interact with a metal or metal compound.

[0146] The first layer may further contain an organic compound different from the organic compound having a phenanthroline ring. 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 fused 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.

[0147] The second layer 162 preferably contains an organic compound having a hole-transporting property. The second layer 162 preferably further contains a substance exhibiting an accepting property, and the substance exhibiting an accepting property is preferably an organic compound exhibiting an accepting property to an organic compound having a hole-transporting property. As the substance exhibiting an accepting property, an organic compound having at least one of a halogen group and a cyano group is particularly preferable, and an organic compound having at least one of a fluorine group and a cyano group is more preferable. It is more preferable that the organic compound contains four or more halogen groups (fluorine) and cyano groups in total.

[0148] When the second layer 162 contains an organic compound having a hole-transporting property and a substance that accepts the organic compound having a hole-transporting property, 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 through the organic compound having a hole-transporting property. This allows the light-emitting device of one embodiment of the present invention to have a low driving voltage.

[0149] The intermediate layer may have a third layer 163 between the first layer 161 and the second layer 162 .

[0150] The third layer 163 contains a substance having an electron transporting property and has functions such as reducing the driving voltage by smoothing the transfer of electrons between the first layer 161 and the second layer 162 and improving reliability by reducing the interaction between the first layer 161 and the second layer 162.

[0151] The thickness of the third layer 163 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 the driving voltage.

[0152] The light-emitting device of the present invention having the above-described structure 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.

[0153] 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. Note that using the composite material constituting the first layer 161 (also referred to as a P-type layer) in the intermediate layer 160 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.

[0154] 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).

[0155] 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.

[0156] 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.

[0157] 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 material has a hole mobility of 1 / Vs or more. The material having hole transport properties 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 ring, a furan ring, and a thiophene ring is preferred, and 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.

[0158] Such a substance having hole-transporting properties preferably has any one of a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and an anthracene ring. In particular, the substance may be an aromatic amine compound having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine compound having a naphthalene ring, or an aromatic monoamine compound 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.

[0159] 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-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-biphenyl 4,4'-diphenyl-4''-([2,1'-binaphthyl]-6-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-([2,1'-binaphthyl]-7-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl -4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-([2,2'-binaphthyl]-6-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-([2,2'-binaphthyl]-7-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-([1,2'-binaphthyl]-4-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-([1,2'-binaphthyl]-5-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''-phenyl Triphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris (Biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), 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-phenylfluorene- 9-yl)phenyl]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- N-(4-biphenyl-9H-fluoren-2-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, Examples include 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, PSiCzCz, and 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9''-tercarbazole (abbreviation: PSiCzGI).

[0160] In addition, other aromatic amine compounds such as 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) can also be used as the substance having hole-transporting properties.

[0161] 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.

[0162] 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.

[0163] 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 In addition to the organic compound having a triarylamine skeleton and a fluorene ring described above, an organic compound having a hole transport property can be used as needed.

[0164] Examples of the substance having hole transport properties 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), and 4-phenyl-3'- (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-9H N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), and other compounds with a triarylamine skeleton, such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 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), Bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviated as BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviated as CzTP), 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviated as PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviated as BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviated as 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':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 azole, 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)-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-( Compounds having a carbazole ring such as 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, and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable compounds include compounds having a thiophene ring, 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 ring, 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 a triarylamine skeleton and compounds having a carbazole ring are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. In addition, 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 forming the hole transport layer 112 (the first hole transport layer 112_1 and the second hole transport layer 112_2).

[0165] The light-emitting layers (the first light-emitting layer 113_1 and the second light-emitting layer 113_2) preferably contain a light-emitting material and a host material. The light-emitting layers may also contain other materials. At least one of the light-emitting layers uses a TADF material as the light-emitting material.

[0166] 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, the first light-emitting layer 113_1 and the second light-emitting layer 113_2 are both light-emitting layers that emit red light. In a light-emitting device used for a green pixel, both of the two light-emitting layers are light-emitting layers that emit green light. In a light-emitting device used for a blue pixel, both of the two light-emitting layers emit blue light. Specifically, the first light-emitting layer 113_1 and the second light-emitting layer 113_2 are light-emitting layers that emit light of similar colors. Specifically, the light-emitting substance contained in the first light-emitting layer 113_1 and the light-emitting substance contained in the second light-emitting layer 113_2 are preferably compounds whose difference in maximum peak wavelength in their emission spectra (fluorescence spectra) is preferably 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 substance contained in the first light-emitting layer 113_1 is the same as the light-emitting substance contained in the second light-emitting layer 113_2.

[0167] The light-emitting material may be a fluorescent material, a phosphorescent material, a material that exhibits thermally activated delayed fluorescence (TADF), or any other light-emitting material.

[0168] For example, if a display device uses red, green, and blue pixels to display full colors, a TADF material can be used in one of the red, green, and blue pixels, a fluorescent material can be used in another pixel, and a phosphorescent material can be used in the remaining pixels. Alternatively, a TADF material can be used in one of the red, green, and blue pixels, and a phosphorescent material can be used in the other pixels. Alternatively, a TADF material can be used in one of the red, green, and blue pixels, and a fluorescent material can be used in the other pixels. Such a configuration can provide a highly efficient display device.

[0169] Examples of fluorescent materials that can be used as the light-emitting material in the light-emitting layer include the following: In addition, other fluorescent materials can also be used.

[0170] 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]] N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds, such as pyrenediamine compounds 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred because of their high hole-trapping properties, excellent luminescence efficiency, and excellent reliability. In addition, compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0171] In addition to these, 9,10,11-tris[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-G), 9,11-bis[ Compounds having an indole skeleton, such as [3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-Y), can be preferably used. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium can also be used.

[0172] When a phosphorescent material is used as the light-emitting material in the light-emitting layer, examples of materials that can be used include the following.

[0173] 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]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) organometallic iridium complexes with a 4H-triazole skeleton, such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]). Organometallic iridium complexes with a triazole skeleton, including fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpim)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), and tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]). 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: [Ir(cb)3]), and organometallic iridium 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 in the wavelength range from 450 nm to 520 nm. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium can also be used.

[0174] 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 containing a pyrimidine ring, 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 containing a pyrazine ring, 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 containing a pyridine ring, 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), as well as rare earth compounds such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). and organometallic platinum complexes such as (2-{1-(5-tert-butylbiphenyl-2-yl)-4-[3-tert-butyl-5-(4-phenyl-2-pyridinyl-κN)phenyl-κC6]-2-benzimidazolyl-κN3}-4,6-di-tert-butylphenolato-κO)platinum(II) (abbreviated as Pt(tBudppymmtBubiz-tBubp)) and [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) (abbreviated as Pt(4tButpppypyp-mmtBup)). These compounds mainly exhibit green phosphorescence, with emission peaks in the wavelength range from over 500 nm to 600 nm. Organometallic iridium complexes having a pyrimidine ring are particularly preferred because they are remarkably superior in reliability and luminous efficiency. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0175] and organometallic iridium complexes having a pyrimidine ring, 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 containing a pyrazine ring, 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’Organometallic iridium compounds containing a pyridine ring, such as 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 compounds that exhibit red phosphorescence, with peak emission in the wavelength range from 600 to 700 nm. Organometallic iridium complexes containing pyrazine rings also exhibit good chromaticity in red light. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0176] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0177] As the host material of the light-emitting layer, in addition to the organic compounds described above, various carrier transport materials such as materials having electron transport properties described below and / or materials having hole transport properties described above, and the TADF materials described above can be used.

[0178] The electron-transporting material is preferably an organic compound having a π-electron-deficient heteroaromatic ring, such as an organic compound having an azole ring-containing heteroaromatic ring, an organic compound having a pyridine ring-containing heteroaromatic ring, an organic compound having a diazine ring-containing heteroaromatic ring, or an organic compound having a triazine ring.

[0179] Among these, organic compounds having a heteroaromatic ring containing a diazine ring (pyrimidine ring, pyrazine ring, or pyridazine ring), organic compounds having a heteroaromatic ring containing a pyridine ring, and organic compounds having a triazine ring are preferred because of their high reliability. In particular, organic compounds having a heteroaromatic ring containing a diazine (pyrimidine or pyrazine) ring and organic compounds having a triazine ring have high electron transport properties and contribute to reducing driving voltage. In addition, benzofuropyrimidine rings, benzothienopyrimidine rings, benzofuropyrazine rings, and benzothienopyrazine rings are preferred because of their high acceptor properties and high reliability.

[0180] 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: CO1 1), organic compounds containing an azole ring such as 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 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy). , 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 (abbreviation: mTpPP Examples of the organic compound include organic compounds having a heteroaromatic ring containing a pyridine ring, such as 2-phenyl-9-(2-triphenylenyl)-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthryl)-1-naphthyl]-1,10-phenanthroline (abbreviation: PnNPhen), and 2-[4-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen), organic compounds having a heteroaromatic ring containing the above-mentioned diazine ring, and organic compounds having the above-mentioned triazine ring.In addition, organic compounds having a heteroaromatic ring containing a diazine ring, an organic compound having a heteroaromatic ring containing a pyridine ring, and an organic compound having a triazine ring are preferred because of their high reliability. In particular, organic compounds having a heteroaromatic ring containing a diazine (pyrimidine or pyrazine) ring and organic compounds having a triazine ring have high electron transport properties and contribute to reducing driving voltage.

[0181] The 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 light-emitting materials. When a fluorescent or phosphorescent material is used as the light-emitting material, using a TADF material as a host material converts the triplet excitation energy generated in the TADF material into singlet excitation energy through reverse intersystem crossing, and then transfers the energy to the light-emitting material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] When a fluorescent emitting substance is used as the emitting substance, a material having an anthracene ring is suitable as the host material. Using a substance having an anthracene ring as the host material for a fluorescent emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. As a substance having an anthracene ring for use as a host material, a substance having a diphenylanthracene ring, particularly a 9,10-diphenylanthracene ring, is preferred due to its chemical stability. Furthermore, host materials containing a carbazole ring are preferred because of their enhanced hole injection and transport properties. However, host materials containing a benzocarbazole ring, in which a benzene ring is further fused to a carbazole ring, are even more preferred because their HOMO is approximately 0.1 eV higher than that of compounds containing a carbazole ring, facilitating hole insertion. In particular, host materials containing a dibenzocarbazole ring are preferred because their HOMO is approximately 0.1 eV higher than that of compounds containing a carbazole ring, facilitating hole insertion, and also providing excellent hole transport properties and heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene ring and a carbazole ring (or a benzocarbazole ring or a dibenzocarbazole ring). Note that, from the viewpoint of the hole injection / transport property, a benzofluorene ring or a dibenzofluorene ring may be used instead of the carbazole ring.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-anthryl)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' -yl]anthracene (abbreviation: FLPPA), 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-anthryl)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-anthryl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0186] The host material may be a mixture of multiple substances. When a mixture of host materials is used, it is preferable to mix a material having electron transport properties with a material having hole transport properties. By mixing a material having electron transport properties with a material having hole transport properties, the transport properties of the light-emitting layer can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole transport properties to the material having electron transport properties is preferably 1:19 to 19:1 (material having hole transport properties:material having electron transport properties), preferably 1:9 to 9:1, and more preferably 3:7 to 7:3.

[0187] 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.

[0188] 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.

[0189] At least one of the materials forming the exciplex may be a phosphorescent material, which allows triplet excitation energy to be efficiently converted into singlet excitation energy by reverse intersystem crossing.

[0190] 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 2A 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 transporting 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 containing an azole ring, an organic compound having a heteroaromatic ring containing a pyridine ring, an organic compound having a heteroaromatic ring containing a diazine ring, and an organic compound having a triazine ring are preferred, and an organic compound having a triazine ring is particularly preferred.

[0191] 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 having a heteroaromatic ring containing a diazine ring, an organic compound having a heteroaromatic ring containing a pyridine ring, and an organic compound having a triazine ring are preferred because of their high reliability. In particular, organic compounds having a heteroaromatic ring containing a diazine (pyrimidine or pyrazine) ring and an organic compound having a triazine ring have high electron transport properties and contribute to reducing driving voltage.

[0192] As described above, the second electron transport layer 114_2 is a layer containing an organic compound having a triazine ring. Details thereof have already been described, so they will not be repeated here.

[0193] Note that the first electron-transport layer 114_1 preferably contains an organic compound having a triazine ring in order 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 ring as the organic compound having a triazine ring 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.

[0194] Furthermore, since the first electron transport layer 114_1 contains an organic compound that does not contain a triazine ring, it becomes easier to control the carrier transport property, and it becomes possible to provide a light-emitting device with better characteristics. As the organic compound that does not contain a triazine ring, an organic compound that has a heteroaromatic ring that contains a pyridine ring, or an organic compound that has a heteroaromatic ring that contains a diazine (pyrimidine or pyrazine) ring is preferred.

[0195] The electron injection layer 115 has the function of promoting electron injection by reducing the electron injection barrier from the second electrode 102, and can be made of, for example, a Group 1 metal, a Group 2 metal, or an oxide, halide, or carbonate thereof. A composite material of the aforementioned electron-transporting material and a material exhibiting electron donating properties can also be used. Examples of electron-donating materials include Group 1 metals, Group 2 metals, and oxides thereof. Specifically, alkali metals, alkaline earth metals, such as lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF), and lithium oxide (LiO), or compounds thereof can be used. Rare earth metal compounds, such as erbium fluoride (ErF), can also be used. The electron injection layer 115 can also be made of an electride. Examples of the electride include a material in which electrons are highly concentrated in a mixed oxide of calcium and aluminum. In addition, the electron-injecting layer 115 may be formed using a substance that can be used in an electron-transporting layer.

[0196] The electron injection layer 115 may also be made of a composite material obtained by mixing an organic compound and an electron donor (donor). Such composite materials have excellent electron injection and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons. Specifically, for example, the above-mentioned substances constituting the electron transport layer can be used. The electron donor may be any substance that exhibits electron donating properties to the organic compound. Specifically, alkali metals, alkaline earth metals, or rare earth metals are preferred, such as lithium, sodium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides or alkaline earth metal oxides are preferred, such as lithium oxide, calcium oxide, and barium oxide. Lewis bases such as magnesium oxide can also be used. Organic compounds such as tetrathiafulvalene (abbreviated as TTF) can also be used.

[0197] 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-quinolinolato-lithium (abbreviated as Liq), and ytterbium (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 layered structure, materials with good conductivity can be used for the components other than the cathode, regardless of their work function.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0203] 2 shows two adjacent light-emitting devices (light-emitting device 130a and light-emitting device 130b) included in a display device according to one embodiment of the present invention. The light-emitting devices 130a and 130b emit light of different colors. Specifically, the difference in the maximum peak wavelengths in the electroluminescence spectra of the light-emitting devices is greater than 30 nm.

[0204] The light-emitting device 130a has 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 has a configuration in which a first light-emitting unit 501a and a second light-emitting unit 502a are stacked with an intermediate layer 160a sandwiched therebetween. While FIG. 2 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 has 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 160a has a second layer 162a, a third layer 163a, and a first layer 161a. The third layer 163a 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.

[0205] The light-emitting device 130b has 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 has a configuration in which a first light-emitting unit 501b and a second light-emitting unit 502b are stacked with an intermediate layer 160b sandwiched therebetween. Note that while FIG. 2 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 has 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 160b has a second layer 162b, a third layer 163b, and a first layer 161b. The third layer 163b 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.

[0206] The first hole transport layer 112a_1 and the second hole transport layer 112a_2 have a laminated structure, and the layer in contact with the light-emitting layer is formed using a material whose LUMO level is higher than the LUMO level of the material constituting the light-emitting layer (at least the host material, preferably the material constituting the light-emitting layer, the material with the largest 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).

[0207] The second electron transport layer 114a_2 and the second electron transport layer 114b_2 are layers containing an organic compound having a triazine ring. The first layer 161a and the first layer 161b are layers containing an organic compound having a phenanthroline ring.

[0208] 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. The light-emitting substances contained in each layer are preferably compounds whose emission spectra have a difference in maximum peak wavelength of 30 nm or less, more preferably compounds whose emission spectra have a difference in maximum peak wavelength of 20 nm or less, and even more preferably compounds whose emission spectra have a difference in maximum peak wavelength of 10 nm or less, and even more preferably compounds whose emission spectra have a difference in maximum peak wavelength of 30 nm or less, more preferably compounds whose emission spectra have a difference in maximum peak wavelength of 20 nm or less, and even more preferably compounds whose emission spectra have a difference in maximum peak wavelength of 10 nm or less, and even more preferably compounds whose emission spectra have a difference in maximum peak wavelength of 10 nm or less.

[0209] Preferably, first light-emitting layer 113a_1 and first light-emitting layer 113b_1 are separated, and second light-emitting layer 113a_2 and second light-emitting layer 113b_2 are separated. Preferably, the emission colors of first light-emitting layer 113a_1 and second light-emitting layer 113a_2 are different from the emission colors of first light-emitting layer 113b_1 and second light-emitting layer 113b_2. Preferably, the light-emitting substance contained in first light-emitting layer 113a_1 is different from the light-emitting substance contained in first light-emitting layer 113b_1, and the light-emitting substance contained in second light-emitting layer 113a_2 is different from the light-emitting substance contained in second light-emitting layer 113b_2.

[0210] 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 160a and the intermediate layer 160b (the second layer 162a and the second layer 162b, the third layer 163a and the third layer 163b, and the first layer 161a and the first layer 161b), 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.

[0211] 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.

[0212] Furthermore, when the light-emitting substance contained in the first light-emitting layer 113a_1 is different from the light-emitting substance contained in the first light-emitting layer 113b_1, and the light-emitting substance contained in the second light-emitting layer 113a_2 is different from the light-emitting 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 light-emitting layer 113a_1 and the second light-emitting layer 113b_2 are blue fluorescent light-emitting layers and green phosphorescent light-emitting layers, respectively, the light-emitting substance contained in the second light-emitting layer 113a_2 is different from the light-emitting 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 light-emitting layer 113a_1 and the second light-emitting layer 113b_2 are green phosphorescent light-emitting layers, the light-emitting substance contained in the second light-emitting layer 113b_2 is different from the light-emitting 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, the light-emitting substance contained in the first light-emitting layer 113a_1 In a case where 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 where 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 using layers containing an organic compound having a triazine ring for the second electron transport layer 114a_2 and the second electron transport layer 114b_2 and using layers containing an organic compound having a phenanthroline ring for the first layer 161a and the first layer 161b, 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 transport layer 114a_2 and the second electron transport layer 114b_2 have the same configuration. In other words, it is possible to achieve both improved productivity and improved performance. Note that the first layer 161a and the first layer 161b may have the same configuration.

[0213] 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.

[0214] FIG. 3(A) is a modified example of FIG. 2. 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 a microcavity structure. 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.

[0215] 3B shows 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. The light-emitting device 130a, the light-emitting device 130b1, and the light-emitting device 130c emit light of different colors.

[0216] 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 160c sandwiched therebetween. While FIG. 3B 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 160c includes a second layer 162c, a third layer 163c, and a first layer 161c. The third layer 163c 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.

[0217] 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 inter-electrode distance of the light-emitting device 130c is adjusted by making the film thicknesses of the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 thinner than those of the other two light-emitting devices.

[0218] The second electron transport layer 114c_2 is a layer containing an organic compound having a triazine ring. The first layer 161c is a layer containing an organic compound having a phenanthroline ring.

[0219] The first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 preferably emit light of similar colors, and the light-emitting substances contained therein are preferably compounds whose maximum peak wavelengths in their emission spectra differ by 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less, and most preferably the light-emitting substances contained therein are the same.

[0220] Preferably, first light-emitting layer 113a_1 and first light-emitting layer 113c_1 are separated, and second light-emitting layer 113a_2 and second light-emitting layer 113c_2 are separated. Preferably, the emission colors of first light-emitting layer 113a_1 and second light-emitting layer 113a_2 are different from the emission colors of first light-emitting layer 113c_1 and second light-emitting layer 113c_2. Preferably, the light-emitting substance contained in first light-emitting layer 113a_1 is different from the light-emitting substance contained in first light-emitting layer 113c_1, and the light-emitting substance contained in second light-emitting layer 113a_2 is different from the light-emitting substance contained in second light-emitting layer 113c_2.

[0221] In the above example, hole injection layer 111a and hole injection layer 111c, first hole transport layer 112a_1 and first hole transport layer 112c_1, first electron transport layer 114a_1 and first electron transport layer 114c_1, intermediate layer 160a and intermediate layer 160c (second layer 162a and second layer 162c, third layer 163a and third layer 163c, first layer 161a and first layer 161c), and second hole transport layer 112a_2 and second hole transport layer 112c_2 are each independently separated between light-emitting device 130a and light-emitting device 130c, while second electron transport layer 114a_2 and 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.

[0222] A light-emitting device according to one embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a schematic diagram of a light-emitting device 130a and a light-emitting device 130b, which are two adjacent light-emitting devices formed on the same insulating surface and which are included in a light-emitting device, and which are modifications of the light-emitting devices described with reference to Figs.

[0223] The light-emitting device 130a is located on the insulating layer 175 and includes a first electrode 101a including an anode, a second electrode 102 including a cathode, and an organic compound layer 103a. The organic compound layer 103a is located between the first electrode 101a and the second electrode 102. The organic compound layer 103a has a configuration in which a first light-emitting unit 501a and a second light-emitting unit 502a are stacked with an intermediate layer 160a sandwiched therebetween.

[0224] The first light-emitting unit 501a includes a first hole-transport layer 112a_1 (hole-transport layer 112a_1a and hole-transport layer 112a_1b), a first light-emitting layer 113a_1, and a first electron-transport layer 114a_1. The intermediate layer 160a includes a first layer 161a and a second layer 162a. The second light-emitting unit 502a includes a second hole-transport layer 112a_2 (hole-transport layer 112a_2a and hole-transport layer 112a_2b), a second light-emitting layer 113a_2, a second electron-transport layer 114a_2, and an electron-injection layer 115. Therefore, it can be said that the intermediate layer 160a is located between the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2.

[0225] In the light-emitting device 130a, the first light-emitting unit 501a preferably includes a hole-injection layer 111a. The intermediate layer 160a may include a third layer 163a between the first layer 161a and the second layer 162a. When the anode-side surface of the light-emitting unit is in contact with the intermediate layer 160a, as in the case of the second light-emitting unit 502a, the second layer 162a of the intermediate layer 160a located on the cathode side can also function as the hole-injection layer for the second light-emitting unit 502a. Therefore, the hole-injection layer 111 may not be provided in the second light-emitting unit. In other words, the hole-injection layer 111 may be provided as needed to achieve the desired performance of the light-emitting device.

[0226] Here, the light-emitting device 130b may have a different structure from the light-emitting device 130a. For example, the light-emitting device 130b shown in FIG. 4 has a first hole transport layer 112a_1 and a second hole transport layer 112a_2 whose structures differ from those of the light-emitting device 130a. When different light-emitting materials are used for the light-emitting layers of the light-emitting device 130a and the light-emitting device 130b, it is advisable to create an appropriate layer structure for each light-emitting material. By creating a structure that optimizes the characteristics for each light-emitting device, the characteristics of the light-emitting device as a whole can be improved.

[0227] The light-emitting device 130b is located on the insulating layer 175 and includes a first electrode 101b including an anode, a second electrode 102 including a cathode, and an organic compound layer 103b. The organic compound layer 103b is located between the first electrode 101b and the second electrode 102. The organic compound layer 103b has a structure in which a first light-emitting unit 501b and a second light-emitting unit 502b are stacked with an intermediate layer 160b sandwiched therebetween.

[0228] The first light-emitting unit 501b includes a first light-emitting layer 113b_1. The intermediate layer 160b includes a first layer 161b and a second layer 162b. The second light-emitting unit 502b includes a second light-emitting layer 113b_2 and an electron injection layer 115. In other words, the intermediate layer 160b is located between the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2.

[0229] In the light-emitting device 130b, the first light-emitting unit 501b preferably includes a hole-injection layer 111b, a first hole-transport layer 112b_1, and a first electron-transport layer 114b_1 in addition to the first light-emitting layer 113b_1. The second light-emitting unit 502b preferably includes a second hole-transport layer 112b_2 and a second electron-transport layer 114b_2 in addition to the second light-emitting layer 113b_2 and the electron-injection layer 115. The intermediate layer 160b may include a third layer 163b between the first layer 161b and the second layer 162b. In addition, when the anode-side surface of the light-emitting unit is in contact with the intermediate layer 160b, as in the second light-emitting unit 502b, the second layer 162b of the intermediate layer 160b located on the cathode side can also serve as the hole-injection layer for the second light-emitting unit 502b, and therefore the light-emitting unit may not be provided with the hole-injection layer 111. In other words, the hole-injection layer 111 may be provided as needed to achieve the desired performance of the light-emitting device.

[0230] Note that the light-emitting device according to one embodiment of the present invention does not necessarily have to include a light-emitting device having the configuration shown in light-emitting device 130b, and may include a plurality of light-emitting devices having the configuration shown in light-emitting device 130a. When the configuration of the light-emitting devices is unified in the light-emitting device, the complexity of the manufacturing equipment can be reduced.

[0231] Although Figure 4 shows an example in which each organic compound layer contains two light-emitting units, one embodiment of the present invention is not limited to this. Each organic compound layer may contain three or more light-emitting units. By stacking multiple light-emitting units between a pair of electrodes with an intermediate layer sandwiched therebetween, a highly reliable light-emitting device can be realized, which can emit light with high luminance while maintaining a low current density. Furthermore, a light-emitting device with low power consumption can be realized.

[0232] Furthermore, the light-emitting device 130, the light-emitting device 130a, or the light-emitting device 130b may be a light-emitting device fabricated using, for example, a lithography method. That is, the light-emitting device 130, the light-emitting device 130a, and the light-emitting device 130b can each be fabricated by processing a part of the organic compound layer using a lithography method. In the case of a light-emitting device fabricated using a lithography method, at least the first light-emitting layer 113_1 or the second light-emitting layer 113_2 and the organic compound layer provided closer to the first electrode 101 than the first light-emitting layer 113_1 or the second light-emitting layer 113_2 are processed simultaneously, so that their edges are aligned or approximately aligned in the vertical direction.

[0233] A light-emitting device of the present invention having the structure shown in Figure 4 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 with favorable visibility. This embodiment mode can be freely combined with other embodiments.

[0234] The configuration shown in Fig. 4 has a particularly remarkable effect when used in a tandem-colored light-emitting device according to one embodiment of the present application. As will be described later, the tandem-colored light-emitting device has different layer structures for the red, green, and blue light-emitting devices, and these are further stacked, resulting in a large number of materials being used or the amount of materials being used. Therefore, by applying a configuration in which the same fused rings are used in multiple layers, a configuration in which the same fused rings are bonded at different positions, or a configuration in which fused rings that are structural isomers are used, as described above, it is possible to achieve manufacturing effects such as reducing raw material costs and simplifying synthesis steps, as well as the advantage of T g The use of such a material in a tandem-type light-emitting device according to one embodiment of the present application makes it possible to realize a light-emitting device suitable for mass production.

[0235] (Embodiment 2) In this embodiment, a display device manufactured using the light-emitting device described in Embodiment 1 will be described with reference to FIG. 5. FIG. 5A is a top view showing the display device, and FIG. 5B is a cross-sectional view taken along lines AB and CD in FIG. 5A. This display device includes a driver circuit section (source line driver circuit) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603, all of which are shown by dotted lines, to control light emission from the light-emitting device. 604 is a sealing substrate, 605 is a sealant, and the inside surrounded by the sealant 605 is a space 607.

[0236] 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.

[0237] Next, the cross-sectional structure will be described with reference to Fig. 5(B) . A driver circuit portion and a pixel portion are formed on an element substrate 610, but here, a source line driver circuit 601, which is the driver circuit portion, and one pixel in a pixel portion 602 are shown.

[0238] The element substrate 610 may be made of a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0239] 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.

[0240] 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.

[0241] 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.

[0242] 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).

[0243] In particular, it is preferable to use an oxide semiconductor film as the semiconductor layer, which has 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 in which no grain boundaries can be found between adjacent crystal parts.

[0244] By using such a material for the semiconductor layer, fluctuations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0245] Furthermore, a transistor having the above-described semiconductor layer can retain charge accumulated 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 a driver circuit while maintaining the gray level of each pixel. As a result, an electronic device with extremely low power consumption can be realized.

[0246] 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.

[0247] Note that FET 623 represents one of the transistors formed in the source line driver circuit 601. The driver circuit may be formed of a CMOS circuit, a PMOS circuit, or an NMOS circuit. Although this embodiment shows a driver-integrated type in which the driver circuit is formed on a substrate, this is not necessarily required, and the driver circuit may also be formed externally rather than on the substrate.

[0248] 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.

[0249] 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.

[0250] 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.

[0251] An organic compound layer 616 and a second electrode 617 are formed on the first electrode 613. Here, it is desirable to use a material with a large work function as the material used for the first electrode 613, which functions as an anode. For example, in addition to a single layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 to 20 wt % zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film, a stacked structure of a titanium nitride film and a film mainly containing aluminum, or a three-layer structure of a titanium nitride film, a film mainly containing aluminum, and a titanium nitride film can be used.

[0252] The organic compound layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, or a spin coating method. The organic compound layer 616 includes the structure described in Embodiment 1. Other materials constituting the organic compound layer 616 may be low-molecular-weight compounds or high-molecular-weight compounds (including oligomers and dendrimers).

[0253] Furthermore, the second electrode 617, which is formed on the organic compound layer 616 and functions as a cathode, is preferably made of a material with a small work function (such as Al, Mg, Li, or Ca, or alloys and compounds thereof (MgAg, MgIn, AlLi, etc.)). When light generated in the organic compound layer 616 is to be transmitted through the second electrode 617, the second electrode 617 is preferably made of a laminate of a thin metal thin film and a transparent conductive film (such as ITO, indium oxide containing 2 to 20 wt % zinc oxide, indium tin oxide containing silicon, or zinc oxide (ZnO)).

[0254] Note that a light-emitting device is formed with the first electrode 613, the organic compound layer 616, and the second electrode 617. The light-emitting device is the light-emitting device described in Embodiment 1. Note that a pixel portion is formed with a plurality of light-emitting devices, but the display device in this embodiment may include both the light-emitting device described in Embodiment 1 and light-emitting devices having other structures.

[0255] 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.

[0256] 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.

[0257] 5, a protective film may be provided on the second electrode 617. The protective film may be formed of an organic resin film or an inorganic insulating film. In addition, the protective film may be formed so as to cover the exposed portion of the sealing material 605.

[0258] 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.

[0259] 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.

[0260] 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 the ALD method for the protective film. By using the ALD method, 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.

[0261] 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.

[0262] In this manner, a display device manufactured using the light-emitting device described in Embodiment 1 can be obtained.

[0263] The display device in this embodiment uses the light-emitting device described in Embodiment 1, and therefore, a display device with favorable characteristics can be obtained. Specifically, the light-emitting device described in Embodiment 1 has high emission efficiency, and therefore, a display device with low power consumption can be obtained. Furthermore, the light-emitting device described in Embodiment 1 has favorable reliability, and therefore, a display device with favorable reliability can be obtained. In addition, the light-emitting device described in Embodiment 1 can be a light-emitting device with favorable chromaticity and color purity, and therefore, a display device with favorable display quality can be obtained.

[0264] This embodiment mode can be freely combined with other embodiment modes.

[0265] (Embodiment 3) 6A and 6B, 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 one embodiment of the present invention will be described in detail.

[0266] 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.

[0267] 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.

[0268] 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 177. 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).

[0269] 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.

[0270] 6A 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.

[0271] A connection portion 140 may be provided outside the pixel portion 177, and a region 141 may be provided. The region 141 is provided between the pixel portion 177 and the connection portion 140. The region 141 is provided with an organic compound layer 103. Furthermore, the connection portion 140 is provided with a conductive layer 151C.

[0272] 6(A) 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.

[0273] Fig. 6(B) is an example of a cross-sectional view taken along dashed line A1-A2 in Fig. 6(A). As shown in Fig. 6(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 layer 175, the insulating layer 174, and the insulating layer 173 have openings that reach the conductive layer 172, and a plug 176 is provided to fill the opening.

[0274] 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.

[0275] 6B shows multiple cross sections of the inorganic insulating layer 125 and the insulating layer 127, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are connected to one another when the display device 100 is viewed from above. That is, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are insulating layers having openings above the first electrodes.

[0276] 6(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. Furthermore, light emitting device 130R, light emitting device 130G, or light emitting device 130B may emit other visible light or infrared light.

[0277] 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.

[0278] The light-emitting device 130R has the configuration described in Embodiment 1. It includes a first electrode (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 common electrode 155 on the common layer 104. The common electrode 155 corresponds to the second electrode 102 in Embodiments 1 and 2. The common layer 104 may or may not be provided, but its provision is preferable because it reduces damage to the organic compound layer 103R during processing. When the common layer 104 is provided, it is preferable that the common layer 104 be an electron injection layer. When the common layer 104 is provided, the laminated structure of the organic compound layer 103R and the common layer 104 corresponds to the organic compound layer 103.

[0279] The light-emitting device 130G has the same configuration as that described in Embodiment 1. It includes a first electrode (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 common electrode 155 on the common layer 104. The common electrode 155 corresponds to the second electrode 102 in Embodiments 1 and 2. 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. When the common layer 104 is provided, it is preferable that the common layer 104 be an electron injection layer. When the common layer 104 is provided, the stacked structure of the organic compound layer 103G and the common layer 104 corresponds to the organic compound layer 103.

[0280] The light-emitting device 130B has the same configuration as that described in Embodiment 1. It includes a first electrode (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 common electrode 155 on the common layer 104. The common electrode 155 corresponds to the second electrode 102 in Embodiments 1 and 2. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103B during processing. When the common layer 104 is provided, it is preferable that the common layer 104 be an electron injection layer. When the common layer 104 is provided, the laminated structure of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103.

[0281] One of the pixel electrode and the common electrode of the light-emitting device 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.

[0282] 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.

[0283] The island-shaped organic compound layer 103 is formed by depositing an EL film and processing the EL film using a lithography method.

[0284] 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 structure. For example, in the example shown in FIG. 6B, the first electrode of the light-emitting device 130 has a stacked structure of a conductive layer 151 (conductive layer 151R, conductive layer 151G, and conductive layer 151B) and a conductive layer 152 (conductive layer 152R, conductive layer 152G, and conductive layer 152B). For example, when the display device 100 is a top-emission type and the pixel electrode of the light-emitting device 130 functions as an anode, it is preferable that the conductive layer 151 has high reflectivity for visible light and the conductive layer 152 has transparency to visible light and a high work function. When the display device 100 is a top-emission type, the higher the reflectivity of the pixel electrode for visible light, the higher the extraction efficiency of light emitted from the organic compound layer 103. When the pixel electrode functions as an anode, the higher the work function of the pixel electrode, the easier it is to inject holes into the organic compound layer 103. As described above, by forming the pixel electrode of the light-emitting device 130 into a laminated structure of the conductive layer 151 having a high reflectivity for visible light and the conductive layer 152 having a high work function, the light-emitting device 130 can be made into a light-emitting device with high light extraction efficiency and low driving voltage.

[0285] When the conductive layer 151 is a layer having high reflectance to visible light, the reflectance of the conductive layer 151 to visible light is preferably, for example, 40% to 100%, or 70% to 100%. When the conductive layer 152 is an electrode that is transparent to visible light, the transmittance of the conductive layer 152 to visible light is preferably, for example, 40% or more.

[0286] 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.

[0287] 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.

[0288] The conductive layer 151 or the conductive layer 152 may have a stacked structure of multiple layers containing different materials. In this case, the conductive layer 151 may be formed using one of the materials selected from those usable for the conductive layer 152, and the conductive layer 152 may be formed using one of the materials selected from those usable for the conductive layer 151. For example, when the conductive layer 151 has a stacked structure of two or more layers, the layer in contact with the conductive layer 152 may be formed using a material usable for the conductive layer 152.

[0289] The side surfaces of the conductive layer 151 or the conductive layer 152 preferably have a tapered shape. Specifically, the side surfaces of the conductive layer 151 or the conductive layer 152 preferably have a tapered shape with a taper angle of less than 90°. The end surfaces of the insulating layer 156 (insulating layer 156R, insulating layer 156G, and insulating layer 156B) may also have a tapered shape. Specifically, when the end surfaces of the insulating layer 156 have a tapered shape with a taper angle of less than 90°, the coverage of structures provided along the side surfaces of the insulating layer 156 can be improved.

[0290] Alternatively, silver or an alloy containing silver may be used for the conductive layer 151. Silver has a characteristic that its reflectance to visible light is higher than that of titanium. Furthermore, silver is less susceptible to oxidation than aluminum, and the electrical resistivity of silver oxide is lower than that of aluminum oxide. As described above, when silver or an alloy containing silver is used for the conductive layer 151, the reflectance of the conductive layer 151 to visible light can be suitably increased while suppressing an increase in the electrical resistance of the pixel electrode due to oxidation. Here, an alloy containing silver can be, for example, an alloy of silver, palladium, and copper (Ag-Pd-Cu, also referred to as APC).

[0291] For example, when a microcavity structure is applied to the light-emitting device 130, the conductive layer 151 can be made of silver or an alloy containing silver, which is a material with high reflectivity for visible light, to suitably improve the light extraction efficiency of the display device 100.

[0292] Furthermore, when the conductive layer 152 has a laminated structure, by making the laminated structure such that the reflectance for visible light (for example, the reflectance for light of a predetermined wavelength in the range of 400 nm or more and less than 750 nm) is different from the reflectance for visible light of the conductive layer 151, it is possible to form a microcavity structure in combination with the conductive layer 151.

[0293] As described above, the characteristics of the display device can be improved by forming the conductive layer 151 or the conductive layer 152 into a stacked structure of multiple layers. For example, the display device 100 can have high light extraction efficiency and high reliability.

[0294] Note that the conductive layer 151 can be formed by a lithography method. Specifically, first, a conductive film to be the conductive layer 151 is formed. Next, a resist mask is formed over the conductive film to be the conductive layer 151. After that, the conductive film in a region that does not overlap with the resist mask is removed by, for example, an etching method. Here, compared to when the conductive layer 151 is formed so that the side surfaces are not tapered, that is, so that the side surfaces are vertical, the conductive film is processed under conditions that make it easy for the resist mask to recede (shrink), whereby the side surfaces of the conductive layer 151 can be tapered.

[0295] The conductive layer 152 may be processed by lithography simultaneously with the conductive layer 151. In this case, the side surface of the conductive layer 152 can also be formed into a tapered shape.

[0296] Here, if the conductive film is processed under conditions that make it easy for the resist mask to recede (shrink), the conductive film may be easily processed in the horizontal direction, which may result in higher isotropy of etching than when the conductive layer 151 is formed so that the side surfaces are vertical.

[0297] Furthermore, when the conductive layer 151 has a laminated structure of a plurality of layers made of different materials, the ease of processing in the horizontal direction may differ between the plurality of layers.

[0298] 6B, the insulating layer 156 can prevent corrosion of the conductive layer 151. Therefore, the display device 100 can be manufactured with a high yield. Furthermore, the occurrence of defects can be prevented, and the display device 100 can be a highly reliable display device.

[0299] 6(B), the insulating layer 156 preferably has a curved surface. This can prevent discontinuities in the conductive layer 152 covering the insulating layer 156, compared to when the side surfaces of the insulating layer 156 are vertical (parallel to the Z direction). Even when the insulating layer 156 has a tapered shape on the side surface, specifically a tapered shape with a taper angle of less than 90°, the occurrence of discontinuities in the conductive layer 152 covering the insulating layer 156 can be prevented, compared to when the side surfaces of the insulating layer 156 are vertical. As described above, the display device 100 can be manufactured by a method with a high yield. Furthermore, the occurrence of defects can be prevented, and the display device 100 can be a highly reliable display device.

[0300] The structure of this embodiment can be used in appropriate combination with structures of other embodiments.

[0301] (Fourth embodiment) In this embodiment, a light-emitting device of one embodiment of the present invention will be described with reference to FIGS. 7A to 7G and FIGS. 8A to 8I.

[0302] [Pixel layout] In this embodiment, pixel layouts different from that shown in Fig. 6(A) will be mainly described. There are no particular limitations on the arrangement of sub-pixels, and various methods can be applied. Examples of sub-pixel arrangements include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a pentile arrangement.

[0303] The top shape of the sub-pixels shown in the drawings in this embodiment mode corresponds to the top shape of the light-emitting region.

[0304] The top surface shape of the subpixel may be, for example, 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.

[0305] Furthermore, the layout of the circuits constituting the sub-pixels is not limited to the range of the sub-pixels shown in the drawings, and may be arranged outside of the range.

[0306] An S-stripe arrangement is applied to the pixel 178 shown in Fig. 7(A). The pixel 178 shown in Fig. 7(A) is composed of three subpixels: a subpixel 110R, a subpixel 110G, and a subpixel 110B.

[0307] The pixel 178 shown in FIG. 7B 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 subpixel 110R has a larger light-emitting area than the subpixel 110G. Thus, the shape and size of each subpixel can be determined independently. For example, the more reliable the light-emitting device, the smaller the size of the subpixel.

[0308] The Pentile arrangement is applied to the pixels 124a and 124b shown in Fig. 7(C). Fig. 7(C) shows an example in which the pixel 124a having the subpixel 110R and the subpixel 110G and the pixel 124b having the subpixel 110G and the subpixel 110B are arranged alternately.

[0309] 7(D) to 7(F) are arranged in a delta configuration. Pixel 124a has two subpixels (subpixel 110R and subpixel 110G) in the top row (first row) and one subpixel (subpixel 110B) in the bottom row (second row). Pixel 124b has one subpixel (subpixel 110B) in the top row (first row) and two subpixels (subpixel 110R and subpixel 110G) in the bottom row (second row).

[0310] Figure 7(D) is an example in which each sub-pixel has an approximately rectangular top surface shape with rounded corners, Figure 7(E) is an example in which each sub-pixel has a circular top surface shape, and Figure 7(F) is an example in which each sub-pixel has an approximately hexagonal top surface shape with rounded corners.

[0311] In Fig. 7(F), each subpixel is arranged inside a densely arranged hexagonal region. Each subpixel is arranged so that it is surrounded by six other subpixels when focusing on one subpixel. Furthermore, subpixels that emit light of the same color are arranged so that they are not adjacent to each other. For example, when focusing on subpixel 110R, three subpixels 110G and three subpixels 110B are arranged alternately so as to surround it.

[0312] 7G 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 sides of two subpixels aligned in the row direction (for example, subpixels 110R and 110G, or subpixels 110G and 110B) are misaligned.

[0313] 7(A) to 7(G), it is preferable that the subpixel 110R is the subpixel R that emits red light, the subpixel 110G is the subpixel G that emits green light, and the subpixel 110B is the subpixel B that emits blue light. Note that the configuration of the subpixels is not limited to this, and the colors that the subpixels emit and their arrangement order can be determined appropriately. For example, the subpixel 110G may be the subpixel R that emits red light, and the subpixel 110R may be the subpixel G that emits green light.

[0314] In photolithography, the finer the pattern to be processed, the more significant the effect of light diffraction becomes. This impairs the fidelity of the photomask pattern when it is transferred by exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, a pattern with rounded corners is likely to be formed. As a result, the top surface shape of the subpixel may become a polygon with rounded corners, an ellipse, a circle, or the like.

[0315] Furthermore, in a method for manufacturing a light-emitting device according to one embodiment of the present invention, an organic compound layer is processed into an island shape using a resist mask. The resist film formed on the organic compound layer needs to be cured at a temperature lower than the heat resistance temperature of the organic compound layer. Therefore, depending on the heat resistance temperature of the material for the organic compound layer and the curing temperature of the resist material, the resist film may not be cured sufficiently. A resist film that is not cured sufficiently may have a shape that is different from the desired shape during processing. As a result, the top surface shape of the organic compound layer may be a polygon with rounded corners, an ellipse, a circle, or the like. For example, when a resist mask with a square top surface shape is formed, a resist mask with a circular top surface shape may be formed, resulting in a circular top surface shape of the organic compound layer.

[0316] In order to form the top surface of the organic compound layer into a desired shape, a technique for correcting the mask pattern in advance (OPC (Optical Proximity Correction) technique) may be used so that the design pattern and the transfer pattern coincide with each other. Specifically, in the OPC technique, a correction pattern is added to, for example, the corners of the figure on the mask pattern.

[0317] As shown in FIGS. 8A to 8I, a pixel can have four types of subpixels.

[0318] The pixels 178 shown in FIGS. 8(A) to 8(C) are arranged in a stripe pattern.

[0319] Figure 8(A) is an example in which each subpixel has a rectangular top surface shape, Figure 8(B) is an example in which each subpixel has a top surface shape that is a combination of two semicircles and a rectangle, and Figure 8(C) is an example in which each subpixel has an elliptical top surface shape.

[0320] The pixels 178 shown in FIGS. 8(D) to 8(F) are arranged in a matrix.

[0321] Figure 8(D) is an example in which each sub-pixel has a square top surface shape, Figure 8(E) is an example in which each sub-pixel has an approximately square top surface shape with rounded corners, and Figure 8(F) is an example in which each sub-pixel has a circular top surface shape.

[0322] 8(G) and 8(H) show an example in which one pixel 178 is configured in two rows and three columns.

[0323] 8(G) 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.

[0324] The pixel 178 shown in FIG. 8(H) has three subpixels (subpixel 110R, subpixel 110G, and subpixel 110B) in the top row (first row) and three subpixels 110W in the bottom row (second row). In other words, the pixel 178 has subpixel 110R and subpixel 110W in the left column (first column), subpixel 110G and subpixel 110W in the center column (second column), and subpixel 110B and subpixel 110W in the right column (third column). By aligning the subpixels in the top row and bottom row as shown in FIG. 8(H), it becomes possible to efficiently remove dust that may occur during the manufacturing process, for example. Therefore, a light-emitting device with high display quality can be provided.

[0325] In the pixel 178 shown in FIGS. 8(G) and 8(H), the subpixels 110R, 110G, and 110B are laid out in a stripe arrangement, which can improve the display quality.

[0326] FIG. 8(I) shows an example in which one pixel 178 is configured in three rows and two columns.

[0327] 8(I) 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.

[0328] In the pixel 178 shown in FIG. 8(I), the layout of the subpixels 110R, 110G, and 110B is a so-called S-stripe arrangement, which can improve the display quality.

[0329] 8A to 8I includes four subpixels: subpixel 110R, subpixel 110G, subpixel 110B, and subpixel 110W. For example, the subpixel 110R may emit red light, the subpixel 110G may emit green light, the subpixel 110B may emit blue light, and the subpixel 110W may emit white light. Note that at least one of the subpixels 110R, 110G, 110B, and 110W may emit cyan light, magenta light, yellow light, or near-infrared light.

[0330] As described above, in the light-emitting device of one embodiment of the present invention, various layouts can be applied to pixels each including a subpixel having a light-emitting device.

[0331] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0332] (Embodiment 5) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0333] 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.

[0334] 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.

[0335] [Display module] 9A 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 the display devices 100B to 100E2 described below.

[0336] 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.

[0337] 9(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.

[0338] 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. 9(B). The various configurations described in the previous embodiments can be applied to the pixel 284a. Fig. 9(B) shows an example in which the pixel 284a has the same configuration as the pixel 178 shown in Fig. 6(A).

[0339] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0340] One pixel circuit 283a is a circuit that controls the driving of a plurality of elements included in one pixel 284a.

[0341] 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.

[0342] 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.

[0343] 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.

[0344] 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.

[0345] [Display device 100A] The display device 100A shown in FIG. 10A 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.

[0346] The substrate 301 corresponds to the substrate 291 in FIGS. 9A and 9B. 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.

[0347] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0348] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0349] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 located therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0350] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0351] An insulating layer 255 is provided to cover the capacitor 240, an insulating layer 174 is provided on the insulating layer 255, and an insulating layer 175 is provided on the insulating layer 174. Light-emitting device 130R, light-emitting device 130G, and light-emitting device 130B are provided on the insulating layer 175. An insulator is provided in the region between adjacent light-emitting devices.

[0352] An insulating layer 156R is provided to have a region overlapping with a side surface of the conductive layer 151R, an insulating layer 156G is provided to have a region overlapping with a side surface of the conductive layer 151G, and an insulating layer 156B is provided to have a region overlapping with a side surface of the conductive layer 151B. Further, a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R, a conductive layer 152G is provided to cover the conductive layer 151G and the insulating layer 156G, and a conductive layer 152B is provided to cover the conductive layer 151B and the insulating layer 156B. Furthermore, a sacrificial layer 158R is located on the organic compound layer 103R of the light-emitting device 130R, a sacrificial layer 158G is located on the organic compound layer 103G of the light-emitting device 130G, and a sacrificial layer 158B is located on the organic compound layer 103B of the light-emitting device 130B.

[0353] The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B are electrically connected to one of the source and drain of the transistor 310 via an insulating layer 243, an insulating layer 255, an insulating layer 174, a plug 256 embedded in the insulating layer 175, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261. Various conductive materials can be used for the plug.

[0354] Furthermore, a protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B via a common electrode 155. A substrate 120 is bonded to the protective layer 131 by a resin layer 122. For details of the components from the light-emitting devices 130 to the substrate 120, refer to embodiment 3. The substrate 120 corresponds to the substrate 292 in FIG. 9(A).

[0355] Fig. 10(B) is a modified example of the display device 100A shown in Fig. 10(A). The display device shown in Fig. 10(B) has a colored layer 132R, a colored layer 132G, and a colored layer 132B, and the light-emitting device 130 has an area where it overlaps with one of the colored layer 132R, the colored layer 132G, and the colored layer 132B. In the display device shown in Fig. 10(B), the light-emitting device 130 can emit, for example, white light. Furthermore, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light.

[0356] [Display device 100B] FIG. 11 shows a perspective view of the display device 100B, and FIG. 12 shows a cross-sectional view of the display device 100C.

[0357] The display device 100B has a configuration in which a substrate 352 and a substrate 351 are bonded together. In Fig. 11, the substrate 352 is indicated by a dashed line.

[0358] The display device 100B has a pixel unit 177, a connection unit 140, a circuit 356, wiring 355, etc. Fig. 11 shows an example in which an IC 354 and an FPC 353 are mounted on the display device 100B. Therefore, the configuration shown in Fig. 11 can also be called a display module having the display device 100B, an IC (integrated circuit), and an FPC. Here, a display device having a connector such as an FPC attached to a substrate, or a display device having an IC mounted on the substrate, is called a display module.

[0359] The connection section 140 is provided outside the pixel section 177. There may be one or more connection sections 140. The connection section 140 electrically connects the common electrode of the light-emitting device and the conductive layer, and can supply a potential to the common electrode.

[0360] The circuit 356 can be, for example, a scanning line driver circuit.

[0361] The wiring 355 has a function of supplying signals and power to the pixel portion 177 and the circuit 356. The signals and power are input to the wiring 355 from the outside via the FPC 353 or from the IC 354.

[0362] 11 shows an example in which an IC 354 is provided on a substrate 351 by a COG (Chip On Glass) method or a COF (Chip on Film) method. The IC 354 may be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 100B and the display module may not necessarily include an IC. Alternatively, the IC may be mounted on an FPC by, for example, a COF method.

[0363] Figure 12 shows an example of a cross section of the display device 100C, showing a portion of the area including the FPC 353, a portion of the circuit 356, a portion of the pixel section 177, a portion of the connection section 140, and a portion of the area including the end portion.

[0364] [Display device 100C] The display device 100C shown in Figure 12 has, between a substrate 351 and a substrate 352, a transistor 201, a transistor 205, a light-emitting device 130R that emits red light, a light-emitting device 130G that emits green light, and a light-emitting device 130B that emits blue light, etc.

[0365] For details of the light emitting devices 130R, 130G, and 130B, refer to the above-described embodiments.

[0366] Light-emitting device 130R has conductive layer 224R, conductive layer 151R on conductive layer 224R, and conductive layer 152R on conductive layer 151R. Light-emitting device 130G has conductive layer 224G, conductive layer 151G on conductive layer 224G, and conductive layer 152G on conductive layer 151G. Light-emitting device 130B has conductive layer 224B, conductive layer 151B on conductive layer 224B, and conductive layer 152B on conductive layer 151B.

[0367] The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. An end of the conductive layer 151R is located outside an end of the conductive layer 224R. An insulating layer 156R is provided to have a region in contact with a side surface of the conductive layer 151R, and a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R.

[0368] Conductive layer 224G, conductive layer 151G, conductive layer 152G, and insulating layer 156G in light-emitting device 130G, and conductive layer 224B, conductive layer 151B, conductive layer 152B, and insulating layer 156B in light-emitting device 130B are similar to conductive layer 224R, conductive layer 151R, conductive layer 152R, and insulating layer 156R in light-emitting device 130R, and therefore detailed description thereof will be omitted.

[0369] Recesses are formed in the conductive layers 224R, 224G, and 224B so as to cover the openings provided in the insulating layer 214. A layer 128 is buried in the recesses.

[0370] Layer 128 has the function of filling in recesses in conductive layer 224R, conductive layer 224G, and conductive layer 224B and planarizing the surface. Conductive layers 151R, 151G, and 151B, which are electrically connected to conductive layer 224R, conductive layer 224G, and conductive layer 224B, are provided on conductive layer 224R, conductive layer 224G, and conductive layer 224B and layer 128. Therefore, the regions overlapping with the recesses in conductive layer 224R, conductive layer 224G, and conductive layer 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixel.

[0371] The layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be used for the layer 128 as appropriate. In particular, the layer 128 is preferably formed using an insulating material, and is particularly preferably formed using an organic insulating material. For example, the organic insulating materials that can be used for the insulating layer 127 described above can be used for the layer 128.

[0372] A protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B via a common electrode 155. The protective layer 131 and the substrate 352 are bonded via an adhesive layer 142. A light-shielding layer 157 is provided on the substrate 352. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting device 130. In FIG. 12, the space between the substrates 352 and 351 is filled with the adhesive layer 142, and a solid sealing structure is applied. Alternatively, the space may be filled with an inert gas (nitrogen, argon, etc.), and a hollow sealing structure may be applied. In this case, the adhesive layer 142 may be provided so as not to overlap with the light-emitting devices. Alternatively, the space may be filled with a resin different from the frame-shaped adhesive layer 142.

[0373] 12 shows an example in which connecting portion 140 has conductive layer 224C obtained by processing the same conductive film as conductive layers 224R, 224G, and 224B, conductive layer 151C obtained by processing the same conductive film as conductive layers 151R, 151G, and 151B, and conductive layer 152C obtained by processing the same conductive film as conductive layers 152R, 152G, and 152B. Also shown in FIG. 12 is an example in which insulating layer 156C is provided so as to have a region overlapping with a side surface of conductive layer 151C.

[0374] The display device 100C is a top-emission type. Light emitted by the light-emitting device is emitted toward the substrate 352. The substrate 352 is preferably made of a material that is highly transparent to visible light. The pixel electrodes contain a material that reflects visible light, and the common electrode 155 contains a material that transmits visible light.

[0375] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 351 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0376] The insulating layers 211, 213, and 215 are each preferably formed using an inorganic insulating film.

[0377] The insulating layer 214, which functions as a planarizing layer, is preferably an organic insulating layer.

[0378] The transistor 201 and the transistor 205 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a conductive layer 222a and a conductive layer 222b functioning as a source and a drain, a semiconductor layer 231, an insulating layer 213 functioning as a gate insulating layer, and a conductive layer 223 functioning as a gate.

[0379] A connection portion 204 is provided in a region of the substrate 351 where the substrate 352 does not overlap. In the connection portion 204, a source electrode or a drain electrode of the transistor 201 is electrically connected to the FPC 353 via a conductive layer 166 and a connection layer 242. The conductive layer 166 has an example of a stacked structure including a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. The conductive layer 166 is exposed on the top surface of the connection portion 204. This allows the connection portion 204 and the FPC 353 to be electrically connected via the connection layer 242.

[0380] It is preferable to provide a light-shielding layer 157 on the surface of the substrate 352 facing the substrate 351. The light-shielding layer 157 can be provided between adjacent light-emitting devices, on the connection section 140, on the circuit 356, etc. Also, various optical members can be arranged on the outside of the substrate 352.

[0381] The substrate 351 and the substrate 352 can be made of the same material as can be used for the substrate 120 .

[0382] The adhesive layer 142 can be made of a material that can be used for the resin layer 122 .

[0383] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0384] [Display device 100D] The display device 100D shown in FIG. 13 differs from the display device 100C shown in FIG. 12 mainly in that it is a bottom-emission display device.

[0385] Light emitted from the light emitting device is emitted toward the substrate 351. It is preferable that a material with high transparency to visible light is used for the substrate 351. On the other hand, the light transparency of the material used for the substrate 352 is not an issue.

[0386] A light-shielding layer 317 is preferably formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205. Figure 13 shows an example in which the light-shielding layer 317 is provided over the substrate 351, the insulating layer 153 is provided over the light-shielding layer 317, and the transistors 201, 205, etc. are provided over the insulating layer 153.

[0387] Light emitting device 130R includes conductive layer 112R, conductive layer 126R on conductive layer 112R, and conductive layer 129R on conductive layer 126R.

[0388] Light emitting device 130B includes conductive layer 112B, conductive layer 126B on conductive layer 112B, and conductive layer 129B on conductive layer 126B.

[0389] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are made of a material that is highly transparent to visible light. The common electrode 155 is preferably made of a material that reflects visible light.

[0390] Although the light emitting device 130G is not shown in FIG. 13, the light emitting device 130G is also provided.

[0391] Although FIG. 13 and other figures show an example in which the top surface of the layer 128 has a flat portion, the shape of the layer 128 is not particularly limited.

[0392] [Display device 100D2] The display device 100D2 shown in Fig. 14(A) is an example of a bottom-emission display device that differs from the display device 100D shown in Fig. 13. The display device 100D2 differs from the display device 100D in that it has an organic resin layer 180. Note that in the drawing, the reference numerals of the same components as those in Fig. 13 may be omitted, and the description in Fig. 13 can be referred to for details.

[0393] 14(B) shows a top view layout of pixel 178 (pixel 178a and pixel 178b) having subpixels 110 (subpixels 110R, 110G, 110B, and 110W), and FIG. 14(C) shows a top view of organic resin layer 180 in a region where subpixels 110R and 110W of pixel 178 are formed. Note that the distance between light-shielding layers 317 is width 110Rw in the light-emitting region of subpixel 110R.

[0394] As shown in FIG. 14(A), the organic resin layer 180 is provided on the insulating layer 214. As shown in the region surrounded by the dashed line in FIG. 14(A) and in FIG. 14(C), the organic resin layer 180 has curved recesses 181 (recesses 181a and 181b) at least in the region where the subpixels are formed. Note that the recesses 181 may be provided outside the light-emitting region, such as recess 181c. Providing recess 181c refracts light emitted in the region overlapping with the light-shielding layer 317 or light traveling to the region overlapping with the light-shielding layer 317, allowing it to be extracted from the light-emitting region, thereby improving light-emitting efficiency.

[0395] A plurality of recesses 181 may be formed in a matrix. Recesses 181a and 181b may be provided in contact with each other, or may have a flat surface between them.

[0396] 14, the recess has a hexagonal top surface shape (FIG. 14(C)) and a semicircular cross-sectional shape (FIG. 14(A)), but other shapes may be used as needed. For example, the recess may have a polygonal top surface shape such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any other polygon with rounded corners, an ellipse, or a circle.

[0397] An insulating layer containing an organic material can be used as the organic resin layer 180. For example, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, precursors of these resins, etc. can be used as the organic resin layer 180. Alternatively, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used as the organic resin layer 180.

[0398] Furthermore, a photosensitive resin can be used as the organic resin layer 180. A photoresist can be used as the photosensitive resin. The photosensitive resin can be a positive type material or a negative type material.

[0399] The organic resin layer 180 may contain a material that absorbs visible light. For example, the organic resin layer 180 itself may be made of a material that absorbs visible light, or the organic resin layer 180 may contain a pigment that absorbs visible light. For example, the organic resin layer 180 may be made of a resin that can be used as a color filter that transmits red, blue, or green light and absorbs other light, or a resin that contains carbon black as a pigment and functions as a black matrix.

[0400] In addition, the first electrode 101 (first electrode 101R and first electrode 101W) is provided on the organic resin layer 180, the organic compound layer 103 is provided on the first electrode 101, and the common electrode 155 is provided on the organic compound layer 103. Ends of the first electrode 101 and the organic compound layer 103 may be covered with an insulating layer 127.

[0401] Furthermore, the first electrode 101 formed on the organic resin layer 180 has a recess similar to the recess of the organic resin layer 180. Furthermore, the organic compound layer 103 formed on the first electrode 101 has a recess similar to the recess of the first electrode 101. Furthermore, the common layer 104 formed on the organic compound layer 103 has a recess similar to the recess of the organic compound layer 103. Furthermore, the common electrode 155 formed on the common layer 104 has a recess similar to the recess of the common layer 104. In other words, the recesses of the organic resin layer 180, the first electrode 101, the organic compound layer 103, the common layer 104, and the common electrode 155 have a structure in which they overlap one another.

[0402] In addition, a common layer 104 is provided on the organic compound layer 103 and the insulating layer 127, and a common electrode 155 is provided on the common layer 104. A protective layer 131 is provided on the common electrode 155, and is bonded to a substrate 352 via an adhesive layer 142.

[0403] Although FIG. 14A shows only the light emitting devices 130R and 130W and does not show the light emitting devices 130G and 130B, the light emitting devices 130G and 130B are also provided.

[0404] The light-emitting device according to one embodiment of the present invention, which includes the organic resin layer 180 as described above, has the structure described in the above embodiment. As a result, an organic semiconductor device with low driving voltage and excellent characteristics can be provided.

[0405] [Display device 100E] The display device 100E shown in FIG. 15 is a modification of the display device 100C shown in FIG. 12, and differs from the display device 100C mainly in that it has colored layers 132R, 132G, and 132B.

[0406] In the display device 100E, the light-emitting device 130 has an area that overlaps one of the colored layer 132R, the colored layer 132G, and the colored layer 132B. The colored layer 132R, the colored layer 132G, and the colored layer 132B can be provided on the surface of the substrate 352 facing the substrate 351. An end of the colored layer 132R, an end of the colored layer 132G, and an end of the colored layer 132B can overlap the light-shielding layer 157.

[0407] In the display device 100E, for example, the colored layer 132R transmits red light, the colored layer 132G transmits green light, and the colored layer 132B transmits blue light. The display device 100E may be configured such that the colored layers 132R, 132G, and 132B are provided between the protective layer 131 and the adhesive layer 142.

[0408] [Display device 100E2] The display device 100E2 shown in Fig. 16(A) is a modified example of the display device 100E shown in Fig. 15, and has microlenses 182 on the colored layers 132R, 132G, and 132B. Note that in the drawing, the reference numerals of the same components as those in Fig. 15 may be omitted, and the description in Fig. 15 can be referred to for details.

[0409] 16(B) shows a top view layout of a pixel 178 (pixels 178a and 178b) having subpixels 110 (subpixels 110R, 110G, and 110B), and FIG. 16(C) shows a top view of a microlens 182 in a region where the subpixels 110R, 110G, and 110B of the pixel 178 are formed. The region where the common electrode 155 and the organic compound layer 103 are in contact has a width 110Gw in the light-emitting region of the subpixel 110G.

[0410] 16(A) has a planarization film 143 provided on a protective layer 131, and colored layers 132R, 132G, and 132B provided on the planarization film 143. A planarization film 144 is provided so as to cover the colored layers 132R, 132G, and 132B. A microlens 182 is provided on the planarization film 144.

[0411] As shown in FIG. 16C, the microlens 182 may be provided for each sub-pixel in a region where the sub-pixel is formed.

[0412] 16(C), the top surface shape of the microlens 182 is shown as a hexagon, but other shapes may be used as needed. For example, the top surface shape of the microlens 182 may be a polygon such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any of these polygons with rounded corners, an ellipse, or a circle.

[0413] The microlenses 182 can be formed using the same material as the organic resin layer 180 .

[0414] The microlens is suitable for use in a light-emitting device according to one embodiment of the present invention (such as a light-emitting device using the nitrogen-containing fused heteroaromatic ring or a color-coded tandem light-emitting device described above). The microlens can concentrate light and increase the light extraction efficiency, which, together with the effect of enhancing the microcavity effect described above, can improve the light-emitting performance of the entire display device. Furthermore, applying the protective layer 131 or a sealing film on the protective layer 131 is preferable because it improves the characteristics and also improves resistance to impurities.

[0415] 16, the effect of the microlenses can be enhanced by overlapping the area between two adjacent microlenses with the area between two adjacent light-emitting devices. It is also preferable to overlap the area where two adjacent colored layers (e.g., 132B and 132G) overlap, the area between the microlenses, and the area between the light-emitting devices. It is also preferable to overlap the insulating layer 127, the area where the colored layers overlap, the area between the microlenses, and the area between the light-emitting devices. It is also preferable to overlap each of these areas with the protective layer 131 or a sealing film on the protective layer 131. The area between the microlenses may be a path for impurities to enter the light-emitting devices, so the protective layer 131 or the sealing film can prevent impurities from entering.

[0416] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0417] (Embodiment 6) In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0418] The electronic devices of this embodiment include the display device of one embodiment of the present invention in their display portions. The display device of one embodiment of the present invention has high display performance and can easily achieve high definition and high resolution. Therefore, the display device of one embodiment of the present invention can be used in the display portions of various electronic devices.

[0419] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0420] In particular, the display device of one embodiment of the present invention can have high resolution and can therefore be suitably used in electronic devices having a relatively small display area. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices (head-mounted displays), eyeglass-type AR devices, and MR devices.

[0421] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0422] An example of a wearable device that can be worn on the head will be described with reference to FIGS. 17(A) to 17(D).

[0423] The electronic device 700A shown in FIG. 17(A) and the electronic device 700B shown in FIG. 17(B) each have a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0424] The display device of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device can be highly reliable.

[0425] The electronic device 700A and the electronic device 700B can each project an image displayed on the display panel 751 onto a display area 756 of the optical member 753. Because the optical member 753 is translucent, the user can see the image displayed in the display area superimposed on a transmitted image visible through the optical member 753.

[0426] Electronic device 700A and electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, electronic device 700A and electronic device 700B may each be provided with an acceleration sensor such as a gyro sensor, thereby detecting the orientation of the user's head and displaying an image corresponding to that orientation in display area 756.

[0427] The communication unit has a wireless communication device, and can supply, for example, a video signal via the wireless communication device. Note that instead of or in addition to the wireless communication device, a connector to which a cable through which a video signal and a power supply potential can be connected may be provided.

[0428] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0429] The housing 721 may be provided with a touch sensor module.

[0430] Various touch sensors can be used as the touch sensor module. For example, various types of touch sensors can be used, such as a capacitance type, a resistive film type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, or an optical type. In particular, it is preferable to use a capacitance type or an optical type sensor in the touch sensor module.

[0431] The electronic device 800A shown in Figure 17(C) and the electronic device 800B shown in Figure 17(D) each have a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0432] The display device of one embodiment of the present invention can be applied to the display portion 820. Therefore, the electronic device can be highly reliable.

[0433] Display unit 820 is provided inside housing 821 at a position that can be viewed through lens 832. Also, by displaying different images on the pair of display units 820, it is possible to perform a three-dimensional display using parallax.

[0434] It is preferable that electronic device 800A and electronic device 800B each have a mechanism that allows the left and right positions of lens 832 and display unit 820 to be adjusted so that they are optimally positioned according to the position of the user's eyes.

[0435] The wearing part 823 allows the user to wear the electronic device 800A or the electronic device 800B on the head.

[0436] The imaging unit 825 has a function of acquiring external information. Data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used for the imaging unit 825. Furthermore, multiple cameras may be provided to support multiple angles of view, such as telephoto and wide angle.

[0437] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone.

[0438] The electronic device 800A and the electronic device 800B may each have an input terminal to which a cable can be connected for supplying a video signal from a video output device or the like and power for charging a battery provided in the electronic device.

[0439] The electronic device of one embodiment of the present invention may have a function of wirelessly communicating with the earphone 750 .

[0440] 17B includes an earphone unit 727. A part of the wiring connecting the earphone unit 727 and a control unit may be disposed inside the housing 721 or the attachment unit 723.

[0441] 17(D) includes an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be configured to be connected to each other by wire.

[0442] As described above, the electronic devices of one embodiment of the present invention are preferably either glasses-type devices (such as the electronic devices 700A and 700B) or goggle-type devices (such as the electronic devices 800A and 800B).

[0443] An electronic device 6500 shown in FIG. 18A is a portable information terminal that can be used as a smartphone.

[0444] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display portion 6502 has a touch panel function.

[0445] The display device of one embodiment of the present invention can be applied to the display portion 6502. Therefore, the electronic device can be highly reliable.

[0446] FIG. 18B is a schematic cross-sectional view including the end portion of the housing 6501 on the microphone 6506 side.

[0447] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0448] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0449] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0450] A light-emitting device can be applied to the display panel 6511. This allows for extremely lightweight electronic devices. In addition, since the display panel 6511 is extremely thin, it is possible to mount a large-capacity battery 6518 while keeping the thickness of the electronic device small. In addition, by folding back a part of the display panel 6511 and arranging a connection part with the FPC 6515 on the back side of the pixel portion, it is possible to realize an electronic device with a narrow frame.

[0451] 18C shows an example of a television set. A television set 7100 includes a display portion 7000 built in a housing 7171. Here, the housing 7171 is supported by a stand 7173.

[0452] The display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can be highly reliable.

[0453] The television set 7100 shown in FIG. 18C can be operated using an operation switch provided on a housing 7171 and a separate remote control 7151.

[0454] 18D shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214. The housing 7211 includes a display portion 7000.

[0455] The display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can be highly reliable.

[0456] 18(E) and 18(F) show an example of digital signage that can be used in a show window, a showcase, or the like.

[0457] 18E includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0458] 18F shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0459] 18E and 18F, the display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can have high reliability.

[0460] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0461] In particular, when the display device of one embodiment of the present invention is used for advertisements or the like using the digital signage 7300 shown in FIG. 18E and the digital signage 7400 shown in FIG. 18F, the degree of freedom of expression can be increased by using a light-transmitting panel. For example, a light-transmitting display device can be manufactured by using wiring and a support member using a conductive film that transmits visible light and adjusting the distance between pixel electrodes. Furthermore, when the pillar 7401 is made of tempered glass or the like, the display device can also be used as a showcase.

[0462] In addition to the wiring and support member using the conductive film that transmits visible light, the tandem light-emitting device according to one embodiment of the present invention can increase the luminance per pixel. That is, even if the aperture ratio of the display device is reduced, a good display can be achieved, and therefore, the light transmittance of the display portion of the display device can be increased. Therefore, such a configuration is suitable for the light-transmitting display device according to one embodiment of the present invention.

[0463] Furthermore, as shown in Figures 18(E) and 18(F), it is preferable that the digital signage 7300 or the digital signage 7400 be able to wirelessly communicate with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user.

[0464] The electronic devices shown in Figures 19(A) to 19(G) include a housing 9000, a display portion 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), a microphone 9008, etc.

[0465] 19(A) to 19(G) have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to control processing by various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc.

[0466] The electronic devices shown in FIGS. 19A to 19G will be described in detail below.

[0467] FIG. 19A is a perspective view showing a mobile information terminal 9171. The mobile information terminal 9171 can be used as, for example, a smartphone. The mobile information terminal 9171 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, or the like. The mobile information terminal 9171 can display text and image information on multiple surfaces thereof. FIG. 19A shows an example in which three icons 9050 are displayed. Information 9051 indicated by a dashed rectangle can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notification of an incoming email, SNS, phone call, etc., the title of the email or SNS, the sender's name, the date and time, the remaining battery level, and radio wave intensity. Alternatively, the icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0468] 19B is a perspective view of a mobile information terminal 9172. The mobile information terminal 9172 has a function of displaying information on three or more surfaces of the display portion 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position where the mobile information terminal 9172 can be observed from above while the mobile information terminal 9172 is placed in a breast pocket of clothes.

[0469] 19(C) is a perspective view of a tablet terminal 9173. The tablet terminal 9173 is capable of executing various applications such as mobile phone calls, e-mails, document browsing and creation, music playback, internet communication, and computer games. The tablet terminal 9173 has a display portion 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front side of a housing 9000, operation keys 9005 as operation buttons on the left side of the housing 9000, and a connection terminal 9006 on the bottom.

[0470] FIG. 19D is a perspective view of a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The mobile information terminal 9200 may include operation keys 9005 as operation buttons on the left side of the housing 9000 and a sensor 9007 on the bottom. Although the curved bangle-type housing 9000 is shown as an example, the housing 9000 may be attached to a belt or the like. The display surface of the display unit 9001 is curved, and a display can be performed along the curved display surface. The power storage device 9004 may be curved along the housing 9000. The power storage device 9004 is flexible and can be bent according to a change in shape when attached or detached. A charge control IC connected to the power storage device 9004 may be included. In particular, the tandem light-emitting device of one embodiment of the present invention consumes low power and can be driven for a long time when used in the display unit 9001. Furthermore, the tandem light-emitting device of one embodiment of the present invention has high emission efficiency, and therefore can provide high visibility even when used outdoors. The portable information terminal 9200 can also perform hands-free conversations by communicating with, for example, a headset capable of wireless communication. The portable information terminal 9200 can also wirelessly transmit data to and from other information terminals and charge the device by wireless power supply. Note that data transmission and charging may be performed by wired communication using a connection terminal 9006 provided in the housing 9000.

[0471] 19(E) to 19(G) are perspective views showing a foldable mobile information terminal 9201. FIG. 19(E) shows the mobile information terminal 9201 in an unfolded state, FIG. 19(G) shows it in a folded state, and FIG. 19(F) is a perspective view showing a state in the process of changing from one of FIG. 19(E) and FIG. 19(G) to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent viewability of the display. A display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm to 150 mm.

[0472] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate. [Example]

[0473] In this example, light-emitting devices B-1 to B-3, G-1 to G-3, R-1, and R-2, which include light-emitting devices according to one embodiment of the present invention, were fabricated and their characteristics were evaluated. Furthermore, the estimation of power consumption of a display device using a light-emitting device according to one embodiment of the present invention will be described.

[0474] Each light-emitting device has the structure shown in Fig. 20 or 21, and has a tandem structure in which a first EL layer 903, an intermediate layer 905, a second EL layer 904, and a second electrode 902 are stacked on a first electrode 901 formed on a glass substrate 900. In addition, a cap layer 909 is formed on the second electrode. The structures of light-emitting devices B-1, B-2, B-3, and G-1 are shown in Fig. 20, and the structures of light-emitting devices G-2, G-3, R-1, and R-2 are shown in Fig. 21.

[0475] 20 , the first EL layer 903 of each of light-emitting devices B-1, B-2, B-3, and G-1 has a structure in which a hole injection layer 910, a first hole transport layer 911 (first hole transport layer 911_1, first hole transport layer 911_2), a first light-emitting layer 912, and a first electron transport layer 913 are sequentially stacked. The second EL layer 904 has a structure in which a second hole transport layer 916 (second hole transport layer 916_1, second hole transport layer 916_2), a second light-emitting layer 917, a second electron transport layer 918 (second electron transport layer 918_1, second electron transport layer 918_2), and an electron injection layer 919 are sequentially stacked.

[0476] 21, the first EL layer 903 of each of light-emitting devices G-2, G-3, R-1, and R-2 has a structure in which a hole injection layer 910, a first hole transport layer 911_1, a first light-emitting layer 912, and a first electron transport layer 913 are sequentially stacked. The second EL layer 904 has a structure in which a second hole transport layer 916_1, a second light-emitting layer 917, a second electron transport layer 918 (a second electron transport layer 918_1, a second electron transport layer 918_2), and an electron injection layer 919 are sequentially stacked.

[0477] The intermediate layer 905 of each light-emitting device includes an electron-injecting buffer region 914 and a layer 915 containing an electron-relay region and a charge-generating region.

[0478] Note that the light-emitting devices B-1 to B-3 are blue light-emitting devices. The light-emitting device B-1 is a light-emitting device according to one embodiment of the present invention, and is a light-emitting device in which a TADF material is used for the first light-emitting layer 912 and the second light-emitting layer 917. On the other hand, the light-emitting devices B-2 and B-3 are light-emitting devices in which a fluorescent light-emitting substance is used for the first light-emitting layer 912 and the second light-emitting layer 917. The light-emitting devices B-1 and B-2 are light-emitting devices in which the second electron-transport layer 918_2 contains an organic compound having a triazine ring, while the light-emitting device B-3 is a light-emitting device in which the second electron-transport layer 918_2 does not contain an organic compound having a triazine ring.

[0479] Light-emitting devices G-1, G-2, and G-3 are green light-emitting devices. Light-emitting device G-1 is a light-emitting device according to one embodiment of the present invention, and is a light-emitting device in which a TADF material is used for the first light-emitting layer 912 and the second light-emitting layer 917. Light-emitting devices G-2 and G-3 are light-emitting devices in which a fluorescent material is used for the first light-emitting layer 912 and the second light-emitting layer 917. Light-emitting devices G-1 and G-2 are light-emitting devices in which the second electron-transport layer 918_2 contains an organic compound having a triazine ring, while light-emitting device G-3 is a light-emitting device in which the second electron-transport layer 918_2 does not contain an organic compound having a triazine ring.

[0480] The light-emitting devices R-1 and R-2 are red light-emitting devices that use phosphorescent materials in the first light-emitting layer 912 and the second light-emitting layer 917. The light-emitting device R-1 is a light-emitting device in which the second electron-transporting layer 918_2 contains an organic compound having a triazine ring, while the light-emitting device R-2 is a light-emitting device in which the second electron-transporting layer 918_2 does not contain an organic compound having a triazine ring.

[0481] Each light-emitting device was fabricated using a vacuum integrated process. The structural formulas of the organic compounds used in each light-emitting device are shown below.

[0482] [ka]

[0483] [ka]

[0484] <Method for producing light-emitting device B-1> First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide (ITSO) film was formed on a transparent electrode by sputtering to a thickness of 85 nm to form a first electrode. The transparent electrode functions as an anode and can be considered the first electrode together with the reflective electrode. The first electrode was 2 mm x 2 mm.

[0485] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate was washed with water and baked at 200°C for 1 hour.

[0486] Then 1×10 -4 The substrate was placed in a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to a heat treatment at 170°C for 30 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0487] Next, the substrate on which the first electrode 901 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 901 was formed faced downward. N-(biphenyl-2-yl)-N-(9,9-dimethylfluoren-2-yl)-9,9′-spirobi[9H-fluorene]-2-amine (abbreviation: oFBiSF(2)), an organic compound having a triarylamine skeleton and a fluorene ring that is a polycyclic aromatic ring, and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited on the first electrode 901 by an evaporation method using resistance heating in a ratio of oFBiSF(2):OCHD-003=1:0.03 (weight ratio) to a film thickness of 10 nm, thereby forming a hole injection layer 910.

[0488] Next, a first hole transport layer 911 (first hole transport layer 911_1 and first hole transport layer 911_2) was formed on the hole injection layer 910. oFBiSF(2), an organic compound having a triarylamine skeleton and a fluorene ring, which is a polycyclic aromatic ring, was deposited by a vapor deposition method using resistance heating to a thickness of 65 nm to form the first hole transport layer 911_1, and then 9-[3-(triphenylsilyl)phenyl]-3,9′-bi-9H-carbazole (abbreviation: PSiCzCz), an organic compound having a carbazole ring, which is a π-electron-rich heteroaromatic ring, but not a triarylamine skeleton, was deposited on the first hole transport layer 911_1 to a thickness of 5 nm to form the first hole transport layer 911_2.

[0489] Next, a first light-emitting layer 912 was formed on the first hole-transporting layer 911. [4-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)phenyl]triphenylsilane (abbreviation: TDBA-Si) and N 7 ,N 7 ,N 13 ,N 13 ,5,9,11,15-Octaphenyl-5H,9H,11H,15H-[1,4]benzazaborino[2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[3,2-b]phenazaborine-7,13-diamine (abbreviation: ν-DABNA) was co-deposited in a ratio of TDBA-Si:ν-DABNA = 1.0:0.015 (weight ratio) to a thickness of 25 nm, to form a first light-emitting layer 912.

[0490] Next, on the first light-emitting layer 912, an organic compound having a triazine ring, 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), was evaporated to a thickness of 10 nm to form a first electron-transporting layer 913.

[0491] Next, an intermediate layer 905 was provided. First, on the first electron transport layer 913, 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), an organic compound having a phenanthroline ring, and lithium oxide (abbreviation: Li2O) were co-deposited by a vapor deposition method using resistance heating in a ratio of mPPhen2P:Li2O=1:0.02 (volume ratio) to a thickness of 5 nm, to form a layer that would become an electron injection buffer region 914.

[0492] Next, a copper phthalocyanine (CuPc) film was formed to a thickness of 2 nm as an electron relay region. Next, a layer 915 including a charge generation region was formed by co-evaporating oFBiSF(2) and a fluorine-containing electron acceptor material (OCHD-003) with a molecular weight of 672 in a weight ratio of oFBiSF(2):OCHD-003 = 1:0.15 to a thickness of 10 nm using a vapor deposition method using resistance heating.

[0493] Next, a second EL layer 904 was provided on the intermediate layer 905 .

[0494] First, the second hole transport layer 916 (second hole transport layer 916_1 and second hole transport layer 916_2) was formed. After the second hole transport layer 916_1 was formed by depositing oFBiSF(2) to a thickness of 55 nm, the second hole transport layer 916_2 was formed by depositing PSiCzCz on the second hole transport layer 916_1 to a thickness of 5 nm.

[0495] Next, TDBA-Si and ν-DABNA were co-deposited on the second hole transport layer 916 by a vapor deposition method using resistance heating so that the weight ratio of TDBA-Si:ν-DABNA was 1.0:0.015 and the film thickness was 25 nm, thereby forming a second light-emitting layer 917.

[0496] Next, on the second light-emitting layer 917, the second electron-transporting layer 918 (the second electron-transporting layer 918_1 and the second electron-transporting layer 918_2) was formed. First, a second electron-transporting layer 918_1 was formed by depositing 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), an organic compound having a triazine ring, to a thickness of 10 nm by a deposition method using resistance heating. Then, a second electron-transporting layer 918_2 was formed by co-depositing 2,2'-(1,2-naphthalenediyldi-4,1-phenylene)bis[4,6-diphenyl-1,3,5-triazine] (abbreviation: TznP2N), an organic compound having a triazine ring, and 8-quinolinolato-lithium (abbreviation: Liq) in a volume ratio of TznP2N:Liq = 1:1 to a thickness of 25 nm.

[0497] Next, Liq was evaporated onto the second electron transport layer 918 to form an electron injection layer 919 with a thickness of 1 nm.

[0498] Next, Ag and Mg were co-evaporated on the electron injection layer 919 at a volume ratio of Ag:Mg=1:0.1 to a thickness of 15 nm to form a second electrode 902. The second electrode 902 is a semi-transmissive / semi-reflective electrode that has the function of reflecting light and the function of transmitting light.

[0499] Then, a capping layer of 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) was evaporated to a thickness of 70 nm to improve the light extraction efficiency.

[0500] Through the above steps, a light-emitting device B-1 was fabricated.

[0501] <Method for fabricating light-emitting device B-2> Light-emitting device B-2 differs from light-emitting device B-1 in the configurations of first light-emitting layer 912, second light-emitting layer 917, first hole-transporting layer 911, and second hole-transporting layer 916. The other configurations were fabricated in the same manner as light-emitting device B-1.

[0502] Specifically, the first light-emitting layer 912 and the second light-emitting layer 917 of the light-emitting device B-2 were formed by co-evaporation using resistance heating of 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) in a weight ratio of αN-βNPAnth:3,10PCA2Nbf(IV)-02 = 1:0.015 to a thickness of 25 nm.

[0503] In addition, the first hole transport layer 911 of the light-emitting device B-2 was formed by first depositing oFBiSF(2) to a thickness of 50 nm by a vapor deposition method using resistance heating to form the first hole transport layer 911_1, and then depositing N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) having a triarylamine skeleton on the first hole transport layer 911_1 to a thickness of 10 nm to form the first hole transport layer 911_2.

[0504] In addition, the second hole transport layer 916 of the light-emitting device B-2 was formed by first depositing oFBiSF(2) to a thickness of 45 nm using a vapor deposition method using resistance heating to form the second hole transport layer 916_1, and then depositing DBfBB1TP on the second hole transport layer 916_1 to a thickness of 10 nm to form the second hole transport layer 916_2.

[0505] <Method for fabricating light-emitting device B-3> Light-emitting device B-3 differs from light-emitting device B-2 in the structure of second electron transport layer 918. The other structures were fabricated in the same manner as light-emitting device B-2.

[0506] Specifically, the second electron-transport layer 918 of the light-emitting device B-3 was formed by first depositing mFBPTzn on the second light-emitting layer 917 by a resistance heating evaporation method to a thickness of 10 nm to form a second electron-transport layer 918_1, and then co-depositing 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), an organic compound not having a triazine ring, and Liq in a volume ratio of 6BP-4Cz2PPm:Liq = 1:1 to a thickness of 25 nm to form a second electron-transport layer 918_2.

[0507] The device structures of light-emitting device B-1, light-emitting device B-2, and light-emitting device B-3 are summarized in the following table.

[0508] [Table 1]

[0509] <Method for fabricating light-emitting device G-1> Light-emitting device G-1 differs from light-emitting device B-1 in the configurations of first light-emitting layer 912, second light-emitting layer 917, first hole-transporting layer 911, and second hole-transporting layer 916. The other configurations were fabricated in the same manner as light-emitting device B-1.

[0510] Specifically, the first light-emitting layer 912 and the second light-emitting layer 917 of the light-emitting device G-1 were formed by co-evaporation of 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) and 3,6-bis(diphenylamino)-9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9H-carbazole (abbreviation: DACT-II) in a weight ratio of 4,6mCzP2Pm:DACT-II = 0.8:0.2 to a thickness of 40 nm.

[0511] The first hole transport layer 911 of the light-emitting device G-1 was formed by first depositing oFBiSF(2) to a thickness of 75 nm by a vapor deposition method using resistance heating to form the first hole transport layer 911_1, and then depositing 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP), an organic compound having a carbazole skeleton, which is a π-electron-rich heteroaromatic ring, but not a triarylamine skeleton, on the first hole transport layer 911_1 to a thickness of 10 nm to form the first hole transport layer 911_2.

[0512] In addition, the second hole transport layer 916 of the light-emitting device G-1 was formed by first depositing oFBiSF(2) to a thickness of 40 nm using a vapor deposition method using resistance heating to form the second hole transport layer 916_1, and then depositing PCCP on the second hole transport layer 916_1 to a thickness of 10 nm to form the second hole transport layer 916_2.

[0513] <Method for fabricating light-emitting device G-2> Light-emitting device G-2 differs from light-emitting device G-1 in the configurations of first light-emitting layer 912, second light-emitting layer 917, first hole-transporting layer 911, and second hole-transporting layer 916. The other configurations were fabricated in the same manner as light-emitting device G-1.

[0514] Specifically, the first light-emitting layer 912 and the second light-emitting layer 917 of the light-emitting device G-2 were formed by co-evaporation of 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA) in a weight ratio of cgDBCzPA:2PCAPA = 1:0.05 to a thickness of 40 nm.

[0515] The first hole transport layer 911_2 of the light-emitting device G-2 was not provided with the first hole transport layer 911. The first hole transport layer 911 (i.e., the first hole transport layer 911_1) was formed by depositing oFBiSF(2), an organic compound having a triarylamine skeleton and a fluorene ring, which is a polycyclic aromatic ring, by a vapor deposition method using resistance heating to a film thickness of 80 nm.

[0516] The second hole transport layer 916 of the light-emitting device G-2 did not include the second hole transport layer 916_2. The second hole transport layer 916 (i.e., the second hole transport layer 916_1) was formed by depositing oFBiSF(2) to a thicknes...

Claims

1. 1. A light-emitting device having a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first hole-transporting layer, and a second hole-transporting layer, the 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 intermediate layer, the second light-emitting layer is located between the intermediate layer and the second electrode, the first hole transport layer is located between the first electrode and the first light-emitting layer; the second hole transport layer is located between the intermediate layer and the second light-emitting layer, the first light-emitting layer comprises a first light-emitting material; the second light-emitting layer comprises a second light-emitting material; the first luminescent material and the second luminescent material are each a TADF material; at least one of the first hole transport layer and the second hole transport layer contains an organic compound having a π-electron-rich heteroaromatic ring and not having a triarylamine skeleton; a difference between a maximum peak wavelength in the emission spectrum of the first luminescent material and a maximum peak wavelength in the emission spectrum of the second luminescent material is 30 nm or less; The first light-emitting layer and the second light-emitting layer have light-emitting layers that emit light of a different hue from the light-emitting layer of at least one of a plurality of other light-emitting devices adjacent to the light-emitting device.

2. 1. A light-emitting device having a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first hole-transporting layer, and a second hole-transporting layer, the 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 intermediate layer, the second light-emitting layer is located between the intermediate layer and the second electrode, the first hole transport layer is located between the first electrode and the first light-emitting layer; the second hole transport layer is located between the intermediate layer and the second light-emitting layer, the first hole transport layer has a first layer and a second layer, the first layer is in contact with the first light-emitting layer, the first light-emitting layer includes a first light-emitting material and a first organic compound; a difference between an emission edge on a short wavelength side in the fluorescence spectrum of the first luminescent substance and an emission edge on a short wavelength side in the phosphorescence spectrum of the first luminescent substance is 30 nm or less; an emission edge on the short wavelength side in the phosphorescence spectrum of the first organic compound is shorter in wavelength than an emission edge on the short wavelength side in the phosphorescence spectrum of the first light-emitting substance; the second light-emitting layer includes a second light-emitting material and a second organic compound; a difference between an emission edge on a shorter wavelength side in the fluorescence spectrum of the second light-emitting substance and an emission edge on a shorter wavelength side in the phosphorescence spectrum of the second light-emitting substance is 30 nm or less; an emission edge on the short wavelength side in the phosphorescence spectrum of the second organic compound is shorter in wavelength than an emission edge on the short wavelength side in the phosphorescence spectrum of the second light-emitting substance; the first layer comprises a third organic compound; the third organic compound has a π-electron-rich heteroaromatic ring and does not have a triarylamine skeleton, the second layer comprises a fourth organic compound; the fourth organic compound has a triarylamine skeleton, a difference between a maximum peak wavelength in the fluorescence spectrum of the first luminescent substance and a maximum peak wavelength in the fluorescence spectrum of the second luminescent substance is 30 nm or less; The first light-emitting layer and the second light-emitting layer have light-emitting layers that emit light of a different hue from the light-emitting layer of at least one of a plurality of other light-emitting devices adjacent to the light-emitting device.

3. In claim 2, an emission edge on a short wavelength side in a fluorescence spectrum of the first organic compound is shorter in wavelength than an absorption edge on a long wavelength side in an absorption spectrum of the first light-emitting substance; a light-emitting device, wherein the emission edge on the short wavelength side in the fluorescence spectrum of the second organic compound is shorter in wavelength than the absorption edge on the long wavelength side in the absorption spectrum of the second light-emitting substance;

4. In claim 2, A light-emitting device, wherein the first luminescent material and the second luminescent material are materials capable of exhibiting thermally activated delayed fluorescence.

5. In claim 1 or claim 2, A light-emitting device, wherein the first luminescent material and the second luminescent material are the same material.

6. In claim 2, The fourth organic compound comprises a polycyclic aromatic ring.

7. In claim 1 or claim 2, the light-emitting device comprises a first electron-transporting layer located between the first light-emitting layer and the intermediate layer; The first electron transport layer comprises an organic compound containing one of a triazine ring, a pyrimidine ring, an imidazole ring, and an anthracene ring.

8. In claim 1 or claim 2, a second electron transport layer between the second light-emitting layer and the second electrode; the second electron transport layer includes a layer including an organic compound having a triazine ring, The intermediate layer comprises a first mixed layer of an organic compound having a phenanthroline ring and lithium or a lithium compound.

9. In claim 8, the second electron transport layer includes a second mixed layer of an organic compound having a triazine ring and lithium or a lithium compound, The second mixed layer is located between the layer containing the organic compound having a triazine ring and the second electrode.

10. A display device having a light-emitting device A and a light-emitting device B, The light-emitting device B has a different emission color from the light-emitting device A, The light-emitting device A has a first electrode A, a second electrode A, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first hole-transporting layer A, and a second hole-transporting layer A; the intermediate layer A is located between the first electrode A and the second electrode A, the first light-emitting layer A is located between the first electrode A and the intermediate layer A, the second light-emitting layer A is located between the intermediate layer A and the second electrode A, the first hole transport layer A is located between the first electrode A and the first light-emitting layer A, the second hole transport layer A is located between the intermediate layer A and the second light-emitting layer A, the first light-emitting layer A contains a first light-emitting material, the second light-emitting layer A contains a second light-emitting material, the first luminescent substance is a substance capable of exhibiting thermally activated delayed fluorescence, the second luminescent substance is a substance capable of exhibiting thermally activated delayed fluorescence, at least one of the first hole transport layer A and the second hole transport layer A contains an organic compound A having a π-electron-rich heteroaromatic ring and not having a triarylamine skeleton; a difference between a maximum peak wavelength in the emission spectrum of the first luminescent material and a maximum peak wavelength in the emission spectrum of the second luminescent material is 30 nm or less; the light-emitting device B has a first electrode B, a second electrode B, an intermediate layer B, a first light-emitting layer B, a second light-emitting layer B, a first hole-transporting layer B, and a second hole-transporting layer B; the intermediate layer B is located between the first electrode B and the second electrode B, the first light-emitting layer B is located between the first electrode B and the intermediate layer B, the second light-emitting layer B is located between the intermediate layer B and the second electrode B, the first hole transport layer B is located between the first electrode B and the first light-emitting layer B, the second hole transport layer B is located between the intermediate layer B and the second light-emitting layer B, the first light-emitting layer B contains a first phosphorescent material, the second light-emitting layer B contains a second phosphorescent material, at least one of the first hole transport layer B and the second hole transport layer B contains an organic compound B having a triarylamine skeleton; a difference between a maximum peak wavelength in the emission spectrum of the first phosphorescent material and a maximum peak wavelength in the emission spectrum of the second phosphorescent material is 30 nm or less.

11. A display device having a light-emitting device A and a light-emitting device B, The light-emitting device B has a different emission color from the light-emitting device A, The light-emitting device A has a first electrode A, a second electrode A, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first hole-transporting layer A, and a second hole-transporting layer A; the intermediate layer A is located between the first electrode A and the second electrode A, the first light-emitting layer A is located between the first electrode A and the intermediate layer A, the second light-emitting layer A is located between the intermediate layer A and the second electrode A, the first hole transport layer A is located between the first electrode A and the first light-emitting layer A, the second hole transport layer A is located between the intermediate layer A and the second light-emitting layer A, the first light-emitting layer A contains a first light-emitting material, the second light-emitting layer A contains a second light-emitting material, the first luminescent substance is a substance capable of exhibiting thermally activated delayed fluorescence, the second luminescent substance is a substance capable of exhibiting thermally activated delayed fluorescence, at least one of the first hole transport layer A and the second hole transport layer A contains an organic compound A that does not have a triarylamine skeleton; a difference between a maximum peak wavelength in the emission spectrum of the first luminescent material and a maximum peak wavelength in the emission spectrum of the second luminescent material is 30 nm or less; the light-emitting device B has a first electrode B, a second electrode B, an intermediate layer B, a first light-emitting layer B, a second light-emitting layer B, a first hole-transporting layer B, and a second hole-transporting layer B; the intermediate layer B is located between the first electrode B and the second electrode B, the first light-emitting layer B is located between the first electrode B and the intermediate layer B, the second light-emitting layer B is located between the intermediate layer B and the second electrode B, the first hole transport layer B is located between the first electrode B and the first light-emitting layer B, the second hole transport layer B is located between the intermediate layer B and the second light-emitting layer B, the first light-emitting layer B comprises a first fluorescent light-emitting material, the second light-emitting layer B comprises a second fluorescent light-emitting material, at least one of the first hole transport layer B and the second hole transport layer B contains an organic compound B having a triarylamine skeleton; a difference between a maximum peak wavelength in the emission spectrum of the first fluorescent luminescent material and a maximum peak wavelength in the emission spectrum of the second fluorescent luminescent material being 30 nm or less;

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