Light-emitting device and display apparatus

Abstract

Provided is a light-emitting device having good characteristics. This light-emitting device comprises first and second electrodes, an intermediate layer located between the first and second electrodes, first and second light-emitting layers, and first and second electron transport layers, wherein 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 electron transport layer is located between the first light-emitting layer and the intermediate layer, the second electron transport layer is located between the second light-emitting layer and the intermediate layer, the second electron transport layer has a third organic compound including a triazine skeleton, the intermediate layer has a fourth organic compound including a phenanthroline skeleton, the first light-emitting layer and the second light-emitting layer have two types of organic compounds forming an excited complex with the same light-emitting center substance, and the first light-emitting layer and the second light-emitting layer have a light-emitting layer different 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.

Description

Light-emitting devices and displays

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

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

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

[0004] Furthermore, these light-emitting devices can have a continuous, planar light-emitting layer, which allows them to emit light in a planar manner. This is a feature that is difficult to obtain with point light sources such as incandescent lamps and LEDs, or linear light sources such as fluorescent lamps, making them highly useful as planar light sources for lighting applications.

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

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

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

[0008] JP 2005-317548 A JP 2023-161850 A

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

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

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

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

[0013] One aspect 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 electron-transporting layer, and a second electron-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 electron-transporting layer is located between the first light-emitting layer and the intermediate layer, and the second electron-transporting layer is located between the second light-emitting layer and the second electrode, and the first light-emitting layer has a first luminescent center substance and a first organic compound, The second light-emitting layer has a second light-emitting center substance and a second organic compound, the first organic compound and the second organic compound are substances capable of exhibiting thermally activated delayed fluorescence, the difference between the maximum peak wavelength in the emission spectrum of the first light-emitting center substance and the maximum peak wavelength in the emission spectrum of the second light-emitting center substance is 30 nm or less, and the first light-emitting layer and the second light-emitting layer are a light-emitting device having a light-emitting layer that emits 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.

[0014] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron-transporting layer, and a second electron-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 electron-transporting layer is located between the first light-emitting layer and the intermediate layer, and the second electron-transporting layer is located between the second light-emitting layer and the second electrode, the second electron-transporting layer includes a third organic compound having a triazine skeleton, and the intermediate layer includes a fourth organic compound having a phenanthroline skeleton and lithium or lithium ion. the first light-emitting layer has a first luminescence center substance and a first organic compound; the second light-emitting layer has a second luminescence center substance and a second organic compound; the first organic compound and the second organic compound are substances capable of exhibiting thermally activated delayed fluorescence; the difference between the maximum peak wavelength in the emission spectrum of the first luminescence center substance and the maximum peak wavelength in the emission spectrum of the second luminescence center substance 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.

[0015] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first electron-transport layer includes a sixth organic compound that does not contain a triazine skeleton.

[0016] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron-transport layer includes a sixth organic compound including at least one of a pyrimidine skeleton, an imidazole skeleton, and an anthracene skeleton.

[0017] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron-transporting layer, and a second electron-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 electron-transporting layer is located between the first light-emitting layer and the intermediate layer, and the second electron-transporting layer is located between the second light-emitting layer and the second electrode, the second electron-transporting layer includes a third organic compound having a triazine skeleton, the intermediate layer includes a fourth organic compound having a phenanthroline skeleton, and the first electron-transporting layer the first light-emitting layer has a first light-emitting center substance and the first organic compound; the second light-emitting layer has a second light-emitting center substance and the second organic compound; the first organic compound and the second organic compound are substances capable of exhibiting thermally activated delayed fluorescence; the difference between the maximum peak wavelength in the emission spectrum of the first light-emitting center substance and the maximum peak wavelength in the emission spectrum of the second light-emitting center substance is 30 nm or less; and the first light-emitting layer and the second light-emitting layer have light-emitting layers different 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.

[0018] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the third organic compound and the fifth organic compound are the same organic compound.

[0019] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the intermediate layer contains lithium or a lithium compound.

[0020] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the intermediate layer includes a mixed layer of the fourth organic compound and lithium or a lithium compound.

[0021] Another embodiment of the present invention is a light-emitting device having any one of the above structures, in which an emission edge on a shorter wavelength side in an emission spectrum of the first organic compound is positioned at a wavelength shorter than an absorption edge on a longer wavelength side in an absorption spectrum of the first luminescence center substance.

[0022] Another embodiment of the present invention is a light-emitting device having any one of the above structures, in which an emission edge on a shorter wavelength side in an emission spectrum of the second organic compound is positioned at a wavelength shorter than an absorption edge on a longer wavelength side in an absorption spectrum of the second luminescence center substance.

[0023] Alternatively, another embodiment of the present invention is a light-emitting device having any of the above structures, in which an emission edge on a short wavelength side in an emission spectrum of the first organic compound is positioned at a wavelength shorter than an absorption edge on a long wavelength side in an absorption spectrum of the first luminescence center substance, and an emission edge on a short wavelength side in an emission spectrum of the second organic compound is positioned at a wavelength shorter than an absorption edge on a long wavelength side in an absorption spectrum of the second luminescence center substance.

[0024] Alternatively, another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the peak wavelength of the emission spectrum of the first organic compound is shorter than the peak wavelength of the emission spectrum of the first luminescence center substance, and the difference between the peak wavelength of the emission spectrum of the first organic compound and the peak wavelength of the emission spectrum of the first luminescence center substance is 30 nm or less.

[0025] Alternatively, another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the peak wavelength of the emission spectrum of the second organic compound is shorter than the peak wavelength of the emission spectrum of the second luminescence center substance, and the difference between the peak wavelength of the emission spectrum of the second organic compound and the peak wavelength of the emission spectrum of the second luminescence center substance is 30 nm or less.

[0026] Alternatively, another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the peak wavelength of the emission spectrum of the first organic compound is shorter than the peak wavelength of the emission spectrum of the first luminescence center substance, and the difference between the peak wavelengths of the emission spectrum of the first organic compound and the first luminescence center substance is 30 nm or less; and the peak wavelength of the emission spectrum of the second organic compound is shorter than the peak wavelength of the emission spectrum of the second luminescence center substance, and the difference between the peak wavelengths of the emission spectrum of the second organic compound and the second luminescence center substance is 30 nm or less.

[0027] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the energy difference between the HOMO level and the LUMO level of the first luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the first organic compound.

[0028] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the energy difference between the HOMO level and the LUMO level of the second luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the second organic compound.

[0029] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the energy difference between the HOMO level and the LUMO level of the first luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the first organic compound, and the energy difference between the HOMO level and the LUMO level of the second luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the second organic compound.

[0030] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the second electron-transporting layer contains lithium or a lithium compound.

[0031] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first luminescent center substance and the second luminescent center substance are the same substance.

[0032] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the intermediate layer includes a first layer containing a fourth organic compound.

[0033] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first layer contains lithium or a lithium compound.

[0034] Another embodiment of the present invention is a light-emitting device having the above structure, in which the intermediate layer further includes a second layer, and the second layer is located between the first layer and the second light-emitting layer.

[0035] Another embodiment of the present invention is a light-emitting device having the above structure, in which the second layer includes an organic compound including a fifth organic compound having a hole-transport property.

[0036] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the second layer contains an organic compound having at least one of a halogen group and a cyano group.

[0037] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the second layer contains an organic compound having at least one of fluorine and a cyano group.

[0038] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the second layer includes an organic compound having four or more groups selected from the group consisting of halogen groups and cyano groups.

[0039] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the second layer contains four or more organic compounds each containing at least one of fluorine and cyano groups.

[0040] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first electron-transport layer includes a second organic compound having a triazine skeleton.

[0041] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the third organic compound and the fifth organic compound are the same organic compound.

[0042] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first electron-transport layer includes a fifth organic compound that does not contain a triazine skeleton.

[0043] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron-transport layer includes a fifth organic compound including at least one of a pyrimidine skeleton, an imidazole skeleton, and an anthracene skeleton.

[0044] Another embodiment of the present invention is a display device including any of the above light-emitting devices.

[0045] 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 A being adjacent to the light-emitting device B. The light-emitting device A includes a first electrode A, a second electrode, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first electron-transport layer A, and a second electron-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 electron-transport layer A is located between the first light-emitting layer A and the intermediate layer A. layer A, and a second electron transport layer A is located between the second light-emitting layer A and the second electrode A; 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 electron transport layer B, and a second electron 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 electron transport layer B is located between the first light-emitting layer B and the intermediate layer B; and the second electron transport layer B is located between the second light-emitting layer B. and a second electrode B, the second electron transport layer A and the second electron transport layer B contain a third organic compound having a triazine skeleton, and the second electron transport layer A and the second electron transport layer B are made of the same material, the intermediate layer A and the intermediate layer B contain a fourth organic compound having a phenanthroline skeleton, and lithium or a lithium compound, the first light-emitting layer A contains a first light-emitting center substance and the first organic compound, and the second light-emitting layer A contains a second light-emitting center substance and the second organic compound, and the first organic compound and the second organic compound are capable of exhibiting thermally activated delayed fluorescence. the first light-emitting layer B has a third light-emitting center substance, the second light-emitting layer B has a fourth light-emitting center substance, the difference between the maximum peak wavelength in the emission spectrum of the first light-emitting center substance and the maximum peak wavelength in the emission spectrum of the second light-emitting center substance is 30 nm or less, the difference between the maximum peak wavelength in the emission spectrum of the third light-emitting center substance and the maximum peak wavelength in the emission spectrum of the fourth light-emitting center substance is 30 nm or less, and the first light-emitting layer A and the first light-emitting layer B, and the second light-emitting layer A and the second light-emitting layer B are different light-emitting layers.

[0046] 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 A being adjacent to the light-emitting device B. The light-emitting device A includes a first electrode A, a second electrode, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first electron-transporting layer A, and a second electron-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 electron-transporting layer A is located between the first light-emitting layer A and the intermediate layer A. A is located between the first electrode B and the second electrode B, and the second electron transport layer A is located between the second light-emitting layer A and the second electrode A. 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 electron transport layer B, and a second electron transport layer B, and 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, and the second light-emitting layer B is located between the intermediate layer B and the second electrode B, and the first electron transport layer B is located between the first light-emitting layer B and the intermediate layer B, and the second electron transport layer B is located between the second light-emitting layer B and the the second electron transport layer A and the second electron transport layer B comprise a third organic compound having a triazine skeleton; the second electron transport layer A and the second electron transport layer B are continuous layers; the intermediate layer A and the intermediate layer B comprise a fourth organic compound having a phenanthroline skeleton, and lithium or a lithium compound; the first light-emitting layer A comprises a first light-emitting center substance and the first organic compound; the second light-emitting layer A comprises a second light-emitting center substance and the second organic compound; and the first organic compound and the second organic compound exhibit thermally activated delayed fluorescence. a first light-emitting layer B having a third light-emitting center substance and a second light-emitting layer B having a fourth light-emitting center substance, the difference between the maximum peak wavelength in the emission spectrum of the first light-emitting center substance and the maximum peak wavelength in the emission spectrum of the second light-emitting center substance is 30 nm or less, the difference between the maximum peak wavelength in the emission spectrum of the third light-emitting center substance and the maximum peak wavelength in the emission spectrum of the fourth light-emitting center substance is 30 nm or less, and the first light-emitting layer A and the first light-emitting layer B, and the second light-emitting layer A and the second light-emitting layer B are different light-emitting layers.

[0047] Another embodiment of the present invention is a display device having the above structure, in which an emission edge on the short-wavelength side in an emission spectrum of the first organic compound is positioned at a wavelength shorter than an absorption edge on the long-wavelength side in an emission spectrum of the first emission center substance.

[0048] Another embodiment of the present invention is a display device having the above structure, in which an emission edge on the short-wavelength side in an emission spectrum of the second organic compound is positioned at a wavelength shorter than an absorption edge on the long-wavelength side in an emission spectrum of the second emission center substance.

[0049] Another embodiment of the present invention is a display device having the above structure, in which an emission edge on the short-wavelength side in an emission spectrum of the first organic compound is positioned at a wavelength shorter than an absorption edge on the long-wavelength side in an emission spectrum of the first luminescence center substance, and an emission edge on the short-wavelength side in an emission spectrum of the second organic compound is positioned at a wavelength shorter than an absorption edge on the long-wavelength side in an emission spectrum of the second luminescence center substance.

[0050] Another embodiment of the present invention is a display device having the above structure, in which the peak wavelength of the emission spectrum of the first organic compound is shorter than the peak wavelength of the emission spectrum of the first emission center substance, and the difference between the peak wavelength of the emission spectrum of the first organic compound and the peak wavelength of the emission spectrum of the first emission center substance is 30 nm or less.

[0051] Another embodiment of the present invention is a display device having the above structure, in which the peak wavelength of the emission spectrum of the second organic compound is shorter than the peak wavelength of the emission spectrum of the second emission center substance, and the difference between the peak wavelength of the emission spectrum of the second organic compound and the peak wavelength of the emission spectrum of the second emission center substance is 30 nm or less.

[0052] Another embodiment of the present invention is a display device having the above structure, wherein the peak wavelength of the emission spectrum of the first organic compound is shorter than the peak wavelength of the emission spectrum of the first luminescence center substance, and the difference between the peak wavelengths of the emission spectrum of the first organic compound and the first luminescence center substance is 30 nm or less; and the peak wavelength of the emission spectrum of the second organic compound is shorter than the peak wavelength of the emission spectrum of the second luminescence center substance, and the difference between the peak wavelengths of the emission spectrum of the second organic compound and the second luminescence center substance is 30 nm or less.

[0053] Another embodiment of the present invention is a display device having the above structure, in which the energy difference between the HOMO level and the LUMO level of the first luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the first organic compound.

[0054] Another embodiment of the present invention is a display device having the above structure, in which the energy difference between the HOMO level and the LUMO level of the second luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the second organic compound.

[0055] Another embodiment of the present invention is a display device having the above structure, in which the energy difference between the HOMO level and the LUMO level of the first luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the first organic compound, and the energy difference between the HOMO level and the LUMO level of the second luminescence center substance is larger than the energy difference between the HOMO level and the LUMO level of the second organic compound.

[0056] Another embodiment of the present invention is an electronic device including any of the above light-emitting devices and a sensor, an operation button, a speaker, or a microphone.

[0057] Another embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing.

[0058] The above is one embodiment of the present invention, and the present invention is not limited to the above configuration.

[0059] 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.

[0060] Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with good characteristics. Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with good emission efficiency. Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with good reliability. Alternatively, one embodiment of the present invention can provide a display device with low driving voltage. Alternatively, one embodiment of the present invention can provide a light-emitting device that can provide a display device with low driving voltage and good reliability.

[0061] Alternatively, it is possible to provide any one of an organic semiconductor device, a light-emitting device, a light-receiving device, a display device, an electronic device, and a lighting device with low power consumption, or any one of an electronic device and a lighting device with high reliability.

[0062] FIGS. 1A to 1C are schematic diagrams of a light-emitting device according to one embodiment of the present invention. FIGS. 2A and 2B are schematic diagrams of a light-emitting device according to one embodiment of the present invention. FIGS. 3A and 3B are diagrams of a display device according to one embodiment of the present invention. FIGS. 4A and 4B are diagrams of a display device according to one embodiment of the present invention. FIGS. 5A to 5E are cross-sectional views illustrating an example of a manufacturing method of a display device. FIGS. 6A and 6B are cross-sectional views illustrating an example of a manufacturing method of a display device. FIGS. 7A to 7D are cross-sectional views illustrating an example of a manufacturing method of a display device. FIGS. 8A to 8C are cross-sectional views illustrating an example of a manufacturing method of a display device. FIGS. 9A to 9C are cross-sectional views illustrating an example of a manufacturing method of a display device. FIGS. 10A to 10C are cross-sectional views illustrating an example of a manufacturing method of a display device. FIGS. 11A and 11B are perspective views illustrating a structural example of a display module. FIGS. 12A and 12B are cross-sectional views illustrating a structural example of a display device. FIG. 13 is a perspective view illustrating a structural example of a display device. FIG. 14 is a cross-sectional view illustrating a structural example of a display device. FIG. 15 is a cross-sectional view illustrating a structural example of a display device. 16A, 16B, and 16C are cross-sectional views showing an example of the configuration of a display device. FIG. 17 is a cross-sectional view showing an example of the configuration of a display device. FIGS. 18A, 18B, and 18C are cross-sectional views showing an example of the configuration of a display device. FIGS. 19A to 19D are diagrams explaining an example of a wearable device. FIGS. 20A and 20F are diagrams showing an example of an electronic device. FIGS. 21A to 21G are diagrams showing an example of an electronic device. FIG. 22 is a diagram showing the fluorescence spectrum and phosphorescence spectrum of a substance (PCCzTzn) capable of exhibiting thermally activated delayed fluorescence. FIG. 23 is a diagram showing the luminance-current density characteristics of the light-emitting device R1 and the comparative light-emitting device R1. FIG. 24 is a diagram showing the current efficiency-luminance characteristics of the light-emitting device R1 and the comparative light-emitting device R1. FIG. 25 is a diagram showing the current density-voltage characteristics of the light-emitting device R1 and the comparative light-emitting device R1. FIG. 26 is a diagram showing the power efficiency-luminance characteristics of the light-emitting device R1 and the comparative light-emitting device R1. Fig. 27 shows electroluminescence spectra of light-emitting device R1 and comparative light-emitting device R1, and Fig. 28 shows luminance-current density characteristics of light-emitting device G1 and comparative light-emitting device G1.FIG. 29 is a graph showing the current efficiency-luminance characteristics of light-emitting device G1, comparative light-emitting device G1-1, and comparative light-emitting device G1-2. FIG. 30 is a graph showing the current density-voltage characteristics of light-emitting device G, comparative light-emitting device G1-1, and comparative light-emitting device G1-2. FIG. 31 is a graph showing the power efficiency-luminance characteristics of light-emitting device G1, comparative light-emitting device G1-1, and comparative light-emitting device G1-2. FIG. 32 is a graph showing electroluminescence spectra of light-emitting device G1, comparative light-emitting device G1-1, and comparative light-emitting device G1-2. FIG. 33 is a graph showing the luminance-current density characteristics of light-emitting device B1 and comparative light-emitting device B1. FIG. 34 is a graph showing the current efficiency-luminance characteristics of light-emitting device B1 and comparative light-emitting device B1. FIG. 35 is a graph showing the current density-voltage characteristics of light-emitting device B1 and comparative light-emitting device B1. FIG. 36 is a graph showing the power efficiency-luminance characteristics of light-emitting device B1 and comparative light-emitting device B1. FIG. 37 is a graph showing the blue index-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1. FIG. 38 is a graph showing the electroluminescence spectra of the light-emitting device B1 and the comparative light-emitting device B1. FIG. 39 is a graph showing the fluorescence spectrum and phosphorescence spectrum of a substance (PCCzTzn) capable of exhibiting thermally activated delayed fluorescence and the luminescent center substance (Ir(5mppy-d). ３ ) ２ (mbfpypy-d ３)) absorption and PL spectra. FIG. 40 is a graph showing the luminance-current density characteristics of light-emitting device R2 and comparative light-emitting device R2. FIG. 41 is a graph showing the current efficiency-luminance characteristics of light-emitting device R2 and comparative light-emitting device R2. FIG. 42 is a graph showing the current density-voltage characteristics of light-emitting device R2 and comparative light-emitting device R2. FIG. 43 is a graph showing the power efficiency-luminance characteristics of light-emitting device R2 and comparative light-emitting device R2. FIG. 44 is a graph showing the electroluminescence spectra of light-emitting device R2 and comparative light-emitting device R2. FIG. 45 is a graph showing the luminance-current density characteristics of light-emitting device G2, comparative light-emitting device G2-1, and comparative light-emitting device G2-2. FIG. 46 is a graph showing the current efficiency-luminance characteristics of light-emitting device G2, comparative light-emitting device G2-1, and comparative light-emitting device G2-2. FIG. 47 is a graph showing the current density-voltage characteristics of light-emitting device G2, comparative light-emitting device G2-1, and comparative light-emitting device G2-2. FIG. 48 shows the power efficiency-luminance characteristics of light-emitting device G2, comparative light-emitting device G2-1, and comparative light-emitting device G2-2. FIG. 49 shows electroluminescence spectra of light-emitting device G2, comparative light-emitting device G2-1, and comparative light-emitting device G2-2. FIG. 50 shows the luminance-current density characteristics of light-emitting device B2 and comparative light-emitting device B2. FIG. 51 shows the current efficiency-luminance characteristics of light-emitting device B2 and comparative light-emitting device B2. FIG. 52 shows the current density-voltage characteristics of light-emitting device B2 and comparative light-emitting device B2. FIG. 53 shows the power efficiency-luminance characteristics of light-emitting device B2 and comparative light-emitting device B2. FIG. 54 shows the blue index-luminance characteristics of light-emitting device B2 and comparative light-emitting device B2. FIG. 55 shows electroluminescence spectra of light-emitting device B2 and comparative light-emitting device B2. FIG. 56 shows the fluorescence and phosphorescence spectra of PCAPA. FIG. 57 shows the fluorescence and phosphorescence spectra of cgDBCzPA.

[0063] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0064] 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.

[0065] A substance capable of exhibiting thermally activated delayed fluorescence refers to a substance that can generate a singlet excited state from a triplet excited state by thermally activated reverse intersystem crossing. Alternatively, a substance capable of exhibiting thermally activated delayed fluorescence can be said to be a substance whose triplet excited state and singlet excited state are close to each other. More specifically, a material in which the difference in energy level between the triplet excited state and the singlet excited state is more than 0 eV and 0.2 eV or less is preferred.

[0066] In this specification, ordinal numbers such as "first" and "second" are used for convenience and do not limit the number of components or the order of the components. The order of the components includes, for example, the order of processes or the order of stacking. In other words, the ordinal numbers used in the embodiments of this specification may not match the ordinal numbers used in the claims. Furthermore, the ordinal numbers used in the examples of this specification may not match the ordinal numbers used in the claims. Furthermore, the ordinal numbers used in the embodiments of this specification may not match the ordinal numbers used in the examples of this specification.

[0067] (Embodiment 1) A tandem light-emitting device has a structure in which a plurality of light-emitting units are stacked between a pair of electrodes with an intermediate layer (charge generation layer) sandwiched therebetween. Each of the plurality of 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 a significantly higher current efficiency than a non-tandem light-emitting device, and therefore can be suitably used for display devices that require high brightness display or high reliability.

[0068] Since tandem light-emitting devices have multiple light-emitting layers, it is easy to obtain white light, and so a white color filter system is often adopted for full-color display systems using tandem light-emitting devices. Color conversion systems using a stacked light-emitting layer that emits blue light and a color conversion layer, typically a quantum dot, have also been put to practical use.

[0069] 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. Light-emitting devices using the color-coded method have no or little energy loss in the color filters or color conversion layers, making them more efficient than the two methods mentioned above.

[0070] In one embodiment of the present invention, at least one of the light-emitting layers of a tandem light-emitting device of one embodiment of the present invention includes an emission center material and a substance capable of exhibiting thermally activated delayed fluorescence. The emission center material is a light-emitting organic compound, and the light-emitting organic compound preferably has a function of converting triplet excitation energy into light emission, and is more preferably a phosphorescent material. The tandem light-emitting device of one embodiment of the present invention has a configuration in which the emission center material emits light upon energy transfer from the substance capable of exhibiting thermally activated delayed fluorescence to the emission center material. This improves the efficiency of excitation energy transfer to the emission center material, resulting in a highly efficient and reliable light-emitting device. Furthermore, a reduction in driving voltage is also achieved.

[0071] The above-described light-emitting layer structure may be included in at least one of the light-emitting layers included in the tandem light-emitting device of one embodiment of the present invention, but it is preferable that two or more or all of the light-emitting layers have the same structure. For example, in the case of a tandem light-emitting device having two light-emitting layers, i.e., a first light-emitting layer and a second light-emitting layer, the first light-emitting layer preferably contains a first light-emitting center substance and a first organic compound, and the first organic compound is a substance capable of exhibiting thermally activated delayed fluorescence, and the second light-emitting layer preferably contains a second light-emitting center substance and a second organic compound, and the second organic compound is a substance capable of exhibiting thermally activated delayed fluorescence.

[0072] A substance capable of exhibiting thermally activated delayed fluorescence has a small difference between the lowest singlet excitation energy level (S1 level) and the lowest triplet excitation energy level (T1 level), and therefore has the function of converting triplet excitation energy into singlet excitation energy by reverse intersystem crossing. The difference between the S1 level and the T1 level of a substance capable of exhibiting thermally activated delayed fluorescence is preferably more than 0 eV and 0.2 eV or less.

[0073] Since a substance capable of exhibiting thermally activated delayed fluorescence can convert triplet excitation energy into singlet excitation energy by reverse intersystem crossing, it is possible to convert a part of the triplet excitation energy generated in the light-emitting layer into singlet excitation energy even at room temperature. Therefore, when the luminescence center substance is a fluorescent substance, it is possible to obtain a light-emitting device with better luminous efficiency than when the host material is not a substance capable of exhibiting thermally activated delayed fluorescence but a normal fluorescent substance.

[0074] The S1 level of the substance capable of exhibiting thermally activated delayed fluorescence is preferably higher than the T1 level of the luminescent center substance. Also, the T1 level of the substance capable of exhibiting thermally activated delayed fluorescence is preferably higher than the T1 level of the luminescent center substance.

[0075] When the luminescent center substance is a phosphorescent substance, the S1 level of the substance capable of exhibiting thermally activated delayed fluorescence is preferably lower than the S1 level of the luminescent center substance. As described above, the difference between the singlet excitation level and the triplet excitation level of the substance capable of exhibiting thermally activated delayed fluorescence is small. Therefore, even if the singlet excitation level of the substance capable of exhibiting thermally activated delayed fluorescence is lower than the S1 level of the luminescent center substance, it is easy to make the singlet excitation level and the triplet excitation level of the substance capable of exhibiting thermally activated delayed fluorescence higher than the T1 level of the luminescent center substance. By doing so, it is possible to minimize the energy required to excite the energy donor substance capable of exhibiting thermally activated delayed fluorescence, thereby obtaining a light-emitting device with a low driving voltage. Note that the S1 level of the substance capable of exhibiting thermally activated delayed fluorescence may be higher than the S1 level of the luminescent center substance.

[0076] The S1 level of an organic compound can be calculated by drawing a tangent at the value where the slope of the short wavelength side of the peak in the fluorescence spectrum is maximum, and the energy of the wavelength at the intersection of the tangent with the horizontal axis (wavelength) or the baseline can be taken as the S1 level. The T1 level of an organic compound can be calculated by drawing a tangent at the value where the slope of the short wavelength side of the peak in the phosphorescence spectrum is maximum, and the energy of the intersection of the tangent with the horizontal axis (wavelength) or the baseline can be taken as the T1 level (see, for example, Daisaku Tanaka et al., "Ultra High Efficiency Green Organic Light-Emitting Devices," Japanese Journal of Applied Physics, Vol. 46, No. 1, 2007, pp. L10-L12). Alternatively, when a ν=0→ν=0 transition (0→0 band) between the vibrational levels of the ground state and the excited state is clearly observed in the fluorescence spectrum or phosphorescence spectrum, the D* level, the S1 level, or the T1 level can also be calculated using the 0→0 band. (Nicholas J. Turro, V. Ramamurthy, J.C. Scaiano, Haruo Inoue, Osamu Ito, Supervising Editor, Translated, "Principles of Molecular Photochemistry", Maruzen Publishing Co., Ltd., July 30, 2013, pp. 165-169; Nicholas J. Turro, V. Ramamurthy, J.C. Scaiano, "MODERN MOLECULAR PHOTOCHEMISTRY OF ORGANIC MOLECULES", University Science Books, published February 10, 2010, pp. 204-208). In this specification, each level is calculated by the former method of drawing a tangent line. Furthermore, when comparing levels, the comparison should be made at levels calculated using the same method.

[0077] The energy difference between the LUMO level and the HOMO level of an organic compound is equal to or slightly larger than the S1 level, and therefore the S1 level can also be interpreted as the energy difference between the LUMO level and the HOMO level.

[0078] The values ​​of the HOMO level and the LUMO level can be determined by cyclic voltammetry (CV) measurement.

[0079] In cyclic voltammetry (CV) measurements, the HOMO and LUMO level values ​​(E) can be calculated based on the oxidation peak potential (Epa) and reduction peak potential (Epc) obtained by changing the potential of the working electrode relative to the reference electrode. In the measurements, the HOMO level can be determined from a potential scan in the positive direction, and the LUMO level can be determined from a potential scan in the negative direction. The scan rate in the measurements can be set to 0.1 V / s.

[0080] Specifically, the standard oxidation-reduction potential (Eo) (= (Epa + Epc) / 2) is calculated from the oxidation peak potential (Epa) and reduction peak potential (Epc) obtained from the cyclic voltammogram of the material, and is subtracted from the potential energy (Ex) of the reference electrode relative to the vacuum level to determine the values ​​of the HOMO level and LUMO level (E) (= Ex - Eo), respectively.

[0081] While the above describes the case where a reversible redox wave is obtained, when an irreversible redox wave is obtained, the HOMO level is calculated by assuming a value obtained by subtracting a fixed value (0.1 eV) from the oxidation peak potential (Epa) as the reduction peak potential (Epc), and the standard redox potential (Eo) is calculated to one decimal place. Furthermore, the LUMO level is calculated by assuming a value obtained by adding a fixed value (0.1 eV) to the reduction peak potential (Epc) as the oxidation peak potential (Epa), and the standard redox potential (Eo) is calculated to one decimal place.

[0082] The emission edges on the short wavelength side of the phosphorescence spectrum and fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence are preferably located at a wavelength shorter than the absorption edge on the long wavelength side in the absorption spectrum of the luminescence center substance. Such a positional relationship between the phosphorescence spectrum and fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence and the absorption edge of the luminescence center substance enables efficient energy transfer. It is preferable that only the emission edge on the short wavelength side of the fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence is located at a wavelength shorter than the absorption edge on the long wavelength side in the absorption spectrum of the luminescence center substance, and that the emission edge on the short wavelength side of the phosphorescence spectrum is located on the long wavelength side, since this allows for a further reduction in driving voltage.

[0083] Alternatively, the peak wavelengths of the phosphorescence spectrum and fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence are preferably shorter than the peak wavelength of the PL spectrum of the luminescence center substance. Furthermore, the difference between the peak wavelengths of the phosphorescence spectrum and fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence and the peak wavelength of the PL spectrum of the luminescence center substance is more preferably 30 nm or less. Such a relationship between the peak wavelengths of the phosphorescence spectrum and fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence and the peak wavelength of the PL spectrum of the luminescence center substance enables efficient energy transfer.

[0084] Alternatively, the difference between the peak wavelengths of the phosphorescence spectrum and fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence and the wavelength of the absorption edge on the long-wavelength side in the absorption spectrum of the luminescence center substance is preferably within 30 nm. When the peak wavelengths of the phosphorescence spectrum and fluorescence spectrum of the substance capable of exhibiting thermally activated delayed fluorescence and the wavelength of the absorption edge on the long-wavelength side in the absorption spectrum of the luminescence center substance have such a relationship, energy can be transferred efficiently.

[0085] The phosphorescence spectrum and fluorescence spectrum of a substance capable of exhibiting thermally activated delayed fluorescence are preferably measured using a vapor-deposited film. On the other hand, the sample form when measuring the PL spectrum or absorption spectrum of a luminescence center substance may be a thin film or a solution, but a solution is preferred from the viewpoint of verifying the state of isolated molecules. As the solvent for the solution, a solvent with relatively low polarity, such as toluene or chloroform, is preferred.

[0086] The absorption edge 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 in the absorption spectrum is maximum, and then calculating from the intersection of the tangent with the horizontal axis or the baseline. The emission edge on the short wavelength side of the emission spectrum can be calculated by drawing a tangent at the value where the slope on the short wavelength side of the peak (or shoulder peak) observed at the shortest wavelength in the emission spectrum is maximum, and then calculating from the intersection of the tangent with the horizontal axis or the baseline.

[0087] The substance capable of exhibiting thermally activated delayed fluorescence preferably has a skeleton having hole-transporting properties and a skeleton having electron-transporting properties. Alternatively, the substance capable of exhibiting thermally activated delayed fluorescence preferably has a π-electron-rich heteroaromatic ring skeleton or an aromatic amine skeleton and a π-electron-deficient heteroaromatic ring skeleton. This facilitates the formation of a donor-acceptor excited state within the molecule. Furthermore, the substance capable of exhibiting thermally activated delayed fluorescence preferably has a structure in which a skeleton having electron-transporting properties and a skeleton having hole-transporting properties are directly bonded to each other so that both donor and acceptor properties are strengthened within the molecule. Alternatively, the substance preferably has a structure in which a π-electron-rich heteroaromatic ring skeleton or an aromatic amine skeleton is directly bonded to a π-electron-deficient heteroaromatic ring skeleton. By strengthening both the donor property and the acceptor property within the molecule, it is possible to reduce the overlap between the region where the molecular orbitals in the HOMO of the substance capable of exhibiting thermally activated delayed fluorescence are distributed and the region where the molecular orbitals in the LUMO are distributed, and it is possible to reduce the energy difference between the S1 level and the T1 level of the substance capable of exhibiting thermally activated delayed fluorescence. In addition, it is possible to maintain the T1 level of the substance capable of exhibiting thermally activated delayed fluorescence at a high energy level.

[0088] When the difference between the T1 level and the S1 level is small, energy can be efficiently converted from the triplet excited state to the singlet excited state by reverse intersystem crossing. Since the triplet excited state can be upconverted to the singlet excited state by a small amount of thermal energy (reverse intersystem crossing), light emission (fluorescence) from the singlet excited state can be efficiently exhibited. In addition, conditions for efficiently obtaining thermally activated delayed fluorescence include an energy difference between the T1 level and the S1 level that is preferably greater than 0 eV and 0.2 eV or less, more preferably greater than 0 eV and 0.1 eV or less.

[0089] Examples of substances capable of exhibiting thermally activated delayed fluorescence include fullerene and its derivatives, acridine and its derivatives, and eosin derivatives. Metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can also be used. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complexes (SnF) represented by the following structural formula: ２ (Proto IX)), mesoporphyrin-tin fluoride complex (SnF ２ (Meso IX)), hematoporphyrin-tin fluoride complex (SnF ２ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ２ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ２ (OEP)), etioporphyrin-tin fluoride complex (SnF ２ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ２ OEP) and the like.

[0090]

[0091] Further, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), and Heterocyclic compounds having one or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10′H-spiro[acridine-9,9′-anthracene]-10′-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. A substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is 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, reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0092]

[0093] Alternatively, a TADF material in which the singlet excited state and the triplet excited state are in thermal equilibrium may be used. Such a TADF material has a short emission lifetime (excitation lifetime), which can suppress a decrease in efficiency in the high-brightness region of a light-emitting device. Specific examples include materials with the molecular structure shown below.

[0094]

[0095] As described above, a substance capable of exhibiting thermally activated delayed fluorescence preferably has a skeleton having electron transport properties and a skeleton having hole transport properties. Furthermore, a combination of these skeletons is preferable in which one skeleton has a π-electron-deficient heteroaromatic ring and the other skeleton is an amine skeleton or a π-electron-rich heteroaromatic ring skeleton, because these skeletons have excellent carrier transport properties and facilitate efficient formation of a donor-acceptor excited state within the molecule. Alternatively, it is more preferable that one skeleton is a heteroaromatic ring-containing skeleton having a diazine (pyrimidine or pyrazine) skeleton or a triazine skeleton, and the other skeleton is a carbazole skeleton, dibenzofuran skeleton, or dibenzothiophene skeleton, because these skeletons have a high triplet excitation energy level. Furthermore, it is preferable that one skeleton is a triazine skeleton or pyrimidine skeleton, and the other skeleton is a carbazole skeleton, because these skeletons are stable and reliable. As a carbazole skeleton, a 3,3′-bicarbazole skeleton is particularly preferable because it has high donor properties and high heat resistance, and a triazine skeleton is extremely preferable because it has a high triplet excitation energy, stability, and reliability.

[0096] 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 or pixel is different from the color of light emitted by at least one of the other adjacent light-emitting devices or pixels, or that the light-emitting center substance of the light-emitting layer of the tandem light-emitting device has a structure different from the light-emitting center substance of the light-emitting layer of at least one of the other adjacent light-emitting devices.

[0097] In the tandem light-emitting device, the electron transport layer of the cathode-side light-emitting unit preferably contains a third organic compound having a triazine skeleton, and the intermediate layer preferably contains a fourth organic compound having a phenanthroline skeleton. By including the third organic compound in the electron transport layer of the cathode-side light-emitting unit and the fourth organic compound in the intermediate layer, a tandem light-emitting device with low driving voltage can be obtained. Furthermore, by including the third organic compound in the electron transport layer of the cathode-side light-emitting unit and the fourth organic compound in the intermediate layer, and by including a luminescent center substance and a substance capable of exhibiting thermally activated delayed fluorescence in either of the light-emitting layers, a tandem light-emitting device with lower driving voltage can be obtained. Furthermore, the luminous efficiency is improved, resulting in a light-emitting device with good power efficiency and energy efficiency.

[0098] Furthermore, the light-emitting layer of the tandem light-emitting device is separated from the light-emitting layer of at least one of the other adjacent light-emitting devices, or the light-emitting layer of the tandem light-emitting device has a light-emitting layer different from the light-emitting layer of at least one of the other adjacent light-emitting devices, or the color of light emitted by the tandem light-emitting device is different from the color of light emitted by at least one of the other adjacent light-emitting devices, or the light-emitting center substance of the light-emitting layer of the tandem light-emitting device has a different composition from the light-emitting center substance of the light-emitting layer of at least one of the other adjacent light-emitting devices, thereby making it possible to make a light-emitting device with very good current efficiency, and therefore better power efficiency and energy efficiency.

[0099] As a result, a display device according to one embodiment of the present invention using such a light-emitting device can be a display device with low power consumption, high reliability, and high luminance, and can provide good visibility and display quality.

[0100] The third organic compound containing a triazine skeleton has an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. −７ cm２ / 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.

[0101] The third organic compound containing a triazine skeleton is preferably a compound containing a triazine skeleton and an aromatic ring. Examples of the aromatic ring include 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, and an aromatic ring having a cyano group as a substituent. The triazine skeleton may have a substituent other than the aromatic ring, and the aromatic ring may have a substituent other than the fluoro group, cyano group, or alkyl group. The triazine skeleton is also called a triazine ring, and the skeleton of other skeletons can also be referred to as a ring.

[0102] Examples of the monocyclic aromatic ring include aromatic hydrocarbon rings such as a benzene ring, and heteroaromatic rings such as a pyrrole ring, a pyridine ring, a pyrimidine ring, a triazine ring, etc. Having an aromatic ring as a substituent improves heat resistance, specifically, has the effect of improving the glass transition temperature (Tg), and has the effect of improving electron transport properties.

[0103] Examples of polycyclic aromatic rings include aromatic hydrocarbon rings such as naphthalene rings, phenanthrene rings, chrysene rings, triphenylene rings, fluorene rings, and spirobifluorene rings, as well as heteroaromatic rings such as carbazole rings, dibenzofuran rings, dibenzothiophene rings, xanthene rings, indolocarbazole rings, and indenocarbazole rings. Compounds having polycyclic aromatic rings as substituents are preferred because they can improve heat resistance compared to compounds having monocyclic aromatic rings such as benzene rings. Furthermore, compounds having a ring in which an aromatic ring (such as a benzene ring, 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 element due to heat can be suppressed when high-temperature treatment such as a patterning step is performed after the layer or the cathode is formed.

[0104] 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 skeleton and an alkyl group in the electron transport layer and a compound having an aromatic amine skeleton and an alkyl group in the hole transport layer can synergistically enhance the effect of improving light extraction efficiency. 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. Furthermore, 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. Furthermore, a compound having a structure in which multiple alkyl groups are bonded to one aromatic ring can further lower the refractive index of the layer. For example, a structure in which two or more tertiary butyl groups are bonded to one benzene ring as a substituent is exemplified. It is not limited to a benzene ring, but may also be a structure in which multiple alkyl groups are bonded to other monocyclic aromatic rings such as a pyridine ring, or a polycyclic aromatic ring such as a fluorene ring. It is also preferable to use a structure in which multiple alkyl groups are bonded to some of the rings constituting a polycyclic aromatic ring (such as a naphthalene ring, a fluorene ring, a carbazole ring, a quinoline ring, or a xanthene ring). For example, a structure in which multiple tertiary butyl groups are bonded to one benzene ring constituting a fluorene ring is exemplified. It is not limited to alkyl groups, but a structure in which multiple fluoro groups are bonded to one aromatic ring, or a structure in which multiple fluoro groups are bonded to some rings of a polycyclic aromatic ring, is also preferred.

[0105] In addition, a compound having a cyano group as a substituent is preferable because it can improve the electron transport property.

[0106] 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.

[0107] 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.

[0108] Specific examples of the third organic compound including a triazine skeleton include 2-(biphenyl-4-yl)-4-phenyl-6-(9,9′-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), and 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn). triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5 -triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3′-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6 -dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3′-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-triazine (abbreviation: βNP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviation: SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviation: BP-mBPI cz(II)Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviation: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3''-diyl]bis(9H-carbazole) (abbreviation: Cz-pmCzBPTzn), 3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole (abbreviation: PDBf-PCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviation: PCzDBtTzn), 2,4-diphenyl-6-[3′-(spiro[7H-benzo[c]fluorene-7,9′-[9H]xanthene]-2-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: mSbfxBPTzn), 3′-[4-phenyl-6-(spiro[9H-fluorene-9,9′-[9H]xanthene]-2′-yl)-1,3,Organic compounds containing a heteroaromatic ring having a triazine skeleton, such as 5-triazin-2-yl]biphenyl-4-carbonitrile (mpCNBP-SFxTzn) and 2,2'-[1,2-naphthalenediyldi(4,1-phenylene)]bis(4,6-diphenyl-1,3,5-triazine) (abbreviation: TznP2N), can be used. However, particularly preferred are TznP2N (100), mSbfxBPTzn (102), mpCNBP-SFxTzn (103), CNBP-NPTzn (104), βNP-SFx(4)Tzn (105), mmtBuBP-mDMePyPTzn (106), and mBnfBPTzn (107), which are represented by the following structural formulas (100) to (106).

[0109]

[0110] The electron transport layer included in the light-emitting unit on the anode side may be a layer containing a fifth organic compound having a triazine skeleton, or a layer containing a sixth organic compound not having a triazine skeleton, similar to the electron transport layer included in the light-emitting unit on the cathode side.

[0111] The electron transport layer included in the light-emitting unit on the anode side preferably contains a fifth organic compound having a triazine skeleton to reduce power consumption. In particular, it is preferable that the fifth organic compound is the same as the third organic compound, because this prevents the manufacturing equipment from becoming complicated and is advantageous in terms of raw material procurement costs.

[0112] Furthermore, the electron transport layer included in the light-emitting unit on the anode side contains a sixth organic compound that does not contain a triazine skeleton, which facilitates control of carrier transport properties and enables the provision of a light-emitting device with better characteristics. As the organic compound that does not contain a triazine skeleton, an organic compound that contains a heteroaromatic ring having a pyridine skeleton and an organic compound that contains a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton are preferred. It should be noted that organic compounds obtained by appropriately deuterating the above-listed organic compounds can also be used.

[0113] The fourth organic compound containing the phenanthroline skeleton contained in the intermediate layer has an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600.−７ cm ２ / Vs or more, preferably 1×10 −６ cm ２ It is preferable that the 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.

[0114] The fourth organic compound containing a phenanthroline skeleton is preferably a compound containing a phenanthroline skeleton and an aromatic ring, which may be a monocyclic aromatic ring or a polycyclic aromatic ring.

[0115] Examples of the monocyclic aromatic ring include a benzene ring, a pyrrole ring, a pyridine ring, and a pyrimidine ring. Furthermore, examples of the polycyclic aromatic ring include aromatic hydrocarbon rings such as a naphthalene ring, a phenanthrene ring, a chrysene ring, a triphenylene ring, and a fluorene ring, and heteroaromatic rings such as a phenanthroline ring and a pyrrole ring. In particular, the inclusion of a plurality of these polycyclic aromatic rings is preferred because it can improve heat resistance or electron transport properties.

[0116] Examples of the fourth organic compound including a phenanthroline skeleton include bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2′-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: mTpPPhen), and 2-phenyl-9-(2-triphenylenyl)phenyl.

[0033] Organic compounds containing a heteroaromatic ring having a phenanthroline skeleton, such as 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: PnNPhen), and 2-[4-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen), can be used. However, PnNPhen(200) and mPPhen2P(201) represented by the following structural formula (200) or (201) are particularly preferred.

[0117]

[0118] In the light-emitting device of one embodiment of the present invention, the intermediate layer may have any structure as long as it contains a fourth organic compound having a phenanthroline skeleton 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, the intermediate layer preferably has a stacked structure including a first layer containing the fourth organic compound and a second layer located closer to the cathode than the first layer.

[0119] The first layer preferably contains a metal or a metal compound in addition to the fourth organic compound. The metal or the metal in the metal compound is preferably an alkali metal (Group 1 element) such as Li, an alkaline earth metal (Group 2 element) such as Mg or Ca, a Group 3 element including a lanthanoid 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.

[0120] The first layer may have a stacked structure of a layer containing an organic compound and a layer having a metal or a metal compound located closer to the cathode than the layer containing the organic compound, or may be a mixed layer of an organic compound and a metal or a metal compound. A mixed layer is preferable because it can reduce the number of required film formation chambers, thereby reducing manufacturing costs, and also because it contributes to improving the stability of the light-emitting device.

[0121] When an organic compound and a metal or metal compound are mixed, the distribution of the organic compound and the distribution of the metal or metal compound show roughly the same tendency when the first layer is analyzed in the film thickness direction. That is, when the distribution of the organic compound is constant, the distribution of the metal or metal compound is also roughly constant. In the case of a layered structure of an organic compound and a metal or metal compound, the metal or metal compound may be detected in regions other than the layer made of the metal or metal compound due to diffusion from the layer made of the metal or metal compound, but since the distribution shows a different distribution from the distribution of the organic compound, the analysis results can be distinguished between diffusion and mixing.

[0122] 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 in thickness, preferably 15 nm or more, and more preferably 20 nm or more in thickness, the first layer can be considered to have a mixed layer in which an organic compound and a metal or metal compound are mixed.

[0123] Among these, the metal in the metal or metal compound is preferably a substance that exhibits donor properties to the fourth organic compound. Examples of substances that exhibit donor properties to the fourth organic compound include metals of Group 1 and Group 2, and lithium or lithium compounds are particularly preferred. Specifically, Li, lithium fluoride (LiF), lithium oxide (Li ２ Preferred examples of the fourth organic compound include 8-hydroxyquinolinatolithium (abbreviation: Liq). When the first layer contains a fourth organic compound and a substance that exhibits donor properties to the fourth organic compound, electrons are generated by charge separation. When a voltage is applied between the first electrode and the second electrode, the electrons are injected into the light-emitting unit on the anode side via the fourth organic compound. This allows the light-emitting device of one embodiment of the present invention to have a low driving voltage.

[0124] In addition to the organic compounds described above, the fourth organic compound is preferably an organic compound containing a phenanthroline skeleton with an electron-donating substituent. The phenanthroline skeleton is a skeleton that easily interacts with metals, etc., and when the fourth organic compound containing such a phenanthroline skeleton further has an electron-donating group, the electron density of the phenanthroline skeleton increases, making it more likely to interact with metals or metal compounds. In particular, when a metal 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.

[0125] 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.

[0126] Specific examples of organic compounds containing a phenanthroline skeleton having an electron-donating substituent are shown in structural formulas (300) to (311).

[0127]

[0128] In addition, a structure in which the first layer contains a Group 1 or Group 2 element, particularly lithium or a lithium compound, and a fourth organic compound having a phenanthroline skeleton with an electron-donating substituent is preferable because it can provide a tandem light-emitting device with lower driving voltage and better reliability.Furthermore, a structure in which the first layer contains a Group 1 or Group 2 element, particularly lithium or a lithium compound, and a fourth organic compound having a phenanthroline skeleton with an electron-donating substituent is preferable because it can suppress an increase in driving voltage when the organic compound of the light-emitting device is processed by photolithography.

[0129] In the intermediate layer having the above-described configuration, the fourth organic compound is preferably an organic compound having a phenanthroline skeleton, particularly an organic compound having a 1,10-phenanthroline skeleton, because the two nitrogen atoms contained therein are capable of coordinating to a metal and therefore are likely to interact with a metal or a metal compound.

[0130] When an electron-donating group is introduced into the 1,10-phenanthroline skeleton, the electron-donating group is preferably substituted at positions 4 and 7 of the 1,10-phenanthroline skeleton. By introducing the electron-donating group into positions 4 and 7 of the 1,10-phenanthroline skeleton, the electron density of the nitrogen atoms at positions 1 and 10 can be increased, making it easier for the compound to interact with a metal or metal compound.

[0131] The first layer may further contain an organic compound different from the fourth organic compound. The organic compound is preferably an organic compound having electron transport properties. In particular, the organic compound preferably has two or more heteroaromatic rings bonded or condensed to each other, and the two or more heteroaromatic rings preferably have a total of three or more heteroatoms. By including such an organic compound in the first layer, improvements in heat resistance and electron transport properties can be achieved.

[0132] The second layer preferably contains a seventh organic compound having hole-transporting properties. The second layer preferably further contains a substance exhibiting acceptor properties, and the substance exhibiting acceptor properties is preferably an organic compound exhibiting acceptor properties to the seventh organic compound. As the substance exhibiting acceptor properties, an organic compound having at least one of a halogen group and a cyano group is particularly preferred, and an organic compound having at least one of a fluorine group and a cyano group is more preferred. It is more preferred that the organic compound contains four or more halogen groups (fluorine) and cyano groups in total.

[0133] When the second layer contains a seventh organic compound and a substance that exhibits acceptor properties for the seventh organic compound, holes are generated by charge separation, and when a voltage is applied between the first electrode and the second electrode, the holes are injected into the light-emitting unit on the cathode side via the seventh organic compound. Thus, the light-emitting device of one embodiment of the present invention can be a light-emitting device with low driving voltage.

[0134] The intermediate layer may have a third layer between the first layer and the second layer.

[0135] The third layer 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 and the second layer, and improving reliability by reducing the interaction between the first layer and the second layer.

[0136] The thickness of the third layer is preferably 1 nm or more and 10 nm or less, more preferably 2 nm or more and 5 nm or less, in order to suppress an increase in driving voltage.

[0137] 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.

[0138] Next, a light-emitting device according to one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1A illustrates a light-emitting device 130 according to one embodiment of the present invention. The light-emitting device according to 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 a second electron-transport layer 114_2, and an intermediate layer 116. Note that the first light-emitting unit may include a first electron-transport layer 114_1 between the first light-emitting layer 113_1 and the intermediate layer 116.

[0139] In the light-emitting device 130, the second electron-transporting layer 114_2 contains a third organic compound having a triazine skeleton, and the intermediate layer 116 contains a fourth organic compound having a phenanthroline skeleton. In addition, the second electron-transporting layer 114_2 containing the third organic compound having a triazine skeleton is preferably in contact with the second electrode 102 in order to reduce power consumption.

[0140] Although the present embodiment describes an example of a light-emitting device having one intermediate layer 116 and two light-emitting units, the light-emitting device may have n (n is an integer of 1 or more) intermediate layers and n+1 light-emitting units. For example, the light-emitting device 130 shown in FIG. 1B is an example of a tandem light-emitting device in which n is 2 and the light-emitting device has a first light-emitting unit 501, a first intermediate layer 116_1, a second light-emitting unit 502, a second intermediate layer 116_2, and a third light-emitting unit 503.

[0141] The first light-emitting unit 501 and the second light-emitting unit may include other functional layers in addition to the above-described light-emitting layer, electron-transport layer, and the like. In FIG. 1A , the first light-emitting unit 501 includes the hole-injection layer 111 and the first hole-transport layer 112_1 in addition to the first light-emitting layer 113_1 and the first electron-transport layer 113_1, and the second light-emitting unit 502 includes the second hole-transport layer 112_2 in addition to the second light-emitting layer 113_2 and the second electron-transport layer 114_2. However, the structure of the organic compound layer 103 in one embodiment of the present invention is not limited thereto, and any of the layers may be omitted, or other layers may be provided. Typical examples of such other layers include a carrier blocking layer and an exciton blocking layer.

[0142] 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 high work function (specifically, 4.0 eV or higher). Specific examples include indium oxide-tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-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 oxide-zinc oxide can be formed by sputtering using a target containing indium oxide and 1 to 20 wt % zinc 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, for example, 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). Alternatively, graphene can be used as the anode material. Note that by using the composite material constituting the second layer 117 in the intermediate layer 116 as a layer in contact with the anode (typically a hole injection layer), electrode materials can be selected regardless of the work function.

[0143] The hole injection layer 111 is provided in contact with the anode and has a function of facilitating injection of holes into the organic compound layer 103 (first light-emitting unit 501). ２The organic EL element can be formed from a phthalocyanine compound or complex compound such as copper phthalocyanine (abbreviated as CuPc), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviated as DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (abbreviated as PEDOT / PSS).

[0144] The hole-injection layer 111 may be formed using 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-TCCNNQ), 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 a plurality of heteroatoms, such as HAT-CN, are thermally stable and preferred. Also, [3]radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group, a cyano group, etc.) are preferred because they have very high electron-accepting properties, and specific examples thereof 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]. 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 also be used as the acceptor material. ２The hole injection layer 111 can also be formed from a phthalocyanine compound or complex compound such as copper phthalocyanine (abbreviated as CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviated as DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (abbreviated as PEDOT / PSS). A substance having acceptor properties can extract electrons from an adjacent hole transport layer (or hole transport material) when an electric field is applied.

[0145] The hole-injection layer 111 is preferably formed using a composite material containing the above-described material having an acceptor property and a substance having a hole-transport property.

[0146] As a substance having a hole transport property used in the composite material, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. −６ cm ２ / Vs or more. The substance 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 preferable. As the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring is preferable, 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 preferable.

[0147] Such a substance having hole-transporting properties preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, the substance may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. It is preferable that the substance having hole-transporting properties is a substance having an N,N-bis(4-biphenyl)amino group, since this allows the manufacture of a light-emitting device with a long lifetime.

[0148] Specific examples of the substance having the hole transport property as described above include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4′-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4″-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-yl, and N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-yl. [b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]- N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβN B-03), 4,4'-diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-Diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl] [4'-(3-phenyl-9H-carbazol-9-yl)biphenyl-4''-[ ... N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9′-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N- Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren- 4,4'-diphenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3 N-(biphenyl-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-4- amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz), 9'-phenyl-9'H-9,3':6',9"-tercarbazole (abbreviation: PSiCzGI), etc.

[0149] Other aromatic amine compounds that can be used as the substance having hole-transporting properties include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0150] 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.

[0151] 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.

[0152] The hole-transporting layers (the first hole-transporting layer 112_1 and the second hole-transporting layer 112_2) are formed by containing an organic compound having a hole-transporting property. −６ cm ２ It is preferable that the material has a hole mobility of 1.0 V or more.

[0153] Examples of the substance having a hole-transporting property 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-methylphenyl-4,4′-diaminobiphenyl (abbreviation: 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB). 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), compounds having an aromatic amine skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di( N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-Bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1' :4',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3' ,1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, compounds having a carbazole skeleton such as N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, and 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz); 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II);Examples of suitable compounds include compounds having a thiophene skeleton, such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the compounds listed above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. The organic compounds listed as the substances having hole-transporting properties used in the composite material of the hole-injection layer 111 can also be suitably used as materials for the hole-transport layer 112. Note that organic compounds obtained by appropriately deuterating the above-listed organic compounds can also be used in the same way.

[0154] Note that the first hole-transport layer 112_1 and the second hole-transport layer 112_2 preferably contain an organic compound having the same skeleton, and more preferably contain the same compound. One or both of the first hole-transport layer 112_1 and the second hole-transport layer 112_2 may have a stacked structure. By forming the hole-transport layer 112 into a stacked structure and using an organic compound with high electron resistance and / or an organic compound with electron blocking properties in the layer closer to the light-emitting layer 113, a highly reliable light-emitting device can be obtained. When the hole-transport layer 112 has a stacked structure, it is preferable to use a material with excellent hole-transport properties, low electron-transport properties, and a high LUMO level in the layer closer to the light-emitting layer 113. The LUMO level of this material is preferably higher than the LUMO level of the material with the highest composition ratio among the materials constituting the light-emitting layer or the material with the highest LUMO level among the materials constituting the light-emitting layer, preferably by 0.30 eV or more. The material is preferably an organic compound having an amine skeleton and a polycyclic heteroaromatic ring, and more preferably an organic compound having an amine skeleton and a furan skeleton or a dibenzofuran skeleton. When the hole-transport layer 112 has a stacked structure, using such a material for the layer closer to the light-emitting layer 113 can prevent electrons from passing through from the light-emitting layer 113 to the first electrode 101, thereby enabling the manufacture of a highly efficient display device with a long lifetime. Note that in the hole-transport layer 112 having a stacked structure, an organic compound having an amine skeleton and a polycyclic hydrocarbon is preferably used for the layer closer to the first electrode 101, and an organic compound having an amine skeleton and a fluorene skeleton is more preferably used. Organic compounds having an amine skeleton and a fluorene skeleton are preferred because they have good reliability and high hole-transport properties, thereby reducing the power consumption of the light-emitting device.

[0155] The light-emitting layers (first light-emitting layer 113_1, second light-emitting layer 113_2) preferably contain a light-emitting center substance and a host material. At least one of the light-emitting layers preferably contains a light-emitting center substance and a substance capable of exhibiting thermally activated delayed fluorescence, and both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 preferably have this structure. The light-emitting layers may also contain other materials.

[0156] 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 the case of a light-emitting device used for a red pixel, both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 are light-emitting layers that emit red light. In the case of a light-emitting device used for a green pixel, both the two light-emitting layers are light-emitting layers that emit green light. In the case of a blue pixel, both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 emit blue light. In this case, the light-emitting center substance contained in the first light-emitting layer 113_1 and the light-emitting center substance contained in the second light-emitting layer 113_2 are preferably compounds whose difference in maximum peak wavelength in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. It is more preferable that the light-emitting center substance contained in the first light-emitting layer 113_1 and the light-emitting center substance contained in the second light-emitting layer 113_2 are the same.

[0157] The luminescent center substance may be a fluorescent substance, a phosphorescent substance, a substance exhibiting thermally activated delayed fluorescence (TADF), or any other luminescent substance.

[0158] Examples of fluorescent substances that can be used as the luminescent center substance in the light-emitting layer include the following: In addition, fluorescent substances other than these can also be used.

[0159] 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-fluorene -9-yl)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-di Phenyl-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) N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, 9,10-diphenyl-2-[N-phenyl-N-(9-phenyl-carbazol-3-yl)amino]anthracene (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-furan 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)ethenyl 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), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM3), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM4), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl -diamine (abbreviation: 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), 2-(2,6-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: BisDCJ™), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b]naphthyl)benzo[b]naphthyl] ... 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 pyrene diamine compounds 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred because they have high hole trapping properties and excellent luminous efficiency or reliability.

[0160] In the light-emitting layer, the phosphorescent material that can be used as the luminescent center material is preferably a metal complex, particularly an iridium complex or a platinum complex, and examples thereof include the following.

[0161] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN]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]), organometallic iridium complexes having 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 ]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me) ３ organometallic iridium complexes having a 1H-triazole skeleton, such as 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 organometallic iridium complexes having an imidazole skeleton, such as tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazol-2-yl-κN}-4-cyanophenyl-κC)iridium(III) (abbreviation: CNImIr), tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC)phenyl-κC]iridium(III) (abbreviation: [Ir(cb) ３ organometallic complexes having 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(CF ３ ppy) ２ (pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’Examples of suitable iridium complexes include organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand, such as ]iridium(III) acetylacetonate (abbreviation: 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) (abbreviation: PtON-TBBI). These compounds exhibit blue phosphorescence and have an emission peak in the wavelength range of 450 nm to 520 nm. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0162] 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-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) ２ (acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm) ２ organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me) ２(acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr) ２ organometallic iridium complexes having a pyrazine skeleton, such as tris(2-phenylpyridinato-N,C(acac)]); 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-d ３ [5-methyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d ３ ) ２ (mbfpypy-d ３ )), {2-(methyl-d ３ )-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d ３ )-2-[5-(methyl-d ３ )-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5mtpy-d6) ２ (mbfpypy-iPr-d ４ )), [2-d ３-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ２ (mbfpypy-d ３ )), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ２ (mdppy)), [2-(4-d ３ -methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(5-d ３ [Ir(5mppy-d-methyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d-methyl-2-pyridinyl-κN)phenyl-κC]iridium(III) ３ )2(mdppy-d ３ ) )]), [2-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[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)]), tris{2-[5-(methyl-d3)-4-phenyl-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5m4dppy-d ３ ) ３In addition to organometallic iridium complexes having a pyridine skeleton 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) (abbreviation: Pt(tBudppymmtBubiz-tBubp)), [2-(4-(3,5-di-te organometallic platinum complexes such as [Tb(acac)]-4-(4-(4-(5'-tert-butylphenyl)-6-{3-[4-(5'-tert-butyl[1,1':3',1''-terphenyl]-2'-yl)-2-pyridinyl-κN]phenyl-κC2}-2-pyridinyl-κN)phenolato-κO]platinum(II) (abbreviation: Pt(4tButppppypyp-mmtBup)); tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)] ３ Examples of suitable iridium complexes include rare earth metal complexes such as iridium fluoride (Phen). These compounds exhibit phosphorescence with a predominantly green hue, and have an emission peak in the wavelength range of 500 nm to 600 nm. Organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because of their outstanding reliability and luminous efficiency. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0163] Also, (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)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(dpm) ２ organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr) ２(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr) ２ (dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq) ２ organometallic iridium complexes having a pyrazine skeleton, such as tris(1-phenylisoquinolinato-N,C(acac)]); ２’ ) Iridium(III) (abbreviation: [Ir(piq) ３ ]), bis(1-phenylisoquinolinato-N,C ２’ ) iridium(III) acetylacetonate (abbreviation: [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), (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 organometallic iridium complexes having a pyridine skeleton such as [ru-κC]iridium(III), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: PtOEP), tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM) ３ (Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA) ３ Examples of suitable compounds include rare earth metal complexes such as iridium fluoride (Phen). These compounds exhibit red phosphorescence and have an emission peak in the wavelength range of 600 nm to 700 nm. Organometallic iridium complexes having a pyrazine skeleton can emit red light with good chromaticity. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0164] In one embodiment of the present invention, the use of a deuterated compound as the luminescent center substance improves luminous efficiency, and therefore the luminescent center substance is preferably a deuterated material.

[0165] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0166] Examples of TADF materials that can be used include fullerene and its derivatives, acridine and its derivatives, and eosin derivatives. Other examples include metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complexes (SnF) represented by the following structural formula: ２ (Proto IX)), mesoporphyrin-tin fluoride complex (SnF ２ (Meso IX)), hematoporphyrin-tin fluoride complex (SnF ２ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ２ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ２ (OEP)), etioporphyrin-tin fluoride complex (SnF ２ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ２ OEP) and the like.

[0167]

[0168] Further, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), and Heterocyclic compounds having one or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10′H-spiro[acridine-9,9′-anthracene]-10′-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton. A substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is 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, and the energy difference between the lowest singlet excitation level (S1 level) and the lowest triplet excitation level (T1) is reduced, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0169]

[0170] Alternatively, a TADF material in which the singlet excited state and the triplet excited state are in thermal equilibrium may be used. Such a TADF material has a short emission lifetime (excitation lifetime), which can suppress a decrease in efficiency in the high-brightness region of a light-emitting device. Specific examples include materials with the molecular structure shown below.

[0171]

[0172] The TADF material is a material that has a small difference between the S1 level and the T1 level and has the function of converting triplet excitation energy to singlet excitation energy by reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) with a small amount of thermal energy, and a singlet excited state can be efficiently generated. Furthermore, triplet excitation energy can be converted into luminescence.

[0173] Furthermore, an exciplex (also called an exciplex) that forms an excited state with two types of substances has an extremely small difference between the S1 level and the T1 level, and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy.

[0174] The T1 level can be determined by using a phosphorescence spectrum observed at low temperatures (e.g., 77 K to 10 K). When a tangent line is drawn at the base of the fluorescence spectrum on the short wavelength side of the TADF material, and the energy of the wavelength of the extrapolated line is defined as the S1 level, and when a tangent line is drawn at the base of the phosphorescence spectrum on the short wavelength side of the TADF material, and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0175] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0176] The case where a substance capable of exhibiting thermally activated delayed fluorescence is used as the host material of the light-emitting layer has been described in detail above, and therefore a repeated description will be omitted. In the case where the light-emitting layer does not have such a structure, various carrier transport materials such as an organic compound having an electron transport property and / or an organic compound having a hole transport property can be used as the host material.

[0177] The organic compound having hole transport properties is preferably an organic compound having an amine skeleton, a π-electron-rich heteroaromatic ring skeleton, etc. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring containing at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton in the ring, and specifically preferably a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to one of these.

[0178] The hole-transporting substance preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, the hole-transporting substance may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. It is preferable that the hole-transporting substance is an organic compound having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of a light-emitting device with a long lifetime.

[0179] As such an organic compound, for example, the following organic compounds are preferable: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3 ... mBPAFLP, 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), )triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), compounds having an aromatic amine skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl ( abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 3,9-bis(9-phenyl-9H-carbazole-3-yl)-9H-carbazole (abbreviation: PCCzPC), 9-(biphenyl-4-yl)-9′-phenyl-3,3′-bi-9H-carbazole (abbreviation: PCCzBP), 9,9′-bis(biphenyl-4-yl)-3,3′-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-Bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole (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, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole Carbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz), 9'-phenyl-9'H-9,3':6',Compounds having a carbazole skeleton such as 9''-tercarbazole (abbreviation: PSiCzGI), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), Examples of suitable materials include compounds having a thiophene skeleton such as [phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. Furthermore, the organic compounds listed as examples of materials having hole transport properties for the hole transport layer can also be used.

[0180] The organic compound having electron transport properties is preferably an organic compound having a π-electron-deficient heteroaromatic ring. Examples of the organic compound having a π-electron-deficient heteroaromatic ring skeleton include an organic compound having a heteroaromatic ring with an azole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0181] Among these, organic compounds containing a heteroaromatic ring having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reducing driving voltage. In addition, benzofuropyrimidine skeletons, benzothienopyrimidine skeletons, benzofuropyrazine skeletons, and benzothienopyrazine skeletons are preferred because of their high acceptor properties and high reliability.

[0182] As the organic compound having a π-electron-deficient heteroaromatic ring skeleton, for example, the following organic compounds are preferred: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), and other organic compounds having an azole skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35 DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10-phenanthroline organic compounds containing a heteroaromatic ring having a pyridine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl 1-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNf pr), 9-[3'-(dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidinyl 4,6-diphenyl-4,6-diylbis(biphenyl-3,3′-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2 ,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (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]pyrimidine [4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), 2,2'-(2,2'-bipyridine-6 organic compounds having a diazine skeleton such as 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), and 2-{3-[3-(benzo[b]naphtho[1,2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9 mH-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3′-(pyridin-3-yl)biphenyl- 3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3′-(triphenylen-2-yl)biphenyl-3-yl]-4,6 -diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthen]-4-yl-1,3,5-triazine (abbreviation: βNP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviation: SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviation: BP-mBPIcz(II)Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]phenyl}-9- Phenyl-9H-carbazole (abbreviation: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3''-diyl]bis(9H-carbazole) (abbreviation: Cz-pmCzBPTzn), 3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole Examples of suitable organic compounds include organic compounds containing a heteroaromatic ring with a triazine skeleton, such as carbazole (abbreviation: PDBf-PCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviation: PCzDBtTzn), and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tz). Organic compounds containing a heteroaromatic ring with a diazine skeleton, organic compounds containing a heteroaromatic ring with a pyridine skeleton, and organic compounds containing a heteroaromatic ring with a triazine skeleton are preferred due to their high reliability. In particular, organic compounds containing a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring with a triazine skeleton have high electron transport properties and contribute to reduced driving voltage.

[0183] When a fluorescent substance is used as the emission center substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as the host material for a fluorescent substance makes it possible to realize an emission layer with both excellent luminous efficiency and durability. As a substance having an anthracene skeleton used as the host material, a diphenylanthracene skeleton, particularly a substance having a 9,10-diphenylanthracene skeleton, is preferred because it is chemically stable. Furthermore, a host material having a carbazole skeleton is preferred because it enhances hole injection and transport properties. However, a host material containing a benzocarbazole skeleton in which a benzene ring is further condensed to carbazole is more preferred because its HOMO is about 0.1 eV higher than that of the carbazole skeleton, making it easier for holes to enter. In particular, a host material containing a dibenzocarbazole skeleton is preferred because its HOMO is about 0.1 eV higher than that of the carbazole skeleton, making it easier for holes to enter, and it also has excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that, in view of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4′- 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)benzo Examples include zo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0184] The host material may be a mixture of a plurality of 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 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole transport properties to the material having electron transport properties may be 1:19 to 19:1 (material having hole transport properties:material having electron transport properties).

[0185] 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.

[0186] 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 or less at a square root of an electric field strength [V / cm] of 600. −７ cm ２ / Vs or more, preferably 1×10 −６ cm ２ A substance having an electron mobility of 1 / Vs or more is preferred. Note that, other substances can be used as long as they have a higher electron transport property than holes. Note that, as the organic compound, an organic compound having a π-electron-deficient heteroaromatic ring is preferred. As the organic compound having a π-electron-deficient heteroaromatic ring, for example, one or more of an organic compound including a heteroaromatic ring having an azole skeleton, an organic compound including a heteroaromatic ring having a pyridine skeleton, an organic compound including a heteroaromatic ring having a diazine skeleton, and an organic compound including a heteroaromatic ring having a triazine skeleton are preferred, and triazine is particularly preferred.

[0187] As the organic compound having electron-transporting properties that can be used in the first electron-transporting layer 114_1, organic compounds that can be used as the organic compound having electron-transporting properties of the host material in the first light-emitting layer 113_1 and the second light-emitting layer 113_2 can be used as well. Among them, organic compounds including a heteroaromatic ring having a diazine skeleton, an organic compound including a heteroaromatic ring having a pyridine skeleton, and an organic compound including a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds including a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds including a heteroaromatic ring having a triazine skeleton have high electron-transporting properties and contribute to reducing driving voltage.

[0188] As described above, the second electron-transporting layer 114_2 is a layer including a third organic compound having a triazine skeleton. Details thereof have already been described, and therefore will not be described again.

[0189] Note that the first electron-transport layer 114_1 preferably contains an organic compound having a triazine skeleton in order to reduce power consumption. In particular, it is preferable that the first electron-transport layer 114_1 contains an organic compound having the same triazine skeleton as the third organic compound having a triazine skeleton contained in the second electron-transport layer 114_2, because this prevents the manufacturing apparatus from becoming complicated and is advantageous in terms of raw material procurement costs.

[0190] Furthermore, since the first electron-transport layer 114_1 contains an organic compound that does not contain a triazine skeleton, it becomes easier to control the carrier transport property, and a light-emitting device with better characteristics can be provided. As the organic compound that does not contain a triazine skeleton, an organic compound that contains a heteroaromatic ring having a pyridine skeleton or an organic compound that contains a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton is preferable.

[0191] The intermediate layer 116 is a layer containing a fourth organic compound having a phenanthroline skeleton. As shown in FIG. 1A , the intermediate layer 116 preferably includes a first layer 119 containing the fourth organic compound having a phenanthroline skeleton. The intermediate layer 116 also preferably includes a second layer 117 containing a seventh organic compound having hole-transporting properties and a substance having acceptor properties. The second layer 117 is located closer to the second electrode 102 than the first layer 119. The intermediate layer 116 may also include a third layer 118 between the first layer 119 and the second layer 117.

[0192] The details of the first layer have been described above, so a repeated description will be omitted.

[0193] The first layer 119 may further contain an organic compound having electron-transporting properties. Examples of organic compounds having electron-transporting properties that can be used for the organic compound include the organic compounds that can be used as the organic compounds having electron-transporting properties of the host materials in the first light-emitting layer 113_1 and the second light-emitting layer 113_2. Furthermore, it is preferable to use an organic compound having two or more heteroaromatic rings bonded to or condensed with each other, and the two or more heteroaromatic rings having three or more heteroatoms in total, because this can further improve resistance to photolithography and suppress an increase in driving voltage.

[0194] The first layer 119 may have a stacked structure of a layer containing an organic compound and a layer having a metal or a metal compound located closer to the cathode than the layer containing the organic compound, or may be a mixed layer of an organic compound and a metal or a metal compound. A mixed layer is preferable because it requires fewer deposition chambers and reduces manufacturing costs, and also contributes to improving the stability of the light-emitting device.

[0195] When an organic compound and a metal or metal compound are mixed, the distribution of the organic compound and the distribution of the metal or metal compound show roughly the same tendency when the first layer 119 is analyzed in the film thickness direction. That is, when the distribution of the organic compound is constant, the distribution of the metal or metal compound is also roughly constant. In the case of a laminated structure of an organic compound and a layer containing a metal or metal compound, the metal or metal compound may be detected in regions other than the layer containing the metal or metal compound due to diffusion from the layer containing the metal or metal compound, but since the distribution shows a different distribution from the distribution of the organic compound, the analysis results can be distinguished as diffusion or mixing.

[0196] The second layer 117 preferably contains a seventh organic compound having a hole-transporting property. The second layer 117 preferably further contains a substance exhibiting an acceptor property, and the substance exhibiting an acceptor property is preferably an organic compound exhibiting an acceptor property to the seventh organic compound.

[0197] When the second layer 117 contains a seventh organic compound and a substance that exhibits acceptor properties for the seventh organic compound, holes are generated by charge separation, and when a voltage is applied between the first electrode 101 and the second electrode 102, the holes are injected into the second light-emitting unit 502 on the cathode side via the seventh organic compound. Thus, the light-emitting device 130 of one embodiment of the present invention can be a light-emitting device with low driving voltage.

[0198] As the seventh organic compound having hole transport properties, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. −６ cm ２ The fifth organic compound is preferably an organic compound having a hole mobility of 1 / Vs or more. The fifth organic compound 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 preferable. As the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferable, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to one of these rings is preferable.

[0199] Such organic compounds having hole-transporting properties preferably have a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. It is preferable that these organic compounds having hole-transporting properties are substances having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of light-emitting devices with a long lifetime.

[0200] Specifically, as the organic compound having a hole-transport property as described above, the organic compounds exemplified as the organic compounds having a hole-transport property that can be used for the hole-injection layer 111 can be similarly used.

[0201] As the substance having acceptor properties, for example, the substances exemplified as organic compounds having acceptor properties that can be used in the hole-injection layer 111 can be similarly used. In particular, an organic compound having at least one of a halogen group and a cyano group is 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. Examples of organic compounds having at least one of a halogen group and a cyano group include α,α',α''-1,2,3-cyclopropane triylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropane triylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0202] The material having acceptor properties preferably has electron-accepting properties for the seventh organic compound having hole-transporting properties. When the material having acceptor properties has electron-accepting properties for the seventh organic compound, charge separation occurs, and the second layer 117 can function as a charge-generating layer and as a tandem intermediate layer. In addition, the second layer 117 preferably exhibits a signal observed by electron spin resonance. For example, the spin density resulting from a signal observed around a g-value of 2.00 is 1×10 １７ spins / cm ３ More preferably, 1×10 １８ spins / cm ３ More preferably, 1×10 １９ spins / cm ３ The above is even more preferable.

[0203] The third layer 118 contains a substance having an electron transporting property, and has functions such as preventing interaction between the first layer 119 and the second layer 117, smoothing the transfer of electrons to reduce the driving voltage, and reducing the interaction between the first layer 119 and the second layer 117 to improve reliability.

[0204] The LUMO level of the substance having electron-transporting properties contained in the third layer 118 is preferably between the LUMO level of the substance having acceptor properties in the second layer 117 and the LUMO level of the organic compound contained in the layer in contact with the first layer 119 in the light-emitting unit on the anode side (the first electron-transporting layer 114_1 in the first light-emitting unit 501 in FIG. 1A ).

[0205] The specific energy level of the LUMO level of the substance having an electron-transporting property used for the third layer 118 is preferably −5.0 eV or higher, preferably −5.0 eV or higher to −3.0 eV or lower, more preferably −4.30 eV or higher to −3.00 eV or lower, and more preferably −4.30 eV or higher to −3.30 eV or lower, in order to suppress an increase in driving voltage. Note that the substance having an electron-transporting property used for the third layer 118 is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0206] Specific examples of the substance having an electron-transporting property that can be used for the third layer 118 include diquinoxalino[2,3-a:2′,3′-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2′,3′-c]phenazine (abbreviation: HATNA-F6), perylene tetracarboxylic acid derivatives such as 3,4,9,10-perylene tetracarboxylic diimide (abbreviation: PTCDI) and 3,4,9,10-perylene tetracarboxylic bis-benzimidazole (abbreviation: PTCBI), (C60-Ih)[5,6]fullerene (abbreviation: C60), and (C70-D5h)[5,6]fullerene (abbreviation: C70). Furthermore, a compound having a heterophane skeleton, which is a cyclophane skeleton containing a heterocycle, can be used. Examples of such a compound include phthalocyanine (abbreviation: H ２Phthalocyanine compounds such as copper phthalocyanine (abbreviated as CuPc), zinc phthalocyanine (abbreviated as ZnPc), cobalt phthalocyanine (abbreviated as CoPc), iron phthalocyanine (abbreviated as FePc), tin phthalocyanine (abbreviated as SnPc), tin oxide phthalocyanine (abbreviated as SnOPc), titanium oxide phthalocyanine (abbreviated as TiOPc), vanadium oxide phthalocyanine (abbreviated as VOPc), and their derivatives can also be used. Phthalocyanine-based metal complexes such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine are particularly preferred.

[0207] The thickness of the third layer 118 is preferably 1 nm or more and 10 nm or less, more preferably 2 nm or more and 5 nm or less.

[0208] Since the second layer 117 in the intermediate layer 116 functions as a hole injection layer, the second light-emitting unit 502 does not have a hole injection layer, but the second light-emitting unit 502 may have a hole injection layer.

[0209] The second electrode 102 is an electrode including a cathode. The second electrode 102 may have a stacked 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 small 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 lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), and the like. ２Examples of the electride include alkali metals, alkaline earth metals, rare earth metals, such as lithium 8-hydroxyquinolinato (abbreviation: Liq), and ytterbium (Yb), or compounds or complexes thereof, or electrides. Examples of the electride include a substance in which electrons are highly concentrated in a mixed oxide of calcium and aluminum. Two or more of these may be mixed and used. When the second electrode 102 has a stacked structure, materials with good conductivity can be used for the electrodes other than the cathode, regardless of the work function.

[0210] 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.

[0211] Note that 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.

[0212] These conductive materials can be formed into films by dry methods such as vacuum deposition or sputtering, inkjet methods, spin coating methods, 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.

[0213] 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.

[0214] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0215] FIG. 1C 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.

[0216] The light-emitting device 130a includes an organic compound layer 103a between a first electrode 101a and a second electrode 102 on an insulating layer 175. The organic compound layer 103a includes a first light-emitting unit 501a and a second light-emitting unit 502a, which are stacked with an intermediate layer 116a sandwiched therebetween. While FIG. 1C illustrates an example in which two light-emitting units are stacked, a configuration in which three or more light-emitting units are stacked may also be used. The first light-emitting unit 501a includes a hole-injection layer 111a, a first hole-transport layer 112a_1, a first light-emitting layer 113a_1, and a first electron-transport layer 114a_1. The intermediate layer 116a includes a second layer 117a, a third layer 118a, and a first layer 119a. The third layer 118a is optional. The second light-emitting unit 502a includes a second hole-transporting layer 112a_2, a second light-emitting layer 113a_2, and a second electron-transporting layer 114a_2.

[0217] The light-emitting device 130b includes an organic compound layer 103b between a first electrode 101b and a second electrode 102 on an insulating layer 175. The organic compound layer 103b includes a first light-emitting unit 501b and a second light-emitting unit 502b stacked with an intermediate layer 116b sandwiched therebetween. While FIG. 1C illustrates an example in which two light-emitting units are stacked, a structure in which three or more light-emitting units are stacked may also be used. The first light-emitting unit 501b includes a hole-injection layer 111b, a first hole-transport layer 112b_1, a first light-emitting layer 113b_1, and a first electron-transport layer 114b_1. The intermediate layer 116b includes a second layer 117b, a third layer 118b, and a first layer 119b. The third layer 118b is optional. The second light-emitting unit 502b includes a second hole-transporting layer 112b_2, a second light-emitting layer 113b_2, and a second electron-transporting layer 114b_2.

[0218] The second electron-transport layer 114a_2 and the second electron-transport layer 114b_2 are layers containing a third organic compound having a triazine skeleton. The first layer 119a and the first layer 119b are layers containing a fourth organic compound having a phenanthroline skeleton. At least one of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 contains a light-emitting center substance and a substance capable of exhibiting thermally activated delayed fluorescence, and at least one of the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 contains a substance capable of exhibiting thermally activated delayed fluorescence. The light-emitting device 130a and the light-emitting device 130b are both light-emitting devices of one embodiment of the present invention.

[0219] The first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are preferably light-emitting layers that emit light of similar colors. Furthermore, the luminescent center substances contained in each layer are preferably compounds whose emission spectra have a difference in maximum peak wavelength of 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less, and it is even more preferable that the luminescent center substances contained in each layer are the same. The first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are preferably light-emitting layers that emit light of similar colors. Furthermore, the luminescent center substances contained in each layer are preferably compounds whose emission spectra have a difference in maximum peak wavelength of 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less, and it is even more preferable that the luminescent center substances contained in each layer are the same.

[0220] It is preferable that the first light-emitting layer 113a_1 and the first light-emitting layer 113b_1 are separated, and the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 are separated. It is preferable that the emission colors of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are different from the emission colors of the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2. It is preferable that the luminescent center substance contained in the first light-emitting layer 113a_1 is different from the luminescent center substance contained in the first light-emitting layer 113b_1, and that the luminescent center substance contained in the second light-emitting layer 113a_2 is different from the luminescent center substance contained in the second light-emitting layer 113b_2.

[0221] The hole injection layer 111a and the hole injection layer 111b, the first hole transport layer 112a_1 and the first hole transport layer 112b_1, the first electron transport layer 114a_1 and the first electron transport layer 114b_1, the intermediate layer 116a and the intermediate layer 116b (the second layer 117a and the second layer 117b, the third layer 118a and the third layer 118b, and the first layer 119a and the first layer 119b), the second hole transport layer 112a_2 and the second hole transport layer 112b_2, and the second electron transport layer 114a_2 and the second electron transport layer 114b_2 may each be a continuous layer, or may be independently separated 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 at low cost. The separate layers for each light-emitting device allow the use of materials suited to the emission color, thereby enabling the manufacture of a light-emitting device or display device with excellent characteristics. In particular, the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 are preferably continuous layers, because this allows both the light-emitting device 130a and the light-emitting device 130b to have excellent characteristics.

[0222] Being a continuous layer means that the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 are layers formed of the same material. That is, when the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 are layers formed 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-transporting layer 114a_2 and the second electron-transporting layer 114b_2 be layers having similar structures, and it is even more preferable that they be layers having the same structure.

[0223] Furthermore, the luminescent center substance contained in the first light-emitting layer 113a_1 is different from the luminescent center substance contained in the first light-emitting layer 113b_1, and the luminescent center substance contained in the second light-emitting layer 113a_2 is different from the luminescent center substance contained in the second light-emitting layer 113b_2 (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 For example, when the first and second light-emitting layers 113a_1 and 113a_2 are blue fluorescent light-emitting layers and the first and second light-emitting layers 113b_1 and 113b_2 are red phosphorescent light-emitting layers, or when the first and second light-emitting layers 113a_1 and 113a_2 are green phosphorescent light-emitting layers and the first and second light-emitting layers 113b_1 and 113b_2 are red phosphorescent light-emitting layers, the carrier balances of the light-emitting layers of the light-emitting devices 130a and 130b are different. Therefore, in order 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 for each device. However, by using a layer containing a third organic compound having a triazine skeleton as the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 and using a layer containing a fourth organic compound having a phenanthroline skeleton as the first layer 119a and the first layer 119b, it is possible to obtain the performance of both the light-emitting device 130a and the light-emitting device 130b even if the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 have the same structure. In other words, it is possible to achieve both improved productivity and improved performance. Note that the first layer 119a and the first layer 119b may have the same structure.

[0224] The continuous layer is a so-called common layer formed across both the light-emitting device 130a and the light-emitting device 130b.

[0225] 2A is a modified example of FIG. 1C. Light-emitting device 130a and light-emitting device 130b emit light of different colors, and therefore have different optical path lengths between electrodes that can amplify light emission using microcavities. Therefore, in light-emitting device 130b1, the distance between the electrodes can be adjusted by increasing the thickness of light-emitting layers such as light-emitting layer 113b_11 and light-emitting layer 113b_21. Alternatively, the optical path length can be changed by thickening or adding a functional layer, such as hole-transport layer 112b_21.

[0226] FIG. 2B 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.

[0227] The light-emitting device 130c includes an organic compound layer 103c between a first electrode 101c and a second electrode 102 on an insulating layer 175. The organic compound layer 103c includes a first light-emitting unit 501c and a second light-emitting unit 502c stacked with an intermediate layer 116c sandwiched therebetween. While FIG. 2B illustrates 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 501c includes a hole-injection layer 111c, a first hole-transport layer 112c_1, a first light-emitting layer 113c_1, and a first electron-transport layer 114c_1. The intermediate layer 116c includes a second layer 117c, a third layer 118c, and a first layer 119c. The third layer 118c is optional. The second light-emitting unit 502c includes a second hole-transporting layer 112c_2, a second light-emitting layer 113c_2, and a second electron-transporting layer 114c_2.

[0228] The light-emitting device 130c is assumed to emit light with 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 light-emitting layers 113c_1 and 113c_2 thinner than the light-emitting layers of the other two light-emitting devices.

[0229] The second electron-transporting layer 114c_2 is a layer including a third organic compound having a triazine skeleton, and the first layer 119c is a layer including a fourth organic compound having a phenanthroline skeleton.

[0230] The first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 are preferably light-emitting layers that emit light of similar colors. The luminescent center substances contained in each of the first and second light-emitting layers are preferably compounds whose difference in maximum peak wavelength in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less, and it is even more preferable that the luminescent center substances contained in each of the first and second light-emitting layers are the same.

[0231] It is preferable that the first light-emitting layer 113a_1 and the first light-emitting layer 113c_1 are separated, and the second light-emitting layer 113a_2 and the second light-emitting layer 113c_2 are separated. It is preferable that the emission colors of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are different from the emission colors of the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2. It is preferable that the luminescent center substance contained in the first light-emitting layer 113a_1 is different from the luminescent center substance contained in the first light-emitting layer 113c_1, and that the luminescent center substance contained in the second light-emitting layer 113a_2 is different from the luminescent center substance contained in the second light-emitting layer 113c_2.

[0232] In the example shown, the hole injection layer 111a and the hole injection layer 111c, the first hole transport layer 112a_1 and the first hole transport layer 112c_1, the first electron transport layer 114a_1 and the first electron transport layer 114c_1, the intermediate layer 116a and the intermediate layer 116c (the second layer 117a and the second layer 117c, the third layer 118a and the third layer 118c, and the first layer 119a and the first layer 119c), the second hole transport layer 112a_2 and the second hole transport layer 112c_2 are independently separated in the light-emitting device 130a and the light-emitting device 130c, while the second electron transport layer 114a_2 and the second electron transport layer 114c_2 are continuous layers. In this way, one light-emitting device may include both continuous layers and separate layers. This allows a light-emitting device or a display device with a good balance between productivity and characteristics 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, because this allows both the light-emitting device 130a and the light-emitting device 130b to have good characteristics.

[0233] For example, in a three-color light-emitting device having two light-emitting devices with fluorescent luminescent center substances and one light-emitting device with phosphorescent luminescent center substances, it is preferable that the carrier transport layer in the light-emitting device with fluorescent luminescent center substances be formed as a continuous layer, and that the carrier transport layer in the light-emitting device with phosphorescent luminescent center substances be formed as a layer separated from the light-emitting devices emitting other luminescent colors. Alternatively, in a three-color light-emitting device having two light-emitting devices with phosphorescent luminescent center substances and one light-emitting device with fluorescent luminescent center substances, it is preferable that the carrier transport layer in the light-emitting device with phosphorescent luminescent center substances be formed as a continuous layer, and that the carrier transport layer in the light-emitting device with fluorescent luminescent center substances be formed as a layer separated from the light-emitting devices emitting other luminescent colors.

[0234] A light-emitting device of the present invention having such a structure can be a light-emitting device with high current efficiency, low energy loss, and favorable characteristics. A display device according to one embodiment of the present invention using such a light-emitting device can be a display device with low power consumption, high reliability, and high luminance, and thus has favorable visibility. This embodiment can be freely combined with other embodiments.

[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. 3. Fig. 3A is a top view showing the display device, and Fig. 3B is a cross-sectional view taken along lines A-B and C-D in Fig. 3A. 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. Also, 604 is a sealing substrate, 605 is a sealant, and the inside surrounded by the sealant 605 is a space 607.

[0236] The lead 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. The display device in this specification 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. 3B. A driver circuit portion and a pixel portion are formed on an element substrate 610, and here, a source line driver circuit 601, which is the driver circuit portion, and one pixel in 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 the like, 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-based 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, as the semiconductor layer, an oxide semiconductor film which has a plurality of crystal parts whose c-axes are oriented perpendicular to a surface on which the semiconductor layer is formed or a top surface of the semiconductor layer and which does not have grain boundaries 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 stored in a capacitor through the transistor for a long period of time due to its low off-state current. By applying such a transistor to a pixel, it is possible to stop the driver circuit while maintaining the gray level of an image displayed in each display region. As a result, an electronic device with extremely low power consumption can be realized.

[0246] For example, to stabilize the characteristics of a transistor, it is preferable to provide a base film. The base film can be formed as a single layer or a stacked layer 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 base 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 base film need not be provided if it is not necessary.

[0247] The FET 623 indicates one of the transistors formed in the drive circuit section 601. The drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. Although this embodiment shows a driver-integrated type in which the drive circuit is formed on a substrate, this is not necessarily required, and the drive circuit may also be formed externally rather than on the substrate.

[0248] Furthermore, the pixel portion 602 is formed by a plurality of pixels 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 capacitance element.

[0249] An insulator 614 is formed to cover an end portion of the first electrode 613. Here, the insulator 614 can be formed by using a positive photosensitive acrylic resin film.

[0250] Furthermore, in order to improve the coverage of organic compound layers and 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 to provide a curved surface having a curvature radius (0.2 μm to 3 μm) only at the upper end of the insulator 614. 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, 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 can be used. It is also possible to use a stacked structure of a titanium nitride film and a film mainly composed of aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film. The stacked structure provides low resistance as a wiring, good ohmic contact, and the first electrode 613 can further function as an anode.

[0252] The organic compound layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an ink-jet 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, as a material used for the second electrode 617 formed on the organic compound layer 616 and functioning as a cathode, a material having a small work function (Al, Mg, Li, Ca, or alloys and compounds thereof (MgAg, MgIn, AlLi, etc.)) is preferably used. Note that, when light generated in the organic compound layer 616 is transmitted through the second electrode 617, it is preferable to use a stack of a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 to 20 wt % zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the second electrode 617.

[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 sealing material 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 sealing material 605. The space 607 is filled with a filler, and in some cases, the space is filled with an inert gas (nitrogen, argon, etc.), or with a sealing material. A recess is formed in the sealing substrate, and by providing a desiccant therein, deterioration due to the influence of moisture can be suppressed, which is a preferable configuration.

[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] Although not shown in FIG. 3 , a protective film may be provided on the second electrode. The protective film may be formed of an organic resin film or an inorganic insulating film. The protective film may also be formed so as to cover the exposed portion of the sealing material 605. The protective film may also be provided so as to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, and the like.

[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. Furthermore, 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 having complex uneven shapes, including the top, side, and back surfaces of the touch panel.

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

[0263] The display device in this embodiment mode 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] 4A and 4B, a display device is formed by forming a plurality of light-emitting devices 130 over an insulating layer 175. In this embodiment, a display device according to another embodiment of the present invention will be described in detail.

[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. Note that in this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are described as an example, but combinations of sub-pixels of other colors may also be used. 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 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] 4A shows an example in which subpixels of different colors are arranged side by side in the X direction, and subpixels of the same color are arranged side by side in the Y direction. Note that subpixels of different colors may also be arranged side by side in the Y direction, and subpixels of the same color may also be arranged side by side in the X direction.

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

[0272] 4 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. 4B is an example of a cross-sectional view taken along dashed line A1-A2 in Fig. 4A. As shown in Fig. 4B, display device 100 has insulating layer 171, conductive layer 172 on insulating layer 171, insulating layer 173 on insulating layer 171 and on conductive layer 172, insulating layer 174 on insulating layer 173, and insulating layer 175 on insulating layer 174. Insulating layer 171 is provided on a substrate (not shown). Insulating layer 175, insulating layer 174, and insulating layer 173 have openings that reach conductive layer 172, and plugs 176 are provided to fill the openings.

[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] Although Figure 4B shows multiple cross sections of the inorganic insulating layer 125 and the insulating layer 127, when viewing the display device 100 from above, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are each connected into one.

[0276] 4B shows light emitting device 130 as 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 in which light is emitted in a direction opposite to a substrate on which a 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 a first electrode 101R (pixel electrode) composed of a conductive layer 151R and a conductive layer 152R, an organic compound layer 103R on the first electrode, a common layer 104 on the organic compound layer 103R, and a second electrode (common electrode) 102 on the common layer. Note that the common layer 104 may or may not be provided, but it is preferable that the common layer 104 be provided because it can reduce damage to the organic compound layer 103R during processing.

[0279] The light-emitting device 130G has a first electrode 101G (pixel electrode) composed of a conductive layer 151G and a conductive layer 152G, an organic compound layer 103G on the first electrode, a common layer 104 on the organic compound layer 103G, and a second electrode (common electrode) 102 on the common layer. Note that the common layer 104 may or may not be provided, but it is preferable that the common layer 104 be provided because it can reduce damage to the organic compound layer 103G during processing.

[0280] The light-emitting device 130B has the same configuration as that described in Embodiment 1. It includes a first electrode 101B (pixel electrode) including a conductive layer 151B and a conductive layer 152B, an organic compound layer 103B on the first electrode, a common layer 104 on the organic compound layer 103B, and a second electrode (common electrode) 102 on the common layer. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103B during processing. When the common layer 104 is provided, the stacked structure of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103 in Embodiment 1. When the common layer 104 is not provided, the organic compound layer 103B corresponds to the organic compound layer 103 in Embodiment 1.

[0281] The common layer 104 is preferably an electron transport layer. In the case of an electron transport layer, the electron transport layer preferably has a stacked structure, and it is more preferable that the layer on the second electrode side is the common layer 104 and the layer on the light-emitting layer side is the organic compound layer 103.

[0282] The light emitting devices 130R and 130G are also light emitting devices fabricated through a photolithography process.

[0283] One of the pixel electrode and the common electrode of the light-emitting device 130 functions as an anode, and the other functions as a cathode. In the following description, unless otherwise specified, the pixel electrode functions as an anode and the common electrode functions as a cathode.

[0284] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independent island-shaped layers for each light-emitting element or each emitted color. 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.

[0285] The island-shaped organic compound layer 103 is formed by depositing an organic compound film and processing the organic compound film by photolithography.

[0286] The organic compound layer 103 is preferably provided so as to cover the top and side surfaces of the first electrode (pixel electrode) of the light-emitting device 130. This makes it easier to increase the aperture ratio of the display device 100 compared to a configuration in which the end of the organic compound layer 103 is located inside the end of the pixel electrode. Furthermore, covering the side surfaces of the pixel electrode of the light-emitting device 130 with the organic compound layer 103 can prevent the pixel electrode and the second electrode 102 from coming into contact with each other, thereby preventing short circuits in the light-emitting device 130.

[0287] In the display device of one embodiment of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a stacked-layer structure. For example, in the example shown in FIG. 4B , the first electrode of the light-emitting device 130 has a stacked-layer structure of a conductive layer 151 and a conductive layer 152.

[0288] For example, a metal material can be used as 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), and neodymium (Nd), as well as alloys containing appropriate combinations of these metals, can also be used.

[0289] An oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used for the conductive layer 152. 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.

[0290] The conductive layer 151 may have a stacked structure of multiple layers containing different materials, and the conductive layer 152 may have a stacked structure of multiple layers containing different materials. In this case, the conductive layer 151 may include a layer containing a material that can be used for the conductive layer 152, such as a conductive oxide, or the conductive layer 152 may include a layer containing a material that can be used for the conductive layer 151, such as a metal material. For example, when the conductive layer 151 has a stacked structure of two or more layers, a layer in contact with the conductive layer 152 can be a layer containing a material that can be used for the conductive layer 152.

[0291] Next, an example of a method for manufacturing the display device 100 having the configuration shown in FIG. 4A will be described with reference to FIGS.

[0292] [Fabrication Method Example 1] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting a display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an ALD method, or the like.

[0293] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by wet film formation methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0294] Furthermore, when processing the thin films that constitute the display device, they can be processed using, for example, photolithography.

[0295] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, and ArF laser light. Exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light or X-rays may also be used as the light used for exposure. An electron beam may also be used instead of the light used for exposure.

[0296] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0297] 3A, an insulating layer 171 is formed on a substrate (not shown). Subsequently, conductive layers 172 and 179 are formed on the insulating layer 171, and an insulating layer 173 is formed on the insulating layer 171 so as to cover the conductive layers 172 and 179. Subsequently, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

[0298] The substrate may be a substrate having heat resistance sufficient to withstand at least a subsequent heat treatment, such as a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, a single crystal semiconductor substrate made of silicon, silicon carbide, or the like, a polycrystalline semiconductor substrate, a compound semiconductor substrate made of silicon germanium, or the like, or an SOI substrate.

[0299] 5A, openings are formed in the insulating layers 175, 174, and 173, reaching the conductive layer 172. Then, plugs 176 are formed to fill the openings.

[0300] 5A , a conductive film 151f, which will later become conductive layers 151R, 151G, 151B, and 151C, and a conductive film 152f, which will later become conductive layers 152R, 152G, 152B, and 152C, are formed on the plug 176 and the insulating layer 175. The conductive film 151f may be formed of, for example, a metal material. The conductive film 152f may be formed of, for example, an oxide containing one or more elements selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon.

[0301] 5A, a resist mask 191 is formed over the conductive film 152f. The resist mask 191 can be formed by applying a photosensitive material (photoresist) and then performing exposure and development.

[0302] 5B, for example, the conductive films 151f and 152f are removed from regions that do not overlap with the resist mask 191. As a result, the conductive layers 151 and 152 are formed.

[0303] 5C, the resist mask 191 is removed by, for example, ashing using oxygen plasma.

[0304] Subsequently, as shown in FIG. 5D , an insulating film 156f, which will later become insulating layers 156R, 156G, 156B, and 156C, is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, the conductive layer 152C, and the insulating layer 175.

[0305] The insulating film 156f can be an inorganic insulating film such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, or an insulating nitride oxide film, for example, a silicon oxynitride film.

[0306] Subsequently, as shown in FIG. 5E, the insulating film 156f is processed to form insulating layers 156R, 156G, 156B, and 156C.

[0307] 6A, the organic compound film 103Rf is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the insulating layer 175. Note that, as shown in FIG. 6A, the organic compound film 103Rf is not formed on the conductive layer 152C.

[0308] Subsequently, as shown in FIG. 6A, a sacrificial film 158Rf and a mask film 159Rf are formed.

[0309] By providing the sacrificial film 158Rf on the organic compound film 103Rf, damage to the organic compound film 103Rf during the manufacturing process of the display device can be reduced, and the reliability of the light-emitting device can be improved.

[0310] The sacrificial film 158Rf is made of a film that is highly resistant to the processing conditions of the organic compound film 103Rf, specifically, a film that has a large etching selectivity with respect to the organic compound film 103Rf.The mask film 159Rf is made of a film that has a large etching selectivity with respect to the sacrificial film 158Rf.

[0311] The sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the heat resistance temperature of the organic compound film 103Rf. The substrate temperature when the sacrificial film 158Rf and the mask film 159Rf are formed is typically 100° C. or higher and 200° C. or lower, preferably 100° C. or higher and 150° C. or lower, and more preferably 100° C. or higher and 120° C. or lower. The light-emitting device of one embodiment of the present invention includes the first compound, and therefore a display device with good display quality can be provided even after a heating step at a higher temperature.

[0312] It is preferable to use a film that can be removed by wet etching or dry etching for the sacrificial film 158Rf and the mask film 159Rf.

[0313] The sacrificial film 158Rf formed on and in contact with the organic compound film 103Rf is preferably formed using a formation method that causes less damage to the organic compound film 103Rf than the mask film 159Rf. For example, the ALD method (Atomic Layer Deposition method) or the vacuum evaporation method is more preferable than the sputtering method.

[0314] The sacrificial film 158Rf and the mask film 159Rf may each be made of one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, an inorganic insulating film, or the like.

[0315] The sacrificial film 158Rf and the mask film 159Rf can be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. It is particularly preferable to use a low-melting-point material such as aluminum or silver. Using a metal material capable of blocking ultraviolet rays for one or both of the sacrificial film 158Rf and the mask film 159Rf is preferable because it can prevent the organic compound film 103Rf from being irradiated with ultraviolet rays during pattern exposure, thereby suppressing deterioration of the organic compound film 103Rf.

[0316] Furthermore, for the sacrificial film 158Rf and the mask film 159Rf, metal oxides such as In—Ga—Zn oxide, indium oxide, In—Zn oxide, In—Sn oxide, indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide), and indium tin oxide containing silicon can be used, respectively.

[0317] In addition, in the above metal oxide, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used instead of gallium.

[0318] The sacrificial film 158Rf and the mask film 159Rf are preferably made of a semiconductor material such as silicon or germanium, which has a high affinity with the semiconductor manufacturing process. Alternatively, compounds containing the semiconductor materials can be used.

[0319] The sacrificial film 158Rf and the mask film 159Rf may be made of various inorganic insulating films, and an oxide insulating film is particularly preferable because it has higher adhesion to the organic compound film 103Rf than a nitride insulating film.

[0320] 6A, a resist mask 190R is formed. The resist mask 190R can be formed by applying a photosensitive material (photoresist) and then performing exposure and development.

[0321] The resist mask 190R is provided in a position overlapping with the conductive layer 152R. The resist mask 190R is preferably provided also in a position overlapping with the conductive layer 152C. This can prevent the conductive layer 152C from being damaged during the manufacturing process of the display device.

[0322] 6B , a resist mask 190R is used to remove a portion of the mask film 159Rf to form a mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. The resist mask 190R is then removed. The mask layer 159R is then used as a mask (also referred to as a hard mask) to remove a portion of the sacrificial film 158Rf to form a sacrificial layer 158R.

[0323] By using the wet etching method, damage to the organic compound film 103Rf during processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced compared to when using the dry etching method. When using the wet etching method, it is preferable to use an acid aqueous solution such as a developing solution, an alkaline aqueous solution such as a tetramethylammonium hydroxide aqueous solution (TMAH), a chemical solution using dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture of these.

[0324] Furthermore, when dry etching is used to process the sacrificial film 158Rf, deterioration of the organic compound film 103Rf can be suppressed by not using a gas containing oxygen as the etching gas.

[0325] The resist mask 190R can be removed in the same manner as the resist mask 191.

[0326] 6B, the organic compound film 103Rf is processed to form the organic compound layer 103R. For example, the mask layer 159R and the sacrificial layer 158R are used as a hard mask to remove a portion of the organic compound film 103Rf, thereby forming the organic compound layer 103R.

[0327] 6B, a laminated structure of the organic compound layer 103R, the sacrificial layer 158R, and the mask layer 159R remains on the conductive layer 152R. Also, the conductive layers 152G and 152B are exposed.

[0328] The organic compound film 103Rf is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0329] When dry etching is used, deterioration of the organic compound film 103Rf can be suppressed by not using a gas containing oxygen as the etching gas.

[0330] Alternatively, a gas containing oxygen may be used as the etching gas. By using an etching gas containing oxygen, the etching rate can be increased. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate. This makes it possible to suppress damage to the organic compound film 103Rf. Furthermore, problems such as adhesion of reaction products generated during etching can be suppressed.

[0331] When dry etching is used, for example, H ２ , C.F. ４ , C ４ F ８ , SF ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ It is preferable to use a gas containing one or more of Group 18 elements such as He and Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of these elements and oxygen as the etching gas. Alternatively, oxygen gas may be used as the etching gas.

[0332] Subsequently, as shown in FIG. 7A, an organic compound film 103Gf, which will later become the organic compound layer 103G, is formed.

[0333] The organic compound film 103Gf can be formed by the same method as that used to form the organic compound film 103Rf, and can have the same structure as the organic compound film 103Rf.

[0334] 7A, a sacrificial film 158Gf and a mask film 159Gf are formed in this order. Then, a resist mask 190G is formed. The materials and forming methods of the sacrificial film 158Gf and the mask film 159Gf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and forming methods of the resist mask 190G are the same as those applicable to the resist mask 190R.

[0335] The resist mask 190G is provided in a position overlapping with the conductive layer 152G.

[0336] 7B, a resist mask 190G is used to remove a portion of the mask film 159Gf to form a mask layer 159G. The mask layer 159G remains on the conductive layer 152G. The resist mask 190G is then removed. The mask layer 159G is then used as a mask to remove a portion of the sacrificial film 158Gf to form a sacrificial layer 158G. The organic compound film 103Gf is then processed to form an organic compound layer 103G.

[0337] Subsequently, as shown in FIG. 7C, an organic compound film 103Bf is formed.

[0338] The organic compound film 103Bf can be formed by the same method as that used to form the organic compound film 103Rf, and can have the same structure as the organic compound film 103Rf.

[0339] 7C, a sacrificial film 158Bf and a mask film 159Bf are formed in this order. Then, a resist mask 190B is formed. The materials and forming methods of the sacrificial film 158Bf and the mask film 159Bf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and forming methods of the resist mask 190B are the same as those applicable to the resist mask 190R.

[0340] The resist mask 190B is provided in a position overlapping with the conductive layer 152B.

[0341] 7D, a resist mask 190B is used to remove a portion of the mask film 159Bf to form a mask layer 159B. The mask layer 159B remains on the conductive layer 152B. The resist mask 190B is then removed. The mask layer 159B is then used as a mask to remove a portion of the sacrificial film 158Bf to form a sacrificial layer 158B. The organic compound film 103Bf is then processed to form the organic compound layer 103B. For example, the mask layer 159B and the sacrificial layer 158B are used as hard masks to remove a portion of the organic compound film 103Bf to form the organic compound layer 103B.

[0342] 7D, a laminated structure of the organic compound layer 103B, the sacrificial layer 158B, and the mask layer 159B remains on the conductive layer 152B, and the mask layers 159R and 159G are exposed.

[0343] It is preferable that the side surfaces of the organic compound layers 103R, 103G, and 103B are perpendicular or substantially perpendicular to the surface on which they are formed. For example, it is preferable that the angle formed between the surface on which they are formed and these side surfaces be 60 degrees or more and 90 degrees or less.

[0344] As described above, the distance between adjacent pairs of the organic compound layers 103R, 103G, and 103B formed using photolithography can be narrowed to 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. Here, the distance can be defined, for example, as the distance between the opposing ends of adjacent pairs of the organic compound layers 103R, 103G, and 103B. By narrowing the distance between the island-shaped organic compound layers in this manner, a display device with high definition and a large aperture ratio can be provided. Furthermore, the distance between the first electrodes of adjacent light-emitting devices can also be narrowed, for example, to 10 μm or less, 8 μm or less, 5 μm or less, 3 μm or less, or 2 μm or less. Note that the distance between the first electrodes of adjacent light-emitting devices is preferably 2 μm or more and 5 μm or less.

[0345] Subsequently, as shown in FIG. 8A, it is preferable to remove the mask layers 159R, 159G, and 159B.

[0346] The mask layer removal process can be performed using the same method as the mask film processing process. In particular, by using a wet etching method, damage to the organic compound layer 103 during the mask layer removal can be reduced compared to when a dry etching method is used.

[0347] The mask layer may also be removed by dissolving it in a polar solvent such as water or alcohol, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0348] After removing the mask layer, a drying treatment may be performed to remove water adsorbed on the surface. For example, a heat treatment can be performed in an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced pressure atmosphere is preferred because it allows drying at a lower temperature.

[0349] Subsequently, as shown in FIG. 8B, an inorganic insulating film 125f is formed.

[0350] Subsequently, as shown in FIG. 8C, an insulating film 127f, which will later become the insulating layer 127, is formed on the inorganic insulating film 125f.

[0351] The substrate temperature when forming the inorganic insulating film 125f and the insulating film 127f is preferably 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher, and 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower, respectively.

[0352] As the inorganic insulating film 125f, it is preferable to form an insulating film having a thickness of 3 nm or more, 5 nm or more, or 10 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less within the above substrate temperature range.

[0353] The inorganic insulating film 125f is preferably formed by, for example, the ALD method. The ALD method is preferable because it can reduce film formation damage and form a film with high coverage. The inorganic insulating film 125f is preferably formed as an aluminum oxide film by, for example, the ALD method.

[0354] The insulating film 127f is preferably formed by the wet film formation method described above. The insulating film 127f is preferably formed by, for example, spin coating using a photosensitive material, more specifically, using a photosensitive resin composition containing an acrylic resin.

[0355] Subsequently, exposure is performed to expose a portion of the insulating film 127f to visible light or ultraviolet light. The insulating layer 127f is formed in a region sandwiched between any two of the conductive layers 152R, 152G, and 152B, and around the conductive layer 152C.

[0356] The width of the insulating layer 127 to be formed later can be controlled by the exposed region of the insulating film 127f. In this embodiment mode, the insulating layer 127 is processed to have a portion overlapping with the top surface of the conductive layer 151.

[0357] The light used for exposure preferably contains i-line (wavelength 365 nm), and may contain at least one of g-line (wavelength 436 nm) and h-line (wavelength 405 nm).

[0358] Subsequently, as shown in FIG. 9A, development is performed to remove the exposed area of ​​the insulating film 127f, thereby forming an insulating layer 127a.

[0359] 9B , an etching process is performed using the insulating layer 127a as a mask to remove a portion of the inorganic insulating film 125f and thin the film thickness of a portion of the sacrificial layers 158R, 158G, and 158B. This results in the formation of the inorganic insulating layer 125 below the insulating layer 127a. Furthermore, the surfaces of the thin portions of the sacrificial layers 158R, 158G, and 158B are exposed. Hereinafter, the etching process using the insulating layer 127a as a mask may be referred to as the first etching process.

[0360] The first etching treatment can be performed by dry etching or wet etching. Note that it is preferable to form the inorganic insulating film 125f using the same material as the sacrificial layers 158R, 158G, and 158B because the first etching treatment can be performed all at once.

[0361] When dry etching is performed, it is preferable to use a chlorine-based gas. ２ , BCl ３ , SiCl ４ , and CCl ４ The chlorine-based gas may be added with oxygen gas, hydrogen gas, helium gas, argon gas, or the like, either alone or in combination of two or more gases. By using dry etching, thin regions of the sacrificial layers 158R, 158G, and 158B can be formed with good in-plane uniformity.

[0362] The dry etching apparatus may be a dry etching apparatus having a high-density plasma source, such as an inductively coupled plasma (ICP) etching apparatus, or a capacitively coupled plasma (CCP) etching apparatus having parallel plate electrodes.

[0363] Furthermore, it is preferable to perform the first etching process by wet etching. Using the wet etching method can reduce damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B compared to using the dry etching method. For example, the wet etching can be performed using an alkaline solution. For example, TMAH, which is an alkaline solution, can be used for wet etching of an aluminum oxide film. Alternatively, an acid solution containing fluoride can also be used. In this case, the wet etching can be performed by the paddle method. Note that if the inorganic insulating film 125f is formed using the same material as the sacrificial layers 158R, 158G, and 158B, the above-mentioned etching process can be performed simultaneously, which is preferable.

[0364] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, and the etching process is stopped when the film thicknesses of the sacrificial layers 158R, 158G, and 158B are reduced. In this manner, by leaving the corresponding sacrificial layers 158R, 158G, and 158B on the organic compound layers 103R, 103G, and 103B, it is possible to prevent the organic compound layers 103R, 103G, and 103B from being damaged in subsequent processes.

[0365] Subsequently, the entire substrate is exposed to visible light or ultraviolet light, and the insulating layer 127a is preferably irradiated with the energy density of the exposure. ２ Larger, 800 mJ / cm ２ It is preferable that the dose is 0 mJ / cm or less. ２ Greater than 500 mJ / cm ２ It is more preferable to perform the following. By performing such exposure after development, the transparency of the insulating layer 127a can be improved in some cases. Furthermore, the substrate temperature required for heat treatment to transform the insulating layer 127a into a tapered shape in a later step can be reduced in some cases.

[0366] Here, the presence of a barrier insulating layer against oxygen (e.g., an aluminum oxide film, etc.) as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B can reduce the diffusion of oxygen into the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B.

[0367] Next, heat treatment (also referred to as post-baking) is performed. By performing the heat treatment, the insulating layer 127a can be transformed into an insulating layer 127 having tapered side surfaces ( FIG. 9C ). The heat treatment is performed at a temperature lower than the heat resistance temperature of the organic compound layer. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., more preferably 70° C. to 130° C. The heating atmosphere may be an air atmosphere or an inert gas atmosphere. The heating atmosphere may be an atmospheric pressure atmosphere or a reduced-pressure atmosphere. This can improve the adhesion between the insulating layer 127 and the inorganic insulating layer 125 and also improve the corrosion resistance of the insulating layer 127.

[0368] By leaving the sacrificial layers 158R, 158G, and 158B in a thinner state without completely removing them in the first etching treatment, the organic compound layers 103R, 103G, and 103B can be prevented from being damaged and deteriorated in the heat treatment, thereby improving the reliability of the light-emitting device.

[0369] 10A , an etching process is performed using the insulating layer 127 as a mask to remove portions of the sacrificial layers 158R, 158G, and 158B. As a result, openings are formed in the sacrificial layers 158R, 158G, and 158B, respectively, and the top surfaces of the organic compound layers 103R, 103G, 103B, and the conductive layer 152C are exposed. Note that, hereinafter, this etching process may be referred to as a second etching process.

[0370] The end of the inorganic insulating layer 125 is covered with the insulating layer 127. Also, Fig. 10A shows an example in which a part of the end of the sacrificial layer 158G (specifically, the tapered portion formed by the first etching process) is covered with the insulating layer 127, and the tapered portion formed by the second etching process is exposed.

[0371] The second etching process is performed by wet etching. By using wet etching, damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be reduced compared to when dry etching is used. Wet etching can be performed using, for example, an alkaline solution or an acidic solution. An aqueous solution is preferably used so that the organic compound layer 103 does not dissolve.

[0372] 10B , a common electrode 155 is formed on the organic compound layer 103R, the organic compound layer 103G, the organic compound layer 103B, the conductive layer 152C, and the insulating layer 127. The common electrode 155 can be formed by a method such as sputtering or vacuum deposition.

[0373] 10C, a protective layer 131 is formed on the common electrode 155. The protective layer 131 can be formed by a method such as a vacuum deposition method, a sputtering method, a CVD method, or an ALD method.

[0374] Subsequently, the substrate 120 is attached over the protective layer 131 using the resin layer 122, whereby a display device can be manufactured. As described above, in the method for manufacturing a display device of one embodiment of the present invention, the insulating layer 156 is provided so as to have a region overlapping with a side surface of the conductive layer 151, and the conductive layer 152 is formed so as to cover the conductive layer 151 and the insulating layer 156. This can increase the yield of the display device and suppress the occurrence of defects.

[0375] As described above, in the manufacturing method of a display device according to one embodiment of the present invention, the island-shaped organic compound layers 103R, 103G, and 103B are formed by forming films over the entire surface and then processing them, rather than using a fine metal mask. This allows the island-shaped layers to be formed with uniform thicknesses. This allows a high-resolution display device or a display device with a high aperture ratio to be realized. Furthermore, even when the resolution or aperture ratio is high and the distance between subpixels is extremely short, the organic compound layers 103R, 103G, and 103B can be prevented from contacting each other in adjacent subpixels. Therefore, leakage current between subpixels can be suppressed. This prevents crosstalk and realizes a display device with extremely high contrast. Furthermore, even in a display device including tandem light-emitting devices manufactured by photolithography, a display device with excellent characteristics can be provided.

[0376] Embodiment 4 In this embodiment, a display device according to one embodiment of the present invention will be described.

[0377] The display device of the present embodiment can be a high-definition display device, and can therefore be used, for example, as a display unit for a wristwatch-type or bracelet-type information terminal (wearable device), as well as a display unit for a wearable device that can be worn on the head, such as a head-mounted display (HMD) for VR, or a glasses-type device for AR.

[0378] 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.

[0379] 11A 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 100E described below.

[0380] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display portion 281. The display portion 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 portion 284 (described later) can be viewed.

[0381] 11B 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 the 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.

[0382] The pixel portion 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of Fig. 11B. The various structures described in the above embodiments can be applied to the pixel 284a.

[0383] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0384] One pixel circuit 283a is a circuit that controls the driving of a plurality of elements included in one pixel 284a.

[0385] The circuit portion 282 includes a circuit for driving each pixel circuit 283 a of the pixel circuit portion 283. For example, the circuit portion 282 preferably 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.

[0386] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit portion 282. An IC may be mounted on the FPC 290.

[0387] 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.

[0388] Because such a display module 280 has extremely high resolution, it can be suitably used in VR devices such as HMDs or eyeglass-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 lens, 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.

[0389] Display Device 100A The display device 100A shown in FIG. 12A 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.

[0390] The substrate 301 corresponds to the substrate 291 in FIGS. 12A and 12B . 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.

[0391] An element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0392] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided over the insulating layer 261 .

[0393] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as a dielectric of the capacitor 240.

[0394] 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 the 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.

[0395] 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.

[0396] 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. Furthermore, 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. A sacrificial layer 158R is located on the organic compound layer 103R, a sacrificial layer 158G is located on the organic compound layer 103G, and a sacrificial layer 158B is located on the organic compound layer 103B.

[0397] The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B are electrically connected to one of the source and the drain of the transistor 310 by 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 plugs.

[0398] Furthermore, a protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B. A substrate 120 is bonded to the protective layer 131 with a resin layer 122. For details of the components from the light-emitting device 130 to the substrate 120, refer to embodiment 3. The substrate 120 corresponds to the substrate 292 in FIG. 11A .

[0399] Fig. 12B is a modified example of the display device 100A shown in Fig. 12A. The display device shown in Fig. 12B 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 layers 132R, 132G, and 132B. In the display device shown in Fig. 12B, 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.

[0400] [Display Device 100B] FIG. 13 shows a perspective view of the display device 100B, and FIG. 13 shows a cross-sectional view of the display device 100C.

[0401] The display device 100B has a configuration in which a substrate 352 and a substrate 351 are bonded together. In Fig. 13, the substrate 352 is indicated by a dashed line.

[0402] The display device 100B includes a pixel portion 177, a connection portion 140, a circuit 356, wiring 355, and the like. Fig. 13 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. 13 can also be called a display module including the display device 100B, an IC (integrated circuit), and an FPC. Here, a display device in which a connector such as an FPC is attached to a substrate or a display device in which an IC is mounted on the substrate is called a display module.

[0403] The connection portion 140 is provided outside the pixel portion 177. There may be one or more connection portions 140. The connection portion 140 electrically connects the common electrode of the light-emitting device and the conductive layer, and can supply a potential to the common electrode.

[0404] The circuit 356 can be, for example, a scanning line driver circuit.

[0405] 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.

[0406] 13 shows an example in which an IC 354 is provided on a substrate 351 by a chip-on-glass (COG) method, a chip-on-film (COF) method, or the like. For example, an IC having a scanning line driver circuit or a signal line driver circuit can be used as the IC 354. Note that the display device 100B and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by a COF method, for example.

[0407] Figure 14 shows an example of a cross section of the display device 100B in Figure 13, in which a portion of the region including the FPC 353, a portion of the circuit 356, a portion of the pixel portion 177, a portion of the connection portion 140, and a portion of the region including the end portion are cut away, as display device 100C.

[0408] [Display Device 100C] The display device 100C shown in FIG. 14 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.

[0409] For details of the light emitting device 130R, the light emitting device 130G, and the light emitting device 130B, refer to the third embodiment.

[0410] 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.

[0411] 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 the 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.

[0412] 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.

[0413] 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.

[0414] The layer 128 has a function of filling in recesses of the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B and planarizing the surface. Conductive layers 151R, 151G, and 151B, which are electrically connected to the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B, are provided on the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B and the layer 128. Therefore, the regions overlapping with the recesses of the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixel.

[0415] 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 as appropriate for the layer 128. In particular, the layer 128 is preferably formed using an insulating material, and more preferably using an organic insulating material. For example, the organic insulating material that can be used for the insulating layer 127 described above can be used for the layer 128.

[0416] A protective layer 131 is provided on the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B. 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. 14 , the space between the substrate 352 and the substrate 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 device. Alternatively, the space may be filled with a resin different from the frame-shaped adhesive layer 142.

[0417] 14 shows an example in which the connection portion 140 has a conductive layer 224C obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive layer 151C obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive layer 152C obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. Also, FIG. 14 shows an example in which an insulating layer 156C is provided so as to have a region overlapping with a side surface of the conductive layer 151C.

[0418] 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 electrode contains a material that reflects visible light, and the counter electrode (common electrode 155) contains a material that transmits visible light.

[0419] 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.

[0420] The insulating layers 211, 213, and 215 are each preferably formed using an inorganic insulating film.

[0421] The insulating layer 214 that functions as a planarizing layer is preferably an organic insulating layer.

[0422] 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.

[0423] 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 through 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.

[0424] 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. In addition, various optical members can be arranged on the outside of the substrate 352.

[0425] The substrate 351 and the substrate 352 can be made of the same material as can be used for the substrate 120 .

[0426] The adhesive layer 142 can be made of a material that can be used for the resin layer 122 .

[0427] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0428] [Display Device 100D] The display device 100D shown in FIG. 15 differs from the display device 100C shown in FIG. 15 mainly in that it is a bottom-emission display device.

[0429] Light emitted from the light-emitting device is emitted toward the substrate 351. A material that is highly transparent to visible light is preferably used for the substrate 351. On the other hand, the light-transmitting property of the material used for the substrate 352 does not matter.

[0430] 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. In the example shown in FIG. 15, 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, and the like are provided over the insulating layer 153.

[0431] Light emitting device 130R includes conductive layer 112R, conductive layer 126R on conductive layer 112R, and conductive layer 129R on conductive layer 126R.

[0432] Light emitting device 130B includes conductive layer 112B, conductive layer 126B on conductive layer 112B, and conductive layer 129B on conductive layer 126B.

[0433] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are each formed using a material that is highly transparent to visible light. The second electrode 102 is preferably formed using a material that reflects visible light.

[0434] Although the light emitting device 130G is not shown in FIG. 15, the light emitting device 130G is also provided.

[0435] Although FIG. 15 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.

[0436] [Display Device 100D2] The display device 100D2 shown in Fig. 16 is an example of a bottom-emission type display device that differs from the display device 100D shown in Fig. 16. The display device 100D2 differs from the display device 100D in that it has an organic resin layer 180. Note that in the figure, the reference numerals of the same components as those in Fig. 16 may be omitted, and the description in Fig. 16 may be referred to for details.

[0437] 16B shows a top view layout of a pixel 178 (pixel 178a and pixel 178b) having subpixels 110 (subpixels 110R, 110G, 110B, and 110W), and Fig. 16C shows a top view of the organic resin layer 180 in a region where the subpixels 110R and 110G of the pixel 178 are formed. Note that the distance between the light-shielding layers 317 is 110Rw in the light-emitting region of the subpixel 110R.

[0438] As shown in FIG. 16A , organic resin layer 180 is provided on insulating layer 214. As shown in the region surrounded by the dashed dotted line in FIG. 16A and in FIG. 16C , organic resin layer 180 has curved recesses 181 (recesses 181 a and 181 b) at least in the region where the subpixels are formed. Note that recesses 181 may be provided outside the light-emitting region, such as recess 181 c. Providing recess 181 c refracts light emitted in the region overlapping with light-shielding layer 317 or light traveling to the region overlapping with light-shielding layer 317, allowing it to be extracted from the light-emitting region, thereby improving light-emitting efficiency.

[0439] 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 therebetween.

[0440] 16, the recess has a hexagonal top surface shape (FIG. 16C) and a semicircular cross-sectional shape (FIG. 16A), but may have other shapes 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.

[0441] 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, phenolic 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.

[0442] 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.

[0443] 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.

[0444] In addition, the first electrode 101 (the first electrode 101R and the first electrode 101W) is provided on the organic resin layer 180, and the organic compound layer 103 is provided on the first electrode 101. Ends of the first electrode 101 and the organic compound layer 103 may be covered with an insulating layer 127.

[0445] 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 second electrode 102 formed on the common layer 104 has a recess similar to the recess of the common layer 104. That is, the recesses of the organic resin layer 180, the first electrode 101, the organic compound layer 103, the common layer 104, and the second electrode 102 have a structure in which they overlap one another.

[0446] In addition, a common layer 104 is provided over the organic compound layer 103 and the insulating layer 127, and a second electrode 102 is provided over the common layer 104. A protective layer 131 is provided over the second electrode 102, and the second electrode 102 is bonded to a substrate 352 via an adhesive layer 142.

[0447] Although the light emitting device 130G and the light emitting device 130B are not shown in FIG. 16, the light emitting device 130G and the light emitting device 130B are also provided.

[0448] The light-emitting device of one embodiment of the present invention having the above-described organic resin layer 180 can provide an organic semiconductor device with high emission efficiency, and therefore, an organic semiconductor device with high reliability, low driving voltage, and low power consumption can be provided.

[0449] [Display Device 100E] The display device 100E shown in FIG. 17 is a modified example of the display device 100C shown in FIG. 14, and differs from the display device 100C mainly in that it has colored layers 132R, 132G, and 132B.

[0450] In the display device 100E, the light-emitting device 130 has an area that overlaps one of the colored layers 132R, 132G, and 132B. The colored layers 132R, 132G, and 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.

[0451] In the display device 100E, 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. 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.

[0452] [Display Device 100E2] The display device 100E2 shown in Fig. 18 is a modified example of the display device 100E shown in Fig. 17, and has microlenses 182 on the colored layers 132R, 132G, and 132B. Note that in the figure, the reference numerals of the same components as those in Fig. 17 may be omitted, and for details, the description in Fig. 17 may be referred to.

[0453] 18B shows a top view layout of a pixel 178 (pixel 178a and pixel 178b) having subpixels 110 (subpixels 110R, 110G, and 110B), and Fig. 18C shows a top view of a microlens 182 in a region where the subpixels 110R and 110G of the pixel 178 are formed. Note that 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.

[0454] 18A has a planarization film 143 provided on a protective layer 131, and colored layers 132R, 132G, and 132B provided on the planarization film 144. The 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.

[0455] As shown in FIG. 18C, the microlens 182 may be provided for each sub-pixel in the region where the sub-pixels are formed.

[0456] 18C, 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 recess may be a polygon such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or a polygon with rounded corners, an ellipse, or a circle.

[0457] The microlenses 182 can be formed using the same material as the organic resin layer 180 .

[0458] The light-emitting device of one embodiment of the present invention having the above-described microlens 182 can provide an organic semiconductor device with high emission efficiency; therefore, an organic semiconductor device that is highly reliable, has a low driving voltage, and consumes low power, and is optimal for a display for mobile applications can be provided.

[0459] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when a plurality of configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0460] Embodiment 5 In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0461] The electronic devices of this embodiment include the display device of one embodiment of the present invention in a display portion. The display device of one embodiment of the present invention has low power consumption and high reliability. Therefore, the display device of one embodiment of the present invention can be used in the display portion of various electronic devices.

[0462] 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.

[0463] An example of a wearable device that can be worn on the head will be described with reference to FIGS. 19A to 19D.

[0464] The electronic device 700A shown in FIG. 19A and the electronic device 700B shown in FIG. 19B 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.

[0465] 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.

[0466] Each of the electronic device 700A and the electronic device 700B can 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.

[0467] The electronic device 700A and the electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, the electronic device 700A and the 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 the display area 756.

[0468] 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.

[0469] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or wired.

[0470] The housing 721 may be provided with a touch sensor module.

[0471] 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.

[0472] The electronic device 800A shown in Figure 19C and the electronic device 800B shown in Figure 19D 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.

[0473] The display device of one embodiment of the present invention can be applied to the display portion 820. Therefore, the electronic device can have high reliability.

[0474] The display unit 820 is provided inside the housing 821 at a position that can be viewed through the lens 832. In addition, by displaying different images on the pair of display units 820, it is possible to perform three-dimensional display using parallax.

[0475] 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.

[0476] The mounting portion 823 allows the user to mount the electronic device 800A or the electronic device 800B on the head.

[0477] 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.

[0478] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone.

[0479] 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.

[0480] The electronic device of one embodiment of the present invention may have a function of wirelessly communicating with the earphone 750 .

[0481] 19B includes earphone unit 727. A portion of the wiring connecting earphone unit 727 and the control unit may be disposed inside housing 721 or attachment unit 723.

[0482] 19D includes an earphone unit 827. For example, the earphone unit 827 and the control unit 824 may be configured to be connected to each other by wire.

[0483] As described above, as electronic devices according to one embodiment of the present invention, both glasses-type devices (such as the electronic devices 700A and 700B) and goggle-type devices (such as the electronic devices 800A and 800B) are suitable.

[0484] The electronic device 6500 shown in FIG. 20A is a portable information terminal that can be used as a smartphone.

[0485] 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, a light source 6508, and the like. The display portion 6502 has a touch panel function.

[0486] The display device of one embodiment of the present invention can be applied to the display portion 6502. Therefore, the electronic device can have high reliability.

[0487] FIG. 20B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0488] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, an optical member 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.

[0489] 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).

[0490] In a region outside the display portion 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.

[0491] The display device of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. Furthermore, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0492] 20C shows an example of a television set. A television set 7100 has a display portion 7000 built into a housing 7171. Here, the housing 7171 is supported by a stand 7173.

[0493] 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.

[0494] The television set 7100 shown in FIG. 20C can be operated using operation switches provided on the housing 7171 and a separate remote control 7151.

[0495] 20D 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.

[0496] 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.

[0497] 20E and 20F show an example of digital signage.

[0498] 20E 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.

[0499] 20F 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.

[0500] 20E and 20F, 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.

[0501] 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.

[0502] Furthermore, as shown in Figures 20E and 20F, it is preferable that the digital signage 7300 or the digital signage 7400 be able to wirelessly link with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user.

[0503] The electronic device shown in Figures 21A to 21G has a housing 9000, a display unit 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.

[0504] 21A to 21G 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 using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc.

[0505] The electronic devices shown in FIGS. 21A to 21G will be described in detail below.

[0506] FIG. 21A is a perspective view showing a mobile information terminal 9171. The mobile information terminal 9171 can be used as, for example, a smartphone. Note that 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. FIG. 21A 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 notifications of incoming emails, SNS messages, phone calls, etc., the title of the email or SNS message, 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.

[0507] 21B is a perspective view showing 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 that can be observed from above the mobile information terminal 9172 while the mobile information terminal 9172 is stored in a breast pocket of clothes.

[0508] 21C is a perspective view showing a tablet terminal 9173. The tablet terminal 9173 is capable of executing various applications such as mobile phone calls, e-mail, text browsing and creation, music playback, internet communication, and computer games, for example. The tablet terminal 9173 has a display unit 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.

[0509] FIG. 21D is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free calling by communicating with, for example, a wirelessly capable headset. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Note that charging may be performed by wireless power supply.

[0510] 21E to 21G are perspective views showing a foldable mobile information terminal 9201. Also, FIG. 21E is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 21G is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 21F is a perspective view of a state in the process of changing from one of FIG. 21E and FIG. 21G to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent visibility of the display. The 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 or more and 150 mm or less.

[0511] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when a plurality of configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0512] In this example, detailed fabrication methods and characteristics of light-emitting devices R1-1, R1-2, G1-1 to G-3, B1-1, and B1-2 will be described. The structural formulae of the main compounds used are shown below.

[0513]

[0514]

[0515] (Method of manufacturing light-emitting device R1-1) First, on a glass substrate, 100 nm of silver (Ag) was deposited as a reflective electrode from the substrate side, and 85 nm of indium tin oxide containing silicon oxide (ITSO) was deposited as a transparent electrode by sputtering to form a 2 mm x 2 mm first electrode 101. The transparent electrode functions as an anode, and is considered to be the first electrode 101 together with the reflective electrode.

[0516] Next, as a pretreatment for forming a light-emitting device on the substrate, the surface of the substrate was washed with water and baked at 200° C. for 1 hour.

[0517] After that, about 1 × 10 −４The substrate was introduced into a vacuum deposition apparatus whose inside had been reduced in pressure to 100 Pa, and vacuum baked at 170° C. for 30 minutes in a heating chamber of the vacuum deposition apparatus, and then the substrate was allowed to cool for about 30 minutes.

[0518] Next, the substrate was fixed to a holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 101 was formed faced downward. N-(biphenyl-2-yl)-N-(9,9-dimethylfluoren-2-yl)-9,9′-spirobi[9H-fluorene]-2-amine (abbreviation: oFBiSF(2)) represented by the above structural formula (i) and a material having electron acceptor properties (OCHD-003) with a molecular weight of 672 and containing fluorine were co-deposited by an evaporation method to a thickness of 10 nm on the inorganic insulating film and the first electrode 101 in a weight ratio of 1:0.03 (=oFBiSF(2):OCHD-003).

[0519] On the hole injection layer 111, oFBiSF(2) was evaporated to a thickness of 150 nm to form a first hole transport layer.

[0520] Subsequently, on the first hole-transporting layer, 11-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9′,10′:4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr) represented by the above structural formula (ii), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (iii), and OCPG-006, a red phosphorescent material, were co-deposited to a thickness of 40 nm to give a weight ratio of 0.7:0.3:0.05 (=11mDBtBPPnfpr:PCBBiF:OCPG-006).

[0521] Thereafter, 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole (abbreviation: mPCCzPTzn-02) represented by the above structural formula (iv) was evaporated to a thickness of 10 nm to form a first electron transport layer.

[0522] After the formation of the first electron transport layer, 2,2′-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) represented by the structural formula (v) above as a fourth organic compound containing a phenanthroline skeleton and lithium oxide (Li ２ O) in a weight ratio of 1:0.02 (=mPPhen2P:Li ２ A first layer was formed by co-evaporating copper phthalocyanine (abbreviation: CuPc) represented by the above structural formula (vii) to a thickness of 5 nm, a third layer was formed by co-evaporating copper phthalocyanine (abbreviation: CuPc) represented by the above structural formula (vii) to a thickness of 2 nm, and a second layer was formed by co-evaporating oFBiSF(2) and OCHD-003 to a weight ratio of 1:0.15 (=oFBiSF(2):OCHD-003) to a thickness of 10 nm, thereby forming an intermediate layer.

[0523] On the intermediate layer, oFBiSF(2) was evaporated to a thickness of 75 nm to form a second hole transport layer.

[0524] A second light-emitting layer was formed on the second hole-transporting layer by co-depositing 11mDBtBPPnfpr, PCBBiF, and OCPG-006 to a thickness of 40 nm in a weight ratio of 0.7:0.3:0.05 (=11mDBtBPPnfpr:PCBBiF:OCPG-006).

[0525] Thereafter, 2,2′-[1,2-naphthalenediyldi(4,1-phenylene)]bis(4,6-diphenyl-1,3,5-triazine) (abbreviation: TznP2N) represented by the above structural formula (viii) and 8-hydroxyquinolinatolithium (abbreviation: Liq) represented by the above structural formula (ix) were co-deposited to a thickness of 25 nm in a weight ratio of 1:1 (=TznP2N:Liq) to form a second electron transport layer.

[0526] Thereafter, Liq was evaporated to a thickness of 1 nm, and silver (Ag) and magnesium (Mg) were co-evaporated to a volume ratio of 1:0.1 to a thickness of 15 nm to form the second electrode 102. In addition, 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (x) was deposited to a thickness of 70 nm on the second electrode 102 as a cap layer to improve light extraction efficiency.

[0527] Next, in a glove box with a nitrogen atmosphere, the light-emitting device was sealed with a glass substrate to prevent it from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only onto the sealant without irradiating the light-emitting device, and heat treatment was performed at 80°C under atmospheric pressure for 1 hour), thereby forming light-emitting device R1.

[0528] (Method for fabricating light-emitting device R1-2) Light-emitting device R1-2 was fabricated in the same manner as light-emitting device R1-1, except that the TznP2N of the second electron-transport layer in light-emitting device R1-1 was replaced with 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm) represented by the above structural formula (xi).

[0529] (Method for Fabricating Light-Emitting Device G1-1) Light-emitting device G1-1 was fabricated by changing the thickness of the first hole transport layer in light-emitting device R1-1 to 80 nm and the thickness of the second hole transport layer to 60 nm, and by forming the first light-emitting layer and the second light-emitting layer from 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: PCCzTzn) represented by the above structural formula (xii) and [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d ３ ) ２ (mbfpypy-d ３ )) in a weight ratio of 1:0.1 (=PCCzTzn:Ir(5mppy-d ３ ) ２ (mbfpypy-d ３ The light-emitting device R1-1 was fabricated in the same manner as the light-emitting device R1-1, except that PCCzTzn was co-evaporated so that the difference between the S1 level and the T1 level was 0.18 eV. ３ ) ２ (mbfpypy-d ３) is a substance that exhibits phosphorescence.

[0530] (Method for Fabricating Light-Emitting Device G1-2) Light-emitting device G1-2 was fabricated in the same manner as light-emitting device G1-1, except that the TznP2N in the second electron-transport layer in light-emitting device G1-1 was changed to 6BP-4Cz2PPm, and the light-emitting layer was formed by co-evaporation of 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) represented by structural formula (xiv) above and 9,10-diphenyl-2-[N-phenyl-N-(9-phenyl-carbazol-3-yl)amino]anthracene (abbreviation: 2PCAPA) represented by structural formula (xv) above at a weight ratio of 1:0.05 (=cgDBCzPA:2PCAPA). Both cgDBCzPA and 2PCAPA are ordinary fluorescent materials with a difference between the S1 level and the T1 level of more than 0.2 eV.

[0531] (Method of Fabricating Light-Emitting Device G1-3) Light-emitting device G1-3 was fabricated in the same manner as light-emitting device G1-1, except that TznP2N in the second electron-transporting layer of light-emitting device G1-1 was changed to 6BP-4Cz2PPm.

[0532] (Method for Fabricating Light-Emitting Device B1-1) Light-emitting device B1-1 was fabricated by changing the thickness of the first hole transport layer in light-emitting device R1-1 to 45 nm and the thickness of the second hole transport layer to 55 nm, and by forming the first light-emitting layer and the second light-emitting layer from 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) represented by the above structural formula (xvi) and N,N′-diphenyl ether represented by the above structural formula (xvii). The light-emitting device was fabricated in the same manner as light-emitting device R1-1, except that a 25 nm thick film was formed by co-evaporation of αN-βNPAnth:3,10PCA2Nbf(IV)-02 and αN-βNPAnth:3,10PCA2Nbf(IV)-02 in a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02).

[0533] (Method of Fabricating Light-Emitting Device B1-2) Light-emitting device B1-2 was fabricated in the same manner as light-emitting device B1-1, except that TznP2N in the second electron-transporting layer of light-emitting device B1-1 was changed to 6BP-4Cz2PPm.

[0534] The device structures of light-emitting devices R1-1, R1-2, G1-1 to G-3, B1-1 and B1-2 are shown below.

[0535]

[0536]

[0537]

[0538]

[0539] FIG. 22 shows the measurement results of the emission spectrum of the thin film of PCCzTzn used as the host material for the light-emitting devices G1-1 and G1-3 fabricated above.

[0540] To measure the emission spectrum, a thin film sample was prepared on a quartz substrate by vacuum deposition. The emission spectrum was measured using a microscopic PL device, LabRAM HR-PL (Horiba, Ltd.), at a measurement temperature of 10 K, a He-Cd laser (wavelength: 325 nm) as the excitation light, and a CCD detector. The S1 level and T1 level were determined from the shortest wavelength peak (including the shoulder) and the rising edge on the short wavelength side in the emission spectrum obtained from the measurement. The thin film had a thickness of 50 nm, and another quartz substrate was attached to the quartz substrate on which the thin film was formed in a nitrogen atmosphere, and then used for the measurement.

[0541] In addition to the normal emission spectrum measurement, the above emission spectrum was also measured with a time-resolved emission spectrum focusing on emission with a long emission lifetime. Because this emission spectrum measurement was performed at a low temperature (10 K), in the normal emission spectrum measurement, some phosphorescence was also observed in addition to fluorescence, which is the main emission component. Furthermore, in the time-resolved emission spectrum measurement focusing on emission with a long emission lifetime, phosphorescence was mainly observed. That is, in the normal emission spectrum measurement, the fluorescent component of the emission was mainly observed, and in the time-resolved emission spectrum, the phosphorescent component of the emission was mainly observed. The spectrum of the fluorescent component is sometimes referred to as the emission spectrum, and the spectrum of the phosphorescent component is sometimes referred to as the phosphorescence spectrum.

[0542] As shown in FIG. 22, the wavelengths of the shortest wavelength peaks (including shoulders) of the fluorescent and phosphorescent components in the emission spectrum of PCCzTzn were 485 nm and 482 nm, respectively.

[0543] 22, the wavelengths of the rising edge on the short wavelength side (the emission edge on the short wavelength side) of the fluorescent component and phosphorescent component of the emission spectrum of PCCzTzn are 434 nm and 464 nm, respectively. Therefore, the S1 level and T1 level calculated from the rising edge wavelengths were derived to be 2.86 eV and 2.67 eV, respectively. That is, PCCzTzn is a material in which the energy difference between the S1 level and the T1 level calculated from the rising edge wavelength of the emission spectrum is also very small, at 0.18 eV. The wavelength of the rising edge on the short wavelength side of the emission spectrum was determined by drawing a tangent at the wavelength where the slope of the tangent in the spectrum is maximum, and the wavelength at the intersection of the tangent with the horizontal axis.

[0544] As described above, the energy difference between the S1 level and the T1 level of PCCzTzn was very small, greater than 0 eV and equal to or less than 0.2 eV. Therefore, PCCzTzn can be said to be a substance that has the function of converting triplet excitation energy into singlet excitation energy by reverse intersystem crossing.

[0545] Next, the fluorescence spectrum and phosphorescence spectrum of 2PCAPA were measured. The measurements were performed in the same manner as for PCCzTzn. However, since it was difficult to obtain phosphorescence from 2PCAPA, (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dppm)) was used as a triplet sensitizer. ２ (acac)) was added to make it easier to observe the phosphorescence of 2PCAPA. The results are shown in Figure 56. In the figure, the wavelength region a represents the fluorescence emission of 2PCAPA, and the wavelength region b represents the fluorescence emission of Ir (dppm). ２ The spectrum in the wavelength region c is mainly due to the phosphorescence of (acac), and the spectrum in the wavelength region c is mainly due to the phosphorescence of 2PCAPA.

[0546] 56, the wavelengths of the shortest wavelength peaks (including shoulders) of the fluorescent and phosphorescent components in the emission spectrum of 2PCAPA were around 516 nm and 746 nm, respectively. This indicates that 2PCAPA is a fluorescent material with a difference between the S1 level and the T1 level of more than 0.2 eV.

[0547] Similarly, the fluorescence spectrum and phosphorescence spectrum of cgDBCzPA were measured. In the measurement of cgDBCzPA, tris(2-phenylpyridinato-N,C) was used as a triplet sensitizer. ２’ ) Iridium (III) (abbreviation: Ir(ppy) ３ The results are shown in Figure 57, where the wavelength region a represents the fluorescence emission of cgDBCzPA, and the wavelength region b represents the fluorescence emission of Ir(ppy). ３ The wavelength region c is a spectrum mainly due to the phosphorescence of cgDBCzPA.

[0548] 57, the wavelengths of the shortest wavelength peaks (including shoulders) of the fluorescent and phosphorescent components in the emission spectrum of cgDBCzPA were 426 nm and 721 nm, respectively. This indicates that cgDBCzPA is a fluorescent substance with a difference between the S1 level and the T1 level of more than 0.2 eV.

[0549] The luminance-current density characteristics, current efficiency-luminance characteristics, current density-voltage characteristics, power efficiency-luminance characteristics, and electroluminescence spectra of light-emitting devices R1-1 and R1-2 are shown in Fig. 23 , Fig. 24 , Fig. 25 , Fig. 26 , and Fig. 27 , respectively. The luminance-current density characteristics, current efficiency-luminance characteristics, current density-voltage characteristics, power efficiency-luminance characteristics, and electroluminescence spectra of light-emitting devices G1-1 to G1-3 are shown in Fig. 28 , Fig. 29 , Fig. 30 , Fig. 31 , and Fig. 32 , respectively. The luminance-current density characteristics, current efficiency-luminance characteristics, current density-voltage characteristics, power efficiency-luminance characteristics, and blue index-luminance characteristics of light-emitting devices B1-1 and B1-2 are shown in Fig. 33 , Fig. 34 , Fig. 35 , Fig. 36 , Fig. 37 , and Fig. 38 , respectively.

[0550] Furthermore, the light emitting device R1-1 and the light emitting device R1-2 have a luminance of...

Claims

a first electrode; a second electrode; and The middle class and a first light-emitting layer; and a second light-emitting layer; and a first electron transport layer; and a second electron transport 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 electron transport layer is located between the first light-emitting layer and the intermediate layer; the second electron transport layer is located between the second light-emitting layer and the second electrode; the first light-emitting layer has a first luminescent center substance and a first organic compound, the second light-emitting layer has a second luminescent center substance and a second organic compound, the first organic compound and the second organic compound are substances capable of exhibiting thermally activated delayed fluorescence, a difference between a maximum peak wavelength in an emission spectrum of the first luminescence center substance and a maximum peak wavelength in an emission spectrum of the second luminescence center substance is 30 nm or less; The 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. a first electrode; a second electrode; and The middle class and a first light-emitting layer; and a second light-emitting layer; and a first electron transport layer; and a second electron transport 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 electron transport layer is located between the first light-emitting layer and the intermediate layer; the second electron transport layer is located between the second light-emitting layer and the second electrode; the second electron transport layer includes a third organic compound including a triazine skeleton, the intermediate layer has a mixed layer of a fourth organic compound having a phenanthroline skeleton and lithium or a lithium compound, the first light-emitting layer has a first luminescent center substance and a first organic compound, the second light-emitting layer has a second luminescent center substance and a second organic compound, the first organic compound and the second organic compound are substances capable of exhibiting thermally activated delayed fluorescence, and a difference between a maximum peak wavelength in an emission spectrum of the first luminescence center substance and a maximum peak wavelength in an emission spectrum of the second luminescence center substance is 30 nm or less; The 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. a first electrode; a second electrode; and The middle class and a first light-emitting layer; and a second light-emitting layer; and a first electron transport layer; and a second electron transport 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 electron transport layer is located between the first light-emitting layer and the intermediate layer; the second electron transport layer is located between the second light-emitting layer and the second electrode; the second electron transport layer includes a third organic compound including a triazine skeleton, the intermediate layer includes a fourth organic compound having a phenanthroline skeleton, the first electron transport layer includes a fifth organic compound including a triazine skeleton, the first light-emitting layer has a first luminescent center substance and a first organic compound, the second light-emitting layer has a second luminescent center substance and a second organic compound, the first organic compound and the second organic compound are substances capable of exhibiting thermally activated delayed fluorescence, a difference between a maximum peak wavelength in an emission spectrum of the first luminescence center substance and a maximum peak wavelength in an emission spectrum of the second luminescence center substance is 30 nm or less; A light-emitting device in which the first light-emitting layer and the second light-emitting layer have light-emitting layers different from light-emitting layers of at least one light-emitting device among a plurality of other light-emitting devices adjacent to the light-emitting device. The light-emitting device according to claim 3 , wherein the third organic compound and the fifth organic compound are the same organic compound. In claim 3, A light-emitting device wherein the intermediate layer comprises lithium or a lithium compound. In claim 5, The intermediate layer comprises a mixed layer of the fourth organic compound and the lithium or lithium compound. In any one of claims 2 to 6, an emission edge on a short wavelength side in an emission spectrum of the first organic compound is positioned at a wavelength shorter than an absorption edge on a long wavelength side in an absorption spectrum of the first luminescence center substance, a light-emitting device in which the emission edge on the short wavelength side in the emission spectrum of the second organic compound is positioned at a wavelength shorter than the absorption edge on the long wavelength side in the absorption spectrum of the second luminescent center substance; In any one of claims 2 to 6, The peak wavelength of the emission spectrum of the first organic compound is located at a wavelength shorter than the peak wavelength of the emission spectrum of the first luminescence center substance; and a difference between a peak wavelength of an emission spectrum of the first organic compound and a peak wavelength of an emission spectrum of the first luminescence center substance is 30 nm or less; the peak wavelength of the emission spectrum of the second organic compound is located at a wavelength shorter than the peak wavelength of the emission spectrum of the second luminescence center substance; and A light-emitting device, wherein the difference between the peak wavelength of the emission spectrum of the second organic compound and the peak wavelength of the emission spectrum of the second luminescent center substance is 30 nm or less. A display device having a light-emitting device A and a light-emitting device B, The light-emitting device A and the light-emitting device B are adjacent to each other, The light-emitting device A is a first electrode A; a second electrode; and A middle layer A; a first light-emitting layer A; and a second light-emitting layer A; and a first electron transport layer A; a second electron 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 electron transport layer A is located between the first light-emitting layer A and the intermediate layer A, the second electron transport layer A is located between the second light-emitting layer A and the second electrode A; The light-emitting device B is a first electrode B; a second electrode B; Middle class B; a first light-emitting layer B; and a second light-emitting layer B; and a first electron transport layer B; and a second electron transport 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 electron transport layer B is located between the first light-emitting layer B and the intermediate layer B, the second electron transport layer B is located between the second light-emitting layer B and the second electrode B; the second electron transport layer A and the second electron transport layer B each contain a third organic compound including a triazine skeleton, the second electron transport layer A and the second electron transport layer B are made of the same material, the intermediate layer A and the intermediate layer B each contain a fourth organic compound having a phenanthroline skeleton, and lithium or a lithium compound; the first light-emitting layer A includes a first luminescent center substance and a first organic compound, the second light-emitting layer A includes a second luminescent center substance and a second organic compound, the first organic compound and the second organic compound are substances capable of exhibiting thermally activated delayed fluorescence, the first light-emitting layer B has a third luminescent center substance, the second light-emitting layer B has a fourth luminescent center substance, a difference between a maximum peak wavelength in an emission spectrum of the first luminescence center substance and a maximum peak wavelength in an emission spectrum of the second luminescence center substance is 30 nm or less; a difference between a maximum peak wavelength in the emission spectrum of the third luminescent center substance and a maximum peak wavelength in the emission spectrum of the fourth luminescent center substance is 30 nm or less; The display device, wherein the first light-emitting layer A and the first light-emitting layer B, and the second light-emitting layer A and the second light-emitting layer B are different light-emitting layers.

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