Light-emitting device and display device

Abstract

Provided is a light-emitting device having good characteristics. In the tandem light-emitting device, the electron transport layer of the light-emitting unit closest to the cathode contains a first organic compound having a triazine skeleton, the intermediate layer contains a second organic compound having a phenanthroline skeleton, and the light-emitting layer of each light-emitting unit contains the same light-emitting central substance and two organic compounds forming an exciplex. One or both of the two organic compounds contain deuterium, and the first light-emitting layer and the second light-emitting layer are different from a light-emitting layer included in at least one of the plurality of light-emitting devices adjacent to the light-emitting device.

Description

Technical Field

[0001] One embodiment of the present invention relates to an organic compound, an organic semiconductor element, a light-emitting device, a photodiode sensor, a display module, a lighting module, a display device, an electronic device, a lighting device, and an electronic device. Note that one embodiment of the present invention is not limited to the above-mentioned technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. One embodiment of the present invention relates to a process, a machine, a product, or a composition of matter. Therefore, more specifically, as an example of the technical field of one embodiment of the present invention disclosed in this specification, a semiconductor device, a display device, a liquid crystal display device, a lighting device, a storage device, a storage device, an imaging device, a driving method of these devices, or a manufacturing method of these devices can be cited. Background Art

[0002] Light-emitting devices (also known as organic EL elements) that utilize electroluminescence (EL) from organic compounds are being actively commercialized. The basic structure of these light-emitting devices consists of an organic compound layer containing a luminescent center material sandwiched between a pair of electrodes. Applying a voltage to the device injects carriers, and the recombination energy of these carriers generates light from the luminescent center material.

[0003] Because light-emitting devices are self-luminous, display devices using them as pixels offer greater visibility than LCDs and require no backlight. Furthermore, displays using these devices can be made thin and lightweight, a significant advantage. Furthermore, they offer exceptionally fast response times.

[0004] Furthermore, because the light-emitting layer of such a light-emitting device can be formed continuously in a flat surface, it can produce surface light. This is a feature that is difficult to achieve with point light sources such as incandescent lamps and LEDs, or linear light sources such as fluorescent lamps. Therefore, these light-emitting devices have high utility as surface light sources for lighting and other applications.

[0005] As described above, display devices and lighting devices using light-emitting devices are applied to various electronic devices. However, research and development of light-emitting devices having even better characteristics are becoming increasingly active.

[0006] In particular, tandem-type light-emitting devices have attracted attention due to their high current efficiency.

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

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2005-317548 [Patent Document 2] Japanese Patent Application Publication No. 2023-161850 Summary of the Invention

[0009] One embodiment of the present invention aims to provide a light-emitting device with excellent characteristics. Another embodiment of the present invention aims to provide a light-emitting device with excellent luminous efficiency. Another embodiment of the present invention aims to provide a light-emitting device with excellent reliability. Another embodiment of the present invention aims to provide a light-emitting device with low driving voltage. Another embodiment of the present invention aims to provide a light-emitting device with excellent reliability and low driving voltage.

[0010] Furthermore, an object of one embodiment of the present invention is to provide a light-emitting device capable of providing a display device with good characteristics. Furthermore, an object of one embodiment of the present invention is to provide a light-emitting device capable of providing a display device with good luminous efficiency. Furthermore, an object of one embodiment of the present invention is to provide a light-emitting device capable of providing a display device with good reliability. Furthermore, an object of one embodiment of the present invention is to provide a light-emitting device capable of providing a display device with a low driving voltage. Furthermore, an object of one embodiment of the present invention is to provide a light-emitting device capable of providing a display device with a low driving voltage and good reliability.

[0011] Another object of one embodiment of the present invention 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 with low power consumption. Another object of one embodiment of the present invention is to provide any one of an electronic device and a lighting device with high reliability. Another object of one embodiment of the present invention is 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 sufficient as long as any one of the above-mentioned objectives is achieved. Note that the inclusion of these objectives does not preclude the existence of other objectives. Note that one embodiment of the present invention does not necessarily achieve all of the above-mentioned objectives. Furthermore, if the description of the specification, drawings, and claims clearly indicates an objective other than the above-mentioned objective, such objective may be derived from the description of the specification, drawings, and claims.

[0013] One embodiment of the present invention is a light-emitting device, which includes a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron transport layer, and a second electron transport 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 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 includes a first light-emitting center substance, a third organic compound, and a fourth organic compound, and the second light-emitting layer includes a second light-emitting center substance, a fifth organic compound, and a sixth organic compound. The present invention relates to a light emitting device comprising a first organic compound, a second organic compound, a third organic compound, a fifth organic compound, a π-electron-deficient heteroaromatic ring, a fourth organic compound, and a sixth organic compound, a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, one or both of the third organic compound and the fourth organic compound or one or both of the fifth organic compound and the sixth organic compound contain deuterium, a difference between a maximum peak wavelength of an emission spectrum of the first luminescent center substance and a maximum peak wavelength of an emission spectrum of the second luminescent center substance is 30 nm or less, and the first light emitting layer and the second light emitting layer emit light of a different hue from a light emitting layer included in at least one light emitting device among the other plurality of light emitting devices adjacent to the light emitting device.

[0014] Another embodiment of the present invention is a light-emitting device, which includes a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron transport layer, and a second electron transport 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 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 includes a first light-emitting center substance, a third organic compound, and a fourth organic compound, and the second light-emitting layer includes a second light-emitting center substance, a fifth organic compound, and a sixth organic compound. The organic compound comprises: the third organic compound and the fifth organic compound having a π-electron-deficient heteroaromatic ring; the fourth organic compound and the sixth organic compound having a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; one or both of the third organic compound and the fourth organic compound and one or both of the fifth organic compound and the sixth organic compound contain deuterium; the difference between the maximum peak wavelength of the emission spectrum of the first luminescent center substance and the maximum peak wavelength of the emission spectrum of the second luminescent center substance is less than 30 nm; and the first luminescent layer and the second luminescent layer emit light of a different hue from a luminescent layer included in at least one of the other multiple light-emitting devices adjacent to the light-emitting device.

[0015] Another embodiment of the present invention is a light-emitting device, which includes a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron transport layer and a second electron transport 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 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 first organic compound having a triazine skeleton, the intermediate layer includes a second organic compound having a phenanthroline skeleton and a mixed layer of lithium or a lithium compound, the first light-emitting layer includes a first light-emitting center substance, a third organic compound and a fourth organic compound, the third organic compound and the fourth organic compound, The second light-emitting layer includes a second light-emitting center substance, a fifth organic compound and a sixth organic compound, the third organic compound and the fifth organic compound have a π-electron-deficient heteroaromatic ring, the fourth organic compound and the sixth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, one or both of the third organic compound and the fourth organic compound or one or both of the fifth organic compound and the sixth organic compound contain deuterium, the difference between the maximum peak wavelength of the emission spectrum of the first light-emitting center substance and the maximum peak wavelength of the emission spectrum of the second light-emitting center substance is less than 30 nm, and the first light-emitting layer and the second light-emitting layer include a light-emitting layer that emits light of a different hue from the light-emitting layer included in at least one of the other multiple light-emitting devices adjacent to the light-emitting device.

[0016] Another embodiment of the present invention is a light-emitting device, which includes a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron transport layer and a second electron transport 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 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 first organic compound having a triazine skeleton, the intermediate layer includes a second organic compound having a phenanthroline skeleton and a mixed layer of lithium or a lithium compound, the first light-emitting layer includes a first light-emitting center substance, a third organic compound and a fourth organic compound, the third organic compound and the fourth organic compound, The second light-emitting layer includes a second light-emitting center substance, a fifth organic compound and a sixth organic compound, the third organic compound and the fifth organic compound have a π-electron-deficient heteroaromatic ring, the fourth organic compound and the sixth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, one or both of the third organic compound and the fourth organic compound and one or both of the fifth organic compound and the sixth organic compound contain deuterium, the difference between the maximum peak wavelength of the emission spectrum of the first light-emitting center substance and the maximum peak wavelength of the emission spectrum of the second light-emitting center substance is less than 30 nm, and the first light-emitting layer and the second light-emitting layer include a light-emitting layer that emits light of a different hue from the light-emitting layer included in at least one of the other multiple light-emitting devices adjacent to the light-emitting device.

[0017] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron transport layer includes a seventh organic compound having a triazine skeleton.

[0018] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first organic compound and the seventh organic compound are the same organic compound.

[0019] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron transport layer includes an eighth organic compound having no triazine skeleton.

[0020] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron transport layer includes an eighth organic compound having at least one of a pyrimidine skeleton, an imidazole skeleton, and an anthracene skeleton.

[0021] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first organic compound and the seventh organic compound are the same organic compound.

[0022] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the intermediate layer contains lithium or a lithium compound.

[0023] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the intermediate layer includes a mixed layer of the second organic compound and lithium or a lithium compound.

[0024] Another embodiment of the present invention is a light-emitting device having the above structure, wherein a difference between the lowest triplet excitation energy level of the third organic compound and the lowest triplet excitation energy level of the fourth organic compound is 0.20 eV or less.

[0025] Another embodiment of the present invention is a light-emitting device having the above structure, wherein a difference between the lowest triplet excitation energy level of the fifth organic compound and the lowest triplet excitation energy level of the sixth organic compound is 0.20 eV or less.

[0026] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the third organic compound and the fourth organic compound are a combination that forms a first exciplex.

[0027] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the fifth organic compound and the sixth organic compound are a combination that forms a second exciplex.

[0028] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the short-wavelength-side emission edge of the first exciplex is located at a shorter wavelength than the long-wavelength-side absorption edge of the first luminescence center substance.

[0029] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the short-wavelength-side emission edge of the second exciplex is located at a shorter wavelength than the long-wavelength-side absorption edge of the second luminescent center substance.

[0030] Another embodiment of the present invention is a light-emitting device having the above-mentioned structure, wherein the light-emitting end on the short-wavelength side of the first exciton complex is located at a wavelength shorter than the absorption end on the long-wavelength side of the first luminescent center substance, and the light-emitting end on the short-wavelength side of the second exciton complex is located at a wavelength shorter than the absorption end on the long-wavelength side of the second luminescent center substance.

[0031] Another embodiment of the present invention is a light-emitting device having the above-mentioned structure, wherein the peak wavelength of the emission spectrum of the first exciton complex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the first luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the first exciton complex and the peak wavelength of the emission spectrum of the first luminescent center substance is less than 30 nm.

[0032] Another embodiment of the present invention is a light-emitting device having the above-mentioned structure, wherein the peak wavelength of the emission spectrum of the second exciton complex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the second luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the second exciton complex and the peak wavelength of the emission spectrum of the second luminescent center substance is less than 30 nm.

[0033] Another embodiment of the present invention is a light-emitting device having the above-mentioned structure, wherein the peak wavelength of the emission spectrum of the first exciplex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the first luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the first exciplex and the peak wavelength of the emission spectrum of the first luminescent center substance is less than 30 nm, and the peak wavelength of the emission spectrum of the second exciplex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the second luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the second exciplex and the peak wavelength of the emission spectrum of the second luminescent center substance is less than 30 nm.

[0034] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first luminescence center substance and the second luminescence center substance are the same substance.

[0035] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the intermediate layer includes a first layer containing a second organic compound.

[0036] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first layer contains lithium or a lithium compound.

[0037] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the intermediate layer further includes a second layer, and the second layer is located between the first layer and the second light-emitting layer.

[0038] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer contains a fifth organic compound having a hole-transporting property.

[0039] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer contains an organic compound having at least one of a halogen group and a cyano group.

[0040] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer contains an organic compound having at least one of a fluorine group and a cyano group.

[0041] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer contains an organic compound having at least one of a halogen group and a cyano group, and the number of the at least one of the halogen group and the cyano group is 4 or more.

[0042] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer contains an organic compound having at least one of a fluorine group and a cyano group, and the number of the at least one of the fluorine group and the cyano group is 4 or more.

[0043] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron transport layer includes a seventh organic compound having a triazine skeleton.

[0044] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first organic compound and the seventh organic compound are the same organic compound.

[0045] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron transport layer includes an eighth organic compound having no triazine skeleton.

[0046] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron transport layer includes an eighth organic compound having at least one of a pyrimidine skeleton, an imidazole skeleton, and an anthracene skeleton.

[0047] Another embodiment of the present invention is a display device including any of the above-mentioned light-emitting devices.

[0048] Another embodiment of the present invention is a display device, which includes a light-emitting device A and a light-emitting device B, wherein the light-emitting device A is adjacent to the light-emitting device B, and the light-emitting device A includes a first electrode A, a second electrode A, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first electron transport layer A, and a second electron transport layer A, wherein 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, and the second electron transport layer A is located between the second light-emitting layer A and the intermediate layer A. A and the second electrode A, the light-emitting device B includes 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, 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 include a first organic compound having a triazine skeleton, and the second The electron transport layer A and the second electron transport layer B are composed of the same material, the intermediate layer A and the intermediate layer B include a second organic compound having a phenanthroline skeleton and lithium or a lithium compound, the first light-emitting layer A includes a first light-emitting center substance, a third organic compound and a fourth organic compound, the second light-emitting layer A includes a second light-emitting center substance, a fifth organic compound and a sixth organic compound, the third organic compound and the fifth organic compound have a π-electron-deficient heteroaromatic ring, the fourth organic compound and the sixth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, one or both of the third organic compound and the fourth organic compound and the fifth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, One or both of the organic compound and the sixth organic compound contain deuterium, the first light-emitting layer B contains a third light-emitting center substance, the second light-emitting layer B contains a fourth light-emitting center substance, the difference between the maximum peak wavelength of the emission spectrum of the first light-emitting center substance and the maximum peak wavelength of the emission spectrum of the second light-emitting center substance is less than 30 nm, the difference between the maximum peak wavelength of the emission spectrum of the third light-emitting center substance and the maximum peak wavelength of the emission spectrum of the fourth light-emitting center substance is less than 30 nm, the first light-emitting layer A and the first light-emitting layer B emit light of different hues from each other, and the second light-emitting layer A and the second light-emitting layer B emit light of different hues from each other.

[0049] Another embodiment of the present invention is a display device, which includes a light-emitting device A and a light-emitting device B, wherein the light-emitting device A is adjacent to the light-emitting device B, and the light-emitting device A includes a first electrode A, a second electrode A, an intermediate layer A, a first light-emitting layer A, a second light-emitting layer A, a first 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, and the second electron transport layer A is located between the first light-emitting layer A and the intermediate layer A. The light-emitting device B includes 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. 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 include a first light-emitting layer having a triazine skeleton an organic compound, 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 second organic compound having a phenanthroline skeleton and lithium or a lithium compound, the first emitting layer A comprises a first luminescent center substance, a third organic compound, and a fourth organic compound, the second emitting layer A comprises a second luminescent center substance, a fifth organic compound, and a sixth organic compound, the third organic compound and the fifth organic compound have a π-electron-deficient heteroaromatic ring, the fourth organic compound and the sixth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, one or both of the third organic compound and the fourth organic compound and one or both of the fifth organic compound and the sixth organic compound contain deuterium, the first luminescent layer B comprises the third luminescent center substance, the second luminescent layer B comprises the fourth luminescent center substance, the difference between the maximum peak wavelength of the emission spectrum of the first luminescent center substance and the maximum peak wavelength of the emission spectrum of the second luminescent center substance is 30 nm or less, the difference between the maximum peak wavelength of the emission spectrum of the third luminescent center substance and the maximum peak wavelength of the emission spectrum of the fourth luminescent center substance is 30 nm or less, the first luminescent layer A and the first luminescent layer B are different from each other, and the second luminescent layer A and the second luminescent layer B are different from each other.

[0050] Another embodiment of the present invention is a display device having the above-mentioned structure, wherein the difference between the lowest triplet excitation energy level of the third organic compound and the lowest triplet excitation energy level of the fourth organic compound is less than 0.20 eV, and the difference between the lowest triplet excitation energy level of the fifth organic compound and the lowest triplet excitation energy level of the sixth organic compound is less than 0.20 eV.

[0051] Another embodiment of the present invention is a display device having the above structure, wherein the third organic compound and the fourth organic compound form a combination of a first exciplex, and the fifth organic compound and the sixth organic compound form a combination of a second exciplex.

[0052] Another embodiment of the present invention is a display device having the above structure, wherein the first electron transport layer includes a seventh organic compound having a triazine skeleton.

[0053] Another embodiment of the present invention is a display device having the above structure, wherein the first organic compound and the seventh organic compound are the same organic compound.

[0054] Another embodiment of the present invention is a display device having the above structure, wherein the first electron transport layer includes an eighth organic compound having no triazine skeleton.

[0055] Another embodiment of the present invention is a display device having the above structure, wherein the first electron transport layer includes an eighth organic compound having at least one of a pyrimidine skeleton, an imidazole skeleton, and an anthracene skeleton.

[0056] Another embodiment of the present invention is a display device having the above structure, wherein the first organic compound and the seventh organic compound are the same organic compound.

[0057] Another embodiment of the present invention is a display device having the above structure, wherein the intermediate layer includes a mixed layer of the second organic compound and lithium or a lithium compound.

[0058] Another embodiment of the present invention is a display device having the above structure, wherein the short-wavelength-side emission edge of the first exciplex is located at a shorter wavelength than the long-wavelength-side absorption edge of the first luminescence center substance.

[0059] Another embodiment of the present invention is a display device having the above structure, wherein the short-wavelength-side emission edge of the second exciplex is located at a shorter wavelength than the long-wavelength-side absorption edge of the second luminescence center substance.

[0060] Another embodiment of the present invention is a display device having the above-mentioned structure, wherein the light-emitting end on the short-wavelength side of the first exciton complex is located at a wavelength shorter than the absorption end on the long-wavelength side of the first luminescent center substance, and the light-emitting end on the short-wavelength side of the second exciton complex is located at a wavelength shorter than the absorption end on the long-wavelength side of the second luminescent center substance.

[0061] Another embodiment of the present invention is a display device having the above-mentioned structure, wherein the peak wavelength of the emission spectrum of the first exciton complex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the first luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the first exciton complex and the peak wavelength of the emission spectrum of the first luminescent center substance is less than 30 nm.

[0062] Another embodiment of the present invention is a display device having the above-mentioned structure, wherein the peak wavelength of the emission spectrum of the second exciton complex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the second luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the second exciton complex and the peak wavelength of the emission spectrum of the second luminescent center substance is less than 30 nm.

[0063] Another embodiment of the present invention is a display device having the above-mentioned structure, wherein the peak wavelength of the emission spectrum of the first exciton complex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the first luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the first exciton complex and the peak wavelength of the emission spectrum of the first luminescent center substance is less than 30 nm, and the peak wavelength of the emission spectrum of the second exciton complex is located on the side of a shorter wavelength than the peak wavelength of the emission spectrum of the second luminescent center substance, and the difference between the peak wavelength of the emission spectrum of the second exciton complex and the peak wavelength of the emission spectrum of the second luminescent center substance is less than 30 nm.

[0064] Furthermore, another embodiment of the present invention is an electronic device including: the above-mentioned light-emitting device; a sensor, an operation button, a speaker, or a microphone.

[0065] Furthermore, another embodiment of the present invention is a lighting device including the above-mentioned light-emitting device and a housing.

[0066] The above is one embodiment of the present invention, and the present invention is not limited to the above configuration.

[0067] According to one embodiment of the present invention, a light-emitting device with excellent characteristics can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device with excellent luminous efficiency can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device with excellent reliability can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device with low driving voltage can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device with excellent reliability and low driving voltage can be provided.

[0068] Furthermore, according to one embodiment of the present invention, a light-emitting device capable of providing a display device with excellent characteristics can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device capable of providing a display device with excellent luminous efficiency can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device capable of providing a display device with excellent reliability can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device capable of providing a display device with a low driving voltage can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device capable of providing a display device with a low driving voltage and excellent reliability can be provided.

[0069] Furthermore, one embodiment of the present invention can provide any 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. Furthermore, one embodiment of the present invention can provide any of an electronic device and a lighting device with high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figures 1A to 1C is a schematic diagram of a light-emitting device according to one embodiment of the present invention; Figure 2A and Figure 2B is a schematic diagram of a light-emitting device according to one embodiment of the present invention; Figure 3A and Figure 3B is a diagram showing a display device according to one embodiment of the present invention; Figure 4A and Figure 4B is a diagram showing a display device according to one embodiment of the present invention; Figures 5A to 5E is a cross-sectional view illustrating an example of a method for manufacturing a display device; Figure 6A and Figure 6B is a cross-sectional view illustrating an example of a method for manufacturing a display device; 7A to 7D is a cross-sectional view illustrating an example of a method for manufacturing a display device; Figures 8A to 8C is a cross-sectional view illustrating an example of a method for manufacturing a display device; Figures 9A to 9C is a cross-sectional view illustrating an example of a method for manufacturing a display device; 10A to 10C is a cross-sectional view illustrating an example of a method for manufacturing a display device; Figure 11A and Figure 11B is a perspective view showing a structural example of a display module; Figure 12A and Figure 12Bis a cross-sectional view showing a structural example of a display device; Figure 13 is a perspective view showing a structural example of a display device; Figure 14 is a cross-sectional view showing a structural example of a display device; Figure 15 is a cross-sectional view showing a structural example of a display device; 16A to 16C is a diagram showing a structural example of a display device; Figure 17 is a cross-sectional view showing a structural example of a display device; 18A to 18C is a diagram showing a structural example of a display device; 19A to 19D is a diagram illustrating an example of a wearable device; 20A to 20F is a diagram showing an example of an electronic device; Figures 21A to 21G is a diagram showing an example of an electronic device; Figure 22 This is a diagram illustrating a method for calculating the luminescence lifetime; Figure 23 is a graph showing the luminance-current density characteristics of the light emitting device R1 and the comparative light emitting device R1; Figure 24 is a graph showing current efficiency-luminance characteristics of the light emitting device R1 and the comparative light emitting device R1; Figure 25 is a graph showing current density-voltage characteristics of the light emitting device R1 and the comparative light emitting device R1; Figure 26 1 is a graph showing power efficiency-luminance characteristics of the light emitting device R1 and the comparative light emitting device R1; Figure 27 is a graph showing electroemission spectra of the light emitting device R1 and the comparative light emitting device R1; Figure 28 is a graph showing luminance-current density characteristics of the light-emitting devices G1 to G3 and the comparative light-emitting device G1; Figure 29 is a graph showing current efficiency-luminance characteristics of the light emitting devices G1 to G3 and the comparative light emitting device G1; Figure 30 is a graph showing current density-voltage characteristics of the light emitting devices G1 to G3 and the comparative light emitting device G1; Figure 31 is a graph showing power efficiency-luminance characteristics of the light emitting devices G1 to G3 and the comparative light emitting device G1; Figure 32is a graph showing electroemission spectra of the light-emitting devices G1 to G3 and the comparative light-emitting device G1; Figure 33 is a graph showing luminance-current density characteristics of the light-emitting device B1 and the comparative light-emitting device B1; Figure 34 is a graph showing current efficiency-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1; Figure 35 is a graph showing current density-voltage characteristics of the light emitting device B1 and the comparative light emitting device B1; Figure 36 Graphs showing power efficiency-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1; Figure 37 is a graph showing blue index-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1; Figure 38 is a graph showing electroemission spectra of the light-emitting device B1 and the comparative light-emitting device B1; Figure 39 is shown as 8mpTP-4mDBtPBfpm-d 13 βNCCP-d 26 and 8mpTP-4mDBtPBfpm-d 13 and βNCCP-d 26 Figure 3 shows the PL spectrum of the exciplex; Figure 40 Graphs showing the PL spectra of the exciplex of 8mpTP-4mDBtPBfpm and βNCCP, and the absorption and PL spectra of Ir(5mppy-d3)2(mbfpypy-d3); Figure 41 1 is a diagram showing an example of calculating the light emitting end and the absorption end; Figure 42 is a graph showing time-varying characteristics of normalized luminance of the light-emitting devices G1 to G3 and the comparative light-emitting device G1; Figure 43 The measurement is shown as 8mpTP-4mDBtPBfpm-d 13 Diagram of the T1 energy level method; Figure 44 1 is a diagram showing a method for measuring the T1 level of 8mpTP-4mDBtPBfpm; Figure 45 is shown to measure βNCCP-d 26 Diagram of the T1 energy level method; Figure 46 is a diagram showing a method for measuring the T1 level of βNCCP; Figure 47is a graph showing brightness-current density characteristics of the light-emitting device R4, the light-emitting device G4, and the light-emitting device B4; Figure 48 is a graph showing current efficiency-luminance characteristics of the light-emitting device R4, the light-emitting device G4, and the light-emitting device B4; Figure 49 is a graph showing current density-voltage characteristics of the light emitting device R4, the light emitting device G4, and the light emitting device B4; Figure 50 1 is a graph showing power efficiency-luminance characteristics of the light emitting device R4, the light emitting device G4, and the light emitting device B4; Figure 51 is a graph showing blue index-current density characteristics of the light-emitting device B4; Figure 52 is a diagram showing electroemission spectra of light-emitting device R4, light-emitting device G4, and light-emitting device B4; Figure 53 is shown 8mpTP-4mDBtPBfpm and βNCCP-d 26 PL spectrum of the exciplex and the absorption spectrum and PL spectrum of Pt(tBudppymmtBubiz-tBubp); Figure 54 1 is a diagram showing an example of calculating the absorption end of Pt(tBudppymmtBubiz-tBubp); Figure 55 is a graph showing 11mDBtBPPnfpr, βNCCP-d 26 and 11mDBtBPPnfpr and βNCCP-d 26 Figure 3 shows the PL spectrum of the exciplex; Figure 56 is shown in Figure 11mDBtBPPnfpr and βNCCP-d 26 PL spectrum of the exciplex and the absorption spectrum and PL spectrum of OCPG-006; Figure 57 This is a diagram showing an example of calculating the absorption edge of OCPG-006. DETAILED DESCRIPTION

[0071] The following describes embodiments of the present invention in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following description, and those skilled in the art will readily appreciate that its embodiments and details can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited solely to the embodiments described below.

[0072] Note that in this specification and other documents, devices manufactured using a metal mask or FMM (Fine Metal Mask) are sometimes referred to as devices with an MM (Metal Mask) structure. Furthermore, in this specification and other documents, devices manufactured without using a metal mask or FMM are sometimes referred to as devices with an MML (Metal Mask Less) structure.

[0073] In this specification, "containing deuterium" refers to a state in which the ratio of deuterium to hydrogen in an organic compound significantly exceeds the naturally occurring ratio of deuterium, specifically, is 500 times or more of the naturally occurring ratio. A "deuterated organic compound" refers to an organic compound in which the ratio of deuterium to hydrogen in an organic compound significantly exceeds the naturally occurring ratio of deuterium, specifically, is 500 times or more of the naturally occurring ratio. The above ratios are not ratios for a single molecule, but rather averages for multiple organic compounds present in a given region.

[0074] Implementation Method 1 Tandem light-emitting devices have a structure in which multiple light-emitting units are stacked between a pair of electrodes, with an intermediate layer (charge generation layer) sandwiched between them. Each of these light-emitting units includes a light-emitting layer, and light can be emitted from any of these layers by passing current through it. Tandem light-emitting devices with this structure offer significantly higher current efficiency than non-tandem devices, making them suitable for display devices requiring high brightness or reliability.

[0075] Tandem light-emitting devices, due to their multiple light-emitting layers, easily produce white light. Therefore, a white filter method is often used as a full-color method for display devices using tandem light-emitting devices. Furthermore, a color conversion method, which stacks blue light-emitting layers and uses a color conversion layer, typically quantum dots, has also been put into practical use.

[0076] Meanwhile, some display devices using tandem-type light-emitting devices, employing a separate coating method for full-colorization, have also been put into practical use. Separate coating light-emitting devices exhibit minimal or no energy loss in the color filters or color conversion layers, resulting in higher luminous efficiency than the two aforementioned methods.

[0077] In one embodiment of the present invention, a tandem light-emitting device includes at least one light-emitting layer comprising a luminescent center substance, a first host material, and a second host material. The luminescent center substance is preferably a phosphorescent substance. In current-excited light-emitting devices, using a substance capable of converting triplet energy into luminescence (phosphorescent substances, substances exhibiting thermally activated delayed fluorescence) as the luminescent substance (guest material) can provide a light-emitting device with high luminescence efficiency.

[0078] Furthermore, a structure is known in which two different organic compounds (specifically, an organic compound having an electron-transporting property and an organic compound having a hole-transporting property) are used as host materials of the light-emitting layer together with a light-emitting substance (guest material).

[0079] Among them, the structure in which an exciplex formed by two different organic compounds is used as an energy donor in the light-emitting layer and a substance capable of converting triplet energy into luminescence (phosphorescent substance, substance exhibiting thermally activated delayed fluorescence) is used as an energy acceptor, namely the so-called ExTET (Exciplex-Triplet Energy Transfer), which is an excellent technology that can simultaneously achieve high efficiency, low driving voltage and long life.

[0080] That is, a light-emitting device containing an exciplex serving as an energy donor and a substance serving as an energy acceptor, ie, a light-emitting substance capable of converting triplet energy into light emission, in a light-emitting layer can have very good characteristics.

[0081] Here, when one or both of the two substances (the first host material and the second host material) used as host materials contain deuterium, a light-emitting device with higher reliability can be obtained.

[0082] In particular, as described later, when the difference between the lowest triplet excitation energy level (T1 level) of the first host material and the T1 level of the second host material is small, that is, when the T1 level of the first host material and the T1 level of the second host material are close, triplet excitation energy is less likely to be concentrated in either organic compound, and energy transfer from the triplet excited state of each compound to a substance capable of converting triplet energy into luminescence may occur. The influence of deuterium improves the efficiency of this energy transfer from each compound, thereby suppressing degradation of the first host material and the second host material, one or both of which contain deuterium.

[0083] This is particularly effective when the two substances form an exciplex. With respect to the singlet excitation energy of the exciplex, its energy is transferred from the exciplex to the luminescent substance. However, with respect to the triplet excitation energy of the exciplex, its energy is not only directly transferred to the luminescent substance, but may also be indirectly transferred through the triplet excited state of the first host material or the second host material. In particular, as described later, when the difference between the lowest triplet excitation energy level (T1 energy level) of the first host material and the T1 energy level of the second host material is small, that is, when the T1 energy level of the first host material is close to the T1 energy level of the second host material, it is possible to transfer energy from the triplet excited state of each compound to a substance capable of converting triplet energy into luminescent energy. This is because the excitation energy is not easily concentrated in any one organic compound. When the energy transfer efficiency from the triplet excited state of each compound is improved by the influence of deuterium, the degradation of the first host material and the second host material can be suppressed. Specifically, the difference between the T1 energy level of the first host material and the T1 energy level of the second host material is preferably 0.20eV or less.

[0084] As a result, compared to a light-emitting device that uses only an exciplex formed from a non-deuterated organic compound as an energy donor, degradation occurring in a light-emitting device that uses an exciplex formed from a deuterated organic compound as an energy donor is suppressed, thereby achieving a light-emitting device with high reliability.

[0085] Alternatively, in one or both of the first host material and the second host material, the entire molecule may be deuterated. However, it is sufficient to deuterate at least the groups or backbones in which the lowest triplet excitation energy level is concentrated, and hydrogen contained in the other groups or backbones is preferably protium. This allows the first host material or the second host material to be obtained by a method that is less expensive than deuterating the entire molecule.

[0086] In addition, the first host material is preferably an organic compound with electron-transporting properties and having a π-electron-deficient heteroaromatic ring. In addition, the second host material is preferably an organic compound with hole-transporting properties and having a π-electron-rich heteroaromatic ring or an aromatic amine skeleton.

[0087] When one or both of the first host material and the second host material in the light-emitting device of one embodiment of the present invention contain deuterium, energy transfer efficiency is improved because the phosphorescence lifetime or delayed fluorescence lifetime of the deuterated organic compound is longer than that of the non-deuterated organic compound. This is because intramolecular vibrations in the lowest triplet excited state (T1 state) of the deuterated organic compound are suppressed compared to intramolecular vibrations in the non-deuterated organic compound, thereby suppressing non-radiative transition from the T1 state to a more stable state.

[0088] Energy transfer efficiency from the energy donor (exciplex in one embodiment of the present invention) to the energy acceptor (substance capable of converting triplet excitation energy into luminescence in one embodiment of the present invention) It is expressed as the following formula (1). According to this formula, in order to improve the energy transfer efficiency Increase the rate constant k of energy transfer h*→g To make the other competing rate constant k r +k nr (=1 / τ) becomes relatively small.

[0089] Note that in equation (1), k r k represents the rate constant of the luminescence process of the energy donor (equivalent to the luminescence process of fluorescence when describing energy transfer from a singlet excited state, and equivalent to the luminescence process of phosphorescence or delayed fluorescence when describing energy transfer from a triplet excited state). nr represents the rate constant of the non-luminescent process (thermal deactivation and intersystem crossing) of the energy donor, and τ represents the lifetime of the excited state of the measured energy donor. h*→g It represents the rate constant of energy transfer (Foster mechanism or Dexter mechanism).

[0090] [Formula 1]

[0091] The atomic configuration and spectral shape of the molecules in the deuterated organic compound and the non-deuterated organic compound are almost unchanged, so the rate constant k of energy transfer is h*→g are roughly the same (see the following formula (2) or formula (3)). Therefore, it can be seen that when comparing deuterated organic compounds and non-deuterated organic compounds, the energy transfer rate constant k h*→g The energy transfer efficiency is greatly affected by the luminescence lifetime (phosphorescence lifetime or delayed fluorescence lifetime) τ. In other words, as the luminescence lifetime (phosphorescence lifetime or delayed fluorescence lifetime) becomes longer, the energy transfer efficiency is improved.

[0092] [Formula 2]

[0093] [Formula 3]

[0094] Formula (2) is the rate constant k of the Förster mechanism h*→g Formula (3) is the rate constant k of the Dexter mechanism h*→g The formula is .

[0095] In formula (2), ν represents the oscillation number, f′ h(ν) represents the normalized emission spectrum of the host material (equivalent to the fluorescence spectrum when accounting for energy transfer from a singlet excited state and equivalent to the phosphorescence spectrum when accounting for energy transfer from a triplet excited state), ε g (ν) represents the molar absorption coefficient of the guest material, N represents the Avogadro number, n represents the refractive index of the medium, R represents the molecular distance between the host material and the guest material, τ represents the measured excited state lifetime (fluorescence lifetime, phosphorescence lifetime), represents the luminescence quantum yield (equivalent to the fluorescence quantum yield when accounting for energy transfer from a singlet excited state and equivalent to the phosphorescence quantum yield when accounting for energy transfer from a triplet excited state), K 2 is a coefficient (0 to 4) representing the orientation of the transition dipole moment of the host material and the guest material. Note that in random orientation, K 2 =2 / 3.

[0096] In formula (3), h represents Planck's constant, K represents a constant with energy dimension, ν represents the oscillation number, and f′ h (ν) represents the normalized emission spectrum of the host material (equivalent to the fluorescence spectrum when describing energy transfer from a singlet excited state, and equivalent to the phosphorescence spectrum when describing energy transfer from a triplet excited state) ε′ g (ν) represents the normalized absorption spectrum of the guest material, L represents the effective molecular radius, and R represents the molecular distance between the host material and the guest material.

[0097] As described above, in energy transfer from the first host material and the second host material, the energy transfer efficiency from their respective triplet excited states is crucial, and therefore the lifetime of the triplet excited state is crucial. Specifically, when one or both of the first host material and the second host material are deuterated, the phosphorescence lifetime or delayed fluorescence lifetime is prolonged, improving the energy transfer efficiency and thereby suppressing degradation of the deuterated organic compound. Consequently, compared to light-emitting devices that do not utilize energy donors containing deuterated organic compounds, light-emitting devices that utilize energy donors containing deuterated organic compounds can suppress degradation of the organic compound, thereby achieving highly reliable light-emitting devices.

[0098] Time-resolved measurements are performed by measuring the decaying luminescence intensity after the excitation light is blocked by a shutter at regular intervals. This allows the transient PL to be measured and the phosphorescence lifetime and delayed fluorescence lifetime to be calculated. Sometimes, fluorescence components are mixed in during the initial decay phase, causing the graph to not appear straight. In such cases, a starting point is set at the straight line portion of the graph, and the time required for the intensity at the starting point to decay to 1 / e is recorded as the phosphorescence lifetime or delayed fluorescence lifetime.

[0099] Note that in the light-emitting device of one embodiment of the present invention, an exciplex formed from a first host material and a second host material is preferably used as an energy donor. However, as described above, in the triplet excited state, there may be a path for energy transfer from the triplet excited state of the exciplex through the triplet excited states of the first host material and the second host material. Therefore, the phosphorescence lifetime or delayed fluorescence lifetime of the first host material and the second host material constituting the exciplex is important. It is understood that in the light-emitting device of one embodiment of the present invention, when the phosphorescence lifetime or delayed fluorescence lifetime is extended by a certain value or more due to the inclusion of deuterium in one or both of the first host material and the second host material, the reliability of the light-emitting device using the exciplex as an energy donor is significantly improved.

[0100] That is, the first host material is preferably an organic compound whose phosphorescence lifetime or delayed fluorescence lifetime is 1.50 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of the first host material. In addition, the second host material is preferably an organic compound whose phosphorescence lifetime or delayed fluorescence lifetime is 3.00 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of the second host material. In this case, it is preferred that the light emitted by the substance capable of converting triplet excitation energy into luminescence (the luminescent substance in the luminescent layer) is preferably luminescence in the green region, in other words, its peak wavelength is typically 500 nm or more and 600 nm or less.

[0101] exist Figure 22 The measurement data ( Figure 22 In the left figure, the starting point is set within the range where the graph shows a straight line, at which time t = 0 (here, the time when the light intensity reaches 50% of the time at the start of measurement is set as t = 0) ( Figure 22 Right). The time it takes for the light intensity to decay to 1 / e of the time at t=0 is considered as the phosphorescence lifetime or delayed fluorescence lifetime. Figure 22 In the graph, the time it takes for the measured data to reach 50% of the intensity at the start of measurement is defined as time 0s. When the light intensity at 0s is considered 1, the time it takes for the light intensity to reach 1 / e is considered the phosphorescence lifetime or delayed fluorescence lifetime. Note that for ease of understanding, an intensity of 50% of the intensity at the start of measurement is preferably used as the starting point, but other values ​​may also be used.

[0102] The phosphorescence lifetime can be measured, for example, by installing a liquid nitrogen cooling device in a fluorescence spectrophotometer such as FP-8600 manufactured by JASCO Corporation and performing the measurement at liquid nitrogen temperature (77K). The material is prepared in a glove box by dissolving the sample in deoxygenated 2-MeTHF and stirring it with a stirrer at room temperature for about 30 minutes (if a material that is not easily soluble is used, heating is also performed) to adjust the concentration to 1.2E -4 A solution of about M is enough.

[0103] By irradiating the sample unit with excitation light for about 30 seconds, measuring the luminous intensity of the excitation light attenuated after being blocked by the light gate at intervals of 10ms, time-resolved measurement can be performed. The wavelength when measuring the phosphorescence lifetime is preferably the peak wavelength of the phosphorescence spectrum. In the case where the phosphorescence spectrum has multiple peaks, it is preferred to select a wavelength with a high peak intensity. Depending on the wavelength, it is sometimes impossible to accurately measure due to the presence of a fluorescence spectrum. In this case, it is preferred to select a phosphorescence wavelength that does not overlap with fluorescence as much as possible by comparing the emission spectrum (including the emission spectrum of phosphorescence) measured at low temperature (for example, 77K) with the emission spectrum (excluding phosphorescence and only including the emission spectrum of fluorescence) measured at room temperature. Alternatively, the peak wavelength of the longest wavelength in the peak of the phosphorescence spectrum can be selected. When using a frozen solution, luminescence from outside the lowest triplet excited state can sometimes also be observed. In this case, the peak wavelength of the longest wavelength can be selected.

[0104] In addition, the excitation wavelength can be appropriately selected within a wavelength range that is not affected by the solvent. As long as the material can be fully excited, it is preferably measured at 330nm because this is not affected by the solvent. In addition, the bandwidth of the excitation light and the measurement light can be around 10nm. Since it is ideal that the luminescence decays as a monoexponential function, a starting point can be set as the straight line portion of the graph, and the time it takes for the intensity at this starting point to decay to 1 / e is defined as the phosphorescence lifetime or delayed fluorescence lifetime.

[0105] Note that the fluorescence lifetime, phosphorescence lifetime, and delayed fluorescence lifetime can be distinguished based on the lifetime length during time-resolved measurement. A luminescence lifetime of approximately n seconds is the fluorescence lifetime, while a luminescence lifetime of μ seconds to m seconds or longer is the phosphorescence lifetime and delayed fluorescence lifetime.

[0106] The reliability of the light-emitting device of one embodiment of the present invention is improved by extending the phosphorescence lifetime of the first host material and the second host material, that is, the lifetime of the triplet exciton. The lifetime of the triplet exciton is extended because the oscillation caused by deuteration is suppressed, which suppresses the non-radiative deactivation of the triplet excitation energy. At this time, since the difference between the T1 energy level of the first host material and the T1 energy level of the second host material is small, the excitation energy is not easily concentrated in any one organic compound, and any organic compound can be prevented from significantly deteriorating. Therefore, the reliability of the light-emitting device is improved, which is preferred. Specifically, the difference between the T1 energy level of the first host material and the T1 energy level of the second host material is preferably 0.20 eV or less, preferably 0.15 eV or less, and more preferably 0.10 eV or less.

[0107] Note that the lowest triplet excitation energy level (T1 level) can be calculated by measuring the emission spectrum (phosphorescence spectrum) at a measurement temperature of 10K using a 50nm thin film of the sample deposited on a quartz substrate. Preferably, a microscopic PL device LabRAM HR-PL (Horiba Ltd.) is used for the measurement, and a He-Cd laser (325nm) is used as the excitation light. Note that the light-emitting end can be calculated by drawing a tangent line at the point where the absolute value of the slope on the short wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is the largest, and from the intersection of the tangent line and the horizontal axis (wavelength) or the baseline.

[0108] In one embodiment of the present invention, the sublimation temperature of the first host material is preferably close to that of the second host material. For example, the difference between the 5% weight loss temperature of the first host material and the 5% weight loss temperature of the second host material, as measured by thermogravimetric measurement, is preferably 60°C or less. Furthermore, it is more preferably 45°C or less, even more preferably 20°C or less, and even more preferably 10°C or less. Thus, since a mixture of the first and second host materials can be used for vapor deposition, the number of vapor deposition sources can be reduced, thereby providing a light-emitting device with excellent characteristics using an inexpensive method.

[0109] The 5% weight loss temperature can be calculated from the relationship between weight and temperature by thermogravimetry-differential thermal analysis (TG-DTA). Note that if the pressure during vapor deposition is predetermined, it is preferable to use the value measured at that pressure.

[0110] Note that a light-emitting device with better characteristics can be realized by combining the extension rate of the phosphorescence lifetime or delayed fluorescence lifetime of the first host material and the second host material by deuteration, their product, the difference in T1 energy level, and the difference in sublimation temperature.

[0111] In addition, the photoluminescence (PL) spectrum of the exciplex formed by the first host material and the second host material preferably overlaps with the PL spectrum of the luminescent substance (a substance that can convert triplet energy into luminescence). This is because the driving voltage of the light-emitting device can be reduced when the excitation energy of the energy donor is close to the excitation energy of the luminescent substance. Therefore, the difference between the maximum peak wavelengths is preferably 30 nm or less. Alternatively, when the light-emitting device has a structure in which the wavelength difference between the light-emitting end on the short wavelength side of the PL spectrum of the exciplex and the light-emitting end on the short wavelength side of the PL spectrum of the luminescent substance is 30 nm or less, the driving voltage can be reduced, which is preferred.

[0112] When measuring the PL spectrum of an exciplex, it is preferred to use a co-evaporated film of the first and second host materials. When measuring the PL spectrum of a luminescent substance (a substance capable of converting triplet energy into luminescence), the sample can be either a thin film or a solution, but from the perspective of verifying the state of isolated molecules, a solution is preferred. When using the same solvent for comparison, the solvent of the solution is not particularly limited, but a less polar solvent such as toluene or chloroform is preferred.

[0113] In addition, when the light emitted by the substance capable of converting triplet excitation energy into luminescence (the luminescent substance in the luminescent layer) is luminescence in the blue region, that is, when its peak wavelength is typically 450 nm or more and less than 500 nm, it is preferred to use an organic compound having at least one of a triazine skeleton and a diazine skeleton as the first host material, and to use an organic compound having a carbazole skeleton as the second host material. Specifically, as the first host material, 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole-1,2,3,4,5,6,7,8,1',2',3',4',5',6',7',8'-d 16 )(Abbreviation: SiTrzCz2-d 16 ), as the second host material, 9-[3-(triphenylsilyl)phenyl]-3,9'-(bi-9H-carbazole-d 15 )(Abbreviation: PSiCzCz-d 15 )、9'-(phenyl-d5)-9'H-9,3':6',9"-tricarbazole-1,1',1",2,2',2",3,3",4,4',4",5,5',5",6,6",7,7',7",8,8',8"-d 22 (Abbreviation: PhCzGI-d 27 ), 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9"-tricarbazole-1,1',1",2,2',2",3,3",4,4',4",5,5',5",6,6",7,7',7",8,8',8"-d 22 (Abbreviation: PSiCzGI-d 22 )wait.

[0114] In addition, when the light emitted by the substance capable of converting triplet excitation energy into luminescence (the luminescent substance in the luminescent layer) is luminescence in the green region, that is, when its peak wavelength is typically greater than 500 nm and less than 600 nm, it is preferred to use an organic compound having at least one of a diazine skeleton and a triazine skeleton as the first host material, and to use an organic compound having a carbazole skeleton as the second host material. Specifically, as the first host material, 8-(1,1':4',1"-terphenyl-3-yl-2,4,5,6,2',3',5',6',2",3",4",5",6"-d 13 )-4-[3-(dibenzothiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as: 8mpTP-4mDBtPBfpm-d 23 )、8-(1,1':4',1"-terphenyl-3-yl-2,4,5,6,2',3',5',6',2",3",4",5",6"-d 13 )-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as: 8mpTP-4mDBtPBfpm-d 13 )、11-[4-(biphenyl-4-yl-2,2′,3,3′,4′,5,5′,6,6′-d9)-6-(phenyl-2,3,4,5,6-d5)-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole-1,2,3,4,5,6,7,8,9,10-d 10 As the second host material, 9-(2-naphthyl-1,3,4,5,6,7,8-d7)-9'-(phenyl-2,3,4,5,6-d5)-3,3'-bi-9H-carbazole-1,1',2,2',4,4',5,5',6,6',7,7',8,8'-d14 (abbreviated as βNCCP-d 26 ), 9-phenyl-9'-(phenyl-2,3,4,5,6-d5)-3,3'-bis(9H-carbazole) (abbreviated as: PCCP-d5), etc.

[0115] The light-emitting device of one embodiment of the present invention is a tandem light-emitting device and therefore includes multiple light-emitting layers. The above-described light-emitting layer structure may be applied to only some of the light-emitting layers, but it is more preferable that all the light-emitting layers have this structure.

[0116] For example, in a tandem light-emitting device comprising two light-emitting layers, a first light-emitting layer and a second light-emitting layer, it is preferred that the first light-emitting layer comprises a first luminescent center substance, a third organic compound, and a fourth organic compound, and the second light-emitting layer comprises a fifth organic compound and a sixth organic compound, one or both of the third and fourth organic compounds are deuterated, and one or both of the fifth and sixth organic compounds are deuterated. Preferably, the third and fifth organic compounds serve as the first host material, the fourth and sixth organic compounds serve as the second host material, and the first and second light-emitting layers have the aforementioned light-emitting layer structure.

[0117] Specifically, it is preferred that the third organic compound and the fifth organic compound are organic compounds having electron transport properties and have a π-electron-deficient heteroaromatic ring. In addition, it is preferred that the fourth organic compound and the sixth organic compound are organic compounds having hole transport properties and have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton. In addition, the combination of the third organic compound and the fourth organic compound and the combination of the fifth organic compound and the sixth organic compound are both combinations that form an exciplex. In addition, the difference between the T1 energy level of the third organic compound and the T1 energy level of the fourth organic compound and the difference between the T1 energy level of the fifth organic compound and the T1 energy level of the sixth organic compound are preferably 0.20 eV or less, preferably 0.15 eV or less, and more preferably 0.10 eV or less. By replacing the first host material with the third organic compound or the fifth organic compound and replacing the second host material with the fourth organic compound or the sixth organic compound, the above-mentioned other structures can also be applied to each light-emitting layer.

[0118] For example, by comparing the emission spectra of an organic compound with hole transport properties, the emission spectra of an organic compound with electron transport properties, and the emission spectra of a mixed film formed by mixing the above organic compounds, the formation of an exciplex can be confirmed by observing that the emission spectrum of the mixed film shifts toward the longer wavelength side compared to the emission spectra of each organic compound (or has a new peak on the longer wavelength side). Alternatively, by comparing the transient photoluminescence (PL) of an organic compound with hole transport properties, the transient PL of an organic compound with electron transport properties, and the transient PL of a mixed film formed by mixing the above organic compounds, the formation of an exciplex can be confirmed by observing differences in transient responses, such as the transient PL lifetime of the mixed film having a longer lifetime component than the transient PL lifetime of each organic compound, or the proportion of the delayed component in the transient PL lifetime of the mixed film being increased. In addition, the above transient PL can be referred to as transient electroluminescence (EL). That is, by comparing the transient EL of an organic compound having hole transport properties, the transient EL of an organic compound having electron transport properties, and the transient EL of a mixed film of these organic compounds and observing the difference in transient response, the formation of an exciplex can also be confirmed.

[0119] In this case, the short-wavelength emission edge of the PL spectrum of the exciplex formed by the first host material and the second host material is preferably located at a wavelength shorter than the long-wavelength absorption edge of the absorption spectrum of the luminescent center substance. When the PL spectrum of the exciplex and the absorption edge of the luminescent center substance have this positional relationship, efficient energy transfer is possible.

[0120] The peak wavelength of the PL spectrum of the exciplex formed by the first host material and the second host material is preferably shorter than the peak wavelength of the PL spectrum of the luminescent center substance. Furthermore, the difference between the peak wavelengths of the PL spectrum of the exciplex and the peak wavelengths of the PL spectrum of the luminescent center substance is preferably 30 nm or less. When the peak wavelengths of the PL spectrum of the exciplex and the peak wavelengths of the PL spectrum of the luminescent center substance have this relationship, efficient energy transfer can be achieved.

[0121] Furthermore, the difference between the peak wavelength of the PL spectrum of the exciplex formed by the first host material and the second host material and the wavelength of the long-wavelength absorption edge of the absorption spectrum of the luminescent center substance is preferably 30 nm or less. When the peak wavelength of the PL spectrum of the exciplex and the wavelength of the long-wavelength absorption edge of the absorption spectrum of the luminescent center substance have this relationship, efficient energy transfer can be achieved.

[0122] When measuring the PL spectrum of an exciplex, it is preferable to use a co-evaporated film of the first and second host materials. Meanwhile, when measuring the PL spectrum or absorption spectrum of the luminescent center substance, the sample can be in the form of a thin film or a solution. However, from the perspective of verifying the state of isolated molecules, a solution is preferred. A relatively low-polarity solvent such as toluene or chloroform is preferably used as the solvent for this solution.

[0123] The absorption edge of the absorption spectrum can be calculated by drawing a tangent line at the point where the absolute value of the slope of the long-wavelength side of the peak (or shoulder) observed at the longest wavelength of the absorption spectrum is maximized, and then calculating the intersection of this tangent line with the horizontal axis or baseline. The emission edge of the PL spectrum can be calculated by drawing a tangent line at the point where the absolute value of the slope of the short-wavelength side of the peak (or shoulder) observed at the shortest wavelength of the PL spectrum is maximized, and then calculating the intersection of this tangent line with the horizontal axis or baseline.

[0124] As described above, in one embodiment of the present invention, it is preferred that the first host material is an organic compound having an electron-transporting property, and the second host material is an organic compound having a hole-transporting property.

[0125] As the organic compound having electron-transporting properties used as the first host material, it is preferable to use an organic compound having an electron mobility of 1×10 -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 / Vs or above organic compounds.

[0126] In addition, as an organic compound having electron-transporting properties, an organic compound containing a π-electron-deficient heteroaromatic ring is preferably used. Examples of organic compounds containing a π-electron-deficient heteroaromatic ring include organic compounds containing a heteroaromatic ring having an azole skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, organic compounds containing a heteroaromatic ring having a diazine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton.

[0127] Among them, organic compounds containing heteroaromatic rings having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing heteroaromatic rings having a pyridine skeleton, or organic compounds containing heteroaromatic rings having a triazine skeleton have good reliability and are therefore preferred. In particular, organic compounds containing heteroaromatic rings having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings having a triazine skeleton have high electron transport properties and contribute to lowering the driving voltage. In addition, benzofuranopyrimidine skeletons, benzothienopyrimidine skeletons, benzofuranopyrazine skeletons, and benzothienopyrazine skeletons have high acceptor properties and high reliability, so they are preferred.

[0128] As an organic compound having a π-electron-deficient heteroaromatic ring that can be used as an organic compound having electron-transporting properties, for example, an organic compound described below is preferably used. Examples of such organic compounds include 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviated as OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviated as CO11), 2,2',2"-(1,3,5-phenyltriyl)tris(1-phenyl-1H-benzimidazole) (abbreviated as TPBI), 2-[ Organic compounds having an azole skeleton, such as 3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviated as mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviated as BzOS); 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviated as 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviated as TmPyPB), bathophenanthroline (abbreviated as BPhen), bathocuproin (abbreviated as BCP), 2,9-di(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), 2, Organic compounds containing a heteroaromatic ring having a pyridine skeleton, such as 2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviated as: mPPhen2P), 2-[3-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as: mTpPPhen), 2-phenyl-9-(2-triphenylene)-1,10-phenanthroline (abbreviated as: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthyl]-1,10-phenanthroline (abbreviated as: PnNPhen), and 2-[4-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as: pTpPPhen); 2-[3-(dibenzothiophene-4-yl)phenyl]-1,10-phenanthroline; )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-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated as 9mDBtBPNfpr), 9-[3'-(dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated as 9pmDBtB PNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviated as: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviated as: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviated as: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviated as: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as: 8BP-4mDBtPBf pm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofurano[2,3-b]pyrazine (abbreviated as: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofurano[3,2-d]pyrimidine (abbreviated as: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furano[3,2-d]pyrimidine (abbreviated as: 8mDBtBPNfpm), 8-[(2,2'-binaphthyl)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofurano[3,2-d]pyrimidine (abbreviated as: : 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-naphthyl-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), 8-(p-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6'(P-Bqn)2 BPy) and other organic compounds having a diazine skeleton; 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluorene]-2-yl)-1,3,5-triazine (abbreviated as BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazole-3- [3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviated as mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviated as mINc (II) PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazine-2-yl]-11,12-dihydro-12-phenylindole[2,3-a]carbazole (abbreviated as BP-Icz(II)Tzn), 2-[3'-(triphenylene-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviated as PCDBfTzn), 2-[4-(2-naphthyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-triazine (abbreviated as βNP -SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviated as SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviated as mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazine-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviated as BP-mBPIcz(II) Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviated as: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3"-diyl]bis(9H-carbazole) (abbreviated as: Cz-pmCzBPTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1"-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 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), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tzn), and other organic compounds containing a heteroaromatic ring having a triazine skeleton. Note that when the first host material is an organic compound containing deuterium, an organic compound in which a portion or all of the hydrogen in the organic compound is deuterated can be used. In particular, it is preferable to use an organic compound in which a group or skeleton in which the triplet excitation energy level is concentrated is deuterated. ,

[0129] As the organic compound having hole-transporting properties used as the second host material, an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring is preferably used. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring having at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton. Specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which these rings are further fused with an aromatic ring or a heteroaromatic ring is preferred.

[0130] Such an organic compound having hole-transporting properties preferably has any one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, it may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine containing 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. Note that when these hole-transporting substances are organic compounds containing an N,N-bis(4-biphenyl)amino group, they are preferred because they allow the production of light-emitting devices with long lifetimes.

[0131] As such an organic compound, for example, the organic compound described below is preferably used. Examples of such organic compounds 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-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), and 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine. (Abbreviation: PCBA1BP), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (Abbreviation: PCBA1BP), 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: 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 (abbreviated as: PCBASF) and other compounds having an aromatic amine skeleton; 1,3-bis(N-carbazolyl)benzene (abbreviated as: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviated as: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), 3,9-bis(9-phenyl-9H-carbazole-3-yl)-9H-carbazole (abbreviated as PCCzPC), 9-(biphenyl-4-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviated as PCCzBP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole azole (abbreviated as: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviated as: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviated as: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviated as: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviated as 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'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviated as: PCCzTp), 9,9'-bis(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenyl-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 (abbreviated as: PSiCzCz), 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9"-tricarbazole (abbreviated as: PSiCzGI), and other compounds having a carbazole skeleton; 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviated as: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as: DBTFLP-III), 4-[4 -(9-phenyl-9H-fluorene-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV) and other compounds having a thiophene skeleton; 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluorene-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) and other compounds having a furan skeleton. Among them, compounds having an aromatic amine skeleton or a carbazole skeleton have good reliability and high hole transport properties and contribute to reducing the driving voltage, so they are preferred. In addition, when the second host material is an organic compound containing deuterium,Organic compounds in which a portion or all of the hydrogen atoms in the above organic compounds are deuterated can be used. In particular, organic compounds in which a radical or skeleton in which triplet excitation energy levels are concentrated are preferably used.

[0132] As described above, it is preferred that an organic compound having electron transport properties is used as the first host material, and an organic compound having hole transport properties is used as the second host material. In addition, when an organic compound having a π-electron-deficient heteroaromatic ring is used as the first host material and an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring is used as the second host material, the combination has high carrier transport properties and can efficiently form an exciplex, so it is preferred. Alternatively, when an organic compound comprising a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton or an organic compound comprising a heteroaromatic ring having a triazine skeleton is used as the first host material and an organic compound having any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton and an anthracene skeleton is used as the second host material, the triplet excitation energy of the combination is high, so it is more preferred. Furthermore, when an organic compound having a triazine skeleton or a pyrimidine skeleton is used as the first host material and an organic compound having a carbazole skeleton is used as the second host material, the combination is stable and has high reliability, so it is preferred. In addition, as an organic compound having a carbazole skeleton, an organic compound having a 3,3'-dicarbazole skeleton is particularly preferably used because this organic compound has high donor properties and high heat resistance. Therefore, when an organic compound having a 3,3'-dicarbazole skeleton is used as the second main material and an organic compound having a triazine skeleton is used as the first main material, the triplet excitation energy of this combination is high, stable and reliable, so it is very preferred.

[0133] Furthermore, by mixing an organic compound having electron-transporting properties with an organic compound having hole-transporting properties, the transport properties of the light-emitting layer can be easily adjusted, thereby making it easier to control the recombination region. The weight ratio of the organic compound having hole-transporting properties to the organic compound having electron-transporting properties can be from 1:19 to 19:1, preferably from 3:7 to 7:3.

[0134] In addition, the light-emitting layer included in the tandem light-emitting device is preferably separated from the light-emitting layer included in at least one of the other adjacent light-emitting devices. Alternatively, the light-emitting layer included in the tandem light-emitting device is preferably a light-emitting layer different from the light-emitting layer included in at least one of the other adjacent light-emitting devices. Alternatively, the color of light emitted by the tandem light-emitting device or a pixel including the tandem light-emitting device is preferably different from the color of light emitted by the other adjacent light-emitting devices or pixels. Alternatively, the luminescent center substance included in the light-emitting layer of the tandem light-emitting device is preferably different from the luminescent center substance included in the light-emitting layer of at least one of the other adjacent light-emitting devices.

[0135] In addition, in a tandem light-emitting device of one embodiment of the present invention, it is preferred that the electron transport layer included in the light-emitting unit on the cathode side comprises a first organic compound having a triazine skeleton, and the intermediate layer comprises a second organic compound having a phenanthroline skeleton. When the electron transport layer of the light-emitting unit on the cathode side comprises a first organic compound and the intermediate layer comprises a second organic compound, a tandem light-emitting device with a low driving voltage can be obtained. In addition, when the electron transport layer of the light-emitting unit on the cathode side comprises a first organic compound, the intermediate layer comprises a second organic compound, and any light-emitting layer comprises a luminescent center substance and a first host material and a second host material, one or both of which are deuterated, a tandem light-emitting device with a lower driving voltage can be obtained, and the luminous efficiency is also improved at this time, so a light-emitting device with high power efficiency and high energy efficiency can be realized.

[0136] Furthermore, as described above, because the light-emitting layer included in the tandem light-emitting device is separated from the light-emitting layer included in at least one of the other adjacent light-emitting devices; the light-emitting layer included in the tandem light-emitting device is a light-emitting layer different from the light-emitting layer included in at least one of the other adjacent light-emitting devices; the light-emitting color emitted by the tandem light-emitting device is different from the light-emitting color emitted by at least one of the other adjacent light-emitting devices; or the light-emitting center substance included in the light-emitting layer of the tandem light-emitting device is different from the light-emitting center substance included in the light-emitting layer of at least one of the other adjacent light-emitting devices, a light-emitting device with extremely high current efficiency can be realized, and a light-emitting device with higher power efficiency and higher energy efficiency can be realized.

[0137] 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, high brightness, and good visibility. Furthermore, it can also be a display device with excellent display quality.

[0138] The electron mobility of the first organic compound having a triazine skeleton when the square root of the electric field intensity [V / cm] is 600 is preferably 1×10-7 cm 2 / Vs or more, more preferably 1×10 -6 cm 2 / Vs or more. In addition, any substance other than the above-mentioned substances may be used as long as the substance has a higher electron-transporting property than a hole-transporting property.

[0139] The first organic compound having a triazine skeleton is preferably a compound having a triazine skeleton and an aromatic ring. The aromatic ring is preferably a monocyclic aromatic ring, a polycyclic aromatic ring, an aromatic ring having an alkyl group as a substituent, an aromatic ring having a fluoro group as a substituent, or an aromatic ring having a cyano group as a substituent. The triazine skeleton may have substituents other than the aforementioned aromatic rings, and the aromatic ring may have substituents other than the aforementioned fluoro group, cyano group, or alkyl group. Note that the triazine skeleton is also referred to as a triazine ring, and other skeletons may also be referred to as rings.

[0140] Examples of the monocyclic aromatic ring include aromatic hydrocarbon rings such as a benzene ring, and heteroaromatic rings such as a pyrrole ring, a pyridine ring, a pyrimidine ring, and a triazine ring. The presence of an aromatic ring as a substituent can improve heat resistance, specifically, increase the glass transition temperature (Tg), and enhance electron transport properties.

[0141] Examples of the polycyclic aromatic ring include naphthalene ring, phenanthrene ring, In some embodiments, the present invention relates to an aromatic hydrocarbon ring such as a benzophenone ring, a triphenylene ring, a fluorene ring, a spirobifluorene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, an xanthene ring, an indolecarbazole ring, an indenocarbazole ring, etc. Compared with the compound with the monocyclic aromatic rings such as a benzene ring, the compound with a polycyclic aromatic ring as a substituent can improve heat resistance, so it is preferred. In addition, in the case of a ring having the above-mentioned polycyclic aromatic ring and an aromatic ring (benzene ring, naphthalene ring, pyridine ring etc.) fused as a substituent, heat resistance can be further improved. As the ring of the polycyclic aromatic ring and the aromatic ring fused, benzofluorene ring, benzonaphthofuran ring, benzoxanthene ring, benzonaphthothiophene ring etc. can be enumerated. By arranging a layer comprising a compound having high heat resistance near the cathode, it is possible to suppress the formation of the layer or cathode after the high temperature treatments such as the pattern forming process are performed to cause thermal damage to the element.

[0142] In addition, as the above-mentioned alkyl group, methyl, ethyl, propyl, tert-butyl, cyclohexyl, adamantyl and the like can be mentioned. The first organic compound having an alkyl group as a substituent can be an organic compound with a low refractive index, and the layer using the first organic compound can reduce the refractive index. Therefore, total reflection at the interface between the layer and other layers can be prevented, and the light extraction efficiency of the light-emitting device using the layer can be improved. In addition, by also using the above-mentioned compound having an alkyl group in the hole transport layer, the refractive index of the hole transport layer can be reduced. In particular, by 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, the effect of improving the light extraction efficiency can be multiplied. In addition, when the number of carbon atoms of the alkyl group in the organic compound is multiple, preferably 3 or more, more preferably 4 or more, and further preferably 5 or more, the effect of reducing the refractive index can be improved. In addition, the layer using a compound having a fluorine group as a substituent can also reduce the refractive index, so it is preferred. In particular, when using an organic compound having multiple fluorine groups, the effect of reducing the refractive index can be enhanced. It is also effective to use a compound having a fluorine group in both the electron transport layer and the hole transport layer. In addition, a compound having a structure in which an aromatic ring is bonded to multiple alkyl groups or multiple fluoro groups can further reduce the refractive index of the layer. For example, a structure in which a benzene ring is bonded to two or more tert-butyl groups as a substituent can be cited. In addition to the benzene ring, other monocyclic aromatic rings such as a pyridine ring, and polycyclic aromatic rings such as a fluorene ring can also be bonded to multiple alkyl groups or multiple fluoro groups. In addition, as a polycyclic aromatic ring (naphthalene ring, fluorene ring, carbazole ring, quinoline ring, xanthene ring, etc.), it is preferred to have a structure in which a partial ring constituting the polycyclic aromatic ring is bonded to multiple alkyl groups or multiple fluoro groups. For example, a structure in which a benzene ring constituting a fluorene ring is bonded to multiple tert-butyl groups can be cited.

[0143] Furthermore, the first organic compound having a cyano group as a substituent is preferred because it can improve electron transport properties.

[0144] In addition, the substituents possessed by the first organic compound are preferably a combination of multiple polycyclic aromatic rings, alkyl groups, fluoro groups, and cyano groups. For example, when a polycyclic aromatic ring and a cyano group are used as substituents, both heat resistance and electron transport properties can be improved. In addition, by having a polycyclic aromatic ring and an alkyl group, both heat resistance and light extraction efficiency can be improved. In this way, substituents can be combined and used according to the desired function.

[0145] In addition, the first organic compound having a plurality of polycyclic aromatic rings as substituents can further improve heat resistance. In this case, the first organic compound preferably has the above-mentioned aromatic hydrocarbon ring and the above-mentioned heteroaromatic ring.

[0146] Specific examples of the first organic compound having a triazine skeleton include 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluorene]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazole-3- yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviated as mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviated as mINc(II)PTzn), 2 -{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazine-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviated as BP-Icz(II)Tz n), 2-[3'-(triphenylene-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviated as PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1"-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviated as mBP-TPDBfTzn), 2-[4-(2-naphthyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-triazine (abbreviated as βNP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviated as SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviated as mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazine-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviated as BP-mBPIcz(II)Tz n), 3-{3-[9-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviated as: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3"-diyl]bis(9H-carbazole) (abbreviated as: Cz-pmCzBPTzn), 3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazine-2-yl]-9H-carbazole (abbreviated as: PDBf-PCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviated as: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3"-diyl]bis(9H-carbazole) (abbreviated as: Cz-pmCzBPTzn), [phenyl-1,3,5-triazine-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviated as PCzDBtTzn), 2,4-diphenyl-6-[3'-(spiro[7H-benzo[c]fluorene-7,9'-[9H]xanthene]-2'-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as mSbfxBPTzn), 3'-[4-phenyl-6-(spiro[9H-fluorene-9,9'-[9H]xanthene]-2'-yl)-1,3,5-triazine-2-yl]biphenyl-4-carbonitrile (abbreviated as mpCNBP-SFxTzn), 2,2'-[1, Organic compounds containing a heteroaromatic ring having a triazine skeleton, such as [2-naphthalenediylbis(4,1-phenylene)]bis(4,6-diphenyl-1,3,5-triazine) (abbreviated as TznP2N), and particularly preferably used are TznP2N (100), mSbfxBPTzn (101), mpCNBP-SFxTzn (102), CNBPNPTzn (103), βNP-SFx(4)Tzn (104), mmtBuBP-mDMePyPTzn (105), and mBnfBPTzn (106) represented by the following structural formulas (100) to (106).

[0147] [Chemical Formula 1]

[0148] In addition, the electron transport layer included in the light-emitting unit on the anode side may be a layer containing the seventh organic compound having a triazine skeleton or a layer containing the eighth organic compound not having a triazine skeleton, similarly to the electron transport layer included in the light-emitting unit on the cathode side.

[0149] To reduce power consumption, the electron transport layer included in the anode-side light-emitting unit preferably contains a seventh organic compound having a triazine skeleton. In particular, using the same organic compound as the first organic compound as the seventh organic compound is preferred because it can reduce the complexity of the manufacturing apparatus and is also advantageous in terms of raw material procurement costs.

[0150] In addition, when the electron transport layer included in the light-emitting unit on the anode side includes an eighth organic compound that does not have a triazine skeleton, the control of carrier transport properties becomes easier, thereby providing a light-emitting device with better characteristics. As the organic compound that does not have a triazine skeleton, an organic compound containing a heteroaromatic ring having a pyridine skeleton or an organic compound containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton is preferably used. In addition, organic compounds in which the above organic compounds are appropriately deuterated can also be used.

[0151] The second organic compound having a phenanthroline skeleton contained in the intermediate layer preferably has an electron mobility of 1×10 -7 cm 2 / Vs or more, more preferably 1×10 -6 cm 2 / Vs or more. In addition, any substance other than the above-mentioned substances may be used as long as the substance has a higher electron-transporting property than a hole-transporting property.

[0152] The second organic compound having a phenanthroline skeleton is preferably a compound having a phenanthroline skeleton and an aromatic ring. As the aromatic ring, a monocyclic aromatic ring, a polycyclic aromatic ring, or the like is preferably used.

[0153] Examples of the monocyclic aromatic ring include a benzene ring, a pyrrole ring, a pyridine ring, and a pyrimidine ring. In addition, examples of the polycyclic aromatic ring include a naphthalene ring, a phenanthrene ring, a ring, triphenylene ring, fluorene ring and other aromatic hydrocarbon rings, phenanthroline ring, pyrrole ring and other heteroaromatic rings, etc. In particular, it is preferred that the polycyclic aromatic rings have a plurality of these rings because they can improve heat resistance or electron transport properties.

[0154] As the second organic compound having a phenanthroline skeleton, for example, bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), 2,9-di(naphthalene-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-triphenylene)phenyl]-1,10-phenanthroline (abbreviation: mTpPPhen), 2-phenyl-9-( Organic compounds containing a heteroaromatic ring having a phenanthroline skeleton, such as 2-triphenyl)-1,10-phenanthroline (abbreviated as Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthyl]-1,10-phenanthroline (abbreviated as PnNPhen), and 2-[4-(2-triphenyl)phenyl]-1,10-phenanthroline (abbreviated as pTpPPhen), are preferably used. PnNPhen (200), mPPhen2P (201), etc. represented by the following structural formula (200) or (201) are preferably used.

[0155] [Chemical Formula 2]

[0156] 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 second organic compound having a phenanthroline skeleton and can inject electrons into the light-emitting unit on the anode side in contact with the intermediate layer and inject holes into the light-emitting unit on the cathode side by applying a voltage between the anode and cathode. Note that the intermediate layer preferably has a stacked structure comprising a first layer containing the second organic compound and a second layer located closer to the cathode than the first layer.

[0157] The first layer preferably contains a metal or metal compound in addition to the second organic compound. The metal in the metal or metal compound is preferably selected from the following elements: alkali metals (Group 1 elements) such as Li; alkaline earth metals (Group 2 elements) such as Mg and Ca; Group 3 elements including lanthanides such as Y, Eu, and Yb; Group 11 elements such as Cu, Ag, and Au; Group 12 elements such as Zn; and earth metals (Group 13 elements) such as Al and In.

[0158] Note that the first layer may have a stacked structure of a layer containing an organic compound and a layer containing a metal or a metal compound located closer to the cathode side than the layer containing the organic compound, or it may be a mixed layer of an organic compound and a metal or a metal compound. When the first layer is a mixed layer, the number of required deposition processing chambers can be reduced, which can reduce manufacturing costs and help improve the stability of the light-emitting device, so it is preferred.

[0159] When an organic compound and a metal or metal compound are mixed, the distribution of the organic compound and the metal or metal compound exhibit roughly the same trend when analyzing the first layer in the thickness direction. In other words, when the distribution of the organic compound is constant, the distribution of the metal or metal compound is also roughly constant. In a stacked structure of a layer containing an organic compound and a layer containing a metal or metal compound, the metal or metal compound may sometimes be detected in areas outside of the layer due to diffusion from the layer containing the metal or metal compound. However, since the distribution is different from that of the organic compound, the analysis results can be distinguished between diffusion and mixing.

[0160] In addition, when the first layer is analyzed in the thickness direction, if the thickness of the area where the metal or metal compound is detected is greater than 10 nm, preferably greater than 15 nm, and more preferably greater than 20 nm, it can be considered that the first layer includes a mixed layer formed by a mixture of organic compounds and metals or metal compounds.

[0161] In particular, the metal in the above-mentioned metal or metal compound is preferably a substance that exhibits donor properties to the second organic compound. As a substance that exhibits donor properties to the second organic compound, for example, metals of Group 1 and Group 2 can be cited, and lithium or a lithium compound is particularly preferably used. Specifically, Li, lithium fluoride (LiF), lithium oxide (Li2O) and 8-hydroxyquinoline-lithium (abbreviated as: Liq) are preferably used. In the case where the first layer contains a second organic compound and a substance that exhibits donor properties to the second organic compound, electrons are generated by charge separation, and when a voltage is applied between the anode and the cathode, the electrons are injected into the light-emitting unit on the anode side through the second organic compound. Thus, the light-emitting device of one embodiment of the present invention can be a light-emitting device with a low driving voltage.

[0162] In addition, the second organic compound is preferably an organic compound including a phenanthroline skeleton with an electron-donating substituent in addition to the above-mentioned organic compound. The phenanthroline skeleton easily interacts with metals etc., and by making the second organic compound with this phenanthroline skeleton also have an electron-donating group, the electron density of the phenanthroline skeleton rises, so as to be further prone to interaction with metals or metallic compounds. Especially, when using the metal of the 3rd family, the 11th family, the 12th family, the 13th family as the metal in the metal or metallic compound, the rise of driving voltage can be suppressed, so as to provide a series-connected light-emitting device with good characteristics.

[0163] As the object lesson of electron-donating group, alkyl, alkoxyl, aryloxy, alkylamino, arylamino, heterocyclic amino etc. can be enumerated.But the electron-donating group preferably introduced on phenanthroline ring is not limited to this.As long as can be by the base that improves the electron density of phenanthroline ring by introducing on phenanthroline ring, just can be used as electron-donating group.In addition, this electron-donating group also can be introduced into phenanthroline ring through arylene groups such as phenylene, and this arylene group is preferably p-phenylene.

[0164] Structural formulas (300) to (311) show specific examples of organic compounds that can be used as the second organic compound.

[0165] [Chemical Formula 3]

[0166] In addition, when the first layer comprises a second organic compound of Group 1 or Group 2, especially lithium or a lithium compound, or a phenanthroline skeleton containing an electron-donating substituent, a tandem light-emitting device with a lower driving voltage and good reliability can be provided, which is preferred. Furthermore, when the first layer comprises a second organic compound of Group 1 or Group 2, especially lithium or a lithium compound, or a phenanthroline skeleton containing an electron-donating substituent, the increase in driving voltage can be suppressed when the organic compound layer of the light-emitting device is processed by photolithography, which is preferred.

[0167] In the intermediate layer having the above structure, the second organic compound is particularly preferably an organic compound having a 1,10-phenanthroline skeleton in a phenanthroline skeleton, because two nitrogen atoms contained in the above organic compound can coordinate to a metal, thereby easily interacting with the metal or the metal compound.

[0168] 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 electron-donating groups at 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, thereby making it easier to interact with metals or metal compounds.

[0169] The first layer may further comprise an organic compound different from the second organic compound. Furthermore, the organic compound is preferably an organic compound having electron transport properties. In particular, the organic compound preferably has two or more heteroaromatic rings bonded or fused to each other, and the two or more heteroaromatic rings have a total of three or more heteroatoms. By including such an organic compound in the first layer, heat resistance and electron transport properties can be improved.

[0170] The second layer preferably includes a ninth organic compound having hole-transporting properties. Furthermore, the second layer preferably further includes a substance exhibiting acceptor properties, preferably an organic compound exhibiting acceptor properties for the ninth organic compound. As the acceptor substance, 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. Furthermore, the total number of halogen (fluorine) and cyano groups contained in the organic compound is preferably 4 or greater.

[0171] When the second layer contains the ninth organic compound and a substance that acts as an acceptor for the ninth organic compound, holes are generated by charge separation. When a voltage is applied between the anode and cathode, these holes are injected into the cathode-side light-emitting unit through the ninth organic compound. Consequently, the light-emitting device of one embodiment of the present invention can have a low driving voltage.

[0172] The intermediate layer may also include a third layer between the first layer and the second layer.

[0173] The third layer contains a substance having electron-transporting properties and has the functions of smoothly transferring electrons between the first and second layers to reduce driving voltage and reducing interaction between the first and second layers to improve reliability.

[0174] Furthermore, the thickness of the third layer is preferably 1 nm to 10 nm, more preferably 2 nm to 5 nm, whereby an increase in driving voltage can be suppressed.

[0175] 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 excellent characteristics. Furthermore, 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 excellent visibility, capable of displaying at high brightness.

[0176] Next, a light-emitting device according to one embodiment of the present invention will be described in detail with reference to the drawings. Figure 1A A light-emitting device 130 according to one embodiment of the present invention is shown. The light-emitting device according to one embodiment of the present invention is a tandem light-emitting element including an organic compound layer 103 (also referred to as an EL layer) between a first electrode 101 including an anode and a second electrode 102 including a cathode. The organic compound layer 103 includes a first light-emitting unit 501 including a first light-emitting layer 113_1, a second light-emitting unit 502 including a second light-emitting layer 113_2 and a second electron-transporting layer 114_2, and an intermediate layer 116. Alternatively, the first light-emitting unit may include a first electron-transporting layer 114_1 between the first light-emitting layer 113_1 and the intermediate layer 116.

[0177] In the light-emitting device 130, the second electron transport layer 114_2 includes a first organic compound having a triazine skeleton, and the intermediate layer 116 includes a second organic compound having a phenanthroline skeleton. In addition, to reduce power consumption, the second electron transport layer 114_2 including the first organic compound having a triazine skeleton is preferably in contact with the second electrode 102.

[0178] In this embodiment, a light-emitting device including one intermediate layer 116 and two light-emitting units is used as an example for description, but a light-emitting device including n (n is an integer greater than 1) intermediate layers and n+1 light-emitting units may also be used. Figure 1B The light emitting device 130 shown is an example of a tandem light emitting device where n is 2 and includes 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 .

[0179] The first light-emitting unit 501 and the second light-emitting unit 502 may also include other functional layers besides the above-mentioned light-emitting layer and electron transport layer. Figure 1A In the embodiment, the first light-emitting unit 501 includes a hole injection layer 111 and a first hole transport layer 112_1 in addition to the first light-emitting layer 113_1 and the first electron transport layer 114_1. The second light-emitting unit 502 includes a 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 of the present invention is not limited thereto. Any of the aforementioned layers may be omitted, and other layers may be provided. Typical examples of these other layers include a carrier blocking layer and an exciton blocking layer.

[0180] The first electrode 101 is an electrode including an anode. The first electrode 101 may also have a stacked structure, in which case the layer in contact with the organic compound layer 103 is used as the anode. The anode is preferably formed using a metal, alloy, conductive compound, or a mixture thereof having a large work function (specifically, 4.0 eV or more). Specifically, for example, indium oxide-tin oxide (ITO: Indium Tin Oxide), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-zinc oxide, indium oxide containing tungsten oxide and zinc oxide (IWZO), etc. may be cited. Although these conductive metal oxide films are usually deposited by sputtering, they can also be formed by applying a sol-gel method. As an example of a formation method, a method of forming indium oxide-zinc oxide by sputtering using a target material having 1 wt% to 20 wt% of zinc oxide added to indium oxide may be cited. In addition, a target material to which 0.5 wt% to 5 wt% of tungsten oxide and 0.1 wt% to 1 wt% of zinc oxide are added to indium oxide can be used to form indium oxide (IWZO) by sputtering. In addition, as materials for the anode, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd) or nitrides of metal materials (for example, titanium nitride) can be cited. In addition, graphene can also be used as a material for the anode. In addition, by using the composite material constituting the second layer 117 in the above-mentioned intermediate layer 116 for the layer in contact with the anode (typically a hole injection layer), it is possible to select an electrode material without taking into account the work function.

[0181] The hole injection layer 111 is in contact with the anode and has the function of easily injecting holes into the organic compound layer 103 (first light-emitting unit 501). The hole injection layer 111 can be formed using phthalocyanine compounds or complexes such as phthalocyanine (abbreviated as: H2Pc) and copper phthalocyanine (abbreviated as: CuPc); aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as: DPAB) and 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviated as: DNTPD); or polymers such as poly(3,4-ethylenedioxythiophene) / polystyrenesulfonic acid (abbreviated as: PEDOT / PSS).

[0182] Alternatively, the hole injection layer 111 may be formed using a substance having electron acceptor properties. Examples of the substance having electron acceptor properties include organic compounds having electron-withdrawing groups (such as halogen groups and cyano groups), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated as HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated as F6-TCNNQ), and 2-(7-dicyanomethylidene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)malononitrile. In particular, compounds such as HAT-CN in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms are thermally stable and therefore preferred. In addition, [3]radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluorine groups, cyano groups, etc.) are particularly preferred because they have very high electron-accepting properties. Specifically, examples include: α, α', α"-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorophenylacetonitrile], α, α', α"-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)phenylacetonitrile], α, α', α"-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorophenylacetonitrile]. As acceptor substances, in addition to the above-mentioned organic compounds, molybdenum oxides, vanadium oxides, ruthenium oxides, tungsten oxides, manganese oxides, etc. can also be used. Transition metal oxides. Furthermore, the hole injection layer 111 can be formed by using phthalocyanine compounds or complexes such as phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine (abbreviated as CuPc); aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviated as DNTPD); or polymers such as poly(3,4-ethylenedioxythiophene) / polystyrenesulfonic acid (abbreviated as PEDOT / PSS). Substances with acceptor properties can extract electrons from an adjacent hole transport layer (or hole transport material) by applying an electric field.

[0183] Furthermore, the hole injection layer 111 is preferably formed of a composite material including the above-mentioned material having an acceptor property and a substance having a hole transport property.

[0184] As the hole-transporting substance used in the composite material, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, high molecular weight compounds (oligomers, dendrimers, polymers, etc.) can be used. As the hole-transporting substance used in the composite material, it is preferred to use a hole mobility of 1×10 -6 cm 2 / Vs or more. The hole-transporting substance used in the composite material is preferably a compound containing a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the fused aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, etc. are preferred. In addition, as the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferred, specifically a carbazole ring, a dibenzothiophene ring, or a ring in which these rings are further fused with an aromatic ring or a heteroaromatic ring.

[0185] Such hole-transporting substances preferably have any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, they may be aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines containing a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. Note that when these hole-transporting substances have an N,N-bis(4-biphenyl)amino group, they are preferred because they allow the production of long-lived light-emitting devices.

[0186] Specific examples of the above-mentioned substances having hole transport properties include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated as BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated as BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4"-phenyltriphenylamine (abbreviated as BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviated as BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine -8-amine (abbreviated as: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviated as: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviated as: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-benzidine (abbreviated as: ThBA1BP), 4-(2-naphthyl)-4',4"-diphenyltriphenylamine (abbreviated as: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4"-diphenyltriphenylamine (abbreviated as: BBAβNBi), 4,4'-diphenyl-4"-(6;1 '-binaphthyl-2-yl) triphenylamine (abbreviated as: BBAαNβNB), 4,4'-diphenyl-4"-(7;1'-binaphthyl-2-yl) triphenylamine (abbreviated as: BBAαNβNB-03), 4,4'-diphenyl-4"-(7-phenyl)naphthyl-2-yl triphenylamine (abbreviated as: BBAPβNB-03), 4,4'-diphenyl-4"-(6;2'-binaphthyl-2-yl) triphenylamine (abbreviated as: BBA(βN2)B), 4,4'-diphenyl-4"-(7;2'-binaphthyl-2-yl) triphenylamine (abbreviated as: BBA(βN2)B-03), 4,4'-diphenyl-4"-(4;2'-binaphthyl-1-yl) triphenylamine (abbreviated as: BBAβNαNB ), 4,4'-diphenyl-4"-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviated as: BBAβNαNB-02), 4-(4-biphenyl)-4'-(2-naphthyl)-4"-phenyltriphenylamine (abbreviated as: TPBiAβNB), 4-(3-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4"-phenyltriphenylamine (abbreviated as: mTPBiAβNBi), 4-(4-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4"-phenyltriphenylamine (abbreviated as: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviated as: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviated as: αNBB1BP), 4,4'-Diphenyl-4"-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviated as YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tri(biphenyl-4-yl)amine (abbreviated as YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4"-phenyltriphenylamine (abbreviated as YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviated as 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-fluorene-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluorene-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-phenylfluorene-9-yl) )triphenylamine (abbreviated as: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviated as: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as: PCBA1BP), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as: PCBANB), 4,4'-di(1-naphthyl)-4"-(9-phenyl-9H-carbazole-3 -yl) triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviated as: PSiCzCz), 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9"-tricarbazole (abbreviated as: PSiCzGI), etc.

[0187] In addition, as substances with hole-transporting properties, the following aromatic amine compounds can also be used: 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), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc.

[0188] By forming the hole injection layer 111, hole injection properties can be improved, thereby obtaining a light-emitting device with low driving voltage.

[0189] Furthermore, among substances having acceptor properties, organic compounds having acceptor properties can be easily deposited by vapor deposition and are therefore easy-to-use materials.

[0190] The hole transport layer (the first hole transport layer 112_1 and the second hole transport layer 112_2) is formed by including an organic compound having a hole transport property. The organic compound having a hole transport property preferably has a 1×10 -6 cm 2 / Vs and above hole mobility.

[0191] Examples of the organic compound having a hole-transporting property include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviated as TPD), N,N'-bis(9,9'-spirobi[9H-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviated as BSPB), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (abbreviated as BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), and 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP). ), compounds having an aromatic amine skeleton, such as 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviated as PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviated as PCBASF);1,3-Bis(N-carbazolyl)benzene (abbreviated as mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviated as CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviated as BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviated as BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviated as mBPCCBP ), 9-(2-naphthyl)-9'-3,3'-bi-9H-carbazole (abbreviated as βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviated as 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, biphenyl]-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':3',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'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylene-2-yl)-3,3'-9H compounds having a carbazole skeleton, such as 9'H-bicarbazole (abbreviated as PCCzTp), 9,9'-bis(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenyl-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 (abbreviated as PSiCzCz);Compounds having a thiophene skeleton, such as 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-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)tris(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among these, compounds having an aromatic amine skeleton and a carbazole skeleton are preferred because they have good reliability and high hole-transport properties, and contribute to lowering the driving voltage. Furthermore, the organic compounds listed as the hole-transporting materials for the composite material used in the hole injection layer 111 can also be suitably used as materials for the hole-transport layer 112. Furthermore, suitably deuterated organic compounds of the above-mentioned organic compounds can also be used.

[0192] In addition, the first hole transport layer 112_1 and the second hole transport layer 112_2 preferably include an organic compound having the same skeleton, more preferably include the same compound. In addition, one or both of the first hole transport layer 112_1 and the second hole transport layer 112_2 may also have a stacked structure. By making the hole transport layer 112 have a stacked structure and using an organic compound with high electron tolerance and / or an organic compound with electron blocking properties for a layer closer to the light-emitting layer 113, a light-emitting device with good reliability can be obtained. When the hole transport layer 112 has a stacked structure, a material with high hole transport, low electron transport and high LUMO energy level is preferably used as a layer closer to the light-emitting layer 113. The material is preferably a material whose LUMO energy level is higher than the material with the highest constituent ratio among the materials constituting the light-emitting layer or the material with the highest LUMO energy level among the materials constituting the light-emitting layer, preferably a material higher than 0.30 eV. The material is preferably an organic compound having an amine skeleton and a polycyclic heteroaromatic ring, 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 the above-mentioned materials as the layer closer to the light-emitting layer 113 can prevent electrons from the light-emitting layer 113 from passing through the first electrode 101, thereby enabling the manufacture of a display device with high efficiency and a long life. Note that, for the layer closer to the first electrode 101 in the stacked structure of the hole-transport layer 112, an organic compound having an amine backbone or a polycyclic hydrocarbon is preferably used, and an organic compound having an amine backbone or a fluorene backbone is more preferably used. Organic compounds having an amine backbone or a fluorene backbone are preferred because they have high reliability and high hole-transport properties, thereby reducing the power consumption of the light-emitting device.

[0193] The light-emitting layers (first light-emitting layer 113_1 and second light-emitting layer 113_2) preferably include a luminescent center substance and a host material. Furthermore, at least one of the light-emitting layers has the following structure: the light-emitting layer includes a luminescent center substance, a first host material, and a second host material, wherein the first host material and the second host material are both organic compounds, and one or both of the first host material and the second host material are deuterated. Furthermore, the first host material and the second host material preferably form an exciplex. Furthermore, both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 preferably have this structure. Furthermore, the light-emitting layers may also include other materials.

[0194] Furthermore, the first light-emitting layer 113_1 and the second light-emitting layer 113_2 preferably emit light of similar colors. For example, in display devices, red, green, and blue pixels are often used to display full colors. In a light-emitting device for a red pixel, both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 emit red light. In a light-emitting device for a green pixel, both emit green light. In a light-emitting device for a blue pixel, both emit blue light. In this case, the luminescent center substance contained in the first light-emitting layer 113_1 and the luminescent center substance contained in the second light-emitting layer 113_2 are preferably compounds whose maximum peak wavelength difference in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. Furthermore, it is more preferred that the luminescent center substance contained in the first light-emitting layer 113_1 and the luminescent center substance contained in the second light-emitting layer 113_2 are the same. Furthermore, it is more preferred that the material constituting the first light-emitting layer 113_1 and the material constituting the second light-emitting layer 113_2 be the same.

[0195] The luminescent center substance may be a fluorescent substance, a phosphorescent substance, a substance exhibiting thermally activated delayed fluorescence (TADF), or other luminescent substances.

[0196] In the light-emitting layer, examples of fluorescent substances that can serve as a luminescent center include the following substances. Note that other fluorescent substances can also be used.

[0197] Examples thereof include 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N , N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviated as: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviated as: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl)phenyl]triphenylamine -2-anthryl) triphenylamine (abbreviated as: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviated as: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviated as: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazole-3-yl) triphenylamine (abbreviated as: PCBAPA), N,N"-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N , N', N'-triphenyl-1,4-phenylenediamine (abbreviated as DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N",N",N"',N"'-octaphenyldibenzo[g,p] -2,7,10,15-tetramine (abbreviated as: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthracenyl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviated as: 2PCAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthracenyl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviated as: 2PCABPhA), N-(9,10-diphenyl-2-anthracenyl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthracenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as: 2DPABPhA), 9,10-bis( biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviated as 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviated as DPhAPhA), coumarin 545T, N,N'-diphenylquinacridone (abbreviated as DPQd), rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenylnaphthacene (abbreviated as BPT), 2-(2-{2-[4-(dimethylamino)phenyl]vinyl}-6-methyl-4H-pyran-4-ylidene)malononitrile (abbreviated as DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethene 1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as DCM2), N,N,N',N'-tetrakis(4-methylphenyl)naphthacene-5,11-diamine (abbreviated as p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviated as p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2 ,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]vinyl}-4H-pyran-4-ylidene)malononitrile (abbreviated as: 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)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphtho[1,[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). In particular, fused aromatic diamine compounds such as pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 are preferred because they have good hole-trapping properties, high luminous efficiency, and good reliability. ,

[0198] In the light-emitting layer, as a phosphorescent substance that can serve as a luminescent center substance, a metal complex is preferably used, and an iridium complex or a platinum complex is particularly preferably used. Examples thereof include the following substances.

[0199] Examples include organometallic iridium complexes having a 4H-triazole skeleton, such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviated as [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazole)iridium(III) (abbreviated as [Ir(Mptz)3]), and the like. tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviated as [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviated as [Ir(Prptz1-Me)3]), etc.; fac-tris[1-(2,6-diisopropyl)-1H-1,2,4-triazole]iridium(III) [1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazole-2-yl]iridium(III) (abbreviated as [Ir(iPrpim)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviated as [Ir(dmpimpt-Me)3]), tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazole-2-yl]iridium(III) -κN3}-4-cyanophenyl-κC)iridium (III) (abbreviated as: CNImIr) and other organometallic iridium complexes with an imidazole skeleton; tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium (III) (abbreviated as: [Ir(cb)3]) and other organometallic complexes with a benzimidazole skeleton; bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2’ ] iridium (III) tetrakis (1-pyrazolyl) borate (abbreviated as: FIr6), bis [2- (4', 6'-difluorophenyl) pyridinium-N, C 2’ ] iridium (III) picolinate (abbreviated as: FIrpic), bis{2-[3', 5'-bis(trifluoromethyl)phenyl]pyridinium-N, C 2’ Iridium(III) picolinate (abbreviated as [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2’] Iridium (III) acetylacetonate (abbreviated as FIracac) and other organometallic iridium complexes with phenylpyridine derivatives having electron-withdrawing groups as ligands; 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-pyridyl-κN)carbazole-2,1-diyl-κC1)platinum (II) (abbreviated as PtON-TBBI). The above substances are compounds that emit phosphorescence with a blue hue and have a luminescence peak in the wavelength region of 450nm to 520nm. In addition, compounds in which a portion of the hydrogen atoms in these compounds are deuterated can also be used.

[0200] In addition, tris(4-methyl-6-phenylpyrimidinyl)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-tert-butyl-6-phenylpyrimidinyl)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinyl)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinyl)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinyl)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinyl]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl -6-(2-methylphenyl)-4-phenylpyrimidinyl]iridium(III) (abbreviated as [Ir(mpmppm)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinyl)iridium(III) (abbreviated as [Ir(dppm)2(acac)]), etc.; (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinyl)iridium(III) (abbreviated as [Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinyl)iridium(III) (abbreviated as [Ir(mppr-iPr)2(acac)]), etc.; tris(2-phenylpyridinyl-N,C 2’ )iridium (III) (abbreviated as [Ir(ppy)3]), bis(2-phenylpyridinium-N, C 2’ )iridium(III) acetylacetonate (abbreviated as [Ir(ppy)2(acac)]), bis(benzo[h]quinolinolato)iridium(III) acetylacetonate (abbreviated as [Ir(bzq)2(acac)]), tris(benzo[h]quinolinolato)iridium(III) (abbreviated as [Ir(bzq)3]), tris(2-phenylquinolinolato-N,C 2’)iridium (III) (abbreviated as [Ir(pq)3]), bis(2-phenylquinoline-N, C 2’)iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridyl-κN2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridyl-κN]benzofuro[2,3-b]pyridin-7-yl- κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridyl-κN]phenyl-κC}iridium(III) (abbreviated as: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviated as: [Ir(ppy)2(mbfpypy-d3)), [2-(4-methyl-5-phenyl-2-pyridyl-κ N)phenyl-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mdppy)), [2-(4-d3-methyl-5-phenyl-2-pyridyl-κN2)phenyl-κC]bis[2-(5-d3-methyl-2-pyridyl-κN2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mdppy-d3)]), [2-methyl-(2-pyridyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2- Organometallic iridium complexes with a pyridine skeleton, such as [2-(4-methyl-5-phenyl-2-pyridyl-κN)phenyl-κC]iridium (III) (abbreviated as [Ir(ppy)2(mbfpypy)]), [2-(4-methyl-5-phenyl-2-pyridyl-κN)phenyl-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium (abbreviated as [Ir(ppy)2(mdppy)]), and tris{2-[5-(methyl-d3)-4-phenyl-2-pyridyl-κN]phenyl-κC}iridium (III) (abbreviated as Ir(5m4dppy-d3)3);(2-{1-(5-tert-butylbiphenyl-2-yl)-4-[3-tert-butyl-5-(4-phenyl-2-pyridyl-κN)phenyl-κC6]-2-benzimidazolyl-κN3}-4,6-di-tert-butylphenol-κO)platinum(II) (abbreviation: Pt(tBudppymmtBubiz-tBubp)), [2-(4-(3,5-di-tert-butylphenyl)-6-{3-[4-(5'-tert-butyl[1,1':3',1"-terphenyl]-2'-yl)-2-pyridyl-κN]phenyl-κC2}-2-pyridyl-κN]phenol-κO}platinum(II) Organometallic platinum complexes such as (abbreviated as Pt(4tButpppypyp-mmtBup)) and rare earth metal complexes such as terbium (III) tris(acetylacetonate)(monophenanthroline) (abbreviated as [Tb(acac)3(Phen)]). These substances are primarily compounds that emit phosphorescence with a green hue and have an emission peak in the 500nm to 600nm wavelength range. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their exceptional reliability and luminous efficiency. Compounds in which some of the hydrogen atoms in these compounds are deuterated may also be used.

[0201] In addition, organometallic iridium complexes having a pyrimidine skeleton include: (diisobutyrylmethane)bis[4,6-bis(3-methylphenyl)pyrimidinyl]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinyl](dipivaloylmethanyl)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di(naphthalene-1-yl)pyrimidinyl](dipivaloylmethanyl)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]); Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviated as [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethane)iridium(III) (abbreviated as [Ir(tppr)2(dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviated as [Ir(Fdpq)2(acac)]); tris(1-phenylisoquinoline-N,C 2’ )iridium (III) (abbreviated as [Ir(piq)3]), bis(1-phenylisoquinoline-N, C 2’Organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedione-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolyl-κN]phenyl-κC]iridium(III), and (3,7-diethyl-4,6-nonanedione-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolyl-κN]phenyl-κC]iridium(III). ; platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum (II) (abbreviated as PtOEP); and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviated as [Eu(DBM)3(Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviated as [Eu(TTA)3(Phen)]). These substances are compounds that emit phosphorescence with a red hue and have an emission peak in the wavelength range of 600nm to 700nm. In addition, organometallic iridium complexes having a pyrazine skeleton can produce red luminescence with good chromaticity. In addition, compounds in which some of the hydrogen atoms in these compounds are deuterated can also be used.

[0202] In one embodiment of the present invention, the luminescence efficiency is improved by using a deuterated compound as the luminescence center substance. Therefore, the luminescence center substance is preferably a deuterated material.

[0203] Furthermore, in addition to the above-mentioned phosphorescent compounds, known phosphorescent compounds can be selected and used.

[0204] As TADF materials, fullerene and its derivatives, acridine and its derivatives, and eosin derivatives can be used. In addition, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can also be used. As the metal-containing porphyrin, for example, there can be mentioned protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), protoporphyrin-tin fluoride complex (SnF2(Etio I)) and octaethylporphyrin-platinum chloride complex (PtCl2OEP) represented by the following structural formula.

[0205] [Chemical Formula 4]

[0206] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindole[2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazine-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-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), Heterocyclic compounds having one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, such as 5-triazine (abbreviation: PXZ-TRZ), 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-xanthene-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridinium)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracenes]-10'-one (abbreviation: ACRSA). The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and both electron transport and hole transport properties are high, so it is preferred. Among them, in the skeleton with a π-electron-deficient heteroaromatic ring, a pyridine skeleton, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and a triazine skeleton are stable and have good reliability, so it is preferred. In particular, the acceptor properties of the benzofuranopyrimidine skeleton, the benzothienopyrimidine skeleton, the benzofuranopyrazine skeleton, and the benzothienopyrazine skeleton are high and have good reliability, so it is preferred. In addition, in the skeleton with a π-electron-rich heteroaromatic ring, an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton and a pyrrole skeleton are stable and have good reliability, so it is preferred to have at least one of the above-mentioned skeletons. In addition, a dibenzofuran skeleton is preferably used as a furan skeleton, and a dibenzothiophene skeleton is preferably used as a thiophene skeleton. As the pyrrole skeleton, it is particularly preferred to use an indole skeleton, a carbazole skeleton, an indolecarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton. In a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded, 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 high, and the energy difference between the S1 energy level and the T1 energy level becomes small, so that thermally activated delayed fluorescence can be efficiently obtained, so it is particularly preferred. Note that an aromatic ring bonded with an electron-withdrawing group such as a cyano group can also be used instead of a π-electron-deficient heteroaromatic ring. In addition, as a π-electron-rich skeleton, an aromatic amine skeleton, a phenazine skeleton, etc. can be used.In addition, as the π-electron-deficient skeleton, 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, boranthrene, an aromatic ring having a nitrile or cyano group such as benzonitrile or cyanophenyl, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. can be used. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used to replace at least one of the π-electron-deficient heteroaromatic ring and the π-electron-rich heteroaromatic ring.

[0207] [Chemical Formula 5]

[0208] Alternatively, TADF materials can be used that are in thermal equilibrium between singlet and triplet excited states. These TADF materials have a short emission lifetime (excitation lifetime), thus suppressing efficiency degradation in high-brightness regions of light-emitting devices. Specifically, materials with the following molecular structures can be used.

[0209] [Chemical Formula 6]

[0210] TADF materials are materials with a small difference between the S1 and T1 energy levels and the ability to convert triplet excitation energy into singlet excitation energy through anti-intersystem crossing. Therefore, they can up-convert triplet excitation energy into singlet excitation energy (anti-intersystem crossing) using minimal thermal energy, efficiently generating singlet excited states. Furthermore, they can convert triplet excitation energy into luminescence.

[0211] The exciplex formed by two substances in an excited state has the function of a TADF material that can convert triplet excitation energy into singlet excitation energy due to the extremely small difference between the S1 energy level and the T1 energy level.

[0212] Note that as an indicator of the T1 level, a phosphorescence spectrum observed at a low temperature (e.g., 77 K to 10 K) can be used. Regarding TADF materials, when the wavelength energy of an extrapolated line obtained by cutting a line at the short-wavelength tail of the fluorescence spectrum is used as the S1 level and the wavelength energy of an extrapolated line obtained by cutting a line at the short-wavelength tail of the phosphorescence spectrum is used as the T1 level, it is preferred that the difference between the S1 level and the T1 level be 0.3 eV or less, more preferably 0.2 eV or less.

[0213] When a TADF material is used as a light-emitting substance, the S1 energy level of the host material is preferably higher than that of the TADF material. In addition, the T1 energy level of the host material is preferably higher than that of the TADF material.

[0214] The host material used for the light-emitting layer when the light-emitting layer has the structure of one embodiment of the present invention has been described in detail above, so repetition will be omitted. Since the light-emitting device of one embodiment of the present invention is a tandem light-emitting device, it includes multiple light-emitting layers. Therefore, some light-emitting layers may not have the above-described structure. In light-emitting layers that do not have this structure, various carrier transport materials such as organic compounds with electron-transport properties and / or organic compounds with hole-transport properties can be used as the host material.

[0215] As the organic compound having hole-transporting properties, an organic compound having an amine skeleton, a π-electron-rich heteroaromatic ring, or the like is preferably used. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring having at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton. Specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which these rings are further fused with an aromatic ring or a heteroaromatic ring is preferred.

[0216] Such hole-transporting substances preferably have any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, they may be aromatic amines containing a substituent having a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines containing a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. Note that when these hole-transporting substances are organic compounds having an N,N-bis(4-biphenyl)amino group, they are preferred because they allow the production of long-life light-emitting devices.

[0217] As such organic compounds, for example, the following organic compounds are preferably used: 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-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1B), P), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as: PCBANB), 4,4'-di(1-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviated as: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviated as: Compounds with aromatic amine skeletons such as PCBASF; 1,3-bis(N-carbazolyl)benzene (abbreviated as mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviated as CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), 3,9-bis(9-phenyl-9H-carbazole-3-yl)-9H-carbazole (abbreviated as PCCzPC), 9-(biphenyl-4-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviated as PCCzBP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviated as BisB PCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviated as BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviated as mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviated as βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviated as 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'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviated as: PCCzTp), 9,9'-bis(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenyl-2-yl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, N,N-bis(9,9 Compounds having a carbazole skeleton, such as 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviated as PSiCzCz), and 9'-[3-(triphenylsilyl)phenyl]-9'H-9,3':6',9"-tricarbazole (abbreviated as PSiCzGI); 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviated as DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III), and 4-[4-(9-phenyl-9H Compounds having a thiophene skeleton, such as 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviated as DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II), are also preferred. Among them, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability and high hole transport properties and contribute to lowering the driving voltage. In addition, the organic compounds listed as examples of materials having hole transport properties can also be used.

[0218] As an organic compound having electron-transporting properties, an organic compound containing a π-electron-deficient heteroaromatic ring is preferably used. Examples of organic compounds containing a π-electron-deficient heteroaromatic ring include organic compounds containing a heteroaromatic ring having an azole skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, organic compounds containing a heteroaromatic ring having a diazine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton.

[0219] Among them, organic compounds containing heteroaromatic rings having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing heteroaromatic rings having a pyridine skeleton, or organic compounds containing heteroaromatic rings having a triazine skeleton have good reliability and are therefore preferred. In particular, organic compounds containing heteroaromatic rings having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings having a triazine skeleton have high electron transport properties, which contribute to reducing the driving voltage. In addition, benzofuranopyrimidine skeletons, benzothienopyrimidine skeletons, benzofuranopyrazine skeletons, and benzothienopyrazine skeletons have high acceptor properties and high reliability, so they are preferred.

[0220] As the organic compound containing a π-electron-deficient heteroaromatic ring, for example, the following organic compounds are preferably used: 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenyl)-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-phenyltriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPB Organic compounds having an azole skeleton, such as benzothiophene-1H-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviated as mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviated as BzOS); 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviated as 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviated as TmPyPB), bathophenanthroline (abbreviated as BPhen), bathocuproin (abbreviated as BCP), 2,9-di(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), 2,2'-(1,3-phenylene) Organic compounds containing a heteroaromatic ring having a pyridine skeleton, such as bis(9-phenyl-1,10-phenanthroline) (abbreviated as: mPPhen2P), 2-[3-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as: mTpPPhen), 2-phenyl-9-(2-triphenylene)-1,10-phenanthroline (abbreviated as: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthyl]-1,10-phenanthroline (abbreviated as: PnNPhen), and 2-[4-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as pTpPPhen); 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTPDBq -II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-Ⅱ), 9-[(3'-dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3'-(dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mP nP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviated as: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviated as: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviated as: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviated as: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviated as: 4,6mCzBP2Pm), [phenyl]benzofuro[2,3-b]pyrazine (abbreviated as: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviated as: 8mDBtBPNfpm), 8-[(2,2'-binaphthyl)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as: 8(βN2)-4mDB tPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviated as 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), 2,6-bis(4-naphthyl-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviated as 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviated as PC-cgDBCzQz), 8-(p-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]- ]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6'(P-Bqn)2BPy), and other organic compounds having a diazine skeleton; 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluorene] -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), 5-triazine (abbreviated as mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviated as, mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviated as: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl] ... Abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazine-2-yl]-11,12-dihydro-12-phenylindole[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylene-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazine-2-yl)-2- dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviated as PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1"-terphenyl)-4-yl-1-dibenzofuranyl}-1,3,5-triazine (abbreviated as mBP-TPDBfTzn), 2-[4-(2-naphthyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-triazine (abbreviated as βNP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviated as SiTr zCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviated as: mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazine-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviated as: BP-mBPIcz(II)Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviated as: mPCPDBfTzn), 9,9'-[6-(biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole (abbreviated as: PDBf-PCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviated as: PCzDBtTzn), 2,4,6-tris(2-pyridyl)-1, Organic compounds containing heteroaromatic rings with a triazine skeleton, such as 3,5-triazine (abbreviated as 2Py3Tzn). In addition, organic compounds containing heteroaromatic rings with a diazine skeleton, organic compounds containing heteroaromatic rings with a pyridine skeleton, and organic compounds containing heteroaromatic rings with a triazine skeleton are preferred because they have high reliability. In particular, organic compounds containing heteroaromatic rings with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings with a triazine skeleton have high electron transport properties, which helps to reduce the driving voltage.

[0221] TADF materials that can be used as host materials can be the same materials listed above as TADF materials that can be used as luminescent center materials. When using a TADF material as a host material, the triplet excitation energy generated by the TADF material is converted to singlet excitation energy through reverse intersystem crossing, and this energy is transferred to the luminescent material, thereby improving the luminescence efficiency of the light-emitting device. In this case, the TADF material acts as an energy donor, and the luminescent material acts as an energy acceptor.

[0222] This is particularly effective when the luminescent material is a fluorescent material. Furthermore, in order to achieve high luminous efficiency, the S1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent material. Furthermore, the T1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent material. Therefore, the T1 energy level of the TADF material is preferably higher than the T1 energy level of the fluorescent material.

[0223] Furthermore, it is preferable to use a TADF material that emits light at a wavelength that overlaps with the lowest energy absorption band of the fluorescent substance. This is preferable because the excitation energy is smoothly transferred from the TADF material to the fluorescent substance, allowing efficient emission of light.

[0224] In order to efficiently generate singlet excitation energy from triplet excitation energy by anti-intersystem crossing, carrier recombination is preferably generated in TADF material. In addition, it is preferred that the triplet excitation energy generated in TADF material is not transferred to the triplet excitation energy of fluorescent material. For this reason, fluorescent material preferably has a protecting group around the luminophore (the skeleton that becomes the cause of luminescence) possessed by fluorescent material. As the protecting group, it is preferably a substituent without a π bond, preferably a saturated hydrocarbon, specifically, an alkyl group having 3 or more and 10 or less carbon atoms, a cycloalkyl group having 3 or more and 10 or less carbon atoms, a trialkylsilyl group having 3 or more and 10 or less carbon atoms, more preferably having multiple protecting groups. The substituent without a π bond has almost no function of transmitting carriers, so it has almost no effect on carrier transport or carrier recombination, and the TADF material and the luminophore of the fluorescent material can be kept away from each other. Here, luminophore refers to the atomic group (skeleton) that becomes the cause of luminescence in the fluorescent material. The luminophore preferably has a π bond skeleton, preferably contains an aromatic ring, and preferably has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of the luminophore include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, skeleton, triphenylene skeleton, tetracene skeleton, pyrene skeleton, perylene skeleton, coumarin skeleton, quinacridone skeleton, naphthobisbenzofuran skeleton, etc. In particular, the skeletons having naphthalene skeleton, anthracene skeleton, fluorene skeleton, Fluorescent substances having a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because they have high fluorescence quantum yields.

[0225] When a fluorescent substance is used as a luminescent center substance, a material having an anthracene skeleton is preferably used as a host material. By using a substance having an anthracene skeleton as a host material of a fluorescent substance, a light-emitting layer with high luminous efficiency and durability can be achieved. Among the substances with an anthracene skeleton used as host materials, substances with a diphenylanthracene skeleton, especially substances with a 9,10-diphenylanthracene skeleton) are chemically stable, so they are preferred. In addition, when the host material has a carbazole skeleton, the injection / transport properties of holes are improved, so it is preferred, but when a benzocarbazole skeleton having a benzene ring fused to a carbazole skeleton is used, its HOMO is about 0.1eV higher than that of a host material with a carbazole skeleton and is easy to inject holes, so it is more preferred. In particular, when the host material has a dibenzocarbazole skeleton, its HOMO is about 0.1eV higher than that of a host material with a carbazole skeleton, not only is it easy to inject holes, but the hole transport and heat resistance are also improved, so it is preferred. Therefore, as a host material, a material having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton) is more preferred. Note that from the perspective of the hole injection / transport properties, 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 (abbreviated as PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPN), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviated as CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviated as cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviated as 2mBnfPPA), 9-phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-9H-carbazole (abbreviated as CzPA),

[0015] anthracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracene-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)benzo[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), and the like. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred because they exhibit very good properties.

[0226] Alternatively, the host material can be a mixture of multiple substances. When using a mixed host material, it is preferred to mix a material with electron-transporting properties with a material with hole-transporting properties. By mixing materials with electron-transporting properties, the transport properties of the light-emitting layer 113 can be adjusted more easily, and the recombination area can be more easily controlled. The weight ratio of the hole-transporting material to the electron-transporting material can be between 1:19 and 19:1.

[0227] Note that a phosphorescent substance may be used as part of the mixed material. When a fluorescent substance is used as the luminescent substance, the phosphorescent substance may be used as an energy donor for supplying excitation energy to the fluorescent substance.

[0228] Furthermore, these mixed materials can also be used to form an exciplex. Selecting a combination of mixed materials to form an exciplex that emits light at a wavelength that overlaps with the lowest energy absorption band of the luminescent substance is preferred because it facilitates energy transfer and allows for efficient luminescence. Furthermore, this structure is preferred because it reduces the driving voltage.

[0229] The first electron transport layer 114_1 is a layer containing a substance having an electron transport property. The substance having an electron transport property preferably has an electron mobility of 1×10 -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 / Vs or more. As long as the electron transport property is higher than the hole transport property of the substance, substances other than the above can be used. As the above-mentioned substance, it is preferred to use an organic compound containing a π-electron-deficient heteroaromatic ring. As an organic compound containing a π-electron-deficient heteroaromatic ring, for example, it is preferred to use an organic compound containing a heteroaromatic ring having an azole skeleton, an organic compound containing a heteroaromatic ring having a pyridine skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton and an organic compound containing a heteroaromatic ring having a triazine skeleton. One or more of the organic compounds are preferably used, and it is particularly preferred to use an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0230] As the organic compound having an electron-transporting property that can be used in the first electron-transporting layer 114_1, the same organic compound having an electron-transporting property that can be used as the host material in the first light-emitting layer 113_1 and the second light-emitting layer 113_2 can be used. In particular, organic compounds containing heteroaromatic rings having a diazine skeleton, organic compounds containing heteroaromatic rings having a pyridine skeleton, and organic compounds containing heteroaromatic rings having a triazine skeleton are preferred due to their good reliability. In particular, organic compounds containing heteroaromatic rings having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings having a triazine skeleton have high electron-transporting properties, which helps reduce the driving voltage.

[0231] As described above, the second electron transport layer 114_2 includes a first organic compound having a triazine skeleton, and the details thereof have been described above and will not be repeated here.

[0232] Note that the first electron-transport layer 114_1 preferably includes an organic compound having a triazine skeleton to reduce power consumption. In particular, the organic compound having a triazine skeleton included in the first electron-transport layer 114_1 is preferably the same as the organic compound having a triazine skeleton included in the second electron-transport layer 114_2. This reduces the complexity of the manufacturing equipment and is also advantageous from the perspective of raw material procurement costs.

[0233] Alternatively, when the first electron transport layer 114_1 includes an organic compound that does not have a triazine skeleton, carrier transport properties can be easily controlled, thereby providing a light-emitting device with better characteristics. As the organic compound that does not have a triazine skeleton, an organic compound containing a heteroaromatic ring having a pyridine skeleton or an organic compound containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton is preferably used.

[0234] The intermediate layer 116 includes a second organic compound having a phenanthroline skeleton. Figure 1A As shown, intermediate layer 116 preferably includes a first layer 119 containing a second organic compound having a phenanthroline skeleton. Furthermore, intermediate layer 116 preferably includes a second layer 117 containing a ninth organic compound having hole-transporting properties and a substance having acceptor properties. Furthermore, second layer 117 is positioned closer to second electrode 102 than first layer 119. Intermediate layer 116 may also include a third layer 118 between first layer 119 and second layer 117.

[0235] The details of the first layer have been described above and repeated description is omitted.

[0236] Furthermore, the first layer 119 may further include an organic compound having an electron-transporting property. The organic compound having an electron-transporting property that can be used as the host material in the first light-emitting layer 113_1 and the second light-emitting layer 113_2 can be used. Furthermore, the organic compound preferably includes two or more heteroaromatic rings bonded or fused to each other, and the two or more heteroaromatic rings contain a total of three or more heteroatoms. This further improves resistance to photolithography and suppresses increases in driving voltage.

[0237] Note that the first layer 119 can be a stacked structure of a layer containing an organic compound and a layer containing a metal or a metal compound located closer to the cathode side than the layer containing the organic compound, or it can be a mixed layer of an organic compound and a metal or a metal compound. When the first layer is a mixed layer, fewer deposition processing chambers are required, the manufacturing cost is reduced, and it helps to improve the stability of the light-emitting device, so it is preferred.

[0238] 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 exhibit approximately the same trend when analyzing the first layer 119 in the thickness direction. In other words, when the distribution of the organic compound is constant, the distribution of the metal or metal compound is also approximately constant. In a stacked structure of a layer containing an organic compound and a layer containing a metal or metal compound, the metal or metal compound may sometimes be detected in areas outside of the layer due to diffusion from the layer containing the metal or metal compound. However, since the distribution differs from that of the organic compound, the analysis results can be distinguished between diffusion and mixing.

[0239] The second layer 117 preferably contains a ninth organic compound having a hole-transporting property. Furthermore, the second layer 117 preferably further contains a substance exhibiting an acceptor property. The substance exhibiting an acceptor property is preferably an organic compound exhibiting an acceptor property for the ninth organic compound.

[0240] When the second layer 117 contains the ninth organic compound and a substance that accepts the ninth organic compound, holes are generated by charge separation. When a voltage is applied between the first electrode 101 and the second electrode 102, these holes are injected into the cathode-side second light-emitting unit 502 through the ninth organic compound. Thus, the light-emitting device 130 according to one embodiment of the present invention can be a light-emitting device with a low driving voltage.

[0241] As the ninth organic compound having hole transport properties, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, high molecular weight compounds (oligomers, dendrimers, polymers, etc.) can be used. In addition, as the ninth organic compound, it is preferable to use an organic compound having a hole mobility of 1×10 -6 cm 2 / Vs or more organic compound. Furthermore, the ninth organic compound is preferably a compound comprising a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. The fused aromatic hydrocarbon ring is preferably an anthracene ring, a naphthalene ring, or the like. Furthermore, the π-electron-rich heteroaromatic ring is preferably a fused aromatic ring having at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton, and more preferably a carbazole ring, a dibenzothiophene ring, or a ring in which these rings are further fused with an aromatic ring or a heteroaromatic ring.

[0242] Such an organic compound having hole-transporting properties preferably has any one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, it may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine containing 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. Note that when these organic compounds having hole-transporting properties include an N,N-bis(4-biphenyl)amino group, they are preferred because they allow the production of light-emitting devices with long lifetimes.

[0243] As the organic compound having a hole-transporting property, specifically, the organic compounds exemplified as the organic compound having a hole-transporting property that can be used for the hole-injection layer 111 can be used in the same manner.

[0244] As a substance having acceptor properties, for example, the substances mentioned as organic compounds having acceptor properties that can be used for the hole injection layer 111 can be used in the same manner. In particular, it is preferred to use an organic compound having at least one of a halogen group and a cyano group, and it is more preferred to use an organic compound having at least one of a fluorine group and a cyano group. In addition, the total number of halogen groups (fluorine) and cyano groups contained in the organic compound is more preferably 4 or more. As an organic compound having at least one of a halogen group and a cyano group, for example, α, α', α"-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorophenylacetonitrile], α, α', α"-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)phenylacetonitrile], α, α', α"-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorophenylacetonitrile], etc. can be mentioned.

[0245] Furthermore, the acceptor substance preferably has electron acceptor properties for the ninth organic compound having hole transport properties. When the acceptor substance has electron acceptor properties for the ninth organic compound, charge separation occurs, and the second layer 117 can be used as a charge generation layer and as an intermediate layer of a tandem light-emitting device. Furthermore, in the second layer 117, it is preferable to observe a signal observed by electron spin resonance. For example, the spin density resulting from the signal observed near a g value of 2.00 is preferably 1×10 17 spins / cm 3 More than 1×10 18 spins / cm 3 More than 1×10 19 spins / cm 3 above.

[0246] The third layer 118 contains a substance with electron transport properties and has the functions of preventing the interaction between the first layer 119 and the second layer 117, smoothly transferring electrons to reduce the driving voltage, and reducing the interaction between the first layer 119 and the second layer 117 to improve reliability.

[0247] The LUMO energy level of the substance having electron transport properties contained in the third layer 118 is preferably equal to the LUMO energy level of the substance having acceptor properties in the second layer 117 and the LUMO energy level of the layer ( Figure 1A Between the LUMO energy levels of the organic compound included in the first electron transport layer 114_1 in the first light-emitting unit 501.

[0248] Specifically, the LUMO energy level of the electron-transporting substance used in the third layer 118 is preferably -5.0 eV or higher, preferably -5.0 eV or higher and -3.0 eV or lower, more preferably -4.30 eV or higher and -3.00 eV or lower, and even more preferably -4.30 eV or higher and -3.30 eV or lower. This is preferable because it can suppress increases in the driving voltage of the light-emitting device. Furthermore, the electron-transporting substance used in the third layer 118 is preferably a phthalocyanine material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0249] As the electron-transporting substance used in the third layer 118, specifically, diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine (abbreviated as HATNA-F6), perylenetetracarboxylic acid derivatives such as 3,4,9,10-perylenetetracarboxylic acid diimide (abbreviated as PTCDI), 3,4,9,10-perylenetetracarboxylic acid-bis-benzimidazole (abbreviated as PTCBI), (C60-Ih)[5,6]fullerene (abbreviated as C60), and (C70-D5h)[5,6]fullerene (abbreviated as C70) can be used. In addition, a compound having a heterocyclic ring-containing cyclophenane skeleton can be used. As such a compound, a phthalocyanine compound such as phthalocyanine (abbreviated as H2Pc) can be used. In addition, metal phthalocyanines containing copper, zinc, cobalt, iron, chromium, nickel, etc., such as copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc), cobalt phthalocyanine (CoPc), iron phthalocyanine (FePc), tin phthalocyanine (SnPc), tin phthalocyanine oxide (SnOPc), titanium phthalocyanine oxide (TiOPc), and vanadium phthalocyanine oxide (VOPc), and their derivatives can be used. In particular, phthalocyanine metal complexes such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluorobisquinoxalino[2,3-a:2',3'-c]phenazine are preferably used.

[0250] Furthermore, the film thickness of the third layer 118 is preferably greater than or equal to 1 nm and less than or equal to 10 nm, and more preferably greater than or equal to 2 nm and less than or equal to 5 nm.

[0251] In addition, since the second layer 117 in the intermediate layer 116 is used as a hole injection layer, the second light-emitting unit 502 is not provided with a hole injection layer, but the second light-emitting unit 502 may also be provided with a hole injection layer.

[0252] The second electrode 102 is an electrode including a cathode. The second electrode 102 may also have a stacked structure, in which case the layer in contact with the organic compound layer 103 serves as a cathode. As a material forming the cathode, metals, alloys, conductive compounds, and mixtures thereof with a small work function (specifically, less than 3.8 eV) can be used. 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 them (MgAg, AlLi), rare earth metals such as europium (Eu), and ytterbium (Yb), and alloys containing them. Specifically, for example, alkali metals, alkaline earth metals, rare earth metals, compounds or complexes thereof, or electron compounds thereof such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-hydroxyquinoline-lithium (abbreviated as: Liq), and ytterbium (Yb) can be cited. Examples of electron compounds include those obtained by adding electrons to a mixed oxide of calcium and aluminum at a high concentration. Furthermore, a mixture of two or more of the above materials may be used. When the second electrode 102 has a laminated structure, a material having good conductivity may be used for portions other than the cathode without regard for the work function.

[0253] 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 obtained.

[0254] In addition, when the second electrode 102 is formed of a material that transmits visible light, a light-emitting device that emits light from the second electrode 102 side can be formed.

[0255] These conductive materials can be deposited by dry methods such as vacuum deposition and sputtering, inkjet, spin coating, etc. Alternatively, they can be formed by wet methods such as sol-gel or wet methods using a metal material paste.

[0256] The organic compound layer 103 can be formed by various methods, whether dry or wet, such as vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating.

[0257] In addition, the above-mentioned electrodes or layers may be formed by using different deposition methods.

[0258] Figure 1C 130 and 130b are diagrams illustrating two adjacent light-emitting devices (a light-emitting device 130a and a light-emitting device 130b) included in a display device according to one embodiment of the present invention.

[0259] The light emitting device 130a includes an organic compound layer 103a between the first electrode 101a and the second electrode 102 on the insulating layer 175. The organic compound layer 103a has a structure in which the first light emitting unit 501a and the second light emitting unit 502a are stacked with the intermediate layer 116a interposed therebetween. Figure 1C While an example of two stacked light-emitting units is shown, a structure with three or more stacked light-emitting units may also be employed. 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 may or may not be included. The second light-emitting unit 502a includes a second hole transport layer 112a_2, a second light-emitting layer 113a_2, and a second electron transport layer 114a_2.

[0260] The light emitting device 130b includes an organic compound layer 103b between the first electrode 101b and the second electrode 102 on the insulating layer 175. The organic compound layer 103b has a structure in which the first light emitting unit 501b and the second light emitting unit 502b are stacked with the intermediate layer 116b interposed therebetween. Figure 1C While an example of two stacked light-emitting units is shown, a structure with three or more stacked light-emitting units may also be employed. 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 may or may not be included. The second light-emitting unit 502b includes a second hole transport layer 112b_2, a second light-emitting layer 113b_2, and a second electron transport layer 114b_2.

[0261] The second electron-transport layer 114a_2 and the second electron-transport layer 114b_2 are layers containing a first organic compound having a triazine skeleton, and the first layer 119a and the first layer 119b are layers containing a second organic compound having a phenanthroline skeleton.

[0262] 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 they contain are preferably compounds whose maximum peak wavelength difference in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. Furthermore, they preferably contain the same luminescent center substance. Furthermore, the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are preferably composed of the same material. Preferably, either the first light-emitting layer 113a_1 or the second light-emitting layer 113a_2 has the structure of a light-emitting layer according to one embodiment of the present invention described above.

[0263] The first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 preferably emit light of similar colors. Furthermore, the luminescent center substances they contain are preferably compounds whose maximum peak wavelength difference in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. Furthermore, they preferably contain the same luminescent center substance. Furthermore, the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are preferably composed of the same material. Preferably, either the first light-emitting layer 113b_1 or the second light-emitting layer 113b_2 has the structure of a light-emitting layer according to one embodiment of the present invention described above.

[0264] Furthermore, it is preferred 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. Furthermore, the emission colors of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are preferably different from the emission colors of the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2. Furthermore, it is preferred that the luminescence center substance contained in the first light-emitting layer 113a_1 be different from the luminescence center substance contained in the first light-emitting layer 113b_1, and the luminescence center substance contained in the second light-emitting layer 113a_2 be different from the luminescence center substance contained in the second light-emitting layer 113b_2.

[0265] In addition, 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, 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 can each be a continuous layer or can be separated between the light-emitting device 130a and the light-emitting device 130b. By adopting a continuous layer, productivity is improved, so that inexpensive light-emitting devices can be manufactured. By adopting a layer separated between each light-emitting device, a material suitable for the luminescent color can be used, so that a light-emitting device or display device with good characteristics can be manufactured. In particular, it is preferable to use a continuous layer as the second electron transport layer 114a_2 and the second electron transport layer 114b_2 because both the light-emitting device 130a and the light-emitting device 130b can have good characteristics.

[0266] Continuous layers mean that second electron transport layer 114a_2 and second electron transport layer 114b_2 are composed of the same material. In other words, by using the same material to form second electron transport layer 114a_2 and second electron transport layer 114b_2, both light-emitting devices 130a and 130b can have excellent characteristics. Furthermore, second electron transport layer 114a_2 and second electron transport layer 114b_2 preferably have the same structure, and even more preferably, have the same structure.

[0267] Furthermore, in the case where the luminescent center substance included in the first luminescent layer 113a_1 is different from the luminescent center substance included in the first luminescent layer 113b_1 and the luminescent center substance included in the second luminescent layer 113a_2 is different from the luminescent center substance included in the second luminescent layer 113b_2 (for example, the first luminescent layer 113a_1 and the second luminescent layer 113a_2 are blue fluorescent luminescent layers, and the first luminescent layer 113b_1 and the second luminescent layer 113b_2 are green fluorescent luminescent layers), (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 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 light-emitting layers of light-emitting devices 130a and 130b have different carrier balances. Therefore, in many cases, in order to achieve the respective performance of light-emitting devices 130a and 130b, it is necessary to select and use appropriate intermediate layers and electron transport layers, respectively. However, by using a layer containing a first organic compound having a triazine skeleton as the second electron transport layer 114a_2 and the second electron transport layer 114b_2, and using a layer containing a second organic compound having a phenanthroline skeleton as the first layer 119a and the first layer 119b, even if the second electron transport layer 114a_2 and the second electron transport layer 114b_2 have the same structure, the performance of both the light-emitting device 130a and the light-emitting device 130b can be achieved. In other words, it is possible to achieve both improved productivity and improved performance. In addition, the first layer 119a and the first layer 119b can also have the same structure.

[0268] Note that the continuous layer refers to a so-called common layer formed across both the light-emitting device 130 a and the light-emitting device 130 b .

[0269] Figure 2A yes Figure 1C Example of a variation. Light-emitting devices 130a and 130b1 emit different colors, so the optical path length between the electrodes that can amplify light emission through the microcavity is different. Therefore, in light-emitting device 130b1, the distance between the electrodes can be adjusted by increasing the thickness of the light-emitting layer, such as in light-emitting layers 113b_11 and 113b_21. Alternatively, the optical path length can be changed by increasing the thickness of the functional layer, such as in hole transport layer 112b_21, or by adding additional functional layers.

[0270] Figure 2B A diagram showing three adjacent light-emitting devices (a light-emitting device 130 a , a light-emitting device 130 b 1 , and a light-emitting device 130 c ) included in a display device according to one embodiment of the present invention.

[0271] The light emitting device 130c includes an organic compound layer 103c between the first electrode 101c and the second electrode 102 on the insulating layer 175. The organic compound layer 103c has a structure in which the first light emitting unit 501c and the second light emitting unit 502c are stacked with the intermediate layer 116c interposed therebetween. Figure 2B While an example of stacking two light-emitting units is shown, three or more light-emitting units may also be stacked. 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 may or may not be included. The second light-emitting unit 502c includes a second hole transport layer 112c_2, a second light-emitting layer 113c_2, and a second electron transport layer 114c_2.

[0272] The wavelength of the light emitting device 130c is assumed to be shorter than that of the light emitting devices 130a and 130b1. The inter-electrode distance of the light emitting device 130c is adjusted by setting the thickness of the first light emitting layer 113c_1 and the second light emitting layer 113c_2 to be thinner than those of the other two light emitting devices.

[0273] The second electron-transport layer 114c_2 is a layer containing a first organic compound having a triazine skeleton, and the first layer 119c is a layer containing a second organic compound having a phenanthroline skeleton.

[0274] The first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 preferably emit light of similar colors. Furthermore, the luminescent center substances they contain are preferably compounds whose maximum peak wavelength difference in their emission spectra is 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. Furthermore, they preferably contain the same luminescent center substance. Furthermore, the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 are preferably composed of the same material. Preferably, either the first light-emitting layer 113c_1 or the second light-emitting layer 113c_2 has the structure of a light-emitting layer according to one embodiment of the present invention described above.

[0275] Furthermore, it is preferred that the first light-emitting layer 113a_1 be separated from the first light-emitting layer 113c_1, and the second light-emitting layer 113a_2 be separated from the second light-emitting layer 113c_2. Furthermore, the emission colors of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are preferably different from the emission colors of the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2. Furthermore, it is preferred that the luminescence center substance contained in the first light-emitting layer 113a_1 be different from the luminescence center substance contained in the first light-emitting layer 113c_1, and the luminescence center substance contained in the second light-emitting layer 113a_2 be different from the luminescence center substance contained in the second light-emitting layer 113c_2.

[0276] Note that the following example is 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), and the second hole transport layer 112a_2 and the second hole transport layer 112c_2 are independent and separate layers between 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, a light-emitting device can include both continuous layers and separate layers. As a result, a light-emitting device or display device with a balance between productivity and characteristics can be manufactured. In particular, the second electron transport layer 114a_2 and the second electron transport layer 114c_2 are preferably continuous layers, thereby enabling both the light-emitting device 130a and the light-emitting device 130c to have good characteristics.

[0277] For example, when two of the three color light-emitting devices include fluorescent luminescence center substances and one includes phosphorescent luminescence center substances, it is preferable that the carrier transport layer be formed as a continuous layer in the light-emitting device including the fluorescent luminescence center substance, and that the carrier transport layer be formed as a layer separate from the light-emitting devices exhibiting other luminescence colors in the light-emitting device including the phosphorescent luminescence center substance. Alternatively, when two of the three color light-emitting devices include phosphorescent luminescence center substances and one includes fluorescent luminescence center substances, it is preferable that the carrier transport layer be formed as a continuous layer in the light-emitting device including the phosphorescent luminescence center substance, and that the carrier transport layer be formed as a layer separate from the light-emitting devices exhibiting other luminescence colors in the light-emitting device including the fluorescent luminescence center substance.

[0278] The 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 excellent 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 good visibility capable of displaying at high brightness. Furthermore, this embodiment can be freely combined with other embodiments.

[0279] Implementation Method 2 In this embodiment, referring to Figure 3A and Figure 3B A display device manufactured using the light-emitting device described in Embodiment 1 will be described. Note that Figure 3A is a top view showing a display device, and Figure 3B It is along Figure 3A , a cross-sectional view taken along lines AB and CD in FIG. This display device includes a driver circuit portion (source line driver circuit) 601, a pixel portion 602, and a driver circuit portion (gate line driver circuit) 603, indicated by dashed lines, as a unit for controlling light emission from the light-emitting device. Reference numeral 604 denotes a sealing substrate, reference numeral 605 denotes a sealing material, and the space within the area surrounded by the sealing material 605 is a space 607.

[0280] Note that the guide wiring 608 is used to transmit 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 the FPC (flexible printed circuit) 609 serving as an external input terminal. Note that although only the FPC is shown here, the FPC can also be mounted with a printed wiring board (PWB). The display device in this specification includes not only the display device body but also a display device mounted with an FPC or PWB.

[0281] Below, refer to Figure 3B A cross-sectional structure will be described. A driver circuit portion and a pixel portion are formed over an element substrate 610 , but here, a source line driver circuit 601 as a driver circuit portion and one pixel in a pixel portion 602 are shown.

[0282] The element substrate 610 may be 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.

[0283] There are no particular restrictions on the structure of transistors used in pixels and driver circuits. For example, inverted-staggered transistors or staggered transistors may be used. Furthermore, top-gate transistors or bottom-gate transistors may also be used. There are no particular restrictions on the semiconductor material used for the transistors; for example, silicon, germanium, silicon carbide, gallium nitride, etc. may be used. Alternatively, oxide semiconductors containing at least one of indium, gallium, and zinc, such as In-Ga-Zn metal oxides, may also be used.

[0284] There are no particular restrictions on the crystallinity of the semiconductor material used for the transistor, and an amorphous semiconductor or a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part thereof) can be used. The use of a crystalline semiconductor is preferred because it can suppress the degradation of transistor characteristics.

[0285] Here, oxide semiconductors are preferably used in semiconductor devices such as transistors provided in the above-mentioned pixels and driver circuits and transistors used in touch sensors and the like described later. Oxide semiconductors having a wider band gap than silicon are particularly preferred. By using oxide semiconductors having a wider band gap than silicon, the off-state current of the transistor can be reduced.

[0286] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn). In addition, the oxide semiconductor is more preferably an oxide semiconductor containing an oxide represented by an In-M-Zn oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0287] In particular, as a semiconductor layer, it is preferred to use an oxide semiconductor film having multiple crystal parts in which the c-axis is oriented in a direction perpendicular to the formed surface of the semiconductor layer or the top surface of the semiconductor layer and has no grain boundaries between adjacent crystal parts.

[0288] By using the above-mentioned materials as the semiconductor layer, variations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0289] Furthermore, because transistors with this semiconductor layer have a low off-state current, they can retain charge stored in capacitors via the transistors for a long period of time. By using these transistors in pixels, the driver circuit can be stopped while maintaining the grayscale of the image displayed in each display area. This results in electronic devices with extremely low power consumption.

[0290] In order to achieve the stabilization of transistor characteristics, etc., it is preferable to provide a base film. As the base film, an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film can be used and manufactured in a single layer or a stacked layer. The base film can be formed by sputtering, CVD (Chemical Vapor Deposition) method (plasma CVD method, thermal CVD method, MOCVD (Metal Organic CVD: Organic Metal Chemical Vapor Deposition) method, etc.), ALD (Atomic Layer Deposition) method, coating method, printing method, etc. Note that the base film can be omitted if it is not required.

[0291] Note that FET 623 is one of the transistors formed in the driver circuit portion 601. Alternatively, the driver circuit may be formed using various CMOS circuits, PMOS circuits, or NMOS circuits. Furthermore, although this embodiment shows a driver-integrated type in which the driver circuit is formed on the substrate, this structure is not necessarily required. The driver circuit may also be formed externally rather than on the substrate.

[0292] In addition, the pixel portion 602 is formed by multiple pixels, each of which includes a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to the drain of the current control FET 612, but is not limited to this. A pixel portion combining more than three FETs and capacitors can also be used.

[0293] Note that the insulator 614 is formed so as to cover the end portion of the first electrode 613. Here, the insulator 614 can be formed using a positive photosensitive acrylic resin film.

[0294] Furthermore, a curved surface with a curvature is formed at the upper or lower end of the insulator 614 to ensure good coverage with the organic compound layer, etc., which will be formed later. For example, when a positive-type photosensitive acrylic resin is used as the material for the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface with a curvature radius of 0.2 μm to 3 μm. Either a negative-type photosensitive resin or a positive-type photosensitive resin can be used as the insulator 614.

[0295] An organic compound layer 616 and a second electrode 617 are formed on the first electrode 613. A material having a large work function is preferably used as the material for the first electrode 613, which serves as the anode. For example, in addition to single-layer films such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 to 20% zinc oxide by weight, a titanium nitride film, a chromium film, a tungsten film, a Zn film, and a Pt film, a stacked layer consisting of a titanium nitride film and a film primarily composed of aluminum, or a three-layer structure consisting of a titanium nitride film, a film primarily composed of aluminum, and a titanium nitride film can also be used. Note that using a stacked layer structure can reduce the wiring resistance, achieve good ohmic contact, and enable the use of the anode.

[0296] The organic compound layer 616 is formed by various methods such as vapor deposition using a vapor deposition mask, inkjet coating, and spin coating. The organic compound layer 616 has the structure described in Embodiment 1. Alternatively, low molecular weight compounds or high molecular weight compounds (including oligomers and dendrimers) may be used as other materials constituting the organic compound layer 616.

[0297] In addition, as a material for the second electrode 617 formed on the organic compound layer 616 and serving as a cathode, a material having a small work function (such as Al, Mg, Li, Ca, or alloys and compounds thereof (such as MgAg, MgIn, and AlLi)) 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 stacked layer composed of a thin metal film and a transparent conductive film (such as ITO, indium oxide containing 2% to 20% by weight of zinc oxide, indium tin oxide containing silicon, and zinc oxide (ZnO)) as the second electrode 617.

[0298] Furthermore, a light-emitting device is formed by a first electrode 613, an organic compound layer 616, and a second electrode 617. This light-emitting device is the light-emitting device described in Embodiment 1. Furthermore, a pixel portion is formed by a plurality of light-emitting devices, and the display device of this embodiment may include both the light-emitting device described in Embodiment 1 and a light-emitting device having another structure.

[0299] Furthermore, the sealing substrate 604 is bonded to the element substrate 610 using the sealing material 605, and the light-emitting device 618 is disposed in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filler. This filler can be an inert gas (nitrogen, argon, etc.) or a sealing material. Forming a recess in the sealing substrate and providing a desiccant therein is preferred because degradation due to moisture can be suppressed.

[0300] Epoxy resin or glass frit is preferably used as the sealing material 605. These materials are preferably as impermeable to moisture and oxygen as possible. The sealing substrate 604 may be made of a glass substrate or a quartz substrate, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, or acrylic resin.

[0301] Although Figure 3B Although not shown, a protective film may be provided on the second electrode 617. The protective film may be formed of an organic resin film or an inorganic insulating film. Alternatively, the protective film may be formed so as to cover the exposed portion of the sealing material 605. Furthermore, the protective film may be provided to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, etc.

[0302] The protective film can be made of a material that is not easily permeable to impurities such as water. Therefore, it is possible to effectively suppress the diffusion of impurities such as water from the outside to the inside.

[0303] As materials constituting the protective film, oxides, nitrides, fluorides, sulfides, ternary compounds, metals or polymers can be used. For example, materials 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 or indium oxide can be used; materials containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride or gallium nitride can be used; materials containing nitrides containing titanium and aluminum, oxides containing titanium and aluminum, oxides containing aluminum and zinc, sulfides containing manganese and zinc, sulfides containing cerium and strontium, oxides containing erbium and aluminum, oxides containing yttrium and zirconium, etc. can be used.

[0304] The protective film is preferably formed using a deposition method with good step coverage. One such method is atomic layer deposition (ALD). Materials that can be formed using ALD are preferably used for the protective film. ALD can form a dense protective film with minimal defects such as cracks and pinholes, and a uniform thickness. Furthermore, damage to the workpiece during protective film formation can be reduced.

[0305] For example, by forming a protective film using the ALD method, a uniform protective film with few defects can be formed on a surface having a complex uneven shape or on the top, side, and back surfaces of a touch panel.

[0306] As described above, a display device manufactured using the light-emitting device described in Embodiment 1 can be obtained.

[0307] Because the display device in this embodiment uses the light-emitting device described in Embodiment 1, a display device with excellent characteristics can be obtained. Specifically, the light-emitting device described in Embodiment 1 has high luminous efficiency, thereby realizing a low-power display device. Furthermore, the light-emitting device described in Embodiment 1 has high reliability, thereby realizing a highly reliable display device. Furthermore, the light-emitting device described in Embodiment 1 can have good chromaticity and high color purity, thereby realizing a display device with excellent display quality.

[0308] In addition, this embodiment mode can be freely combined with other embodiment modes.

[0309] Implementation 3 like Figure 4A and Figure 4B As shown, a plurality of light-emitting devices 130 are formed on an insulating layer 175 to form a display device. In this embodiment, a display device according to another embodiment of the present invention is described in detail.

[0310] The display device 100 includes a pixel portion 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 includes a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0311] In this specification, for example, when describing common features among sub-pixel 110R, sub-pixel 110G, and sub-pixel 110B, sub-pixel 110 may be referred to as sub-pixel 110. Similarly, when describing common features among other components identified by letters, the letters may be omitted.

[0312] Sub-pixel 110R emits red light, sub-pixel 110G emits green light, and sub-pixel 110B emits blue light. Thus, an image can be displayed on the pixel portion 177. Note that in this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are used as examples for description, but a combination of sub-pixels of other colors can also be used. In addition, the number of sub-pixels is not limited to three, and four or more can also be used. As four sub-pixels, for example, there can be mentioned: sub-pixels of four colors, R, G, B, and white (W); sub-pixels of four colors, R, G, B, and Y; and four sub-pixels of R, G, B, and infrared light (IR); and the like.

[0313] In this specification and the like, 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 intersect.

[0314] exist Figure 4AIn the example shown, sub-pixels of different colors are arranged in the X direction, and sub-pixels of the same color are arranged in the Y direction. Note that sub-pixels of different colors can also be arranged in the Y direction, and sub-pixels of the same color can also be arranged in the X direction.

[0315] Connecting portion 140 is provided outside pixel portion 177, and region 141 may also be provided. If region 141 is provided, it is provided between pixel portion 177 and connecting portion 140. If region 141 is provided, an organic compound layer is provided in region 141. Furthermore, conductive layer 151C is provided in connecting portion 140.

[0316] exist Figure 4A In the example shown, the region 141 and the connection portion 140 are located on the right side of the pixel portion 177. However, there is no particular limitation on the positions of the region 141 and the connection portion 140. Alternatively, there may be one or more regions 141 and the connection portion 140.

[0317] Figure 4B It is along Figure 4A An example of a cross-sectional view along the dotted line A1-A2 in FIG. Figure 4B As shown, display device 100 includes an insulating layer 171, a conductive layer 172 on insulating layer 171, an insulating layer 173 on insulating layer 171 and on conductive layer 172, an insulating layer 174 on insulating layer 173, and an 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 are provided with openings that reach conductive layer 172, and plugs 176 are provided so as to fit into these openings.

[0318] In pixel portion 177, light-emitting devices 130 are provided on insulating layer 175 and plug 176. Furthermore, protective layer 131 is provided to cover light-emitting devices 130. Substrate 120 is bonded to protective layer 131 via resin layer 122. Furthermore, an inorganic insulating layer 125 and an insulating layer 127 on inorganic insulating layer 125 are preferably provided between adjacent light-emitting devices 130.

[0319] Figure 4B Although cross sections of the plurality of inorganic insulating layers 125 and the plurality of insulating layers 127 are shown, the inorganic insulating layers 125 and the insulating layers 127 are preferably formed as one continuous layer when the display device 100 is viewed from above.

[0320] exist Figure 4B130R, 130G, and 130B are shown as light-emitting devices 130. Light-emitting devices 130R, 130G, and 130B can 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 devices 130R, 130G, and 130B can also emit other visible light or infrared light.

[0321] A display device according to one embodiment of the present invention may have, for example, a top-emission structure that emits light in a direction opposite to a substrate on which a light-emitting device is formed. Alternatively, a display device according to one embodiment of the present invention may have a bottom-emission structure.

[0322] The light-emitting device 130R includes 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 104. Note that the common layer 104 may not be provided, but providing the common layer 104 is preferred because it can reduce damage to the organic compound layer 103R during processing.

[0323] The light-emitting device 130G includes a first electrode 101G (pixel electrode) composed of a conductive layer 151G and a conductive layer 152G, an organic compound layer 103G on the first electrode, a common layer 104 on the organic compound layer 103G, and a second electrode (common electrode) 102 on the common layer 104. The common layer 104 may not be provided, but providing the common layer 104 is preferred because it can reduce damage to the organic compound layer 103G during processing.

[0324] The light-emitting device 130B has the structure described in Embodiment 1. The light-emitting device 130B includes a first electrode 101B (pixel electrode) composed of a conductive layer 151B and a conductive layer 152B, an organic compound layer 103B on the first electrode, a common layer 104 on the organic compound layer 103B, and a second electrode (common electrode) 102 on the common layer 104. The common layer 104 may not be provided, but providing the common layer 104 is preferred because it reduces damage to the organic compound layer 103B during processing. When the common layer 104 is provided, the stacked structure of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103 in Embodiment 1. When the common layer 104 is not provided, the organic compound layer 103B corresponds to the organic compound layer 103 in Embodiment 1.

[0325] The common layer 104 is preferably an electron transport layer. When the common layer 104 is an electron transport layer, the electron transport layer preferably has a stacked structure. More preferably, the common layer 104 is disposed on the second electrode side of the stack, and the organic compound layer 103 is disposed on the light-emitting layer side.

[0326] Furthermore, the light emitting device 130R and the light emitting device 130G are also light emitting devices manufactured through a photolithography process.

[0327] One of the pixel electrode and the common electrode included in the light emitting device 130 is used as an anode and the other is used as a cathode. Unless otherwise specified, the following description assumes that the pixel electrode is used as an anode and the common electrode is used as a cathode.

[0328] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are formed into islands for each light-emitting device or each light-emitting color. By forming the organic compound layer 103 into islands for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in high-definition display devices. This prevents crosstalk and enables a display device with extremely high contrast. In particular, a display device with high current efficiency can be achieved at low brightness.

[0329] The island-shaped organic compound layer 103 is formed by depositing an organic compound film and processing the organic compound film by photolithography.

[0330] 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 facilitates increasing the aperture ratio of the display device 100 compared to a structure in which the end of the organic compound layer 103 is located inward of the end of the pixel electrode. Furthermore, by covering the side surfaces of the pixel electrode of the light-emitting device 130 with the organic compound layer 103, contact between the pixel electrode and the second electrode 102 can be suppressed, thereby preventing short circuits in the light-emitting device 130.

[0331] In the display device of one embodiment of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a stacked structure. Figure 4B In the illustrated example, the first electrode of the light emitting device 130 has a stacked-layer structure of a conductive layer 151 and a conductive layer 152 .

[0332] 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), and alloys obtained by appropriately combining these metals can be used.

[0333] The conductive layer 152 can be made of an oxide containing one or more selected from the group consisting of indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, preferably used are conductive oxides 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. Indium tin oxide containing silicon has a particularly large work function, for example, 4.0 eV or greater, and is therefore suitable for use as the conductive layer 152.

[0334] Conductive layer 151 and conductive layer 152 may each have a stacked-layer structure including a plurality of layers of different materials. In this case, conductive layer 151 may include a layer using a material that can be used for conductive layer 152, such as a conductive oxide, and conductive layer 152 may include a layer using a material that can be used for conductive layer 151, such as a metal material. For example, when conductive layer 151 has a stacked-layer structure with two or more layers, the layer in contact with conductive layer 152 may be a layer using a material that can be used for conductive layer 152.

[0335] Next, refer to 5A to 10C Description Figure 4A An example of a method for manufacturing the display device 100 having the structure shown is shown.

[0336] [Manufacturing method example 1] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting a display device can be formed by sputtering, chemical vapor deposition (CVD), vacuum evaporation, pulsed laser deposition (PLD), ALD, or the like.

[0337] In addition, thin films (insulating films, semiconductor films, and conductive films, etc.) that constitute the display device can be formed using wet deposition methods such as spin coating, dipping, spraying, inkjet, dispenser, screen printing, offset printing, doctor knife, slit coating, roller coating, curtain coating, or doctor knife coating.

[0338] Furthermore, when processing thin films constituting the display device, for example, photolithography can be used.

[0339] In photolithography, as light used for exposure, for example, i-line (wavelength 365nm), g-line (wavelength 436nm), h-line (wavelength 405nm), or a mixture of these can be used. Furthermore, ultraviolet light, KrF laser, ArF laser, etc. can also be used. Furthermore, exposure can also be performed using liquid immersion exposure technology. Furthermore, as light used for exposure, extreme ultraviolet (EUV) light or X-rays can also be used. Furthermore, instead of light used for exposure, an electron beam can also be used.

[0340] For etching of the thin film, dry etching, wet etching, sand blasting, or the like can be used.

[0341] First, if Figure 5A As shown, an insulating layer 171 is formed on a substrate (not shown). Next, conductive layers 172 and 179 are formed on insulating layer 171, and insulating layer 173 is formed on insulating layer 171 to cover conductive layers 172 and 179. Next, insulating layer 174 is formed on insulating layer 173, and insulating layer 175 is formed on insulating layer 174.

[0342] As the substrate, a substrate having heat resistance at least sufficient to withstand the subsequent heat treatment can be used. Examples include glass substrates, quartz substrates, sapphire substrates, ceramic substrates, organic resin substrates, or semiconductor substrates such as single crystal or polycrystalline semiconductor substrates made of silicon or silicon carbide, compound semiconductor substrates such as silicon germanium, and SOI substrates.

[0343] Then, if Figure 5A As shown in FIG. 1 , openings reaching the conductive layer 172 are formed in the insulating layers 175, 174, and 173. Next, plugs 176 are formed so as to fit into the openings.

[0344] Then, if Figure 5A As shown, a conductive film 151f, which will later become the conductive layers 151R, 151G, 151B, and 151C, and a conductive film 152f, which will later become the conductive layers 152R, 152G, 152B, and 152C, are formed on the plug 176 and the insulating layer 175. For example, a metal material can be used as the conductive film 151f. For example, an oxide containing one or more selected from the group consisting of indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used as the conductive film 152f.

[0345] Then, if Figure 5AAs shown in FIG. 1 , a resist mask 191 is formed on the conductive film 152f. The resist mask 191 can be formed by applying a photosensitive material (photoresist), exposing the material to light, and developing the material.

[0346] Then, if Figure 5B As shown, for example, the conductive film 151f and the conductive film 152f are removed in the region that does not overlap with the resist mask 191. Thus, the conductive layer 151 and the conductive layer 152 are formed.

[0347] Then, if Figure 5C As shown, the resist mask 191 is removed. The resist mask 191 can be removed by ashing using oxygen plasma, for example.

[0348] Then, if Figure 5D As shown, an insulating film 156f, which will later become the insulating layer 156R, the insulating layer 156G, the insulating layer 156B and the insulating layer 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.

[0349] The insulating film 156f can be formed using an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film. For example, silicon oxynitride can be used.

[0350] Then, if Figure 5E As shown, by processing the insulating film 156f, the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, and the insulating layer 156C are formed.

[0351] Then, if Figure 6A As shown in FIG. 1 , an organic compound film 103Rf is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the insulating layer 175. Figure 6A As shown, the organic compound film 103Rf is not formed on the conductive layer 152C.

[0352] Then, if Figure 6A As shown, a sacrificial film 158Rf and a mask film 159Rf are formed.

[0353] 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.

[0354] The sacrificial film 158Rf is a film having high resistance to the processing conditions of the organic compound film 103Rf, specifically, a film having a large etching selectivity with the organic compound film 103Rf. The mask film 159Rf is a film having a large etching selectivity with the sacrificial film 158Rf.

[0355] Furthermore, sacrificial film 158Rf and mask film 159Rf are formed at a temperature lower than the heat resistance temperature of organic compound film 103Rf. The substrate temperature during formation of sacrificial film 158Rf and mask film 159Rf is typically 100°C to 200°C, preferably 100°C to 150°C, and more preferably 100°C to 120°C. Because the light-emitting device of one embodiment of the present invention includes the first organic compound, a high-quality display device can be provided even through a higher-temperature heating process.

[0356] As the sacrificial film 158Rf and the mask film 159Rf, films that can be removed by wet etching or dry etching are preferably used.

[0357] The sacrificial film 158Rf formed 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, ALD or vacuum deposition is more preferable than sputtering.

[0358] As the sacrificial film 158Rf and the mask film 159Rf, for example, one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, and an inorganic insulating film can be used.

[0359] For example, the sacrificial film 158Rf and the mask film 159Rf can each 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 containing such a metal material. Low-melting-point materials such as aluminum or silver are particularly preferred. Using a metal material that blocks ultraviolet light for one or both of the sacrificial film 158Rf and the mask film 159Rf is preferred because it prevents ultraviolet light from reaching the organic compound film 103Rf during pattern exposure, thereby suppressing degradation of the organic compound film 103Rf.

[0360] In addition, 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), indium tin oxide containing silicon, etc. can be used as the sacrificial film 158Rf and the mask film 159Rf, respectively.

[0361] Note that element M (M is one or more selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten and magnesium) can also be used in the above-mentioned metal oxides instead of gallium.

[0362] For example, semiconductor materials such as silicon and germanium are preferably used as the sacrificial film 158Rf and the mask film 159Rf because these materials have high affinity with the semiconductor manufacturing process. Alternatively, a compound containing the above semiconductor materials may be used.

[0363] Various inorganic insulating films can be used as the sacrificial film 158Rf and the mask film 159Rf. In particular, an oxide insulating film is preferred because it has higher adhesion to the organic compound film 103Rf than a nitride insulating film.

[0364] Then, if Figure 6A As shown, a resist mask 190R is formed. The resist mask 190R can be formed by applying a photosensitive material (photoresist), exposing it to light, and developing it.

[0365] Resist mask 190R is provided at a position overlapping conductive layer 152R. Resist mask 190R is preferably also provided at a position overlapping conductive layer 152C. This can prevent conductive layer 152C from being damaged during the manufacturing process of the display device.

[0366] Then, if Figure 6B As shown, a portion of mask film 159Rf is removed using resist mask 190R to form mask layer 159R. Mask layer 159R remains on conductive layer 152R and conductive layer 152C. Resist mask 190R is then removed. Next, mask layer 159R is used as a mask (also referred to as a hard mask) to remove a portion of sacrificial film 158Rf to form sacrificial layer 158R.

[0367] 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 the case of using the dry etching method. When using the wet etching method, for example, it is preferable to use an acidic aqueous solution such as a developer, an alkaline aqueous solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH), or a chemical solution using dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0368] Furthermore, when dry etching is used in processing the sacrificial film 158Rf, degradation of the organic compound film 103Rf can be suppressed by not using an oxygen-containing gas as an etching gas.

[0369] The resist mask 190R can be removed by the same method as the resist mask 191 .

[0370] Then, if Figure 6BAs shown, the organic compound film 103Rf is processed to form the organic compound layer 103R. For example, the organic compound layer 103R is formed by removing a portion of the organic compound film 103Rf using the mask layer 159R and the sacrificial layer 158R as a hard mask.

[0371] Therefore, if Figure 6B As shown, the stacked structure of the organic compound layer 103R, the sacrificial layer 158R, and the mask layer 159R remains on the conductive layer 152R. In addition, the conductive layer 152G and the conductive layer 152B are exposed.

[0372] The organic compound film 103Rf is preferably processed by anisotropic etching, particularly preferably anisotropic dry etching. Alternatively, wet etching may be used.

[0373] When dry etching is used, by not using an oxygen-containing gas as etching gas, degradation of the organic compound film 103Rf can be suppressed.

[0374] Alternatively, an oxygen-containing gas may be used as the etching gas. When the etching gas contains oxygen, the etching rate can be increased. Therefore, etching can be performed at low power while maintaining a sufficient etching rate. This reduces damage to the organic compound film 103Rf and prevents defects such as adhesion of reaction products produced during etching.

[0375] When dry etching is used, for example, a gas containing H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, and one or more Group 18 elements such as He and Ar is preferably used as the etching gas. Alternatively, a gas containing one or more of the above gases and oxygen is preferably used as the etching gas. Alternatively, oxygen gas may be used as the etching gas.

[0376] Then, if Figure 7A As shown, an organic compound film 103Gf which will later become the organic compound layer 103G is formed.

[0377] The organic compound film 103Gf can be formed using the same method as that used for forming the organic compound film 103Rf. Furthermore, the organic compound film 103Gf can have the same structure as that of the organic compound film 103Rf.

[0378] Then, if Figure 7A As shown, a sacrificial film 158Gf and a mask film 159Gf are sequentially formed. Then, a resist mask 190G is formed. The materials and formation methods of the sacrificial film 158Gf and the mask film 159Gf are the same as those used for the sacrificial film 158Rf and the mask film 159Rf. The materials and formation methods of the resist mask 190G are the same as those used for the resist mask 190R.

[0379] The resist mask 190G is provided at a position overlapping with the conductive layer 152G.

[0380] Then, if Figure 7B As shown, a portion of mask film 159Gf is removed using resist mask 190G, thereby forming mask layer 159G. Mask layer 159G remains on conductive layer 152G. Resist mask 190G is then removed. Next, using mask layer 159G as a mask, a portion of sacrificial film 158Gf is removed, thereby forming sacrificial layer 158G. Next, organic compound film 103Gf is processed to form organic compound layer 103G.

[0381] Then, if Figure 7C As shown, an organic compound film 103Bf is formed.

[0382] The organic compound film 103Bf can be formed using the same method as that used for forming the organic compound film 103Rf. Furthermore, the organic compound film 103Bf can have the same structure as that of the organic compound film 103Rf.

[0383] Then, if Figure 7C As shown, sacrificial film 158Bf and mask film 159Bf are sequentially formed. Then, resist mask 190B is formed. The materials and formation methods of sacrificial film 158Bf and mask film 159Bf are the same as those used for sacrificial film 158Rf and mask film 159Rf. The materials and formation methods of resist mask 190B are the same as those used for resist mask 190R.

[0384] Resist mask 190B is formed at a position overlapping with conductive layer 152B.

[0385] Then, if Figure 7D As shown, a portion of the mask film 159Bf is removed using a resist mask 190B, thereby forming a mask layer 159B. Mask layer 159B remains on conductive layer 152B. Resist mask 190B is then removed. Next, using mask layer 159B as a mask, a portion of sacrificial film 158Bf is removed, thereby forming sacrificial layer 158B. Next, the organic compound film 103Bf is processed to form an organic compound layer 103B. For example, mask layer 159B and sacrificial layer 158B are used as hard masks to remove a portion of the organic compound film 103Bf, thereby forming an organic compound layer 103B.

[0386] Therefore, if Figure 7D As shown, the stacked structure of the organic compound layer 103B, the sacrificial layer 158B, and the mask layer 159B remains on the conductive layer 152B. In addition, the mask layer 159R and the mask layer 159G are exposed.

[0387] Note that the side surfaces of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are preferably perpendicular or substantially perpendicular to the surface on which they are formed. For example, the angle formed between the surface on which they are formed and these side surfaces is preferably not less than 60 degrees and not more than 90 degrees.

[0388] As described above, the distance between two adjacent organic compound layers 103R, 103G, and 103B formed using photolithography can be reduced to less than 8 μm, less than 5 μm, less than 3 μm, less than 2 μm, or less than 1 μm. Here, the distance can be specified, for example, based on the distance between the opposing ends of two adjacent organic compound layers 103R, 103G, and 103B. In this way, by reducing the distance between the island-shaped organic compound layers, 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 be reduced, for example, to less than 10 μm, less than 8 μm, less than 5 μm, less than 3 μm, or less than 2 μm. Furthermore, the distance between the first electrodes of adjacent light-emitting devices is preferably greater than 2 μm and less than 5 μm.

[0389] Then, if Figure 8A As shown, mask layer 159R, mask layer 159G, and mask layer 159B are preferably removed.

[0390] The mask layer can be removed by the same method as the mask film processing step. In particular, wet etching can reduce damage to the organic compound layer 103 during mask layer removal compared to dry etching.

[0391] Alternatively, the mask layer may be removed by dissolving it in a polar solvent such as water or alcohol. Examples of the alcohol include ethanol, methanol, isopropyl alcohol (IPA), and glycerin.

[0392] After removing the mask layer, a drying process may be performed to remove water adsorbed on the surface. For example, heat treatment can be performed in an inert gas atmosphere or a reduced pressure atmosphere. Heat treatment can be performed at a substrate temperature of 50°C to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 120°C. Using a reduced pressure atmosphere is preferred because it allows drying at a lower temperature.

[0393] Then, if Figure 8B As shown, an inorganic insulating film 125f is formed.

[0394] Then, if Figure 8CAs shown in FIG. 1 , an insulating film 127 f which will later become the insulating layer 127 is formed on the inorganic insulating film 125 f.

[0395] The substrate temperature during formation of 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.

[0396] As the inorganic insulating film 125f, it is preferable to form an insulating film with a thickness of 3 nm, 5 nm, or 10 nm and 200 nm, 150 nm, 100 nm, or 50 nm within the above-mentioned substrate temperature range.

[0397] The inorganic insulating film 125f is preferably formed using, for example, ALD. Using ALD is preferred because it reduces deposition damage and allows for deposition of a film with high coverage. For example, an aluminum oxide film is preferably formed using ALD as the inorganic insulating film 125f.

[0398] The insulating film 127f is preferably formed using the aforementioned wet deposition method. For example, the insulating film 127f is preferably formed using a photosensitive material by spin coating, and more specifically, is preferably formed using a photosensitive resin composition containing an acrylic resin.

[0399] Next, exposure is performed to sensitize a portion of the insulating film 127f with visible light or ultraviolet light. The insulating layer 127 is formed in a region sandwiched between any two of the conductive layers 152R, 152G, and 152B and around the conductive layer 152C.

[0400] The width of the insulating layer 127 to be formed later can be controlled by the region where the insulating film 127f is exposed. In this embodiment, the insulating layer 127 is processed so that a portion overlaps with the top surface of the conductive layer 151.

[0401] The light used for exposure preferably includes i-line (wavelength: 365 nm). Alternatively, the light used for exposure may include at least one of g-line (wavelength: 436 nm) and h-line (wavelength: 405 nm).

[0402] Then, if Figure 9A As shown, development is performed to remove the exposed regions in the insulating film 127f, thereby forming the insulating layer 127a.

[0403] Then, if Figure 9BAs shown, etching is performed using insulating layer 127a as a mask to remove a portion of inorganic insulating film 125f, thereby reducing the thickness of a portion of sacrificial layer 158R, sacrificial layer 158G, and sacrificial layer 158B. Thus, inorganic insulating layer 125 is formed under insulating layer 127a. Furthermore, the surfaces of the thinner portions of sacrificial layer 158R, sacrificial layer 158G, and sacrificial layer 158B are exposed. Note that below, etching using insulating layer 127a as a mask may be referred to as first etching.

[0404] The first etching process can be performed by dry etching or wet etching. When the inorganic insulating film 125f is deposited using the same material as the sacrificial layers 158R, 158G, and 158B, the first etching process can be performed at once, which is preferable.

[0405] When dry etching is performed, a chlorine-based gas is preferably used. As the chlorine-based gas, one gas selected from Cl2, BCl3, SiCl4, and CCl4, or a mixture of two or more thereof, can be used. Furthermore, one gas selected from oxygen, hydrogen, helium, and argon, or a mixture of two or more thereof, can be appropriately added to the chlorine-based gas. By utilizing dry etching, thin regions of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B can be formed with excellent in-plane uniformity.

[0406] As a dry etching apparatus, a dry etching apparatus having a high-density plasma source can be used. As a dry etching apparatus having a high-density plasma source, for example, an inductively coupled plasma (ICP) etching apparatus can be used. Alternatively, a capacitively coupled plasma (CCP) etching apparatus including parallel plate electrodes can be used.

[0407] In addition, it is preferred to perform the first etching treatment using wet etching. By using a wet etching method, the damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be reduced compared to the case of using a dry etching method. For example, an alkaline solution can be used for wet etching. For example, when wet etching an aluminum oxide film, an alkaline solution TMAH can be used. In addition, an acidic solution containing fluoride can also be used. In this case, wet etching can be performed in a coating manner. Note that when the inorganic insulating film 125f is deposited using the same material as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, the above-mentioned etching treatment can be performed at one time, so it is preferred.

[0408] The first etching process does not completely remove the sacrificial layers 158R, 158G, and 158B, but stops the etching process while the thickness of the sacrificial layers is reduced. Thus, by leaving the corresponding sacrificial layers 158R, 158G, and 158B on the organic compound layers 103R, 103G, and 103B, the organic compound layers 103R, 103G, and 103B can be prevented from being damaged in subsequent processing steps.

[0409] Next, the entire substrate is preferably exposed to visible light or ultraviolet light to irradiate the insulating layer 127a. The energy density of this exposure is preferably greater than 0 mJ / cm 2 and 800mJ / cm 2 Below, more preferably greater than 0 mJ / cm 2 and 500mJ / cm 2 By performing this exposure after development, the transparency of the insulating layer 127a can sometimes be improved. In addition, the substrate temperature required for the heat treatment in a later step to deform the insulating layer 127a into a tapered shape can sometimes be reduced.

[0410] Here, by providing an oxygen blocking insulating layer (for example, an aluminum oxide film) as the sacrificial layers 158R, 158G, and 158B, oxygen diffusion into the organic compound layers 103R, 103G, and 103B can be reduced.

[0411] Next, a heat treatment (also called post-baking) is performed. By performing the heat treatment, the insulating layer 127a can be deformed into an insulating layer 127 having a tapered shape on its side. Figure 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, and more preferably 70°C to 130°C. The heating atmosphere can be an air atmosphere or an inert gas atmosphere. In addition, the heating atmosphere can be an air atmosphere or a reduced pressure atmosphere. Thus, the adhesion between the insulating layer 127 and the inorganic insulating layer 125 can be improved, and the corrosion resistance of the insulating layer 127 can also be improved.

[0412] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, but the sacrificial layers 158R, 158G, and 158B are left thin. This prevents the organic compound layers 103R, 103G, and 103B from being damaged and deteriorated during the heat treatment. This improves the reliability of the light-emitting device.

[0413] Then, if Figure 10A As shown, etching is performed using the insulating layer 127 as a mask to remove portions of the sacrificial layers 158R, 158G, and 158B. This forms openings in the sacrificial layers 158R, 158G, and 158B, exposing the top surfaces of the organic compound layers 103R, 103G, and 103B, and the conductive layer 152C. Note that this etching process may be referred to as a second etching process hereinafter.

[0414] The end portion of the inorganic insulating layer 125 is covered with the insulating layer 127. Figure 10A An example is shown in which a portion of the end portion of the sacrificial layer 158G (specifically, the tapered portion formed by the first etching process) is covered by the insulating layer 127 and the tapered portion formed by the second etching process is exposed.

[0415] The second etching process is performed using wet etching. Wet etching can reduce damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B compared to dry etching. For example, wet etching can be performed using an alkaline solution or an acidic solution. To prevent dissolution of the organic compound layer 103, an aqueous solution is preferably used.

[0416] Then, if Figure 10B As shown, a common electrode 155 is formed over 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 evaporation.

[0417] Then, if Figure 10C As shown, a protective layer 131 is formed on the common electrode 155. The protective layer 131 can be formed by vacuum evaporation, sputtering, CVD, ALD or other methods.

[0418] Next, the substrate 120 is bonded to the protective layer 131 using the resin layer 122, thereby manufacturing the display device. As described above, in the method for manufacturing a display device according to one embodiment of the present invention, the insulating layer 156 is provided so as to have a region overlapping with the 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 improves the yield of the display device and prevents the occurrence of defects.

[0419] As described above, in a method for manufacturing a display device according to one embodiment of the present invention, the island-shaped organic compound layer 103R, the island-shaped organic compound layer 103G, and the island-shaped organic compound layer 103B are not formed using a high-precision metal mask, but are formed by depositing a film on one surface and then processing it, so that the island layer can be formed with a uniform thickness. In addition, a high-definition display device or a display device with a high aperture ratio can be realized. In addition, even if the clarity or aperture ratio is high and the distance between sub-pixels is extremely short, the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be prevented from contacting each other between adjacent sub-pixels. Therefore, leakage current can be suppressed from occurring between sub-pixels. Thus, crosstalk can be prevented to realize a display device with extremely high contrast. In addition, even a display device including a tandem light-emitting device manufactured using a photolithography method can provide a display device with good characteristics.

[0420] Implementation 4 In this embodiment, a display device which is one embodiment of the present invention is described.

[0421] The display device of this embodiment can be a high-definition display device. Therefore, for example, the display device of this embodiment can be used as the display portion of information terminal devices (wearable devices) such as watches and bracelets, as well as the display portion of wearable devices such as head-mounted displays (HMDs) for VR devices and glasses-type AR devices that can be worn on the head.

[0422] Furthermore, the display device of this embodiment can be a high-resolution display device or a large display device. Therefore, for example, the display device of this embodiment can be used as a display portion of electronic devices with large screens, such as televisions, desktop or notebook personal computers, monitors for computers, etc., digital signage, and large-scale game machines such as pinball machines; digital cameras; digital video cameras; digital photo frames; mobile phones; portable game consoles; portable information terminals; and audio reproduction devices.

[0423] [Display module] Figure 11A A perspective view of a display module 280 is shown. 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 also be any of the display devices 100B, 100C, 100D, 100D2, 100E, and 100E2, which will be described later.

[0424] The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display portion 281. The display portion 281 is an image display region in the display module 280, and is a region where light from each pixel provided in a pixel portion 284 described below can be seen.

[0425] Figure 11B This is a perspective schematic diagram of the structure on one side of a substrate 291. A circuit portion 282, a pixel circuit portion 283 on circuit portion 282, and a pixel portion 284 on pixel circuit portion 283 are stacked on substrate 291. Furthermore, a terminal portion 285 for connecting to an FPC 290 is provided on a portion of substrate 291 that does not overlap with pixel portion 284. The terminal portion 285 is electrically connected to the circuit portion 282 via a wiring portion 286 composed of a plurality of wiring lines.

[0426] The pixel portion 284 includes a plurality of pixels 284 a arranged periodically. Figure 11B An enlarged view of one pixel 284a is shown on the right side of FIG. The pixel 284a can adopt the various structures described in the above embodiment.

[0427] The pixel circuit portion 283 includes a plurality of pixel circuits 283 a arranged periodically.

[0428] One pixel circuit 283a controls driving of a plurality of elements included in one pixel 284a.

[0429] The circuit unit 282 includes circuits for driving each pixel circuit 283a of the pixel circuit unit 283. For example, it preferably includes one or both of a gate line driver circuit and a source line driver circuit. In addition, it may include at least one of a calculation circuit, a storage circuit, and a power supply circuit.

[0430] The FPC 290 is used as wiring for supplying video signals, power supply potential, etc. from the outside to the circuit portion 282. In addition, an IC may be mounted on the FPC 290.

[0431] The display module 280 may have a structure in which one or both of the pixel circuit portion 283 and the circuit portion 282 are stacked below the pixel portion 284 , so that the display portion 281 may have an extremely high aperture ratio (effective display area ratio).

[0432] The display module 280 has an extremely high definition, making it suitable for use in VR devices such as HMDs or glasses-type AR devices. For example, in a configuration where the display portion of the display module 280 is viewed through a lens, because the display module 280 has an extremely high definition display portion 281, even if the user magnifies the display portion with a lens, the pixels cannot be seen, thereby achieving a highly immersive display. Furthermore, the display module 280 is not limited to this embodiment and can also be applied to electronic devices with smaller display portions.

[0433] [Display device 100A] Figure 12A The display device 100A shown 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 .

[0434] Substrate 301 is equivalent to Figure 12A and Figure 12B The transistor 310 is a transistor having a channel formation region in the substrate 301. As the substrate 301, a semiconductor substrate such as a single crystal silicon substrate can be used. The transistor 310 includes a portion 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 serves as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and serves as a gate insulating layer. The low resistance region 312 is a region doped with impurities in the substrate 301 and serves as a source or drain. The insulating layer 314 covers the side surfaces of the conductive layer 311.

[0435] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0436] Furthermore, an insulating layer 261 is provided to cover the transistor 310 , and the capacitor 240 is provided over the insulating layer 261 .

[0437] Capacitor 240 includes conductive layer 241, conductive layer 245, and insulating layer 243 therebetween. Conductive layer 241 serves as one electrode of capacitor 240, conductive layer 245 serves as the other electrode of capacitor 240, and insulating layer 243 serves as a dielectric of capacitor 240.

[0438] Conductive layer 241 is provided on insulating layer 261 and embedded in insulating layer 254. Conductive layer 241 is electrically connected to one of the source and drain of transistor 310 via plug 271 embedded in insulating layer 261. Insulating layer 243 is provided to cover conductive layer 241. Conductive layer 245 is provided in a region overlapping conductive layer 241 with insulating layer 243 interposed therebetween.

[0439] An insulating layer 255 is provided to cover capacitor 240. Insulating layer 174 is provided on insulating layer 255, and insulating layer 175 is provided on insulating layer 174. Light-emitting devices 130R, 130G, and 130B are provided on insulating layer 175. Insulators are provided in regions between adjacent light-emitting devices.

[0440] Insulating layer 156R is provided so as to have a region overlapping with the side surfaces of conductive layer 151R, insulating layer 156G is provided so as to have a region overlapping with the side surfaces of conductive layer 151G, and insulating layer 156B is provided so as to have a region overlapping with the side surfaces of conductive layer 151B. Furthermore, conductive layer 152R is provided so as to cover conductive layer 151R and insulating layer 156R, conductive layer 152G is provided so as to cover conductive layer 151G and insulating layer 156G, and conductive layer 152B is provided so as to cover conductive layer 151B and insulating layer 156B. Sacrificial layer 158R is provided on organic compound layer 103R, sacrificial layer 158G is provided on organic compound layer 103G, and sacrificial layer 158B is provided on organic compound layer 103B.

[0441] Conductive layer 151R, conductive layer 151G, and conductive layer 151B are electrically connected to one of the source and drain of transistor 310 via plug 256 embedded in insulating layer 243, insulating layer 255, insulating layer 174, and insulating layer 175, conductive layer 241 embedded in insulating layer 254, and plug 271 embedded in insulating layer 261. Various conductive materials can be used for the plug.

[0442] Furthermore, a protective layer 131 is provided on the light emitting device 130R, the light emitting device 130G, and the light emitting device 130B. The substrate 120 is bonded to the protective layer 131 via a resin layer 122. The details of the components of the light emitting device 130 to the substrate 120 can be referred to Embodiment 3. The substrate 120 corresponds to Figure 11A substrate 292.

[0443] Figure 12B Show Figure 12A This is a modified example of the display device 100A shown. Figure 12B The display device shown includes a coloring layer 132R, a coloring layer 132G, and a coloring layer 132B, and the light emitting device 130 has a region overlapping one of the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B. Figure 12B In the display device shown, the light emitting device 130 can emit white light, for example. In addition, the colored layer 132R, the colored layer 132G, and the colored layer 132B can transmit red light, green light, and blue light, respectively.

[0444] [Display device 100B] Figure 13 A perspective view showing a display device 100B is shown. Figure 14 A cross-sectional view of the display device 100C is shown.

[0445] The display device 100B has a structure in which a substrate 352 and a substrate 351 are bonded together. Figure 13 , the substrate 352 is indicated by a dotted line.

[0446] The display device 100B includes a pixel portion 177 , a connection portion 140 , a circuit 356 , a wiring 355 , and the like. Figure 13 The example in which the display device 100B is mounted with IC354 and FPC353 is shown. Figure 13 The structure shown is called a display module including the display device 100B, an IC (integrated circuit), and an FPC. Here, a substrate of a display device with a connector such as an FPC mounted thereon or a substrate with an IC mounted thereon is called a display module.

[0447] The connection portion 140 is provided outside the pixel portion 177. There may be one or more connection portions 140. In the connection portion 140, the common electrode of the light emitting device is electrically connected to the conductive layer, and a potential can be supplied to the common electrode.

[0448] As the circuit 356 , for example, a scan line driver circuit can be used.

[0449] 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 through the FPC 353 or from the IC 354.

[0450] Figure 13 An example is shown in which an IC 354 is provided on a substrate 351 using a COG (Chip On Glass) method or a COF (Chip On Film) method. For example, an IC including a scan 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 do not necessarily need to be provided with an IC. Alternatively, the IC can be mounted on an FPC using a COF method, for example.

[0451] exist Figure 14 In the example, the display device 100C is shown as Figure 13 FIG. 1 is an example of a cross section of the display device 100B including 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.

[0452] [Display device 100C] Figure 14 The display device 100C shown includes a transistor 201 , a transistor 205 , a light-emitting device 130R that emits red light, a light-emitting device 130G that emits green light, a light-emitting device 130B that emits blue light, and the like between a substrate 351 and a substrate 352 .

[0453] For details of the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B, reference may be made to Embodiment 3.

[0454] Light-emitting device 130R includes a conductive layer 224R, a conductive layer 151R on conductive layer 224R, and a conductive layer 152R on conductive layer 151R. Light-emitting device 130G includes a conductive layer 224G, a conductive layer 151G on conductive layer 224G, and a conductive layer 152G on conductive layer 151G. Light-emitting device 130B includes a conductive layer 224B, a conductive layer 151B on conductive layer 224B, and a conductive layer 152B on conductive layer 151B.

[0455] Conductive layer 224R is connected to conductive layer 222b included in transistor 205 through an opening provided in insulating layer 214. An end portion of conductive layer 151R is located outside an end portion of conductive layer 224R. Insulating layer 156R is provided to have a region in contact with a side surface of conductive layer 151R, and conductive layer 152R is provided to cover conductive layer 151R and insulating layer 156R.

[0456] The conductive layer 224G, conductive layer 151G, conductive layer 152G, and insulating layer 156G in the light-emitting device 130G and the conductive layer 224B, conductive layer 151B, conductive layer 152B, and insulating layer 156B in the light-emitting device 130B are the same as the conductive layer 224R, conductive layer 151R, conductive layer 152R, and insulating layer 156R in the light-emitting device 130R, so detailed description is omitted.

[0457] Concave portions are formed in conductive layer 224R, conductive layer 224G, and conductive layer 224B so as to cover the openings provided in insulating layer 214. The concave portions are filled with layer 128.

[0458] Layer 128 fills the recessed portions of conductive layers 224R, 224G, and 224B to flatten them. Conductive layers 151R, 151G, and 151B are provided on conductive layers 224R, 224G, 224B, and layer 128, and are electrically connected to conductive layers 224R, 224G, and 224B. Therefore, the areas overlapping the recessed portions of conductive layers 224R, 224G, and 224B can also be used as light-emitting areas, thereby increasing the pixel aperture ratio.

[0459] 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 layer 128. In particular, layer 128 is preferably formed of an insulating material, more preferably an organic insulating material. For example, the organic insulating materials described above for insulating layer 127 can be used for layer 128.

[0460] 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 by an adhesive layer 142. The substrate 352 is provided with a light shielding layer 157. The sealing of the light emitting device 130 can adopt a solid sealing structure or a hollow sealing structure. Figure 14 In the embodiment, the space between substrate 352 and substrate 351 is filled with adhesive layer 142, i.e., a solid sealing structure is adopted. Alternatively, the space can be filled with an inert gas (such as nitrogen or argon), i.e., a hollow sealing structure is adopted. In this case, adhesive layer 142 can also be arranged so as not to overlap with the light-emitting device. In addition, a resin different from the adhesive layer 142 arranged in a frame shape can also be used to fill the space.

[0461] Figure 14 In the example shown below, the connection portion 140 includes a conductive layer 224C formed by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive layer 151C formed by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive layer 152C formed by processing the same conductive film as the conductive layers 152R, 152G, and 152B. Figure 14 An example is shown in which the insulating layer 156C is provided so as to have a region overlapping with the side surface of the conductive layer 151C.

[0462] The display device 100C has a top-emission structure. The light-emitting device emits light toward the substrate 352. The substrate 352 is preferably made of a material that is highly transmissive to visible light. The pixel electrode is made of a material that reflects visible light, while the counter electrode (common electrode 155) is made of a material that transmits visible light.

[0463] Insulating layer 211, insulating layer 213, insulating layer 215, and insulating layer 214 are sequentially provided on substrate 351. A portion of insulating layer 211 serves as a gate insulating layer for each transistor. A portion of insulating layer 213 serves as a gate insulating layer for each transistor. Insulating layer 215 is provided to cover the transistors. Insulating layer 214 is provided to cover the transistors and serves as a planarization layer. There are no particular restrictions on the number of gate insulating layers or insulating layers covering transistors; there may be one or more.

[0464] As the insulating layer 211 , the insulating layer 213 , and the insulating layer 215 , an inorganic insulating film is preferably used.

[0465] As the insulating layer 214 serving as a planarizing layer, an organic insulating layer is preferably used.

[0466] Transistor 201 and transistor 205 include: a conductive layer 221 serving as a gate; an insulating layer 211 serving as a gate insulating layer; a conductive layer 222a and a conductive layer 222b serving as a source and a drain; a semiconductor layer 231; an insulating layer 213 serving as a gate insulating layer; and a conductive layer 223 serving as a gate.

[0467] Connecting portion 204 is provided in a region of substrate 351 that does not overlap with substrate 352. In connecting portion 204, the source electrode or drain electrode of transistor 201 is electrically connected to FPC 353 via conductive layer 166 and connecting layer 242. In the example shown, conductive layer 166 has a stacked structure comprising a conductive film processed from the same conductive film as conductive layers 224R, 224G, and 224B, a conductive film processed from the same conductive film as conductive layers 151R, 151G, and 151B, and a conductive film processed from the same conductive film as conductive layers 152R, 152G, and 152B. Conductive layer 166 is exposed on the top surface of connecting portion 204. Therefore, connecting portion 204 can be electrically connected to FPC 353 via connecting layer 242.

[0468] A light shielding layer 157 is preferably provided on the substrate 351 side surface of the substrate 352. The light shielding layer 157 can be provided between adjacent light emitting devices, in the connection portion 140 and the circuit 356, etc. Various optical components can be arranged outside the substrate 352.

[0469] The substrate 351 and the substrate 352 can each adopt a material that can be used for the substrate 120 .

[0470] As the adhesive layer 142 , a material that can be used for the resin layer 122 can be used.

[0471] As the connection layer 242 , an anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) can be used.

[0472] [Display device 100D] Figure 15 The display device 100D shown is Figure 14 The main difference between the display device 100C shown is that the display device 100D is a bottom emission structure display device.

[0473] The light emitting device emits light toward the substrate 351. A material having high transmittance to visible light is preferably used for the substrate 351. On the other hand, there is no limitation on the transmittance of the material used for the substrate 352.

[0474] A light-shielding layer 317 is preferably formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205 . Figure 15 An example is shown in which a light-shielding layer 317 is provided over a substrate 351 , an insulating layer 153 is provided over the light-shielding layer 317 , and transistors 201 , 205 , and the like are provided over the insulating layer 153 .

[0475] The light emitting device 130R includes a conductive layer 112R, a conductive layer 126R on the conductive layer 112R, and a conductive layer 129R on the conductive layer 126R.

[0476] The light emitting device 130B includes a conductive layer 112B, a conductive layer 126B on the conductive layer 112B, and a conductive layer 129B on the conductive layer 126B.

[0477] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are all made of a material having high transmittance to visible light. The second electrode 102 is preferably made of a material that reflects visible light.

[0478] Note that although Figure 15 The light emitting device 130G is not shown in the figure, but the light emitting device 130G is also provided.

[0479] also, Figure 15 The examples in which the top surface of the layer 128 has a flat portion are shown in the figures, but the shape of the layer 128 is not particularly limited.

[0480] [Display device 100D2] Figure 16A The display device 100D2 shown is Figure 15 The display device 100D2 is an example of a bottom emission structure display device different from the display device 100D shown in FIG. The display device 100D2 is different from the display device 100D in that the former includes an organic resin layer 180. Note that the organic resin layer 180 is sometimes omitted in the drawings. Figure 15 The same symbols of the components are used in the Figure 15 Records of.

[0481] also, Figure 16B 1 shows the top surface layout of the pixel 178 (pixel 178a and pixel 178b) including the sub-pixel 110 (sub-pixel 110R, sub-pixel 110G, sub-pixel 110B, sub-pixel 110W). Figure 16C The top view shows the organic resin layer 180 in the region where the sub-pixels 110R and 110W included in the pixel 178 are formed. The width between the light-shielding layers 317 is the width 110Rw in the light-emitting region of the sub-pixel 110R.

[0482] like Figure 16AAs shown, the organic resin layer 180 is disposed on the insulating layer 214. Figure 16A The area surrounded by dotted lines and Figure 16C As shown, organic resin layer 180 includes curved recesses 181 (recesses 181a and 181b) at least in the regions where the subpixels are formed. Alternatively, recesses 181, like recess 181c, may be positioned outside the light-emitting region. By providing recesses 181c, light generated in the region overlapping light-shielding layer 317 or light e...

Claims

1. A light-emitting device, comprising: a first electrode; a second electrode; middle layer; a first light-emitting layer; a second light-emitting layer; a first electron transport layer; as well as The second electron transport 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 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 includes a first light-emitting center substance, a third organic compound and a fourth organic compound. The second light-emitting layer includes a second light-emitting center substance, a fifth organic compound and a sixth organic compound. The third organic compound and the fifth organic compound have a π-electron-deficient heteroaromatic ring, The fourth organic compound and the sixth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, One or both of the third organic compound and the fourth organic compound or one or both of the fifth organic compound and the sixth organic compound contain deuterium, The difference between the maximum peak wavelength of the emission spectrum of the first luminescence center substance and the maximum peak wavelength of the emission spectrum of the second luminescence center substance is 30 nm or less, The first light-emitting layer emits light of a different hue from that of the first light-emitting layer included in at least one of the other plurality of light-emitting devices adjacent to the light-emitting device. Furthermore, the second light-emitting layer emits light of a hue different from that of the second light-emitting layer included in the at least one light-emitting device among the other plurality of light-emitting devices adjacent to the light-emitting device.

2. A light-emitting device comprising: a first electrode; a second electrode; middle layer; a first light-emitting layer; a second light-emitting layer; a first electron transport layer; as well as The second electron transport 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 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 includes a first light-emitting center substance, a third organic compound and a fourth organic compound. The second light-emitting layer includes a second light-emitting center substance, a fifth organic compound and a sixth organic compound. The third organic compound and the fifth organic compound have a π-electron-deficient heteroaromatic ring, The fourth organic compound and the sixth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, One or both of the third organic compound and the fourth organic compound and one or both of the fifth organic compound and the sixth organic compound contain deuterium, The difference between the maximum peak wavelength of the emission spectrum of the first luminescence center substance and the maximum peak wavelength of the emission spectrum of the second luminescence center substance is 30 nm or less, The first light-emitting layer emits light of a different hue from that of the first light-emitting layer included in at least one of the other plurality of light-emitting devices adjacent to the light-emitting device. Furthermore, the second light-emitting layer emits light of a hue different from that of the second light-emitting layer included in the at least one light-emitting device among the other plurality of light-emitting devices adjacent to the light-emitting device.

3. The light emitting device according to claim 1, wherein the second electron transport layer comprises a first organic compound having a triazine skeleton, The intermediate layer includes a mixed layer of a second organic compound having a phenanthroline skeleton and one of lithium and a lithium compound.

4. The light emitting device according to claim 2, wherein the second electron transport layer comprises a first organic compound having a triazine skeleton, The intermediate layer includes a mixed layer of a second organic compound having a phenanthroline skeleton and one of lithium and a lithium compound.

5. The light emitting device according to claim 1, The intermediate layer contains lithium or a lithium compound.

6. The light emitting device according to claim 5, The intermediate layer includes a mixed layer of a second organic compound and one of the lithium and the lithium compound.

7. The light emitting device according to claim 1, wherein the third organic compound and the fourth organic compound form a first exciplex, Furthermore, the fifth organic compound and the sixth organic compound form a second exciplex.

8. The light emitting device according to claim 7, wherein the difference between the lowest triplet excitation energy level of the third organic compound and the lowest triplet excitation energy level of the fourth organic compound is 0.20 eV or less, Furthermore, a difference between the lowest triplet excitation energy level of the fifth organic compound and the lowest triplet excitation energy level of the sixth organic compound is 0.20 eV or less.

9. The light emitting device according to claim 7, wherein the emission end on the short wavelength side of the PL spectrum of the first exciplex is located at a shorter wavelength than the absorption end on the long wavelength side of the absorption spectrum of the first luminescent center substance, Furthermore, the emission end on the short wavelength side of the PL spectrum of the second exciplex is located at a shorter wavelength than the absorption end on the long wavelength side of the absorption spectrum of the second luminescence center substance.

10. The light emitting device according to claim 7, wherein the peak wavelength of the emission spectrum of the first exciplex is located on the shorter wavelength side than the peak wavelength of the emission spectrum of the first luminescent center substance, The difference between the peak wavelength of the emission spectrum of the first exciplex and the peak wavelength of the emission spectrum of the first luminescent center substance is 30 nm or less, The peak wavelength of the emission spectrum of the second exciplex is located on the shorter wavelength side than the peak wavelength of the emission spectrum of the second luminescent center substance, Furthermore, a difference between the peak wavelength of the emission spectrum of the second exciplex and the peak wavelength of the emission spectrum of the second luminescence center substance is 30 nm or less.

11. The light emitting device according to claim 2, The intermediate layer contains lithium or a lithium compound.

12. The light emitting device according to claim 11, The intermediate layer includes a mixed layer of a second organic compound and one of the lithium and the lithium compound.

13. The light emitting device according to claim 2, wherein the third organic compound and the fourth organic compound form a first exciplex, Furthermore, the fifth organic compound and the sixth organic compound form a second exciplex.

14. The light emitting device according to claim 13, wherein the difference between the lowest triplet excitation energy level of the third organic compound and the lowest triplet excitation energy level of the fourth organic compound is 0.20 eV or less, Furthermore, a difference between the lowest triplet excitation energy level of the fifth organic compound and the lowest triplet excitation energy level of the sixth organic compound is 0.20 eV or less.

15. The light emitting device according to claim 13, wherein the emission end on the short wavelength side of the PL spectrum of the first exciplex is located at a shorter wavelength than the absorption end on the long wavelength side of the absorption spectrum of the first luminescent center substance, Furthermore, the emission end on the short wavelength side of the PL spectrum of the second exciplex is located at a shorter wavelength than the absorption end on the long wavelength side of the absorption spectrum of the second luminescence center substance.

16. The light emitting device according to claim 13, wherein the peak wavelength of the emission spectrum of the first exciplex is located on the shorter wavelength side than the peak wavelength of the emission spectrum of the first luminescent center substance, The difference between the peak wavelength of the emission spectrum of the first exciplex and the peak wavelength of the emission spectrum of the first luminescent center substance is 30 nm or less, The peak wavelength of the emission spectrum of the second exciplex is located on the shorter wavelength side than the peak wavelength of the emission spectrum of the second luminescent center substance, Furthermore, a difference between the peak wavelength of the emission spectrum of the second exciplex and the peak wavelength of the emission spectrum of the second luminescence center substance is 30 nm or less.

17. A display device comprising: a first light emitting device; as well as a second light emitting device, wherein the first light emitting device is adjacent to the second light emitting device, The first light emitting device comprises: a first electrode; a second electrode; First intermediate layer; a first light-emitting layer; a second light-emitting layer; a first electron transport layer; and The second electron transport layer, The first intermediate layer is located between the first electrode and the second electrode, The first light-emitting layer is located between the first electrode and the first intermediate layer. The second light-emitting layer is located between the first intermediate layer and the second electrode, The first electron transport layer is located between the first light-emitting layer and the first intermediate layer, the second electron transport layer is located between the second light-emitting layer and the second electrode, and the second light-emitting device includes: a third electrode; a fourth electrode; Second middle layer a third light-emitting layer; a fourth light-emitting layer; a third electron transport layer; and The fourth electron transport layer, The second intermediate layer is located between the third electrode and the fourth electrode, The third light-emitting layer is located between the third electrode and the second intermediate layer, The fourth light-emitting layer is located between the second intermediate layer and the fourth electrode, The third electron transport layer is located between the third light-emitting layer and the second intermediate layer, the fourth electron transport layer is located between the fourth light-emitting layer and the fourth electrode, and the second electron transport layer and the fourth electron transport layer include a first organic compound having a triazine skeleton. The second electron transport layer and the fourth electron transport layer are made of the same material, the first intermediate layer and the second intermediate layer contain one of lithium and a lithium compound and a second organic compound having a phenanthroline skeleton, The first light-emitting layer includes a first light-emitting center substance, a third organic compound and a fourth organic compound. The second light-emitting layer includes a second light-emitting center substance, a fifth organic compound and a sixth organic compound. The third organic compound and the fifth organic compound have a π-electron-deficient heteroaromatic ring, The fourth organic compound and the sixth organic compound have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, One or both of the third organic compound and the fourth organic compound and one or both of the fifth organic compound and the sixth organic compound contain deuterium, and the third light-emitting layer contains a third light-emitting center substance. The fourth light-emitting layer includes a fourth light-emitting center substance, The difference between the maximum peak wavelength of the emission spectrum of the first luminescence center substance and the maximum peak wavelength of the emission spectrum of the second luminescence center substance is 30 nm or less, The difference between the maximum peak wavelength of the emission spectrum of the third luminescence center substance and the maximum peak wavelength of the emission spectrum of the fourth luminescence center substance is 30 nm or less, The first light-emitting layer emits light of a different hue from that of the third light-emitting layer. Furthermore, the second light-emitting layer emits light of a different hue from that of the fourth light-emitting layer.

18. The display device according to claim 17, wherein the third organic compound and the fourth organic compound form a first exciplex, Furthermore, the fifth organic compound and the sixth organic compound form a second exciplex.

Images