Light emitting device

Abstract

The invention provides a light emitting device with good reliability. The light emitting device includes a first electrode, a second electrode, and an EL layer, the EL layer is located between the first electrode and the second electrode, the EL layer includes a light emitting layer, an electron transport layer, and an electron injection layer, the electron transport layer is in contact with the electron injection layer, the electron injection layer has a hole blocking function, and the electron injection layer has a hole blocking function. The electron transport layer is a layer containing an organic compound having an electron transport property and an organic compound having a hole transport property.

Description

Technical Field

[0001] One aspect of the present invention relates to a light-emitting device.

[0002] Note that one aspect of the present invention is not limited to the above technical field. As an example of the technical field of one aspect of the present invention, semiconductor devices, display devices, light-emitting devices, power storage devices, storage devices, electronic devices, lighting devices, input devices (e.g., touch sensors), input / output devices (e.g., touch panels), and driving methods or manufacturing methods of the above devices can be cited. Background Art

[0003] In recent years, display devices have been applied to various uses. For example, as uses of large display devices, research and development have been carried out on home television devices (also called TVs or television receivers), digital signage, and public information displays (PID: Public Information Display), etc., and as uses of small display devices, research and development have been carried out on smartphones or tablet terminals equipped with touch panels, etc.

[0004] At the same time, high definition of display devices is also being carried out. As devices that require high-definition display devices, for example, research and development have been carried out on devices for virtual reality (VR: Virtual Reality), augmented reality (AR: Augmented Reality), substitutional reality (SR: Substitutional Reality), and mixed reality (MR: Mixed Reality).

[0005] As a display element for a display device, the development of light-emitting devices (also called light-emitting elements) has been increasingly active. A light-emitting device (also called an EL device, EL element) that utilizes the electroluminescence (hereinafter referred to as EL) phenomenon, especially an organic EL device mainly using organic compounds, has the following characteristics: it is easy to achieve thin and lightweight; it can respond to input signals at high speed; and it can be driven using a DC constant voltage power supply, etc., and thus it is preferably applied to display devices.

[0006] In order to obtain a higher-definition light-emitting device using an organic EL device, a technique of patterning an organic layer by using a photolithography method using a photoresist or the like instead of an evaporation method using a metal mask has been studied. By using the photolithography method, a high-definition display device with an interval of the EL layer of several μm can be obtained (for example, refer to Patent Document 1). [Prior Art Documents] [Patent Documents]

[0007] [Patent Document 1] Japanese PCT International Application Translation, Publication No. 2018-521459 [Patent Document 2] International Patent Application Publication No. 2021 / 045178 Summary of the Invention Technical Problem to be Solved by the Invention

[0008] In organic EL devices known heretofore, the initial characteristics or reliability of the EL layer are affected when it is exposed to atmospheric components such as water and oxygen, and the EL layer is processed in an atmosphere close to vacuum in a common sense step. In particular, the electron injection layer uses an alkali metal or an alkaline earth metal or a compound thereof, and these metals and compounds have a very high reactivity with water or oxygen. When the surface of the EL layer is exposed to the atmosphere, the electron injection layer rapidly deteriorates and loses its function as an electron injection layer.

[0009] However, in the above-described process of processing by photolithography, it is inevitable to expose the surface of the EL layer to the atmosphere.

[0010] Accordingly, an object of one aspect of the present invention is to provide a novel light-emitting device. Another object of the present invention is to provide a novel light-emitting device having good efficiency. Another object of the present invention is to provide a novel light-emitting device having good reliability.

[0011] Another object of the present invention is to provide a novel light-emitting device that can be used in a high-definition display device. Another object of the present invention is to provide a novel light-emitting device having good efficiency that can be used in a high-definition display device. Another object of the present invention is to provide a novel light-emitting device having good reliability that can be used in a high-definition display device.

[0012] Another object of one aspect of the present invention is to provide a display device having high reliability. Another object of one aspect of the present invention is to provide a high-definition display device. Another object of one aspect of the present invention is to provide a high-definition and highly reliable display device.

[0013] Another object of one aspect of the present invention is to provide a novel organic compound, a novel light-emitting device, a novel display device, a novel display module, and a novel electronic device, respectively.

[0014] Note that the description of these objects does not preclude the existence of other objects. One aspect of the present invention does not need to achieve all of the above objects. Objects other than the above can be extracted from the description of the specification, the drawings, and the claims. Means for Solving the Technical Problem

[0015] One aspect of the present invention is a light-emitting device including a first electrode, a second electrode, and an EL layer disposed between the first electrode and the second electrode. The EL layer includes a light-emitting layer, an electron transport layer, and an electron injection layer. The electron transport layer is in contact with the electron injection layer. The electron injection layer has a function of blocking holes, and the electron transport layer is a bipolar layer.

[0016] In addition, another aspect of the present invention is a light-emitting device including a first electrode, a second electrode, and an EL layer disposed between the first electrode and the second electrode. The EL layer includes a light-emitting layer, an electron transport layer, and an electron injection layer. The electron transport layer is in contact with the electron injection layer. The electron injection layer has a function of blocking holes, and the electron transport layer is a layer containing an organic compound having electron-transporting properties and an organic compound having hole-transporting properties.

[0017] In addition, another aspect of the present invention is a light-emitting device including a first electrode, a second electrode, and an EL layer disposed between the first electrode and the second electrode. The EL layer includes a light-emitting layer, an electron transport layer, and an electron injection layer. The electron transport layer is in contact with the electron injection layer. The electron injection layer contains an organic compound having a strong basicity with a pKa of 8 or more, and the electron transport layer contains an organic compound having electron-transporting properties and an organic compound having hole-transporting properties.

[0018] In addition, another aspect of the present invention is a light-emitting device having the above structure. The EL layer further includes an intermediate layer and a second light-emitting layer. The second light-emitting layer is disposed between the intermediate layer and the first electrode, and the intermediate layer includes a layer containing an organic compound having a strong basicity with a pKa of 8 or more.

[0019] In addition, another aspect of the present invention is a light-emitting device having the above structure. The EL layer further includes an intermediate layer, a second light-emitting layer, and a second electron transport layer. The second light-emitting layer is disposed between the intermediate layer and the first electrode, the second electron transport layer is disposed between the second light-emitting layer and the intermediate layer, and the intermediate layer includes a layer containing an organic compound having a strong basicity with a pKa of 8 or more.

[0020] In addition, another aspect of the present invention is a light-emitting device having the above structure. The EL layer further includes an intermediate layer, a second light-emitting layer, and a second electron transport layer. The second light-emitting layer is disposed between the intermediate layer and the first electrode, the second electron transport layer is disposed between the second light-emitting layer and the intermediate layer, the intermediate layer includes a layer containing an organic compound having a strong basicity with a pKa of 8 or more, and the second electron transport layer is bipolar.

[0021] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the intermediate layer includes a P-type layer, and the P-type layer is located between a layer containing an organic compound having a strong basicity with a pKa of 8 or more and the light-emitting layer.

[0022] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the HOMO energy level of the above-mentioned hole-transporting organic compound is -5.9 eV or more and -5.0 eV or less.

[0023] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the LUMO energy level of the above-mentioned electron-transporting organic compound is -3.15 eV or more and -2.50 eV or less.

[0024] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the above-mentioned organic compound having a strong basicity with a pKa of 8 or more has a guanidine skeleton.

[0025] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the above-mentioned organic compound having a strong basicity with a pKa of 8 or more has a 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine skeleton.

[0026] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the above-mentioned organic compound having a strong basicity with a pKa of 8 or more does not have an electron-transporting skeleton.

[0027] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the above-mentioned organic compound having a strong basicity with a pKa of 8 or more has a guanidine skeleton and does not have an electron-transporting skeleton.

[0028] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the above-mentioned electron injection layer further contains an organic compound having a second electron-transporting property.

[0029] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the above-mentioned organic compound having a strong basicity with a pKa of 8 or more does not have an electron-donating property to the above-mentioned organic compound having a second electron-transporting property.

[0030] Further, another aspect of the present invention is a light-emitting device having the above structure, wherein the spin density obtained by measuring the above-mentioned electron injection layer using electron spin resonance method is 1×10 17 spins / cm 3 Hereinafter, preferably less than 1×10 16 spins / cm 3 .

[0031] In addition, another aspect of the present invention is a display module, which includes at least one of the above-mentioned light-emitting device, a connector, and an integrated circuit.

[0032] In addition, another aspect of the present invention is an electronic device, which includes at least one of the above-mentioned light-emitting device, a housing, a battery, a camera, a speaker, and a microphone. Advantages of the Invention

[0033] According to one aspect of the present invention, a novel light-emitting device can be provided. In addition, according to another aspect of the present invention, a novel light-emitting device with good efficiency can be provided. In addition, according to another aspect of the present invention, a novel light-emitting device with good reliability can be provided.

[0034] In addition, according to another aspect of the present invention, a novel light-emitting device applicable to a high-definition display device can be provided. In addition, according to another aspect of the present invention, a novel light-emitting device with good efficiency applicable to a high-definition display device can be provided. In addition, according to another aspect of the present invention, a novel light-emitting device with good reliability applicable to a high-definition display device can be provided.

[0035] In addition, according to another aspect of the present invention, a display device with high reliability can be provided. In addition, according to another aspect of the present invention, a high-definition display device can be provided. In addition, according to another aspect of the present invention, a high-definition and reliable display device can be provided.

[0036] In addition, according to one aspect of the present invention, a novel organic compound, a novel light-emitting device, a novel display device, a novel display module, and a novel electronic device can be provided.

[0037] Note that the description of these effects does not preclude the existence of other effects. One aspect of the present invention does not necessarily have all of the above effects. Effects other than the above can be extracted from the description in the specification, drawings, and claims. Brief Description of the Drawings

[0038] Figure 1A and Figure 1B are diagrams showing the driving mechanism of the light-emitting device of the present invention. Figure 2A and Figure 2B are diagrams showing the light-emitting device. Figure 3A and Figure 3B are diagrams showing the light-emitting device. Figure 4A and Figure 4B are a top view and a cross-sectional view of the light-emitting device. Figures 5A to 5EIt is a cross-sectional view showing an example of a method for manufacturing a display device. Figures 6A to 6D It is a cross-sectional view showing an example of a method for manufacturing a display device. Figures 7A to 7D It is a cross-sectional view showing an example of a method for manufacturing a display device. Figures 8A to 8C It is a cross-sectional view showing an example of a method for manufacturing a display device. Figures 9A to 9C It is a cross-sectional view showing an example of a method for manufacturing a display device. Figures 10A to 10C It is a cross-sectional view showing an example of a method for manufacturing a display device. Figure 11A and Figure 11B It is a perspective view showing an example of the structure of a display module. Figure 12A and Figure 12B It is a cross-sectional view showing an example of the structure of a display device. Figure 13 It is a perspective view showing an example of the structure of a display device. Figure 14 It is a cross-sectional view showing an example of the structure of a display device. Figure 15 It is a cross-sectional view showing an example of the structure of a display device. Figure 16 It is a cross-sectional view showing an example of the structure of a display device. Figures 17A to 17D It is a diagram showing an example of an electronic device. Figures 18A to 18F It is a diagram showing an example of an electronic device. Figures 19A to 19G It is a diagram showing an example of an electronic device. Figure 20 It is a diagram showing current density-voltage characteristics. Mode for Carrying Out the Invention

[0039] The embodiments will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following description, and it is easily understandable by those of ordinary skill in the art that its modes and details can be changed into various forms without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited only to the content described in the following embodiments.

[0040] Note that in this specification and the like, a device fabricated using a metal mask or an FMM (Fine Metal Mask) is sometimes referred to as a device having an MM (Metal Mask) structure. Further, in this specification and the like, a device fabricated without using a metal mask or an FMM is sometimes referred to as a device having an MML (Metal Mask Less) structure.

[0041] (Embodiment 1) As one of the methods for forming an organic semiconductor film into a specified shape, vacuum evaporation using a metal mask (mask evaporation) is widely employed. However, recently, with the progress of high density and high definition, due to various reasons typified by problems in positional alignment accuracy and problems in the arrangement interval with respect to the substrate, further high definition of mask evaporation is approaching its limit. On the other hand, it is desired to realize an organic semiconductor device having a denser pattern by processing the shape of the organic semiconductor film using photolithography. Moreover, since it is easier to achieve large area processing with photolithography than with mask evaporation, research on processing an organic semiconductor film using photolithography is underway.

[0042] On the other hand, it has been known that the initial characteristics or reliability of the EL layer in an organic EL device are affected when exposed to atmospheric components such as water and oxygen, and thus processing is generally performed in an atmosphere close to vacuum.

[0043] In particular, an electron injection layer of a light-emitting device often uses an alkali metal, an alkaline earth metal, or a compound thereof (hereinafter also referred to as Li compounds, etc.), but these Li compounds, etc. have high reactivity with water or oxygen and rapidly deteriorate when exposed to the atmosphere, losing their function as an electron injection layer.

[0044] However, in the process of processing by photolithography as described above, the surface of the EL layer has to be exposed to the atmosphere, and thus the electron injection property of the electron injection layer using Li compounds, etc. significantly decreases.

[0045] Here, the present inventors have found that a light-emitting device using an organic compound having strong basicity as an electron injection layer has good characteristics.

[0046] An organic compound having strong basicity is not easily deteriorated when exposed to the atmosphere like an alkali metal, an alkaline earth metal, or a compound thereof. Therefore, even in a light-emitting device in a process of processing by photolithography having an atmospheric exposure in the process, deterioration of the light-emitting device due to deterioration of the organic compound having strong basicity itself is not likely to occur.

[0047] Note that, on the other hand, when comparing devices always fabricated under vacuum, the driving voltage of a light-emitting device sometimes becomes higher when an organic compound with strong basicity is used for the electron injection layer, as compared with a light-emitting device using an alkali metal or alkaline earth metal or a compound thereof for the electron injection layer.

[0048] Due to these facts and various additional experiments, the present inventors have found that, in a light-emitting device using an organic compound with strong basicity for the electron injection layer, by making the electron transport layer include a mixed layer of an organic compound with electron-transporting property and an organic compound with hole-transporting property, a light-emitting device can be fabricated which has resistance to processing in air, good reliability, and a low driving voltage.

[0049] Hereinafter, the mechanism of a light-emitting device using an organic compound with strong basicity for the electron injection layer and a light-emitting device according to one embodiment of the present invention will be described.

[0050] When an organic compound with strong basicity is used instead of an alkali metal or alkaline earth metal or a compound thereof typified by a Li compound, the organic compound with strong basicity is not used as a donor, and thus, when the difference between the Fermi level (E F ) of the electrode and the LUMO level of the electron-transporting material is large, it is difficult to inject electrons ( Figure 1A ). Therefore, the driving voltage of a light-emitting device using an organic compound with basicity for the electron injection layer instead of a Li compound increases significantly.

[0051] Here, the present inventors have found that, by making the electron transport layer include a mixed layer of an organic compound with electron-transporting property and an organic compound with hole-transporting property, a light-emitting device using an organic compound with strong basicity for the electron injection layer instead of a Li compound can suppress a significant increase in the driving voltage.

[0052] This can be explained based on new knowledge that electrons flow but holes are blocked (do not flow) in the EL layer containing an organic compound with strong basicity, the generation of an electric dipole due to the accumulation of charges, and a driving mechanism such as the drift of the vacuum level caused thereby.

[0053] First, holes injected from the anode accumulate rapidly at the interface on the electron transport layer side in the electron injection layer as Figure 1B shown. This is because, in a light-emitting device according to one embodiment of the present invention, the electron transport layer is a mixed layer of an organic compound with electron-transporting property and an organic compound with hole-transporting property, whereby the electron transport layer transports holes smoothly, and the electron injection layer contains an organic compound with strong basicity having an acid dissociation constant pKa of 8 or more, whereby holes are blocked.

[0054] On the other hand, in a light-emitting device using an electron injection layer containing an organic compound with strong alkalinity, even when a voltage is applied as described above, electrons are not easily injected due to the difference between the Fermi level of the electrode and the LUMO level of the material with electron-transporting properties, and electrons accumulate at the interface on the electron injection layer side in the cathode (note that when the electron injection layer does not contain a material with electron-transporting properties, i.e., it is a single film of an organic compound with strong alkalinity, electrons accumulate on the side of the single film of the organic compound with strong alkalinity).

[0055] Thus, in a light-emitting device according to one embodiment of the present invention, holes accumulate at the interface on the electron-transporting layer side of the electron injection layer, and electrons accumulate on the electron injection layer side of the cathode. The accumulated charges form a double layer, generating an electric dipole and causing a vacuum level shift, and the Fermi level of the cathode material approaches the LUMO level of the material with electron-transporting properties in the electron injection layer, and electrons are injected into the EL layer at a low voltage.

[0056] Note that generally, from the viewpoints of luminous efficiency and reliability, it is not preferable for holes passing through the light-emitting layer to flow through the electron-transporting layer. Therefore, a material with low hole-transporting properties is selected as the material constituting the electron-transporting layer, and in many cases, a hole-blocking layer is provided in contact with the light-emitting layer between the light-emitting layer and the electron-transporting layer. However, in contrast to this, a light-emitting device according to one embodiment of the present invention can provide a light-emitting device with good characteristics by making the electron-transporting layer bipolar.

[0057] In addition, in a light-emitting device having a general structure in which the electron-transporting layer is not a mixed layer of an organic compound with electron-transporting properties and an organic compound with hole-transporting properties (the electron-transporting layer does not transport or block holes), the position where holes accumulate is the interface on the electron-transporting layer side in the light-emitting layer. Therefore, the accumulation positions of the holes accumulated at the interface on the electron-transporting layer side in the light-emitting layer and the electrons accumulated on the electron injection layer side of the cathode are far apart. Thus, when comparing the cases where the same amount of charge accumulates, the electric field of the electric dipole in the light-emitting device with the general structure is weaker, and the driving voltage increases.

[0058] The electron transport layer is preferably a layer having high hole transportability as described above. Thus, the highest occupied molecular orbital (HOMO) energy level of the organic compound having hole transportability in the electron transport layer is preferably -5.90 eV or higher and -5.00 eV or lower, more preferably -5.80 eV or higher and -5.00 eV or lower, and further preferably -5.70 eV or higher and -5.15 eV or lower. Since the electron transport layer also needs to have good electron transportability, the lowest unoccupied molecular orbital (LUMO) energy level of the organic compound having electron transportability in the electron transport layer is preferably -3.15 eV or higher and -2.50 eV or lower, more preferably -3.00 eV or higher and -2.70 eV or lower.

[0059] In addition, the electron transport layer preferably contains an organic compound having an acid dissociation constant pKa of 4 or less and having electron transportability.

[0060] In addition, the organic compound having electron transportability preferably has an electron transport skeleton. In addition, the organic compound having hole transportability preferably has a hole transport skeleton.

[0061] Note that the electron transport skeleton is preferably a skeleton having a π-deficient heteroaromatic ring. As the skeleton having a π-deficient heteroaromatic ring, for example, a skeleton containing at least any one of a triazole skeleton, a pyridine skeleton, a diazine skeleton, and a triazine skeleton in the ring is preferably used. Specifically preferred are a pyrimidine skeleton, a pyrazine skeleton, a pyridazine skeleton, a pyridine skeleton, a triazine skeleton, a benzofuro[2,3-d]pyrimidine skeleton, a benzothieno[2,3-d]pyrimidine skeleton, a benzofuro[2,3-b]pyrazine skeleton, a benzothieno[2,3-b]pyrazine skeleton, etc. Particularly preferred are a pyrimidine skeleton, a pyrazine skeleton, a triazine skeleton, and a benzofuro[2,3-d]pyrimidine skeleton. In addition, the hole transport skeleton is preferably a skeleton having a π-rich heteroaromatic ring. As the π-rich heteroaromatic ring, for example, a fused aromatic ring containing at least any one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring is preferably used. Specifically preferred are a carbazole skeleton, a dibenzothiophene skeleton, or a skeleton in which these skeletons are further fused with an aromatic ring or a heteroaromatic ring. Particularly preferred are a carbazole skeleton, a biscarbazole skeleton, and an indolocarbazole skeleton. In addition, an amine skeleton, particularly a triphenylamine skeleton, is also preferably used.

[0062] Examples of organic compounds having electron transport properties include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 3-(4-biphenylyl)-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-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviated as TPBI), 2-[3-( organic compounds having an azole skeleton, such as 1,4-dibenzothiophene-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-carbazole-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-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBphen), 2,2'-(1,3-phenylene)bis(9-phenylene)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-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBphen), organic compounds containing a heteroaromatic ring having a pyridine skeleton, such as 2-[4-(9-phenanthrenyl)-1-naphthyl]-1,10-phenanthroline (abbreviated as: pTpPPhen), 2-[3-(2-triphenylene)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), 2-[4-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as: pTpPPhen); 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTPDBq-I I), 2-[3-(3'-dibenzothiophene-4-yl)biphenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazole-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2CzPDBq-III), 7-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]Quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenz[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-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-Bis[3-(4-dibenzothiophenyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[Pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(Biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-Bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-Bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(Dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-Binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(Pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(Pyridine-2,6-diyl)bis{4-[4-(naphthalen-2-yl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(Biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-Bis(4-naphthalen-1-ylphenyl)-4-[4-(pyridin-3-yl)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) and other organic compounds with 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-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylene-2-yl)-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1”-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn) and other organic compounds containing a heteroaromatic ring having a triazine skeleton. Organic compounds containing a heteroaromatic ring having a diazine skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, or organic compounds containing a heteroaromatic ring having a triazine skeleton have good reliability and are therefore preferred. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reducing the driving voltage.

[0063] As organic compounds having hole-transporting properties, for example, N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthalen-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthalen-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthalen-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenyl)-4'[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenyl)-4'[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-bis(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-Spirobi-9H-fluorene-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-1-amine, 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.

[0064] The thickness of the electron transport layer is preferably thin, but a light-emitting device with good reliability can be manufactured when its thickness is 5 nm to 10 nm, so it is preferred.

[0065] The electron injection layer accumulates holes injected from the anode. Therefore, the electron injection layer is a layer having a function of blocking holes or a layer that does not transport holes. In addition, the electron injection layer needs to transport electrons injected from the cathode and inject them into the electron transport layer. Therefore, the electron injection layer is a layer having electron transport properties.

[0066] By manufacturing an electronic device through which only holes flow (hereinafter referred to as a single-hole device) and measuring the relationship between current density and voltage, it can be determined whether the electron injection layer blocks holes. For example, when the current density significantly decreases when the layer to be clamped in the single-hole device as shown in Table 1, specifically, when measuring while clamping the layer to be measured in the device for measurement shown in Table 1, the current density at 10 V is 0.01 mA / cm 2 In the following cases, the layer of interest can be regarded as a hole-blocking layer.

[0067] [Table 1]

[0068] Note that in the table, ITSO refers to indium tin oxide containing silicon oxide, PCBBiF refers to N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine, and OCHD-003 refers to an electron acceptor material containing fluorine and having a molecular weight of 672.

[0069] By using such a device, it is possible to compare the relationship between the current density and voltage when layer 3 is not formed with the relationship between the current density and voltage when layer 3 is formed as a layer for an object of 10 nm. When measuring while sandwiching a layer of an object of 10 nm as layer 3, a layer with a current density of 0.01 mA / cm at 10 V 2 or less can be regarded as a hole-blocking layer.

[0070] Figure 20 Examples of measurements using such a device are shown. Figure 20 The results of devices with films of N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), 1-(2',7'-di-tert-butyl-9,9'-spirobi[9H-fluorene]-2-yl)-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (abbreviation: 2',7'tBu-2hppSF), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), mPPhen2P:PCBBiF (1:1, weight ratio), mPPhen2P:βNCCP (1:1, weight ratio), and mPPhen2P:2',7'tBu-2hppSF (1:1, weight ratio) as layer 3 of the above-mentioned single-hole device for measurement are shown.

[0071] As shown in this drawing, it can be said that layers formed of PCBBiF, βNCCP, mPPhen2P, mPPhen2P:PCBBiF (1:1, weight ratio), and mPPhen2P:βNCCP (1:1, weight ratio) are non-hole-blocking layers, and layers formed of mPPhen2P:2',7'tBu-hppSF (1:1, weight ratio) and layers formed of 2',7'tBu-2hppSF are hole-blocking layers.

[0072] Furthermore, in the case where the layer to be measured is a mixed layer of material A and material B, a device (device A) in which this layer is provided as the measurement target layer of the above-mentioned single-hole device and a device (device B) in which a single layer of the material with a deeper HOMO energy level among material A and material B is provided as the measurement target layer are manufactured, and when the voltage of device A at 1 mA / cm 2 migrates to a high voltage of 1 V or more, this layer can be regarded as a hole-blocking layer.

[0073] The electron injection layer preferably contains a strongly basic organic compound having an acid dissociation constant pKa of 8 or more. By containing a strongly basic organic compound having a pKa of 8 or more, the electron injection layer can block holes and accumulate holes in the electron transport layer. Note that a strongly basic substance having an acid dissociation constant pKa of 8 or more, preferably pKa of 10 or more, and more preferably pKa of 12 or more preferably does not have an electron transport skeleton. Note that 2hppSF is a strongly basic substance having an acid dissociation constant of 13.95.

[0074] The fact that a material with a large acid dissociation constant pKa blocks holes stems from the large dipole moment of the material with a large pKa. Through the interaction between this dipole moment and holes, the electron injection layer containing a material with a large acid dissociation constant pKa can block holes.

[0075] In addition, the high nucleophilicity of a material with a large acid dissociation constant pKa is also one of the reasons. A material with high nucleophilicity sometimes reacts with a molecule that accepts a hole and becomes a cation radical to generate a new molecule or an intermediate state. By this reaction, holes are consumed, and sometimes the hole transport property of the electron injection layer is greatly reduced.

[0076] Note that the above-mentioned strongly basic substance having a pKa of 8 or more preferably does not have an electron transport skeleton. This is because the recombination of electrons injected into the electron injection layer and holes replaced by a material with a large acid dissociation constant pKa is inhibited, and electrons are efficiently injected into the electron transport layer.

[0077] Note that the above-mentioned substance having an acid dissociation constant pKa of 8 or more is an organic compound having a basic skeleton, preferably an organic compound having an acid dissociation constant pKa of 10 or more for this basic skeleton. In addition, more preferably, it is an organic compound having an acid dissociation constant pKa of 12 or more for this basic skeleton.

[0078] In addition, as the acid dissociation constant pKa of the basic skeleton, the value of an organic compound in which a part of the skeleton is replaced by hydrogen can be used. In addition, as an index of the acidity of an organic compound having a basic skeleton, the acid dissociation constant pKa of this basic skeleton can be used. In addition, for an organic compound having multiple basic skeletons, the acid dissociation constant pKa of the basic skeleton with the highest acid dissociation constant pKa can be used as an index of the acidity of this organic compound. The acid dissociation constant pKa is preferably a value measured using water as a solvent.

[0079] Alternatively, the acid dissociation constant pKa of an organic compound can also be obtained by the following calculation.

[0080] First, the initial structure of the molecular structure of each molecule serving as the calculation model is the most stable structure (singlet ground state) obtained by first-principles calculation.

[0081] For the above first-principles calculations, the most stable structure in the singlet ground state was calculated by density functional theory (DFT) using Jaguar, a quantum chemistry calculation software manufactured by Schrodinger, Inc. The 6-31G** basis function was used, and the B3LYP-D3 functional was used. As the structure for performing quantum chemistry calculations, the Maestro GUI manufactured by Schrodinger, Inc. was used, and conformational analysis was performed by Mixed torsional / Low-mode sampling for sampling.

[0082] In the pKa calculation, one or more atoms of each molecule were specified as basic sites. To explore the stable structure of the protonated molecule in water, Macro Model was used, conformational search was performed using the OPLS2005 force field, and the lowest energy conformer was used. Then, the structure was optimized using the pKa calculation module of Jaguar at B3LYP / 6-31G*, followed by a single-point calculation using cc-pVTZ(+), and the pKa value was calculated using empirical correction for functional groups. For the molecule with one or more atoms specified as basic sites, the largest value among the obtained results was used as the pKa value.

[0083] Organic compounds with a high acid dissociation constant pKa are preferably organic compounds having a pyrrolidine skeleton, a piperidine skeleton, or a hexahydropyrimido[1,2-a]pyrimidine skeleton. In addition, the above organic compounds are preferably organic compounds having a guanidine skeleton. Specifically, as examples, organic compounds having a basic skeleton represented by the following structural formulas (120) to (123) can be cited.

[0084] [Chemical formula 1]

[0085] Furthermore, preferably, the above organic compounds with an acid dissociation constant pKa of 8 or more are specifically organic compounds having a bicyclic structure with two or more nitrogens in the ring-forming atoms, a heteroaromatic ring with 2 to 30 carbon atoms in the ring, or an aromatic ring with 6 to 30 carbon atoms in the ring. More specifically, they are organic compounds having a 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine skeleton, a heteroaromatic ring with 2 to 30 carbon atoms in the ring, or an aromatic ring with 6 to 30 carbon atoms in the ring. More preferably, the above organic compounds are organic compounds having a bicyclic structure with two or more nitrogens in the ring-forming atoms and a heteroaromatic ring with 2 to 30 carbon atoms in the ring, and more specifically, they are organic compounds having a 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine skeleton and a heteroaromatic ring with 2 to 30 carbon atoms in the ring.

[0086] In addition, preferably, more specifically, it is an organic compound represented by the following general formula (G1).

[0087] [Chemical formula 2]

[0088] Note that in the organic compound represented by the above general formula (G1), X is a group represented by the following general formula (G1-1), and Y is a group represented by the following general formula (G1-2). In addition, R 1 and R 2 each independently represents hydrogen or deuterium, h represents an integer from 1 to 6, and Ar represents a substituted or unsubstituted heteroaromatic ring having 2 to 30 carbon atoms forming the ring or an aromatic ring having 6 to 30 carbon atoms forming the ring. In addition, Ar is preferably a substituted or unsubstituted heteroaromatic ring having 2 to 30 carbon atoms forming the ring.

[0089] [Chemical formula 3]

[0090] Note that in the above general formulas (G1-1) and (G1-2), R 3 to R 6 each independently represents hydrogen or deuterium, m represents an integer from 0 to 4, n represents an integer from 1 to 5, and mn + 1 ≥. When m or n is 2 or more, the plurality of R 3 to R 6 may be the same as or different from each other.

[0091] In addition, the organic compound represented by the above general formula (G1) is preferably any one of the following general formulas (G2-1) to (G2-6).

[0092] [Chemical formula 4]

[0093] Note that R 11 to R 26 each independently represents hydrogen or deuterium, h represents an integer from 1 to 6, and Ar represents a substituted or unsubstituted heteroaromatic ring having 2 to 30 carbon atoms forming the ring or a substituted or unsubstituted aromatic ring having 6 to 30 carbon atoms forming the ring. In addition, Ar is preferably a substituted or unsubstituted heteroaromatic ring having 2 to 30 carbon atoms forming the ring.

[0094] In addition, in the above general formulas (G1) and (G2-1) to (G2-6), as the substituted or unsubstituted heteroaromatic ring having 2 to 30 carbon atoms forming the ring or the aromatic ring having 6 to 30 carbon atoms forming the ring represented by Ar, specifically, a pyridine ring, a bipyridine ring, a pyrimidine ring, a bipyrimidine ring, a pyrazine ring, a bipyrazine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a benzoquinoline ring, a phenanthroline ring, a quinoxaline ring, a benzoquinoxaline ring, a dibenzoquinoxaline ring, an azofluorene ring, a diazofluorene ring, a carbazole ring, a benzocarbazole ring, a dibenzocarbazole ring, a dibenzofuran ring, a benzonaphthofuran ring, a dinaphthofuran ring, a dibenzothiophene ring, a benzonaphthothiophene ring, a dinaphthothiophene ring, a benzofuranopyridine ring, a benzofuranopyrimidine ring, a benzothiophenopyridine ring, a benzothiophenopyrimidine ring, a naphthofuranopyridine ring, a naphthofuranopyrimidine ring, a naphthothiophenopyridine ring, a naphthothiophenopyrimidine ring, an acridine ring, a xanthene ring, a phenothiazine ring, a phenoxazine ring, a phenazine ring, a triazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, a thiadiazole ring, an imidazole ring, a benzimidazole ring, a pyrazole ring or a pyrrole ring, etc. can be mentioned. In addition, in the above general formulas (G1) and (G2-1) to (G2-6), as the substituted or unsubstituted heteroaromatic ring having 6 to 30 carbon atoms forming the ring represented by Ar, specifically, a benzene ring, a naphthalene ring, a fluorene ring, a dimethylfluorene ring, a diphenylfluorene ring, a spirofluorene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a pyrene ring, a tetracene ring, (chrysene) ring, a benzo[a]anthracene ring, etc. can be mentioned. In addition, any one of the following structural formulas (Ar-1) to (Ar-27) is particularly preferred.

[0095] [Chemical formula 5]

[0096] Note that the above Ar contains nitrogen as an atom forming the ring, and this Ar is preferably bonded to the skeleton represented in parentheses in the above general formula (G1) by a bond of the nitrogen or the carbon adjacent to the nitrogen.

[0097] As the organic compounds represented by the above general formula (G1) and general formulas (G2-1) to (G2-6), specifically, for example, 1,1'-(9,9'-spirobi[9H-fluorene]-2,7-diyl)bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) (abbreviation: 2,7hpp2SF) (structural formula 108), 1-(9,9'-spirobi[9H-fluorene]-2-yl)-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (abbreviation: 2hppSF) (structural formula 109), etc., and organic compounds represented by the following structural formulas (101) to (117) can be cited. In addition, among them, organic compounds having a spirofluorene skeleton as shown in (106) to (109) or organic compounds having one hexahydropyrimidopyrimidine skeleton as shown in (102), (104), (105), (109), (110), and (115) are preferred, and the organic compound represented by (109) is particularly preferred.

[0098] [Chemical formula 6]

[0099] Different from alkali metals or alkaline earth metals or their compounds, such organic compounds have the following advantages in addition to being stable: less concern about metal contamination in the production line; easy evaporation coating; etc. Therefore, they are more suitable for light-emitting devices manufactured using a photolithography process. Of course, they are also suitable for light-emitting devices manufactured through processes that do not use photolithography.

[0100] Note that strong basic substances having a pKa of 8 or more preferably do not include an electron transport skeleton in order to suppress the recombination of injected electrons and blocked holes on the strong basic substance having a pKa of 8 or more. As substances having strong basicity with an acidity coefficient pKa of 8 or more, specifically, 1-(9,9'-spirobi[9H-fluorene]-2-yl)-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (abbreviation: 2hppSF), 2,9-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline (abbreviation: 2,9hpp2Phen), 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviation: Pyrrd-Phen), or 8,8'-pyridine-2,6-diyl-bis(5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine) (abbreviation: 2,6tip2Py) and other organic compounds can be used.

[0101] In addition, the electron injection layer preferably contains a material having electron transporting properties in addition to a substance having a strong basicity with a pKa of 8 or higher. As the material having electron transporting properties, for example, it is preferable to use: bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-hydroxyquinolinato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-hydroxyquinolinato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), and other metal complexes, and organic compounds including π-deficient heteroaromatic rings. As the organic compounds including a π-deficient heteroaromatic skeleton, for example, organic compounds including a heteroaromatic ring having a triazole skeleton, organic compounds including a heteroaromatic ring having a pyridine skeleton, organic compounds including a heteroaromatic ring having a diazine skeleton, and organic compounds including a heteroaromatic ring having a triazine skeleton can be cited.

[0102] Among them, organic compounds including a heteroaromatic ring having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds including a heteroaromatic ring having a pyridine skeleton, or organic compounds including a heteroaromatic ring having a triazine skeleton have good reliability, and thus are preferable. In particular, organic compounds including a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds including a heteroaromatic ring having a triazine skeleton have high electron transporting properties, which helps to reduce the driving voltage. In addition, benzofuranopyrimidine skeletons, benzothiophenopyrimidine skeletons, benzofuranopyrazine skeletons, and benzothiophenopyrazine skeletons have high reliability, and thus are preferable.

[0103] As the organic compounds having a π-deficient heteroaromatic skeleton, the materials exemplified as the organic compounds having electron transporting properties in the above-mentioned first electron transport layer can be used. Among them, organic compounds including a heteroaromatic ring having a diazine skeleton, organic compounds including a heteroaromatic ring having a pyridine skeleton, or organic compounds including a heteroaromatic ring having a triazine skeleton have good reliability, and thus are preferable. In particular, organic compounds including a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds including a heteroaromatic ring having a triazine skeleton have high electron transporting properties, which helps to reduce the driving voltage. Among them, it is preferable to use organic compounds having a phenanthroline skeleton such as mTpPPhen, PnNPhen, and mPPhen2P, and more preferably use organic compounds having a phenanthroline dimer structure such as mPPhen2P because it has good stability. In addition, materials having a pyridine skeleton or a phenanthroline skeleton have a high pKa and a high hole blocking property, and thus are particularly preferably used as the electron transporting material of the electron injection layer of the light-emitting device according to one embodiment of the present invention.

[0104] In addition, the LUMO level of the material with electron-transporting property in the electron injection layer is preferably -3.00 eV or more and -2.00 eV or less, because the electron injection barrier to the light-emitting layer is reduced.

[0105] Note that the thickness of the electron injection layer is preferably thin. However, since the driving voltage increases when it is too thick and the characteristics, especially the reliability, deteriorate when it is too thin, its thickness is preferably 2 nm or more and 13 nm or less, more preferably 5 nm or more and 10 nm or less.

[0106] In addition, the substance with strong basicity in the electron injection layer preferably does not have electron-donating property. Further, the substance with strong basicity preferably does not have electron-donating property to the material with electron-transporting property. When the substance with strong basicity has electron-donating property, it easily reacts with atmospheric components such as water or oxygen, and thus the stability is poor. By including the substance with strong basicity and the material with electron-transporting property, the hole-transporting property of the electron injection layer can be significantly reduced. Therefore, even if the substance with strong basicity does not have electron-donating property, it can be used as the intermediate layer in the tandem structure. Thereby, an intermediate layer and a tandem light-emitting device that are stable to atmospheric components such as water or oxygen can be manufactured. In addition, in the electron injection layer, the signal observed by the electron spin resonance method (ESR: Electron Spin Resonance) is preferably small or no signal is observed. For example, the spin density due to the signal observed around the g value of 2.00 is preferably 1×10 17 spins / cm 3 Hereinafter, it is more preferably less than 1×10 16 spins / cm 3 .

[0107] The light-emitting device of one embodiment of the present invention having the above structure can be a light-emitting device with high current efficiency, suppressed increase in driving voltage, and high reliability.

[0108] In addition, although the light-emitting device of one embodiment of the present invention is particularly preferably used as a light-emitting device through a photolithography process, the light-emitting device manufactured without a photolithography process also has high stability to the atmosphere. Therefore, the yield is increased and the atmosphere management in the manufacturing process does not need to be too strict, which helps to reduce the cost.

[0109] (Embodiment 2) In this embodiment, a light-emitting device of one embodiment of the present invention will be described in detail.

[0110] Figure 2 is a schematic diagram of a light-emitting device according to an embodiment of the present invention. In the light-emitting device, a first electrode 101 is provided on an insulator 100, and an EL layer 103 is included between the first electrode 101 and the second electrode 102. The EL layer 103 includes at least a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115. The light-emitting layer 113 is a layer containing a light-emitting substance, and emits light when a voltage is applied between the first electrode 101 and the second electrode 102.

[0111] As Figure 2A shown, the EL layer 103 preferably further includes functional layers such as a hole injection layer 111 and a hole transport layer 112 in addition to the light-emitting layer 113, the electron transport layer 114, and the electron injection layer 115. In addition, the EL layer 103 may also include functional layers other than the above functional layers, such as a hole blocking layer, an electron blocking layer, an exciton blocking layer, and a charge generation layer. Conversely, any of the above layers may not be provided.

[0112] In addition, the electron injection layer 115 is a layer containing an organic compound having strong basicity as described in Embodiment 1. The electron injection layer 115 may also further contain an organic compound having electron transport properties.

[0113] In addition, the electron transport layer 114 is a layer containing an organic compound having electron transport properties and an organic compound having hole transport properties.

[0114] The specific structures of the electron transport layer 114 and the electron injection layer 115 have been described in detail in Embodiment 1, so repeated description is omitted here.

[0115] Note that although in this embodiment, an example is shown in which the first electrode 101 is an electrode including an anode, the second electrode 102 is an electrode including a cathode, and the first electrode 101 is formed on one side of the insulator 100, a structure in which the second electrode 102 is formed on one side of the insulator 100, that is, a so-called reverse stacked structure, may also be adopted. At this time, the light-emitting device has a stacked structure in which a second electrode 102, an electron injection layer 115, (an electron transport layer 114,) a light-emitting layer 113, (a hole transport layer 112, a hole injection layer 111,) and a first electrode 101 are sequentially stacked from one side of the insulator 100. When the light-emitting device having this reverse stacked structure is adopted, the relatively stable hole injection layer 111 becomes the surface, and thus a light-emitting device with higher reliability can be realized.

[0116] In addition, the first electrode 101 and the second electrode 102 are formed into a single-layer structure or a stacked structure. When having a stacked structure, the layer in contact with the EL layer 103 is used as an anode or a cathode. When the electrode has a stacked structure, there is no work function limitation on the layers other than the layer in contact with the EL layer 103, and materials can be selected according to required characteristics such as resistance value, processability, reflectance, light transmittance, and stability.

[0117] The anode is preferably formed of a metal, an alloy, a conductive compound, and a mixture thereof having a large work function (specifically, 4.0 eV or more). Specifically, for example, indium tin oxide (ITO: Indium Tin Oxide), indium tin silicon oxide (ITSO: Indium Tin Silicon Oxide) containing silicon or silicon oxide, indium zinc oxide, indium oxide containing tungsten oxide and zinc oxide (IWZO), etc. can be cited. Although these conductive metal oxide films are usually formed by a sputtering method, a sol-gel method or the like can also be applied for formation. As an example of the formation method, a method of forming indium zinc oxide by sputtering using a target in which 1 wt% to 20 wt% of zinc oxide is added to indium oxide can be cited. In addition, indium oxide containing tungsten oxide and zinc oxide (IWZO) can be formed by sputtering using a target in 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. 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), titanium (Ti), aluminum (Al), or nitrides of metal materials (for example, titanium nitride) etc. can be cited. In addition, a layer obtained by laminating them can also be used as the anode. For example, a film in which Al, Ti, and ITSO are sequentially laminated on Ti has high efficiency due to good reflectance and can achieve a high resolution of several thousand ppi, and thus is preferred. In addition, graphene can also be used as a material for the anode. In addition, by using a composite material that can constitute the hole injection layer 111 described later for the layer in contact with the anode (typically the hole injection layer), it is not necessary to consider the work function when selecting the electrode material.

[0118] The hole injection layer 111 is in contact with the anode and has the function of facilitating the injection of holes into the EL layer 103. Phthalocyanine compounds or complexes such as phthalocyanine (abbreviation: H2Pc) and copper phthalocyanine (abbreviation: CuPc) can be used; aromatic amine compounds such as 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), etc.; or polymers such as poly(3,4-ethylenedioxythiophene) / (polystyrenesulfonic acid) (abbreviation: PEDOT / PSS) can be used to form the hole injection layer 111.

[0119] In addition, the hole injection layer 111 can also be composed of a substance with an electron-accepting property. As the substance with an accepting property, organic compounds having an electron-withdrawing group (halogen group, cyano group) can be used, and examples include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloroquinone, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)malononitrile, etc. In particular, compounds such as HAT-CN in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms are thermally stable, so they are preferred. In addition, [3]axylene derivatives including an electron-withdrawing group (especially a halogen group such as a fluorine group, a cyano group, etc.) have a very high electron-accepting property, so they are particularly preferred. Specifically, examples include: α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriyl tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriyl tris[2,3,4,5,6-pentafluorobenzeneacetonitrile], etc. As the substance with an accepting property, in addition to the above organic compounds, transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide can also be used.

[0120] In addition, the hole injection layer 111 is preferably formed using a composite material containing the above-mentioned material with an accepting property and an organic compound with a hole-transporting property.

[0121] As the organic compound having hole transport property for the composite material, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. As the organic compound having hole transport property for the composite material, it is preferable to use an organic compound having a hole mobility of 1×10 -6 cm 2 / Vs or more. The organic compound having hole transport property for 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, anthracene ring, naphthalene ring, etc. are preferable. In addition, as the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least any one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferable, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which these rings are further fused with an aromatic ring or a heteroaromatic ring is preferable.

[0122] This organic compound having hole transport property preferably has any one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, it can be an aromatic amine having a substituent including a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine including a naphthalene ring, or an aromatic monoamine in which 9-fluorenyl is bonded to the nitrogen of the amine through an arylene group. Note that when these organic compounds having hole transport property are substances including N,N-bis(4-biphenyl)amino, a light-emitting device having a long lifetime can be manufactured, so they are preferable.

[0123] As the above-mentioned organic compound having hole-transporting properties, specifically, N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthalen-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthalen-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthalen-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-bis(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-Spirobi-9H-fluorene-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-1-amine, etc.

[0124] In addition, as materials with hole-transporting properties, as other aromatic amine compounds, 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. can also be used.

[0125] By forming the hole injection layer 111, the hole injection property can be improved, and thus a light-emitting device with a low driving voltage can be obtained.

[0126] In addition, organic compounds having acceptivity among substances having acceptivity can be easily formed by evaporation deposition, so they are materials that are easy to use.

[0127] The hole transport layer 112 is formed by including an organic compound having hole-transporting properties. As the organic compound having hole-transporting properties, it preferably has a hole mobility of 1×10 -6 cm 2 / Vs or more.

[0128] Examples of the above hole-transporting materials include compounds with an aromatic amine backbone such as 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: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-bis(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 (abbreviation: PCBASF), etc.;1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylene-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]phenanthrene (abbreviation: PcPPn) and other compounds with a carbazole skeleton;Compounds with a thiophene backbone 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), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV); and compounds with a furan backbone such as 4,4’,4”-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among them, compounds with an aromatic amine backbone and compounds with a carbazole backbone have high reliability and excellent hole transport properties and contribute to reducing the driving voltage, so they are preferred. Note that substances listed as hole-transporting materials that can also be appropriately used as composite materials for the hole injection layer 111 can also be used as the material constituting the hole transport layer 112.;

[0129] The light-emitting layer 113 is a layer containing a light-emitting substance, and preferably contains a light-emitting substance and a host material. Note that the light-emitting layer may also contain other materials. In addition, it may also be a laminate of two layers with different compositions.

[0130] The light-emitting substance can be a fluorescent light-emitting substance, a phosphorescent light-emitting substance, a substance presenting thermally activated delayed fluorescence (TADF), or other light-emitting substances.

[0131] In the light-emitting layer, as materials that can be used as fluorescent light-emitting substances, for example, the following substances can be cited. Note that in addition to this, other fluorescent light-emitting substances can also be used.

[0132] Examples 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 (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenyldistyrene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butyldiperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyl-di-4,1-phenylene)bis(N,N',N'-triphenyl-1,4-benzenediamine) (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-benzenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N''' - octaphenyldibenzo[g,p] (chrysene)-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]vinyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-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}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]vinyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02), etc. In particular, fused aromatic diamine compounds represented by pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, 1,6BnfAPrn-03, etc. have high hole trapping properties, high luminous efficiency, and high reliability, so they are preferred.,

[0133] In addition, 5,9-diphenyl-5,9-diaza-13b-borata-anthra[3,2,1-de]anthracene (abbreviation: DABNA1), 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5,9-dihydro-5,9-diaza-13b-borata-anthra[3,2,1-de]anthracen-3-amine (abbreviation: DABNA2), 2,12-bis(tert-butyl)-5,9-bis(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborolo[2,3,4-kl]phenazaborole-7-amine (abbreviation: DPhA-tBu4DABNA), 2,12-bis(tert-butyl)-N,N,5,9-tetrakis(4-tert-butylphenyl)-5H,9H-[1,4]benzazaborolo[2,3,4-kl]phenazaborole-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-bis(tert-butyl)-5,9-bis(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzazaborolo[2,3,4-kl]phenazaborole (abbreviation: Me-tBu4DABNA), N 7 ,N 7 ,N 13 ,N 13 ,5,9,11,15-octaphenyl-5H,9H,11H,15H-[1,4]benzazaborolo[2,3,4-kl][1,4]benzazaborolo[4',3',2':4,5][1,4]benzazaborolo[3,2-b]phenazaborole-7,13-diamine (abbreviation: ν-DABNA), 2-(4-tert-butylphenyl)benzo[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc), etc. nitrogen- and boron-containing fused heteroaromatic compounds, especially compounds having a diaza-borata-anthracene skeleton have a narrow emission spectrum and can obtain blue light emission with good color purity, so they can be used appropriately.,

[0134] In addition to the above, 9,10,11-tris[3,6-bis(1,1-dimethylethyl)-9H-carbazol-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3’,2’,1’:8,1][1,4]benzazaborino[2,3,4-kl]phenazaborole (abbreviation: BBCz-G), 9,11-bis[3,6-bis(1,1-dimethylethyl)-9H-carbazol-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3’,2’,1’:8,1][1,4]benzazaborino[2,3,4-kl]phenazaborole (abbreviation: BBCz-Y), etc. can also be appropriately used.

[0135] When a phosphorescent light-emitting material is used as a light-emitting material in the light-emitting layer, examples of the materials that can be used include the following.

[0136] 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) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazole)iridium(III) (abbreviation: [Ir(Mptz)3]); organometallic iridium complexes having a 1H-triazole skeleton such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); organometallic iridium complexes having an imidazole skeleton such as fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpim)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazol-2-yl-κN3}-4-cyanophenyl-κC) (abbreviation: CNImIr); organometallic complexes having a benzimidazolylidene skeleton such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]); and bis[2-(4’,6’-difluorophenyl)pyridinato-N,C 2’Iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ iridium(III) acetylacetonate (abbreviation: FIr(acac)), etc., which are organometallic iridium complexes with phenylpyridine derivatives having electron-withdrawing groups as ligands. The above substances are compounds that emit blue phosphorescence and are compounds having a luminescence peak in the wavelength region of 450 nm to 520 nm.

[0137] In addition, examples include: tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-tert-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), etc., which are organometallic iridium complexes having a pyrimidine skeleton; (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), etc., which are organometallic iridium complexes having a pyrazine skeleton; tris(2-phenylpyridinato-N,C 2’ )iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’ ) iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-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-d3-methyl-(2-pyridyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy-d3)]), [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-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy)]), [2-(4-methyl-5-phenyl-2-pyridyl-κN)phenyl-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium (abbreviation: [Ir(ppy)2(mdppy)]), etc., organometallic iridium complexes having a pyridine skeleton; and rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). The above substances are mainly compounds showing green phosphorescence and have a luminescence peak in the wavelength region of 500 nm to 600 nm. In addition, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they have particularly excellent reliability or luminescence efficiency.

[0138] In addition, examples include: bis[4,6-bis(3-methylphenyl)pyrimidinato](dibenzoylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](neopentanedionato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](neopentanedionato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]) and other organometallic iridium complexes with a pyrimidine skeleton; bis(2,3,5-triphenylpyrazinato)(acetylacetonato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(neopentanedionato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), bis(2,3-bis(4-fluorophenyl)quinoxalinato)(acetylacetonato)iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]) and other organometallic iridium complexes with a pyrazine skeleton; tris(1-phenylisoquinoline-N,C 2’ )iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinoline-N,C 2’ )iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III), (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III) and other organometallic iridium complexes with a pyridine skeleton; platinum(II) 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin (abbreviation: PtOEP) and other platinum complexes; and tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]), tris[1-(2-thienoyl)-3,3,3-trifluoroacetone](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]) and other rare earth metal complexes. The above substances are compounds that exhibit red phosphorescence and have a luminescence peak in the wavelength region of 600 nm to 700 nm. In addition, organometallic iridium complexes with a pyrazine skeleton can obtain red luminescence with good chromaticity.

[0139] In addition, in addition to the above phosphorescent compounds, known phosphorescent compounds can also be selected and used.

[0140] As TADF materials, fullerenes and their derivatives, acridine and its derivatives, eosin derivatives, etc. can be used. In addition, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. can also be cited. As such metal-containing porphyrins, for example, protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. represented by the following structural formulas can also be cited.

[0141] [Chemical formula 7]

[0142] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: 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-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridin)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), etc., which have one or both of a heteroaromatic ring with a rich π-electron and a heteroaromatic ring with a deficient π-electron, can be used. The heteroaromatic compound has a heteroaromatic ring with a rich π-electron and a heteroaromatic ring with a deficient π-electron, and has high electron transportability and hole transportability, so it is preferred. Among them, in the skeleton having a heteroaromatic ring with a deficient π-electron, the pyridine skeleton, the diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and the triazine skeleton are stable and have good reliability, so they are preferred. In particular, the benzofuranopyrimidine skeleton, the benzothiophenopyrimidine skeleton, the benzofuranopyrazine skeleton, and the benzothiophenopyrazine skeleton have high acceptor properties and good reliability, so they are preferred. In addition, in the skeleton having a heteroaromatic ring with a rich π-electron, the acridine skeleton, the phenoxazine skeleton, the phenothiazine skeleton, the furan skeleton, the thiophene skeleton, and the pyrrole skeleton are stable and have good reliability, so it is preferred to have at least one of the above skeletons. In addition, as the furan skeleton, a dibenzofuran skeleton is preferably used, and as the thiophene skeleton, a dibenzothiophene skeleton is preferably used. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferably used. In a substance in which a heteroaromatic ring with a rich π-electron and a heteroaromatic ring with a deficient π-electron are directly bonded, the electron donating property of the heteroaromatic ring with a rich π-electron and the electron accepting property of the heteroaromatic ring with a deficient π-electron are both high, and the energy difference between the S1 energy level and the T1 energy level becomes small, so 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 the heteroaromatic ring with a deficient π-electron. In addition, as the rich π-electron skeleton, an aromatic amine skeleton, a phenazine skeleton, etc. can be used.In addition, as the π-deficient electron skeleton, an oxygen xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. can be used. Thus, at least one of the π-deficient electron skeleton and the π-rich electron skeleton can be used in place of the π-deficient electron heteroaromatic ring and the π-rich electron heteroaromatic ring.

[0143] [Chemical formula 8]

[0144] TADF materials refer to materials in which the energy difference between the S1 energy level and the T1 energy level is small and which have the function of converting triplet excitation energy into singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be up-converted into singlet excitation energy (reverse intersystem crossing) by a small amount of thermal energy and singlet excited states can be efficiently generated. In addition, triplet excitation energy can be converted into light emission.

[0145] An 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 because the energy difference between the S1 energy level and the T1 energy level is extremely small.

[0146] Note that as an index of the T1 energy level, a phosphorescence spectrum observed at low temperature (for example, 77K to 10K) can be used. For TADF materials, preferably, when the wavelength energy of the extrapolated line obtained by drawing a tangent at the tail on the short wavelength side of the fluorescence spectrum is the S1 energy level and the wavelength energy of the extrapolated line obtained by drawing a tangent at the tail on the short wavelength side of the phosphorescence spectrum is the T1 energy level, the difference between S1 and T1 is 0.3 eV or less, more preferably 0.2 eV or less.

[0147] In addition, when a TADF material is used as a light-emitting substance, the S1 energy level of the host material is preferably higher than the S1 energy level of the TADF material. In addition, the T1 energy level of the host material is preferably higher than the T1 energy level of the TADF material.

[0148] As the host material of the light-emitting layer, various carrier transport materials such as a material having electron-transporting properties and / or a material having hole-transporting properties, and the above-mentioned TADF materials can be used.

[0149] As a material having hole transporting properties, an organic compound having an amine skeleton, a π-electron rich heteroaromatic ring skeleton, etc. is preferably used. As the π-electron rich heteroaromatic ring, a fused aromatic ring containing at least any one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton and a pyrrole skeleton is preferred, and 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.

[0150] 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 can be an aromatic amine having a substituent including a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine including a naphthalene ring, or an aromatic monoamine in which 9-fluorenyl is bonded to the nitrogen of the amine through an arylene group. Note that when these organic compounds having hole transporting properties are substances including N,N-bis(4-biphenyl)amino, a light emitting device having a long lifetime can be manufactured, so they are preferred.

[0151] 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), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-bis(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]fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), etc., compounds having an aromatic amine skeleton; 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP), etc., compounds having a carbazole skeleton; 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), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), etc., compounds having a thiophene skeleton; and 4,4',4''-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), etc., compounds having a furan skeleton. Among them, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton have good reliability and high hole transportability and contribute to reducing the driving voltage, so they are preferred. In addition, organic compounds exemplified as examples of hole-transporting materials for the hole-transporting layer can also be used.

[0152] As a material having electron-transporting properties, for example, it is preferably used: beryllium(II) bis(10-hydroxybenzo[h]quinoline) (abbreviation: BeBq2), aluminum(III) bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol) (abbreviation: BAlq), zinc(II) bis(8-hydroxyquinoline) (abbreviation: Znq), zinc(II) bis[2-(2-benzoxazolyl)phenol] (abbreviation: ZnPBO), zinc(II) bis[2-(2-benzothiazolyl)phenol] (abbreviation: ZnBTZ) and other metal complexes, organic compounds including π-deficient heteroaromatic rings. As the organic compounds containing a π-deficient heteroaromatic skeleton, for example, organic compounds containing a heteroaromatic ring having a triazole 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 can be cited.

[0153] Among them, organic compounds containing a heteroaromatic ring having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing a heteroaromatic ring having a pyridine skeleton, or organic compounds containing a heteroaromatic ring having a triazine skeleton have good reliability, so they are preferred. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton, organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron-transporting properties, which helps to reduce the driving voltage. In addition, benzofuranopyrimidine skeleton, benzothiophenopyrimidine skeleton, benzofuranopyrazine skeleton, benzothiophenopyrazine skeleton have high acceptor properties and high reliability, so they are preferred.

[0154] Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2"-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3 -(dibenzothiophene-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), 2,2'-(1,3-phenylene)bis(9- Organic compounds containing a heteroaromatic ring having a pyridine skeleton, such as 2-[4-(2-triphenylene)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), 2-[4-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as: pTpPPhen); 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTPDBq-I I), 2-[3-(3'-(dibenzothiophene-4-yl)biphenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazole-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2CzPDBq-Ⅲ), 7-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]Quinoxaline (abbreviation: 7mDBTPDBq-II) and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzothiophene[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-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothiophenyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(naphthalen-2-yl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(pyridin-3-yl)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), and other organic compounds with 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-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenyl-indolo[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-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1”-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn) and other organic compounds containing heteroaromatic rings having a triazine skeleton. In addition, organic compounds containing heteroaromatic rings having a diazine skeleton, organic compounds containing heteroaromatic rings having a pyridine skeleton, or organic compounds containing heteroaromatic rings having a triazine skeleton have high reliability, and thus are 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 helps to reduce the driving voltage.

[0155] As the TADF material that can be used as the host material, the same materials as those exemplified above as the TADF material can be used. When the TADF material is used as the host material, the triplet excitation energy generated by the TADF material is converted into singlet excitation energy through reverse intersystem crossing and further energy is transferred to the luminescent material, whereby the luminous efficiency of the light-emitting device can be improved. At this time, the TADF material is used as the energy donor and the luminescent material is used as the energy acceptor.

[0156] This is very effective when the above-mentioned luminescent material is a fluorescent luminescent material. In addition, at this time, in order to obtain high luminous efficiency, the S1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent luminescent material. In addition, the T1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent luminescent material. Therefore, the T1 energy level of the TADF material is preferably higher than the T1 energy level of the fluorescent luminescent material.

[0157] In addition, it is preferable to use a TADF material that emits light with a wavelength overlapping the absorption band on the lowest energy side of the fluorescent luminescent material. Thereby, the excitation energy is smoothly transferred from the TADF material to the fluorescent luminescent material, and high-efficiency light emission can be obtained, so it is preferred.

[0158] In order to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, it is preferable to generate carrier recombination in the TADF material. In addition, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent emitter. For this purpose, the fluorescent emitter preferably has a protecting group around the emitter (the skeleton that causes luminescence) possessed by the fluorescent emitter. As this protecting group, a substituent having no π bond is preferable, and a saturated hydrocarbon is preferable. Specifically, an alkyl group having 3 or more and 10 or less carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 or more and 10 or less carbon atoms, or a trialkylsilyl group having 3 or more and 10 or less carbon atoms can be mentioned. More preferably, it has a plurality of protecting groups. Since a substituent having no π bond has almost no function of transporting carriers, it has almost no influence on carrier transport or carrier recombination, and can keep the emitter of the TADF material and the fluorescent emitter away from each other. Here, the emitter refers to the atomic group (skeleton) that causes luminescence in the fluorescent emitter. The emitter preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. As the above emitter, for example, a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, a naphthobisbenzofuran skeleton, etc. In particular, a fluorescent emitter having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, a naphthobisbenzofuran skeleton has a high fluorescence quantum yield, so it is preferable.

[0159] In the case of using a fluorescent luminescent substance as the luminescent substance, as the host material, a material having an anthracene skeleton is preferably used. By using a substance having an anthracene skeleton as the host material of the fluorescent luminescent substance, a luminescent layer with high luminous efficiency and durability can be achieved. Among the substances having an anthracene skeleton used as the host material, a substance having a diphenylanthracene skeleton, especially a 9,10-diphenylanthracene skeleton, is chemically stable, so it is preferred. In addition, when the host material has a carbazole skeleton, the hole injection / transport property is improved, so it is preferred. In the case of including a benzocarbazole skeleton in which a benzene ring is fused to carbazole, its HOMO level is about 0.1 eV shallower than that of the carbazole skeleton, and holes are easily injected, so it is more preferred. In particular, when the host material has a dibenzocarbazole skeleton, its HOMO level is about 0.1 eV shallower than that of the carbazole skeleton. Not only are holes easily injected, but also the hole transport property and heat resistance are improved, so it is preferred. Therefore, a substance further preferably used as the host material is a substance having a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that from the above perspective of hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton can also be used instead of the carbazole skeleton. Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4'-yl]-anthracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthryl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthryl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good properties, so they are preferred.

[0160] In addition, the host material may also be a material that mixes multiple substances. When using a mixed host material, it is preferable to mix a material with electron-transporting properties and a material with hole-transporting properties. By mixing a material with electron-transporting properties and a material with hole-transporting properties, it becomes easier to adjust the transport properties of the light-emitting layer 113, and it is also possible to more simply control the recombination region. The weight ratio of the content of the material with hole-transporting properties to the material with electron-transporting properties may be from 1:19 to 19:1.

[0161] Note that, as part of the above-mentioned mixed materials, a phosphorescent light-emitting substance may be used. The phosphorescent light-emitting substance can be used as an energy donor that supplies excitation energy to the fluorescent light-emitting substance when the fluorescent light-emitting substance is used as the light-emitting substance.

[0162] In addition, an exciplex may also be formed using these mixed materials. By selecting a combination of exciplexes that emit light with a wavelength overlapping the absorption band on the lowest energy side of the light-emitting substance, energy transfer can be made smooth, and thus light emission can be obtained efficiently, so it is preferable. In addition, by adopting this structure, the driving voltage can be reduced, so it is preferable.

[0163] Note that at least any one of the materials forming the exciplex may be a phosphorescent light-emitting substance. Thereby, triplet excitation energy can be efficiently converted into singlet excitation energy through reverse intersystem crossing.

[0164] Regarding the combination of materials that efficiently form an exciplex, the HOMO energy level of the material with hole-transporting properties is preferably higher than the HOMO energy level of the material with electron-transporting properties. In addition, the LUMO energy level of the material with hole-transporting properties is preferably higher than the LUMO energy level of the material with electron-transporting properties. Note that the LUMO energy level and HOMO energy level of the material can be obtained from the electrochemical characteristics (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV) measurement.

[0165] Note that the formation of an exciplex can be confirmed, for example, by comparing the emission spectra of a hole-transporting material, the emission spectra of an electron-transporting material, and the emission spectra of a mixed film formed by mixing these materials. When it is observed that the emission spectrum of the mixed film is shifted toward the longer wavelength side (or has a new peak on the longer wavelength side) compared to the emission spectra of the respective materials, it indicates the formation of an exciplex. Alternatively, by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and the transient PL of a mixed film formed by mixing these materials, when it is observed that the transient PL lifetime of the mixed film has a long-lived component or the ratio of the delayed component becomes larger compared to the transient PL lifetimes of the respective materials, it indicates the formation of an exciplex. In addition, the above transient PL can be referred to as transient electroluminescence (EL). In other words, by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and the transient EL of a mixed film of these materials and observing the difference in transient response, the formation of an exciplex can be confirmed.

[0166] The structure of the electron transport layer 114 has been described in detail in Embodiment 1, and thus repeated description is omitted.

[0167] Note that the electron transport layer 114 may also have a stacked structure. In the case where the electron transport layer 114 has a stacked structure, preferably, all the layers in the stack have the structure as shown in Embodiment 1.

[0168] An electron injection layer 115 is formed between the electron transport layer 114 and the second electrode 102. The structure of the electron injection layer 115 has been described in detail in Embodiment 1, and thus repeated description is omitted.

[0169] The second electrode 102 is an electrode including a cathode. The second electrode 102 may also have a stacked structure. In this case, the layer in contact with the EL layer 103 is used as the cathode. As the material for forming the cathode, a metal, alloy, conductive compound, or a mixture thereof having a small work function (specifically, 3.8 eV or less) 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), or strontium (Sr), alloys containing them (MgAg, AlLi), compounds (lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), etc.), rare earth metals such as europium (Eu) or ytterbium (Yb), and alloys containing them. However, by providing an electron injection layer 115 or a thin film of the above material having a small work function between the second electrode 102 and the electron transport layer, various conductive materials such as Al, Ag, ITO, indium tin oxide containing silicon or silicon oxide, etc. can be used as the cathode regardless of the work function.

[0170] When the second electrode 102 is made of a material that is transparent to visible light, a light-emitting device that emits light from the side of the second electrode 102 can be formed. When the first electrode 101 is made of a material that is transparent to visible light, a light-emitting device that emits light from the side of the first electrode 101 can be formed.

[0171] These conductive materials can be formed by dry methods such as vacuum evaporation and sputtering, inkjet methods, spin coating methods, etc. In addition, they can also be formed by wet methods such as sol-gel methods or wet methods using pastes of metal materials.

[0172] In addition, as a method for forming the EL layer 103, various methods can be used regardless of whether it is a dry method or a wet method. For example, vacuum evaporation, gravure printing, offset printing, screen printing, inkjet printing, or spin coating methods can also be used.

[0173] In addition, the above-described electrodes or layers can also be formed by using different deposition methods.

[0174] Next, with reference to Figure 2B A light-emitting device (also referred to as a stacked device or a series device) having a structure in which a plurality of light-emitting units are stacked will be described. This light-emitting device is a light-emitting device having a plurality of light-emitting units between an anode and a cathode. One light-emitting unit has a structure substantially the same as the Figure 2A shown EL layer 103. That is to say, it can be said that the Figure 2B shown light-emitting device is a light-emitting device having a plurality of light-emitting units, while the Figure 2A shown light-emitting device is a light-emitting device having one light-emitting unit.

[0175] In Figure 2B the first light-emitting unit 511 and the second light-emitting unit 512 are stacked between the first electrode 501 and the second electrode 502, and an intermediate layer 116 is provided between the first light-emitting unit 511 and the second light-emitting unit 512. The first electrode 501 and the second electrode 502 respectively correspond to the Figure 2A first electrode 101 and the second electrode 102 in Figure 2A and the same materials as those described in

[0176] The intermediate layer 116 has a function of injecting electrons into one light-emitting unit and injecting holes into the other light-emitting unit when a voltage is applied to the first electrode 501 and the second electrode 502. That is to say, in Figure 2BIn the case where a voltage is applied such that the potential of the anode is higher than that of the cathode, the intermediate layer 116 may be a layer that injects electrons into the first light-emitting unit 511 and injects holes into the second light-emitting unit 512.

[0177] The intermediate layer 116 includes a charge generation layer. In addition, the charge generation layer includes at least a P-type layer 117. The P-type layer 117 is preferably formed using the above-described composite material constituting the hole injection layer 111. In addition, the P-type layer 117 may also be formed by laminating a film containing the acceptor material and a film containing the hole transport material as materials constituting the composite material. By applying a potential to the P-type layer 117, electrons and holes are respectively injected into the electron transport layer 114 and the cathode, causing the light-emitting device to operate.

[0178] In addition, the intermediate layer 116 preferably further includes one or both of an electron relay layer 118 and an N-type layer 119 in addition to the P-type layer 117.

[0179] The electron relay layer 118 contains at least a substance having electron-transporting properties, and can prevent the interaction between the N-type layer 119 and the P-type layer 117 and smoothly transfer electrons. It is preferable to set the LUMO energy level of the substance having electron-transporting properties contained in the electron relay layer 118 between the LUMO energy level of the acceptor substance in the P-type layer 117 and the LUMO energy level of the substance contained in the layer in contact with the intermediate layer 116 in the electron transport layer 114. Specifically, the LUMO energy level of the substance having electron-transporting properties in the electron relay layer 118 is -5.0 eV or more, preferably -5.0 eV or more and -3.0 eV or less. In addition, as the substance having electron-transporting properties in the electron relay layer 118, a phthalocyanine material or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used.

[0180] The N-type layer 119 can use substances with high electron injection properties such as alkali metals, alkaline earth metals, rare earth metals, and compounds of these substances (alkali metal compounds (including oxides such as lithium oxide, halides, lithium carbonate, cesium carbonate, etc.), alkaline earth metal compounds (including oxides, halides, carbonates), or compounds of rare earth metals (including oxides, halides, carbonates)).

[0181] In addition, when the N-type layer 119 contains a substance having electron-transporting properties and a donor substance, as the donor substance, in addition to alkali metals, alkaline earth metals, rare earth metals, and compounds of these substances (alkali metal compounds (including oxides such as lithium oxide, halides, lithium carbonate, cesium carbonate, etc.), alkaline earth metal compounds (including oxides, halides, carbonates), or compounds of rare earth metals (including oxides, halides, carbonates)), organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethyl nickelocene can also be used. In addition, as the substance having electron-transporting properties, the same materials as those described above for the electron-transporting layer 114 can be used.

[0182] In addition, a layer described as a layer used as an electron injection layer in Embodiment 1 can be provided at the same position as the N-type layer 119 instead of the N-type layer 119. This layer contains an organic compound having strong basicity. When adopting this structure, a tandem light-emitting device can also be manufactured.

[0183] In this case, even when a voltage is applied to the tandem light-emitting device using a layer containing an organic compound having strong basicity instead of the N-type layer 119, the organic compound having strong basicity is not used as a donor, and thus no electrons are generated in the layer containing the organic compound having strong basicity (hereinafter, this layer is referred to as DLL). On the other hand, holes injected from the anode accumulate between the DLL or the light-emitting layer of the first light-emitting unit and the electron-transporting layer.

[0184] Due to the application of voltage and the accumulation of holes, electrons are induced by the P-type layer 117. The difference in the LUMO energy levels of the acceptor material contained in the P-type layer 117 and the electron-transporting material contained in the DLL is large in the initial state, so these electrons accumulate at the interface of the P-type layer 117 on the DLL side (note that when the DLL does not contain an electron-transporting material, that is, a single film of an organic compound having strong basicity, the electrons generated in the P-type layer 117 accumulate on the side of the single film of the organic compound having strong basicity). The accumulated electrons and the holes accumulated between the DLL or the light-emitting layer of the first light-emitting unit and the electron-transporting layer form a double layer, and an electric dipole is generated.

[0185] As a result, a vacuum level shift occurs, the LUMO levels of the acceptor-type material contained in the P-type layer 117 and the electron-transporting material of the DLL approach each other, and electrons generated in the P-type layer 117 are injected into the DLL. Then, the electrons injected into the DLL are also injected into the light-emitting unit 1, reach the first light-emitting layer and recombine, so that light emission is obtained in the light-emitting unit 1, and a light-emitting device using a DLL containing a strongly basic organic compound instead of the N-type layer 119 can be used as a tandem light-emitting device.

[0186] In addition, in this case, the electron transport layer of the first light-emitting unit 511 preferably has bipolarity. This is because in the light-emitting device of one embodiment of the present invention, holes are trapped by the DLL containing a strongly basic organic compound having an acid dissociation constant pKa of 8 or more to block holes, but the holes are quickly transported to the DLL due to the bipolarity of the electron transport layer. Therefore, a reduction in driving voltage can be achieved. In addition, similar to the electron injection layer described in Embodiment 1, the electron transport layer of the first light-emitting unit 511 can also be a mixed layer of an organic compound having electron-transporting properties and an organic compound having hole-transporting properties. This mixed layer can obtain a good tandem light-emitting device containing a substance having both electron-transporting and hole-transporting properties, so it is preferred. In addition, the substance having both electron-transporting and hole-transporting properties is preferably an organic compound having both an electron-transporting skeleton and a hole-transporting skeleton. The electron-transporting skeleton is preferably a π-deficient heteroaromatic ring skeleton, and the hole-transporting skeleton is preferably a π-rich heteroaromatic ring skeleton or an arylamine skeleton.

[0187] When the anode side of the light-emitting unit is in surface contact with the intermediate layer 116, the charge generation layer of the intermediate layer 116 can also serve as the hole injection layer of the light-emitting unit, so the light-emitting unit may not be provided with a hole injection layer. When the cathode side of the light-emitting unit is in surface contact with the intermediate layer 116, the intermediate layer 116 can also serve as the electron injection layer of the light-emitting unit, so the light-emitting unit may not be provided with an electron injection layer.

[0188] Although a light-emitting device having two light-emitting units has been described Figure 2B in, a light-emitting device in which three or more light-emitting units are stacked can be applied in the same manner. As in the light-emitting device according to the present embodiment, by separating and arranging a plurality of light-emitting units using the intermediate layer 116 between a pair of electrodes, an element can be realized that can achieve high-brightness light emission while maintaining a low current density and has a long lifespan. In addition, a light-emitting device capable of low-voltage driving and low power consumption can be realized.

[0189] In addition, by making the emission colors of the respective light-emitting units different, light emission of a desired color can be obtained from the entire light-emitting device. For example, in a light-emitting device having two light-emitting units, by obtaining red and green emission colors from the first light-emitting unit and a blue emission color from the second light-emitting unit, a light-emitting device that emits white light can be obtained from the entire light-emitting device.

[0190] In addition, each layer and electrode such as the above-described EL layer 103, the first light-emitting unit 511, the second light-emitting unit 512, and the intermediate layer can be formed by methods such as vapor deposition (including vacuum vapor deposition), droplet ejection (also referred to as inkjet), coating, gravure printing, and the like. Further, it may include a low molecular weight material, a medium molecular weight material (including oligomers, dendrimers), or a high molecular weight material.

[0191] Figure 3A It is a diagram of two adjacent light-emitting devices (light-emitting device 130a and light-emitting device 130b) included in a display device according to one embodiment of the present invention.

[0192] The light-emitting device 130a includes an EL layer 103a between a first electrode 101a on an insulating layer 175 and a second electrode 102 opposite to the first electrode 101a. Although the EL layer 103a is shown to have a structure including a hole injection layer 111a, a hole transport layer 112a, a light-emitting layer 113a, an electron transport layer 114a, and an electron injection layer 115a, the EL layer 103a may also have a stacked structure different from the above structure.

[0193] The light-emitting device 130b includes an EL layer 103b between a first electrode 101b on an insulating layer 175 and a second electrode 102 opposite to the first electrode 101b. Although the EL layer 103b is shown to have a structure including a hole injection layer 111b, a hole transport layer 112b, a light-emitting layer 113b, an electron transport layer 114b, and an electron injection layer 115b, the EL layer 103b may also have a stacked structure different from the above structure.

[0194] The structures of the electron transport layer 114a and the electron injection layer 115a in the light-emitting device 130a and the structures of the electron transport layer 114b and the electron injection layer 115b in the light-emitting device 130b are preferably the structures described in Embodiment 1.

[0195] The second electrode 102 is preferably a continuous layer shared by the light-emitting devices 130a and 130b. In addition, the EL layer 103a and the EL layer 103b are processed by photolithography after forming the electron injection layer 115a and after forming the electron injection layer 115b, respectively, so they are independent of each other. In addition, the end portions (profiles) of the EL layer 103a are processed by photolithography, so they are substantially aligned in the direction perpendicular to the substrate. In addition, the end portions (profiles) of the EL layer 103b are processed by photolithography, so they are substantially aligned in the direction perpendicular to the substrate.

[0196] In addition, due to the processing by photolithography, there is a gap d between the EL layer 103a and the EL layer 103d. In addition, by processing the EL layer by photolithography, the distance between the first electrode 101c and the first electrode 101d can be made smaller than that distance during mask evaporation, and it can be made 2 μm or more and 5 μm or less.

[0197] Figure 3B It is a diagram of two adjacent series-connected light-emitting elements (light-emitting devices 130c, 130d) manufactured by photolithography.

[0198] The light-emitting device 130c includes an EL layer 103c between the first electrode 101c and the second electrode 102 on the insulating layer 175. The EL layer 103c has a structure in which a first light-emitting unit 511c and a second light-emitting unit 512c are stacked with an intermediate layer 116c therebetween. Note that although FIG. 3 shows an example in which two light-emitting units are stacked, three or more light-emitting units may be stacked. The first light-emitting unit 511c 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 P-type layer 117c, an electron relay layer 118c, and an N-type layer 119c. Regardless of the presence or absence of the electron relay layer 118c. The second light-emitting unit 512c includes a second hole transport layer 112c_2, a second light-emitting layer 113c_2, a second electron transport layer 114c_2, and an electron injection layer 115.

[0199] The light-emitting device 130d includes an EL layer 103d between a first electrode 101d on an insulating layer 175 and a second electrode 102. The EL layer 103d has a structure in which a first light-emitting unit 511d and a second light-emitting unit 512d are stacked with an intermediate layer 116d therebetween. Note that although FIG. 3 shows an example in which two light-emitting units are stacked, three or more light-emitting units may be stacked. The first light-emitting unit 511d includes a hole injection layer 111d, a first hole transport layer 112d_1, a first light-emitting layer 113d_1, and a first electron transport layer 114d_1. The intermediate layer 116d includes a P-type layer 117d, an electron relay layer 118d, and an N-type layer 119d. Regardless of the presence or absence of the electron relay layer 118d. The second light-emitting unit 512d includes a second hole transport layer 112d_2, a second light-emitting layer 113d_2, a second electron transport layer 114d_2, and an electron injection layer 115.

[0200] In the light-emitting devices 130c and 130d, the second electron transport layer 114c_1 and the electron injection layer 115c, and the second electron transport layer 114d_1 and the electron injection layer 115d preferably have the structures described in Embodiment 1.

[0201] The second electrode 102 is preferably a continuous layer shared by the light-emitting devices 130c and 130d. In addition, since the EL layer 103c and the EL layer 103d are processed by photolithography after forming the electron injection layer 115c and after forming the electron injection layer 115d, respectively, they are independent of each other. In addition, since the end (profile) of the EL layer 103c is processed by photolithography, it is substantially the same in the direction perpendicular to the substrate. In addition, since the end (profile) of the EL layer 103d is processed by photolithography, it is substantially the same in the direction perpendicular to the substrate.

[0202] In addition, due to processing by photolithography, there is a gap d between the EL layer 103c and the EL layer 103d. In addition, by processing the EL layer by photolithography, the distance between the first electrode 101c and the first electrode 101d can be made smaller than that distance during mask evaporation, and it can be 2 μm or more and 5 μm or less.

[0203] The light-emitting element according to one embodiment of the present invention can process an organic compound layer by photolithography with sufficient precision, and thus a high-definition display device can be manufactured. In addition, since the photolithography process can be performed on the electron injection layer far from the light-emitting layer without being contaminated by alkali metals, a light-emitting element having good characteristics can be realized. As described above, the light-emitting element according to one embodiment of the present invention having the above structure can realize a high-definition display device and can realize a light-emitting element having good characteristics.

[0204] In addition, since the organic compound layer of the light-emitting element according to one embodiment of the present invention is processed at once by photolithography, the outlines of the layers included in the organic compound layer are substantially the same. Here, "substantially the same" in this specification means that the difference between the outline A of layer A and the outline B of layer B included in the organic compound layer is within 5% of the width of the organic compound layer on a line perpendicular to the outline of the portion being compared. In addition, when the end face of the organic compound layer has a tapered shape, continuous change of the outline is allowed.

[0205] The structure of this embodiment can be used in appropriate combination with other structures.

[0206] (Embodiment 3) In this embodiment, a mode in which a light-emitting device according to one embodiment of the present invention is used as a display element of a display device will be described.

[0207] As Figure 4A and Figure 4B shown, a plurality of light-emitting devices 130 are formed on an insulating layer 175 and constitute a display device.

[0208] The display device includes a pixel portion 177 in which a plurality of pixels 178 are arranged in a matrix. Each pixel 178 includes a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0209] In this specification and the like, for example, when describing the common content among the sub-pixels 110R, the sub-pixels 110G, and the sub-pixels 110B, it is sometimes described as the sub-pixel 110. Similarly, when describing the common content among other constituent elements distinguished by letters, it is sometimes described using symbols omitting the letters.

[0210] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. Thus, an image can be displayed on the pixel portion 177. In this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are taken as an example for description, but combinations 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, sub-pixels of four colors, R, G, B, and white (W); sub-pixels of four colors, R, G, B, and yellow (Y); and sub-pixels of four colors, R, G, B, and infrared light (IR); etc. can be cited.

[0211] In this specification and the like, the row direction is sometimes denoted as the X direction and the column direction is denoted as the Y direction. The X direction intersects the Y direction, for example, perpendicularly.

[0212] In Figure 4AIn the example shown, sub-pixels of different colors are arranged and configured in the X direction, and sub-pixels of the same color are arranged and configured in the Y direction. Note that sub-pixels of different colors can also be arranged and configured in the Y direction, and sub-pixels of the same color can be arranged and configured in the X direction.

[0213] A connection portion 140 is provided outside the pixel portion 177, and a region 141 can also be provided. The region 141 is provided between the pixel portion 177 and the connection portion 140. An EL layer 103 is provided in the region 141. In addition, a conductive layer 151C is provided in the connection portion 140.

[0214] In 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, but there are no particular restrictions on the positions of the region 141 and the connection portion 140. In addition, the region 141 and the connection portion 140 can also be one or more.

[0215] Figure 4B Is an example of a cross-sectional view along the dotted line A1 - A2 in Figure 4A As Figure 4B shown, the display device includes an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and on the conductive layer 172, an insulating layer 174 on the insulating layer 173, and an insulating layer 175 on the insulating layer 174. The insulating layer 171 is provided on a substrate (not shown). The insulating layer 175, the insulating layer 174, and the insulating layer 173 are provided with openings reaching the conductive layer 172, and plugs 176 are provided in such a way as to be embedded in the openings.

[0216] In the pixel portion 177, a light-emitting device 130 is provided on the insulating layer 175 and the plugs 176. In addition, a protective layer 131 is provided so as to cover the light-emitting device 130. A substrate 120 is adhered to the protective layer 131 by a resin layer 122. In addition, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are preferably provided between adjacent light-emitting devices 130.

[0217] Figure 4B The cross-section showing a plurality of inorganic insulating layers 125 and a plurality of insulating layers 127 is shown, but when looking down at the display device, the inorganic insulating layer 125 and the insulating layer 127 are preferably formed as a connected single layer respectively. In other words, the insulating layer 127 is preferably an insulating layer having an opening portion on the first electrode.

[0218] In Figure 4BThe light-emitting devices 130R, 130G, and 130B are shown as light-emitting device 130. The light-emitting devices 130R, 130G, and 130B can emit light of different colors from each other. For example, the light-emitting device 130R can emit red light, the light-emitting device 130G can emit green light, and the light-emitting device 130B can emit blue light. In addition, the light-emitting device 130R, 130G, or 130B can also emit other visible light or infrared light.

[0219] A display device according to one embodiment of the present invention can have, for example, a top emission structure that emits light in a direction opposite to the substrate on which the light-emitting device is formed. In addition, a display device according to one embodiment of the present invention can also have a bottom emission structure.

[0220] The light-emitting device 130R has the structure shown in Embodiment 1 and Embodiment 2. The light-emitting device 130R includes a first electrode 101R (pixel electrode) composed of a conductive layer 151R and a conductive layer 152R, an EL layer 103R on the first electrode 101R, and a second electrode 102 (common electrode) on the EL layer 103R. The electron injection layer, which is the outermost surface layer of the EL layer 103R, has the structure described in Embodiment 1. By having this structure, damage to the light-emitting layer or the active layer in the photolithography process can be suppressed, and good film quality and electrical characteristics can be expected. In addition, when the electron transport layer is a mixed layer of an organic compound having electron transport properties and an organic compound having hole transport properties, a display device with suppressed increase in driving voltage can be realized.

[0221] The light-emitting device 130G has the structure shown in Embodiment 1 and Embodiment 2. The light-emitting device 130G includes a first electrode 101G (pixel electrode) composed of a conductive layer 151G and a conductive layer 152G, an EL layer 103G on the first electrode 101G, and a second electrode 102 (common electrode) on the EL layer 103G. The electron injection layer, which is the outermost surface layer of the EL layer 103G, has the structure described in Embodiment 1. By having this structure, damage to the light-emitting layer or the active layer in the photolithography process can be suppressed, and good film quality and electrical characteristics can be expected. In addition, when the electron transport layer is a mixed layer of an organic compound having electron transport properties and an organic compound having hole transport properties, a display device with suppressed increase in driving voltage can be realized.

[0222] The light-emitting device 130B has the structure shown in Embodiment 1 and Embodiment 2. It includes a first electrode 101B (pixel electrode) composed of a conductive layer 151B and a conductive layer 152B, an EL layer 103B on the first electrode 101B, and a second electrode 102 (common electrode) on the EL layer 103B. The electron injection layer, which is the outermost surface layer of the EL layer 103B, has the structure described in Embodiment 1. By having this structure, damage to the light-emitting layer or the active layer in the lithography process can be suppressed, and good film quality and electrical characteristics can be expected. In addition, when the electron transport layer is a mixed layer of an organic compound having electron transport properties and an organic compound having hole transport properties, a display device with suppressed increase in driving voltage can be realized.

[0223] One of the pixel electrode (first electrode) and the common electrode (second electrode) included in the light-emitting device is used as the anode, and the other is used as the cathode. In the present embodiment, unless otherwise specified, the case where the pixel electrode is used as the anode and the common electrode is used as the cathode is sometimes assumed for explanation.

[0224] The EL layer 103R, the EL layer 103G, and the EL layer 103B are island-shaped layers that are independent in each light-emitting device or for each emission color. Note that the EL layer 103R, the EL layer 103G, and the EL layer 103B preferably do not overlap with each other. By setting the EL layer 103 as an island shape for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in a high-definition display device. Thereby, crosstalk can be prevented to realize a display device with extremely high contrast. In particular, a display device with high current efficiency at low brightness can be realized.

[0225] The island-shaped EL layer 103 is formed by depositing an EL film and processing the EL by photolithography.

[0226] The EL layer 103 is preferably provided so as to cover the top surface and the side surface of the first electrode 101 (pixel electrode) of the light-emitting device 130. Thereby, compared with the structure in which the end portion of the EL layer 103 is located inside the end portion of the pixel electrode, it is easy to increase the aperture ratio of the display device. In addition, by covering the side surface of the pixel electrode of the light-emitting device 130 with the EL layer 103, contact between the pixel electrode and the second electrode 102 can be suppressed, and thus short circuit of the light-emitting device 130 can be suppressed.

[0227] In a display device according to one aspect of the present invention, the first electrode 101 (pixel electrode) of the light-emitting device preferably has a stacked structure. For example, in the Figure 4B example shown, the first electrode 101 of the light-emitting device 130 has a stacked structure including a conductive layer 151 provided on one side of the insulating layer 171 and a conductive layer 152 provided on the side of the EL layer.

[0228] As the conductive layer 151, a metal material can be used, for example. Specifically, metals such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), neodymium (Nd), etc. and alloys obtained by appropriately combining them can be used.

[0229] As the conductive layer 152, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, a conductive oxide including 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 is preferably used. In particular, indium tin oxide containing silicon has a relatively large work function, and its work function is, for example, 4.0 eV or more, so it can be suitably used as the conductive layer 152.

[0230] The conductive layer 151 and the conductive layer 152 may each have a laminated structure including a plurality of layers containing different materials. In this case, the conductive layer 151 may include a layer using a material such as a conductive oxide that can be used for the conductive layer 152, and the conductive layer 152 may include a layer using a material such as a metal material that can be used for the conductive layer 151. For example, when the conductive layer 151 has a laminated structure of two or more layers, the layer in contact with the conductive layer 152 may be a layer using a material that can be used for the conductive layer 152.

[0231] The end of the conductive layer 151 preferably has a tapered shape. Specifically, the end of the conductive layer 151 preferably has a tapered shape with a taper angle less than 90°. At this time, the conductive layer 152 provided along the side surface of the conductive layer 151 also has a tapered shape. By making the end of the conductive layer 152 have a tapered shape, the coverage of the EL layer 103 provided along the side surface of the conductive layer 152 can be improved.

[0232] In the display device according to one embodiment of the present invention, the light-emitting device 130 has the structures shown in Embodiment 1 and Embodiment 2, whereby a display device with good reliability can be realized.

[0233] Next, an example of a manufacturing method of a display device having the Figure 4A shown structure will be described with reference to FIGS. 5 to 10.

[0234] [Example of Manufacturing Method 1] The thin films (such as insulating films, semiconductor films, and conductive films) constituting the display device can be formed by sputtering, chemical vapor deposition (CVD: Chemical Vapor Deposition), vacuum evaporation, pulsed laser deposition (PLD: Pulsed Laser Deposition), atomic layer deposition (ALD), etc.

[0235] In addition, the thin films (such as insulating films, semiconductor films, and conductive films) constituting the display device can be formed by wet deposition methods such as spin coating, dipping, spraying, inkjet, dispenser, screen printing, offset printing, doctor knife, slot die coating, roll coating, curtain coating, or blade coating.

[0236] In addition, when processing the thin films constituting the display device, for example, photolithography can be used for processing.

[0237] In photolithography, as the light for exposure, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or light mixed with these lights can be used. In addition, ultraviolet light, KrF laser, or ArF laser can also be used. In addition, immersion exposure technology can also be used for exposure. In addition, as the light for exposure, extreme ultraviolet (EUV) light or X-rays can also be used. In addition, instead of the light for exposure, an electron beam can also be used.

[0238] In the etching of thin films, dry etching, wet etching, sandblasting, etc. can be used.

[0239] First, as Figure 5A shown, an insulating layer 171 is formed on a substrate (not shown). Then, a conductive layer 172 and a conductive layer 179 are formed on the insulating layer 171, and an insulating layer 173 is formed on the insulating layer 171 so as to cover the conductive layer 172 and the conductive layer 179. Then, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

[0240] As the substrate, a substrate having at least heat resistance capable of withstanding subsequent heat treatment can be used. For example, a glass substrate; a quartz substrate; a sapphire substrate; a ceramic substrate; an organic resin substrate; or a semiconductor substrate such as a single-crystal semiconductor substrate or a polycrystalline semiconductor substrate made of silicon or silicon carbide, a compound semiconductor substrate such as silicon germanium, an SOI substrate, etc. can be used.

[0241] Next, as Figure 5AAs shown, openings reaching the conductive layer 172 are formed in the insulating layer 175, insulating layer 174, and insulating layer 173. Then, a plug 176 is formed in such a way as to embed in the openings.

[0242] Then, as Figure 5A shown, a conductive film 151f that will later become the conductive layers 151R, 151G, 151B, and 151C is formed on the plug 176 and the insulating layer 175. As the conductive film 151f, for example, a metal material can be used.

[0243] Then, as Figure 5A shown, a resist mask 191 is formed on the conductive film 151f. The resist mask 191 can be formed by applying a photosensitive material (photoresist) and then performing exposure and development.

[0244] Then, as Figure 5B shown, for example, the conductive film 151f in the area that does not overlap with the resist mask 191 is removed. Thus, the conductive layer 151 is formed.

[0245] Then, as Figure 5C shown, the resist mask 191 is removed. The resist mask 191 can be removed, for example, by ashing using oxygen plasma.

[0246] Then, as Figure 5D shown, an insulating film 156f that will later become the insulating layers 156R, 156G, 156B, and 156C is formed on the conductive layers 151R, 151G, 151B, 151C, and the insulating layer 175.

[0247] The insulating film 156f can be an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitrogen oxide insulating film. For example, silicon oxynitride can be used.

[0248] Then, as Figure 5E shown, the insulating layers 156R, 156G, 156B, and 156C are formed by processing the insulating film 156f.

[0249] Then, as Figure 6A shown, a conductive film 152f is formed on the conductive layers 151R, 151G, 151B, 151C, the insulating layers 156R, 156G, 156B, 156C, and the insulating layer 175.

[0250] As the conductive film 152f, for example, a conductive oxide can be used. The conductive film 152f can also have a laminated structure.

[0251] Then, asFigure 6B As shown, the conductive film 152f is processed to form the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the conductive layer 152C.

[0252] Next, as Figure 6C shown, the organic compound film 103Rf is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the insulating layer 175. In addition, as Figure 6C shown, the organic compound film 103Rf is not formed on the conductive layer 152C.

[0253] Next, as Figure 6C shown, the sacrificial film 158Rf and the mask film 159Rf are formed.

[0254] 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.

[0255] As the sacrificial film 158Rf, a film with high resistance to the processing conditions of the organic compound film 103Rf is used. Specifically, a film with a large etching selectivity ratio with respect to the organic compound film 103Rf. As the mask film 159Rf, a film with a large etching selectivity ratio with respect to the sacrificial film 158Rf is used.

[0256] In addition, the sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the heat-resistant temperature of the organic compound film 103Rf. The substrate temperature when forming the sacrificial film 158Rf and the mask film 159Rf is typically 100°C or higher and 200°C or lower, preferably 100°C or higher and 150°C or lower, and more preferably 100°C or higher and 120°C or lower.

[0257] As the sacrificial film 158Rf and the mask film 159Rf, a film that can be removed by wet etching or dry etching is preferably used.

[0258] In addition, the sacrificial film 158Rf formed in contact with the organic compound film 103Rf is preferably formed by a formation method in which the damage to the organic compound film 103Rf is less than that of the mask film 159Rf. For example, compared with the sputtering method, the ALD method or the vacuum evaporation method is more preferably used.

[0259] 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.

[0260] As the sacrificial film 158Rf and the mask film 159Rf, for example, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metal materials can be used respectively. In particular, low melting point materials such as aluminum or silver are preferably used. By using a metal material capable of shielding ultraviolet rays as one or both of the sacrificial film 158Rf and the mask film 159Rf, the ultraviolet rays during pattern exposure can be suppressed from irradiating the organic compound film 103Rf, and the deterioration of the organic compound film 103Rf can be suppressed, so it is preferable.

[0261] In addition, as the sacrificial film 158Rf and the mask film 159Rf, metal oxides such as In-Ga-Zn oxide, indium oxide, In-Zn oxide, In-Sn oxide, indium-titanium oxide (In-Ti oxide), indium-tin-zinc oxide (In-Sn-Zn oxide), indium-titanium-zinc oxide (In-Ti-Zn oxide), indium-gallium-tin-zinc oxide (In-Ga-Sn-Zn oxide), indium-tin oxide containing silicon, etc. can be used respectively.

[0262] Note that an element M (M is one or more of aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) can be used in place of the above gallium in the above metal oxides.

[0263] As the sacrificial film 158Rf and the mask film 159Rf, for example, semiconductor materials such as silicon or germanium are used. This has a high affinity with the semiconductor manufacturing process, so it is preferable. In addition, compounds containing the above semiconductor materials can be used.

[0264] As the sacrificial film 158Rf and the mask film 159Rf, various inorganic insulating films can be used respectively. In particular, the adhesion of the oxide insulating film to the organic compound film 103Rf is higher than that of the nitride insulating film to the organic compound film 103Rf, so it is preferable.

[0265] Next, as Figure 6C shown, a resist mask 190R is formed. The resist mask 190R can be formed by coating a photosensitive material (photoresist) and then performing exposure and development.

[0266] The resist mask 190R is provided at a position overlapping with the conductive layer 152R. The resist mask 190R is preferably also provided at a position overlapping with the conductive layer 152C. Thereby, damage to the conductive layer 152C during the manufacturing process of the display device can be suppressed.

[0267] Next, as Figure 6DAs shown, a part of the mask film 159Rf is removed using the resist mask 190R to form the mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. Then, the resist mask 190R is removed. Next, the mask layer 159R is used as a mask (also referred to as a hard mask) to remove a part of the sacrificial film 158Rf to form the sacrificial layer 158R.

[0268] By using a wet etching method, compared with the case of using a dry etching method, damage to the organic compound film 103Rf during the processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced. When using a wet etching method, for example, it is preferable to use a developer, an aqueous alkali solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH), or an aqueous acid solution such as a dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixed liquid thereof.

[0269] In addition, when using a dry etching method during the processing of the sacrificial film 158Rf, deterioration of the organic compound film 103Rf can be suppressed by not using an oxygen-containing gas as the etching gas.

[0270] The resist mask 190R can be removed by the same method as the resist mask 191.

[0271] Next, as Figure 6D shown, the organic compound film 103Rf is processed to form the EL layer 103R. For example, the mask layer 159R and the sacrificial layer 158R are used as hard masks and a part of the organic compound film 103Rf is removed, thereby forming the EL layer 103R.

[0272] Thus, as Figure 6D shown, a stacked structure of the EL 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.

[0273] Processing of the organic compound film 103Rf is preferably performed using anisotropic etching. Anisotropic dry etching is particularly preferred. Alternatively, wet etching can also be used.

[0274] When using a dry etching method, deterioration of the organic compound film 103Rf can be suppressed by not using an oxygen-containing gas as the etching gas.

[0275] In addition, an oxygen-containing gas can also be used as the etching gas. When the etching gas contains oxygen, the etching rate can be increased. Therefore, etching can be performed under low-power conditions while maintaining a sufficient etching rate. Therefore, damage to the organic compound film 103Rf can be suppressed. And, defects such as adhesion of reaction products generated during etching can be suppressed.

[0276] When using the dry etching method, for example, it is preferable to use a gas containing one or more of the Group 18 elements such as H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, He, Ar, etc. as the etching gas. Alternatively, it is preferable to use a gas containing one or more of the above gases and oxygen as the etching gas. Alternatively, oxygen gas can also be used as the etching gas.

[0277] Next, as Figure 7A shown, an organic compound film 103Gf that will later become the EL layer 103G is formed.

[0278] The organic compound film 103Gf can be formed using the same method as that applicable to the formation of the organic compound film 103Rf. In addition, the organic compound film 103Gf can have the same structure as the organic compound film 103Rf.

[0279] Next, as Figure 7A 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 the conditions applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and formation methods of the resist mask 190G are the same as the conditions applicable to the resist mask 190R.

[0280] The resist mask 190G is provided at a position overlapping with the conductive layer 152G.

[0281] Next, as Figure 7B shown, a part of the mask film 159Gf is removed using the resist mask 190G, thereby forming a mask layer 159G. The mask layer 159G remains on the conductive layer 152G. Then, the resist mask 190G is removed. Next, using the mask layer 159G as a mask, a part of the sacrificial film 158Gf is removed, thereby forming a sacrificial layer 158G. Next, the organic compound film 103Gf is processed to form the EL layer 103G.

[0282] Next, as Figure 7C shown, an organic compound film 103Bf is formed.

[0283] The organic compound film 103Bf can be formed using the same method as that applicable to the formation of the organic compound film 103Rf. In addition, the organic compound film 103Bf can have the same structure as the organic compound film 103Rf.

[0284] Next, as Figure 7CAs shown, a sacrificial film 158Bf and a mask film 159Bf are formed in sequence. Then, a resist mask 190B is formed. The materials and formation methods of the sacrificial film 158Bf and the mask film 159Bf are the same as the conditions applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and formation methods of the resist mask 190B are the same as the conditions applicable to the resist mask 190R.

[0285] The resist mask 190B is provided at a position overlapping with the conductive layer 152B.

[0286] Next, as Figure 7D shown, a part of the mask film 159Bf is removed using the resist mask 190B, thereby forming a mask layer 159B. The mask layer 159B remains on the conductive layer 152B. Then, the resist mask 190B is removed. Next, a part of the sacrificial film 158Bf is removed using the mask layer 159B as a mask, thereby forming a sacrificial layer 158B. Then, the organic compound film 103Bf is processed to form an EL layer 103B. For example, a part of the organic compound film 103Bf is removed using the mask layer 159B and the sacrificial layer 158B as hard masks, thereby forming the EL layer 103B.

[0287] Thus, as Figure 7D shown, a stacked structure of the EL 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.

[0288] Note that the sides of the EL layer 103R, the EL layer 103G, and the EL layer 103B are each preferably perpendicular or substantially perpendicular to the formation surface. For example, the angle formed by the formation surface and these sides is preferably 60 degrees or more and 90 degrees or less.

[0289] As described above, the distance between two adjacent EL layers among the EL layer 103R, the EL layer 103G, and the EL layer 103B formed using photolithography can be reduced to 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. Here, for example, this distance can be defined based on the distance between the opposite ends of two adjacent EL layers among the EL layer 103R, the EL layer 103G, and the EL layer 103B. Thus, by reducing the distance between the island-shaped EL layers, a display device with high clarity and a large aperture ratio can be provided. In addition, the distance between the first electrodes of adjacent light-emitting devices can be reduced, for example, to 10 μm or less, 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less. In addition, the distance between the first electrodes of adjacent light-emitting devices is preferably 2 μm or more and 5 μm or less.

[0290] Next, as Figure 8AAs shown, it is preferable to remove the mask layer 159R, the mask layer 159G, and the mask layer 159B.

[0291] As the process for removing the mask layer, the same method as the processing process of the mask layer can be used. In particular, by using the wet etching method, compared with the case of using the dry etching method, the damage to the EL layer 103 during the removal of the mask layer can be reduced.

[0292] In addition, the mask film can also be removed by dissolving it in a polar solvent such as water or alcohol. As the alcohol, ethanol, methanol, isopropyl alcohol (IPA), or glycerol, etc. can be cited.

[0293] After removing the mask layer, a drying process can also be performed to remove the water on the surface. For example, a heat treatment can also be performed in an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. By adopting a reduced pressure atmosphere, drying can be performed at a lower temperature, so it is preferable.

[0294] Next, as Figure 8B shown, an inorganic insulating film 125f is formed.

[0295] Next, as Figure 8C shown, an insulating film 127f that will become the insulating layer 127 later is formed on the inorganic insulating film 125f.

[0296] When forming the inorganic insulating film 125f and the insulating film 127f, the substrate temperature 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.

[0297] As the inorganic insulating film 125f, it is preferable to form an insulating film with a thickness of 3 nm or more, 5 nm or more, or 10 nm or more and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less within the above substrate temperature range.

[0298] The inorganic insulating film 125f is preferably formed by the ALD method, for example. By using the ALD method, deposition damage can be reduced, and a film with high coverage can be deposited, so it is preferable. As the inorganic insulating film 125f, an alumina film is preferably formed by the ALD method, for example.

[0299] The insulating film 127f is preferably formed by the above wet deposition method. The insulating film 127f is preferably formed by spin coating using a photosensitive material, for example, and more specifically, preferably formed using a photosensitive resin composition containing an acrylic resin.

[0300] 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 layer 152R, the conductive layer 152G, and the conductive layer 152B and around the conductive layer 152C.

[0301] The width of the insulating layer 127 to be formed later can be controlled by the region in which the insulating film 127f is exposed. In this embodiment, the insulating layer 127 is processed so that the insulating layer 127 has a portion overlapping with the top surface of the conductive layer 151.

[0302] 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).

[0303] Then, if Figure 9A As shown, development is performed to remove the exposed region in the insulating film 127f, thereby forming the insulating layer 127a.

[0304] Then, if Figure 9B As shown, the insulating layer 127a is used as a mask to perform etching to remove a portion of the inorganic insulating film 125f, thereby reducing the thickness of a portion of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B. As a result, the inorganic insulating layer 125 is formed under the insulating layer 127a. In addition, the surface of the thin portion of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B is exposed. Hereinafter, the etching process using the insulating layer 127a as a mask is sometimes referred to as the first etching process.

[0305] 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 layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, the first etching process can be performed at once, which is preferable.

[0306] When dry etching is performed, 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 of the above gases, can be used. In addition, one gas selected from oxygen gas, hydrogen gas, helium gas, and argon gas, or a mixture of two or more of the above gases can be appropriately added to the above 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.

[0307] As a dry etching device, a dry etching device having a high-density plasma source can be used. As a dry etching device having a high-density plasma source, for example, an inductively coupled plasma (ICP: Inductively Coupled Plasma) etching device can be used. Alternatively, a capacitively coupled plasma (CCP: Capacitively Coupled Plasma) etching device including parallel plate electrodes can be used.

[0308] In addition, it is preferable to perform the first etching treatment by wet etching. By using the wet etching method, the damage to the EL layer 103R, the EL layer 103G, and the EL layer 103B can be reduced compared with the case of using the dry etching method. For example, wet etching can be performed using an alkaline solution. For example, TMAH can be used as an alkaline solution in the wet etching of an aluminum oxide film. In addition, an acidic solution containing a fluoride can also be used. In this case, wet etching can be performed in a glue coating manner. 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 preferable.

[0309] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, and the etching process is stopped in a state where the thickness is reduced. In this way, by leaving the corresponding sacrificial layers 158R, 158G, and 158B on the EL layers 103R, 103G, and 103B, it is possible to prevent the EL layers 103R, 103G, and 103B from being damaged in the subsequent process.

[0310] 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 such exposure after development, the transparency of the insulating layer 127a can be improved. In addition, the substrate temperature required for heat treatment in a later step for deforming the insulating layer 127a into a tapered shape can be reduced.

[0311] Here, by providing an oxygen blocking insulating layer (for example, an aluminum oxide film) as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, diffusion of oxygen into the EL layer 103R, the EL layer 103G, and the EL layer 103B can be reduced.

[0312] Next, a heat treatment (also referred to as 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 surface ( Figure 9C ). The heat treatment is performed at a temperature lower than the heat-resistant temperature of the EL layer. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, more preferably 70°C or higher and 130°C or lower. The heating atmosphere can be either an air atmosphere or an inert gas atmosphere. In addition, the heating atmosphere can be either an air atmosphere or a reduced-pressure atmosphere. Thereby, 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.

[0313] In the first etching process, by not completely removing the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B and leaving the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B in a state where their thicknesses are thinned, it is possible to prevent the EL layer 103R, the EL layer 103G, and the EL layer 103B from being damaged and deteriorated during the heat treatment. Thereby, the reliability of the light-emitting device can be improved.

[0314] Next, as Figure 10A shown, using the insulating layer 127 as a mask, an etching process is performed to remove a part of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B. Thereby, openings are formed in each of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, and the top surfaces of the EL layer 103R, the EL layer 103G, the EL layer 103B, and the conductive layer 152C are exposed. Note that hereinafter, this etching process is sometimes referred to as the second etching process.

[0315] The end portion of the inorganic insulating layer 125 is covered by the insulating layer 127. In addition, Figure 10A an example is shown in which a part of the end portion of the sacrificial layer 158G (specifically, a tapered portion formed by the first etching process) is covered by the insulating layer 127 and a tapered portion formed by the second etching process is exposed.

[0316] In addition, the second etching process is performed using wet etching. By using the wet etching method, the damage to the EL layer 103R, the EL layer 103G, and the EL layer 103B can be reduced compared with the case of using the dry etching method. For example, wet etching can be performed using an alkaline solution or an acidic solution. In order to prevent the EL layer 103 from dissolving, wet etching is preferably performed using an aqueous solution.

[0317] Next, as Figure 10BAs shown, a common electrode 155 is formed on the EL layer 103R, the EL layer 103G, the EL layer 103B, the conductive layer 152C, and the insulating layer 127. The common electrode 155 can be formed by a method such as a sputtering method or a vacuum evaporation method.

[0318] Next, as Figure 10C shown, a protective layer 131 is formed on the common electrode 155. The protective layer 131 can be formed by a method such as a vacuum evaporation method, a sputtering method, a CVD method, or an ALD method.

[0319] Next, the substrate 120 is bonded to the protective layer 131 using the resin layer 122, whereby a display device can be manufactured. As described above, in the method for manufacturing a display device according to one embodiment of the present invention, the insulating layer 156 is provided so as to include a region overlapping 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. Thereby, the yield of the display device can be improved, and the occurrence of defects can be suppressed.

[0320] As described above, in the method for manufacturing a display device according to one embodiment of the present invention, the island-shaped EL layer 103R, the island-shaped EL layer 103G, and the EL layer 103B are not formed using a high-precision metal mask but are formed by depositing a film on one surface and then performing processing. Therefore, the island-shaped layers 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. Furthermore, even if the definition or aperture ratio is high and the distance between sub-pixels is extremely short, it is possible to suppress the EL layer 103R, the EL layer 103G, and the EL layer 103B from contacting each other in adjacent sub-pixels. Therefore, it is possible to suppress the occurrence of leakage current between sub-pixels. Thereby, crosstalk can be prevented to realize a display device with extremely high contrast. In addition, even for a display device including a tandem light-emitting device manufactured by a photolithography method, a display device with good characteristics can be provided.

[0321] (Embodiment 4) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0322] 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 a display unit of information terminal devices (wearable devices) such as watch-type and bracelet-type, and a display unit of wearable devices that can be worn on the head such as VR devices such as head-mounted displays (HMDs) and glasses-type AR devices.

[0323] In addition, the display device of the present embodiment can be a high-resolution display device or a large display device. Therefore, for example, the display device of the present embodiment can be used as the display unit of the following devices: electronic devices with a large screen such as television devices, desktop or notebook personal computers, monitors for computers, digital signage, and large gaming machines such as pachinko machines; digital cameras; digital video cameras; digital photo frames; mobile phones; portable gaming machines; portable information terminals; and sound reproduction devices.

[0324] [Display module] Figure 11A is a perspective view of the display module 280. The display module 280 includes the display device 100A and the FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A, and can also be any one of the display devices 100B and 100E to be described later.

[0325] The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display unit 281. The display unit 281 is the image display area in the display module 280, and light from each pixel provided in the following pixel unit 284 can be seen.

[0326] Figure 11B is a perspective schematic view of the structure on the side of the substrate 291. A circuit unit 282 is laminated on the substrate 291, a pixel circuit unit 283 is on the circuit unit 282, and a pixel unit 284 is on the pixel circuit unit 283. In addition, a terminal unit 285 for connecting to the FPC 290 is provided on a portion of the substrate 291 that does not overlap with the pixel unit 284. The terminal unit 285 and the circuit unit 282 are electrically connected through a wiring portion 286 composed of a plurality of wirings.

[0327] The pixel unit 284 includes a plurality of pixels 284a arranged periodically. Figure 11B An enlarged view of one pixel 284a is shown on the right side of. The pixel 284a can adopt various structures described in the above embodiment. Figure 11B shows an example of the case where the pixel 284a has the same structure as the pixel 178 shown in FIG. 4.

[0328] The pixel circuit unit 283 includes a plurality of pixel circuits 283a arranged periodically.

[0329] One pixel circuit 283a controls the driving of a plurality of elements included in one pixel 284a.

[0330] The circuit section 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit section 283. For example, it preferably includes one or both of a gate line driving circuit and a source line driving circuit. In addition, it may also have at least one of an arithmetic circuit, a storage circuit, a power supply circuit, etc.

[0331] The FPC 290 serves as a wiring for supplying a video signal, a power supply potential, etc. from the outside to the circuit section 282. In addition, an IC may also be mounted on the FPC 290.

[0332] The display module 280 may adopt a structure in which one or both of the pixel circuit section 283 and the circuit section 282 are laminated on the lower side of the pixel section 284, so the display section 281 can have an extremely high aperture ratio (effective display area ratio).

[0333] Such a high-definition display module 280 is suitable for VR devices such as HMDs or glasses-type AR devices. For example, because the display module 280 has an extremely high-definition display section 281, in the structure of viewing the display section of the display module 280 through a lens, even if the display section is magnified by the lens, the user will not see pixels, and thus a highly immersive display can be achieved. In addition, the display module 280 can also be applied to electronic devices with a relatively small display section.

[0334] [Display device 100A] Figure 12A The shown display device 100A 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.

[0335] The substrate 301 corresponds to Figure 11A and Figure 11B the substrate 291 in. The transistor 310 is a transistor having a channel formation region in the substrate 301. As the substrate 301, for example, a semiconductor substrate such as a single-crystalline silicon substrate can be used. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 is used as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and is used as a gate insulating layer. The low-resistance region 312 is a region in the substrate 301 doped with impurities and is used as a source or a drain. The insulating layer 314 covers the side surface of the conductive layer 311.

[0336] In addition, an element isolation layer 315 is provided between two adjacent transistors 310 in a manner of being embedded in the substrate 301.

[0337] In addition, an insulating layer 261 is provided to cover the transistor 310, and a capacitor 240 is provided on the insulating layer 261.

[0338] The capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 therebetween. The conductive layer 241 serves as one electrode in the capacitor 240, the conductive layer 245 serves as the other electrode in the capacitor 240, and the insulating layer 243 serves as the dielectric of the capacitor 240.

[0339] The conductive layer 241 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 through a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided so as to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping the conductive layer 241 with the insulating layer 243 therebetween.

[0340] An insulating layer 255 is provided so as to cover the capacitor 240. An insulating layer 174 is provided on the insulating layer 255, and an insulating layer 175 is provided on the insulating layer 174. Light-emitting devices 130R, 130G, and 130B are provided on the insulating layer 175. An insulator is provided in a region between adjacent light-emitting devices.

[0341] The insulating layer 156R is provided so as to include a region overlapping the side surface of the conductive layer 151R, the insulating layer 156G is provided so as to include a region overlapping the side surface of the conductive layer 151G, and the insulating layer 156B is provided so as to include a region overlapping the side surface of the conductive layer 151B. In addition, the conductive layer 152R is provided so as to cover the conductive layer 151R and the insulating layer 156R, the conductive layer 152G is provided so as to cover the conductive layer 151G and the insulating layer 156G, and the conductive layer 152B is provided so as to cover the conductive layer 151B and the insulating layer 156B. The sacrificial layer 158R is located on the EL layer 103R, the sacrificial layer 158G is located on the EL layer 103G, and the sacrificial layer 158B is located on the EL layer 103B.

[0342] The conductive layers 151R, 151G, and 151B are electrically connected to one of the source and drain of the transistor 310 through plugs 256 embedded in the insulating layers 243, 255, 174, and 175, the conductive layer 241 embedded in the insulating layer 254, and the plug 271 embedded in the insulating layer 261. Various conductive materials can be used for the plugs.

[0343] In addition, a protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B. A substrate 120 is bonded to the protective layer 131 by a resin layer 122. Details of the components from the light-emitting devices 130 to the substrate 120 can be referred to in Embodiment 3. The substrate 120 corresponds to Figure 11A the substrate 292.

[0344] Figure 12B shows Figure 12A 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 an area overlapping one of the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B. In Figure 12B the display device shown, the light-emitting device 130 can emit white light, for example. In addition, for example, the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B can transmit red light, green light, and blue light, respectively.

[0345] [Display device 100B] Figure 13 shows a perspective view of the display device 100B, Figure 14 shows a cross-sectional view of the display device 100B.

[0346] The display device 100B has a structure in which a bonding substrate 352 and a substrate 351 are bonded. In Figure 13 this, the substrate 352 is shown by a dashed line.

[0347] The display device 100B includes a pixel portion 177, a connection portion 140, a circuit 356, a wiring 355, and the like. Figure 13 shows an example in which the display device 100B is mounted with an IC 354 and an FPC 353. Therefore, it is also possible to Figure 13 call the structure shown a display module including the display device 100B, an IC (integrated circuit), and an FPC. Here, the substrate of the display device on which a connector such as an FPC is mounted or the substrate on which an IC is mounted is called a display module.

[0348] The connection portion 140 is provided outside the pixel portion 177. The connection portion 140 can be one or more. In the connection portion 140, the common electrode of the light-emitting device is electrically connected to the conductive layer, and power can be supplied to the common electrode.

[0349] As the circuit 356, for example, a scan line driving circuit can be used.

[0350] The wiring 355 has a function of supplying signals and power to the pixel portion 177 and the circuit 356. The signals and power are input to the wiring 355 from the outside via the FPC 353 or input to the wiring 355 from the IC 354.

[0351] Figure 13An example of setting the IC 354 on the substrate 351 by a method such as COG (Chip On Glass) or COF (Chip on Film) is shown. As the IC 354, for example, an IC including a scan line driving circuit or a signal line driving circuit or the like can be used. Note that the display device 100B and the display module do not necessarily have to be provided with an IC. In addition, for example, the IC can also be mounted on the FPC by the COF method.

[0352] Figure 14 An example of a cross-section showing a part of the region including the FPC 353, a part of the circuit 356, a part of the pixel portion 177, a part of the connection portion 140, and a part of the region including the end portion of the display device 100B is shown.

[0353] [Display device 100C] Figure 14 The shown display device 100C 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, and a light-emitting device 130B that emits blue light, etc. between the substrate 351 and the substrate 352.

[0354] Details of the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B can be referred to in Embodiment 1 to Embodiment 2.

[0355] The light-emitting device 130R includes a conductive layer 224R, a conductive layer 151R on the conductive layer 224R, and a conductive layer 152R on the conductive layer 151R. The light-emitting device 130G includes a conductive layer 224G, a conductive layer 151G on the conductive layer 224G, and a conductive layer 152G on the conductive layer 151G. The light-emitting device 130B includes a conductive layer 224B, a conductive layer 151B on the conductive layer 224B, and a conductive layer 152B on the conductive layer 151B.

[0356] The conductive layer 224R is connected to the conductive layer 222b included in the transistor 205 through an opening provided in the insulating layer 214. The end portion of the conductive layer 151R is located outside the end portion of the conductive layer 224R. The insulating layer 156R is provided in a manner including a region in contact with the side surface of the conductive layer 151R, and the conductive layer 152R is provided so as to cover the conductive layer 151R and the insulating layer 156R.

[0357] The conductive layer 224G, the conductive layer 151G, the conductive layer 152G, the insulating layer 156G in the light-emitting device 130G and the conductive layer 224B, the conductive layer 151B, the conductive layer 152B, the insulating layer 156B in the light-emitting device 130B are the same as the conductive layer 224R, the conductive layer 151R, the conductive layer 152R, and the insulating layer 156R in the light-emitting device 130R, so detailed description thereof is omitted.

[0358] Recesses are formed in the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B so as to cover the openings formed in the insulating layer 214. The recesses are filled with the layer 128.

[0359] The layer 128 has a function of planarizing the recesses of the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B. The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B which are electrically connected to the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B are provided on the conductive layer 224R, the conductive layer 224G, the conductive layer 224B, and the layer 128. Therefore, the region overlapping with the recesses of the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B can also be used as a light-emitting region, and the aperture ratio of the pixel can be increased.

[0360] The layer 128 may also be an insulating layer or a conductive layer. The layer 128 may appropriately use various inorganic insulating materials, organic insulating materials, and conductive materials. In particular, the layer 128 is preferably formed of an insulating material, and more preferably formed of an organic insulating material. For example, the layer 128 may use the organic insulating material that can be used for the insulating layer 127 as described above.

[0361] A protective layer 131 is provided on the light-emitting devices 130R, the light-emitting devices 130G, and the light-emitting devices 130B. The protective layer 131 and the substrate 352 are bonded by the bonding layer 142. A light-shielding layer 157 is provided on the substrate 352. The light-emitting device 130 may be sealed with a solid-sealing structure or a hollow-sealing structure, etc. In Figure 14 this case, the space between the substrate 352 and the substrate 351 is filled with the bonding layer 142, that is, a solid-sealing structure is adopted. Alternatively, the space may be filled with an inert gas (such as nitrogen or argon), that is, a hollow-sealing structure is adopted. At this time, the bonding layer 142 may also be provided in a manner that does not overlap with the light-emitting device. In addition, the space may be filled with a resin different from the bonding layer 142 provided in a frame shape.

[0362] Figure 14 An example is shown in which the connecting portion 140 includes a conductive layer 224C obtained by processing a conductive film the same as the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B, a conductive layer 151C obtained by processing a conductive film the same as the conductive layer 151R, the conductive layer 151G, and the conductive layer 151B, and a conductive layer 152C obtained by processing a conductive film the same as the conductive layer 152R, the conductive layer 152G, and the conductive layer 152B. In addition, Figure 14 an example is shown in which the insulating layer 156C is provided in a manner that includes a region overlapping with the side surface of the conductive layer 151C.

[0363] The display device 100B is a top-emission type display device. The light-emitting device emits light toward the side of the substrate 352. The substrate 352 is preferably made of a material with high visible light transmittance. When the light-emitting device emits infrared light or near-infrared light, a material with high transmittance for them is preferably used. The pixel electrode contains a material that reflects visible light, and the counter electrode (common electrode 155) contains a material that transmits visible light.

[0364] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are sequentially provided on the substrate 351. A part of the insulating layer 211 serves as a gate insulating layer for each transistor. A part of the insulating layer 213 serves as a gate insulating layer for each transistor. The insulating layer 215 is provided so as to cover the transistors. The insulating layer 214 is provided so as to cover the transistors and serves as a planarization layer. In addition, there is no particular limitation on the number of gate insulating layers and the number of insulating layers covering the transistors, and it may be one or two or more.

[0365] An inorganic insulating film is preferably used as the insulating layer 211, the insulating layer 213, and the insulating layer 215.

[0366] The insulating layer 214 serving as a planarization layer is preferably an organic insulating layer.

[0367] The transistors 201 and 205 include: a conductive layer 221 serving as a gate; an insulating layer 211 serving as a gate insulating layer; conductive layers 222a and 222b serving as source and drain electrodes; a semiconductor layer 231; an insulating layer 213 serving as a gate insulating layer; and a conductive layer 223 serving as a gate.

[0368] A connection portion 204 is provided in a region of the substrate 351 that is not overlapped by the substrate 352. In the connection portion 204, the source electrode or the drain electrode of the transistor 201 is electrically connected to the FPC 353 through the conductive layer 166 and the connection layer 242. The following example is shown: The conductive layer 166 has a laminated structure of a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. The conductive layer 166 is exposed on the top surface of the connection portion 204. Therefore, the connection portion 204 can be electrically connected to the FPC 353 through the connection layer 242.

[0369] A light-shielding layer 157 is preferably provided on the surface of the substrate 351 on the side of the substrate 352. The light-shielding layer 157 can be provided between adjacent light-emitting devices, in the connection portion 140, the circuit 356, etc. In addition, various optical members can be arranged outside the substrate 352.

[0370] The substrate 351 and the substrate 352 can each be made of a material that can be used for the substrate 120.

[0371] As the adhesive layer 142, a material that can be used for the resin layer 122 can be used.

[0372] As the connection layer 242, an anisotropic conductive film (ACF: Anisotropic Conductive Film), an anisotropic conductive paste (ACP: Anisotropic Conductive Paste), etc. can be used.

[0373] [Display device 100D] Figure 15 The shown display device 100D Figure 14 The main difference from the shown display device 100C is that the display device 100D is a bottom-emission type display device.

[0374] The light emitted by the light-emitting device is emitted to the side of the substrate 351. The substrate 351 is preferably made of a material having high transmittance to visible light. On the other hand, there is no limitation on the light transmittance of the material used for the substrate 352.

[0375] It is preferable to form a light-shielding layer 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 157 is provided on the substrate 351, an insulating layer 153 is provided on the light-shielding layer, and transistors 201, 205, etc. are provided on the insulating layer 153.

[0376] 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.

[0377] 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.

[0378] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B all use materials having high transmittance to visible light. As the common electrode 155, a material that reflects visible light is preferably used.

[0379] Note that although Figure 15 the light-emitting device 130G is not shown in, the light-emitting device 130G is also provided.

[0380] In addition, Figure 15 etc. show examples in which the top surface of the layer 128 has a flat portion, but the shape of the layer 128 is not particularly limited.

[0381] [Display device 100E] Figure 16 The display device 100E shown is Figure 14 a modified example of the display device 100C shown. The main difference between the display device 100E and the display device 100C is that the display device 100E includes a coloring layer 132R, a coloring layer 132G, and a coloring layer 132B.

[0382] In the display device 100E, the light-emitting device 130 has an area that overlaps with one of the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B. The coloring layer 132R, the coloring layer 132G, and the coloring layer 132B can be provided on the surface of the substrate 351 on the side of the substrate 352. The ends of the coloring layer 132R, the ends of the coloring layer 132G, and the ends of the coloring layer 132B can overlap with the light-shielding layer 157.

[0383] In the display device 100E, the light-emitting device 130 can emit white light, for example. In addition, for example, the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B can transmit red light, green light, and blue light, respectively. In addition, the display device 100E can also adopt a structure in which the coloring layer 132R, the coloring layer 132G, and the coloring layer 132B are provided between the protective layer 131 and the adhesive layer 142.

[0384] Figure 14 and Figure 16 etc. show examples where the top surface of the layer 128 has a flat portion, but there is no particular limitation on the shape of the layer 128.

[0385] This embodiment can be appropriately combined with other embodiments or examples. In addition, in this specification, in the case where a plurality of structural examples are shown in one embodiment, the structural examples can be appropriately combined.

[0386] (Embodiment 5) In this embodiment, an electronic device of one aspect of the present invention is described.

[0387] The electronic device of this embodiment includes a display device of one aspect of the present invention in the display unit. The display device of one aspect of the present invention has high display performance and is easily high-definition and high-resolution. Therefore, it can be used in the display units of various electronic devices.

[0388] As electronic devices, for example, in addition to electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, monitors for computers, digital signage, and large game machines such as pachinko machines, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, portable information terminals, and sound reproduction devices can also be cited.

[0389] In particular, since the display device according to one embodiment of the present invention can improve clarity, it can be suitably used for electronic devices including a smaller display unit. Examples of such electronic devices include watch-type and bracelet-type information terminal devices (wearable devices), wearable devices that can be worn on the head such as VR devices like head-mounted displays, glasses-type AR devices, and MR devices.

[0390] The electronic device according to the present embodiment may also include a sensor (the sensor has a function of measuring factors such as force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electric power, radiation, flow rate, humidity, inclination, vibration, odor, or infrared rays).

[0391] Refer to Figures 17A to 17D An example of a wearable device that can be worn on the head will be described.

[0392] Figure 17A The illustrated electronic device 700A and Figure 17B The illustrated electronic device 700B both include a pair of display panels 751, a pair of outer casings 721, a communication unit (not shown), a pair of mounting portions 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0393] The display panel 751 may apply the display device according to one embodiment of the present invention. Thereby, a highly reliable electronic device can be realized.

[0394] Both the electronic device 700A and the electronic device 700B can project the image displayed on the display panel 751 onto the display area 756 in the optical member 753. Since the optical member 753 has translucency, the user can see the image displayed in the display area overlapping with the transmitted image seen through the optical member 753.

[0395] A camera capable of photographing the front may also be provided as the imaging unit on the electronic device 700A and the electronic device 700B. In addition, by providing an acceleration sensor such as a gyro sensor on the electronic device 700A and the electronic device 700B, the user's head orientation can be detected and the image corresponding to the direction can be displayed on the display area 756.

[0396] The communication unit has a wireless communication device, and an image signal can be supplied through the wireless communication device, for example. In addition, instead of or in addition to the wireless communication device, a connector capable of connecting a cable for supplying an image signal and a power potential may be included.

[0397] In addition, the electronic device 700A and the electronic device 700B are provided with a battery and can be charged in one or both of a wireless manner and a wired manner.

[0398] The housing 721 may also be provided with a touch sensor module.

[0399] As the touch sensor module, various touch sensors can be used. For example, various methods such as a capacitive method, a resistive film method, an infrared method, an electromagnetic induction method, a surface acoustic wave method, and an optical method can be adopted. In particular, it is preferable to apply a capacitive method or an optical method sensor to the touch sensor module.

[0400] Figure 17C The illustrated electronic device 800A and Figure 17D the illustrated electronic device 800B both include a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0401] The display unit 820 may apply a display device of one aspect of the present invention. Thus, a highly reliable electronic device can be realized.

[0402] The display unit 820 is disposed at a position visible through the lens 832 inside the housing 821. In addition, by displaying different images on each of the pair of display units 820, three-dimensional display using parallax can be performed.

[0403] The electronic device 800A and the electronic device 800B preferably have a mechanism in which the left and right positions of the lens 832 and the display unit 820 can be adjusted so that the lens 832 and the display unit 820 are located at the most suitable positions according to the position of the user's eyes.

[0404] The user can mount the electronic device 800A or the electronic device 800B on the head using the mounting unit 823.

[0405] The imaging unit 825 has a function of acquiring external information. The data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used in the imaging unit 825. In addition, a plurality of cameras may be provided to be able to correspond to various perspectives such as telephoto and wide-angle.

[0406] The electronic device 800A may also include a vibration mechanism used as a bone conduction headphone.

[0407] The electronic device 800A and the electronic device 800B may both include input terminals. A cable for supplying an image signal from an image output device or the like and power for charging a battery provided in the electronic device can be connected to the input terminals.

[0408] An electronic device according to one embodiment of the present invention may also have a function of wirelessly communicating with the earphone 750.

[0409] In addition, the electronic device may also include an earphone unit. Figure 17B The illustrated electronic device 700B includes an earphone unit 727. A part of the wiring connecting the earphone unit 727 and the control unit may also be disposed inside the housing 721 or the mounting portion 723.

[0410] Similarly, Figure 17D The illustrated electronic device 800B includes an earphone unit 827. For example, a structure in which the earphone unit 827 and the control unit 824 are connected in a wired manner may be employed.

[0411] Thus, as an electronic device according to one embodiment of the present invention, both the glasses type (such as the electronic devices 700A and 700B) and the goggles type (such as the electronic devices 800A and 800B) are preferred.

[0412] Figure 18A The illustrated electronic device 6500 is a portable information terminal device that can be used as a smart phone.

[0413] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, etc. The display unit 6502 has a touch panel function.

[0414] The display unit 6502 may use a display device according to one embodiment of the present invention. Thereby, a highly reliable electronic device can be realized.

[0415] Figure 18B It is a cross-sectional schematic view of an end portion on the microphone 6506 side including the housing 6501.

[0416] A protective member 6510 having translucency is provided on the display surface side of the housing 6501, and a display panel 6511, an optical member 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are provided in a space surrounded by the housing 6501 and the protective member 6510.

[0417] The display panel 6511, the optical member 6512, and the touch sensor panel 6513 are fixed to the protective member 6510 using an adhesive layer (not shown).

[0418] In the region outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded-back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on the printed circuit board 6517.

[0419] The display panel 6511 can be a display device of one aspect of the present invention. Thus, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted while suppressing the thickness of the electronic device. Further, by folding a part of the display panel 6511 to provide a connection portion with the FPC 6515 on the back surface of the pixel portion, a narrow-bezel electronic device can be realized.

[0420] Figure 18C An example of a television device is shown. In the television device 7100, a display unit 7000 is assembled in a housing 7171. A structure in which the housing 7171 is supported by a bracket 7173 is shown here.

[0421] The display unit 7000 can be a display device of one aspect of the present invention. Thus, a highly reliable electronic device can be realized.

[0422] The operation of the television device 7100 shown can be performed by using operation switches provided in the housing 7171 and a separately provided remote operation machine 7151. Figure 18C The operation of the television device 7100 shown is performed.

[0423] Figure 18D An example of a notebook personal computer is shown. The notebook personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. A display unit 7000 is assembled in the housing 7211.

[0424] The display unit 7000 can be a display device of one aspect of the present invention. Thus, a highly reliable electronic device can be realized.

[0425] Figure 18E and Figure 18F An example of a digital signage is shown.

[0426] Figure 18E The digital signage 7300 shown includes a housing 7301, a display unit 7000, a speaker 7303, and the like. In addition, it may further include an LED lamp, operation keys (including a power switch or operation switches), connection terminals, various sensors, a microphone, and the like.

[0427] Figure 18F A digital signage 7400 provided on a cylindrical column 7401 is shown. The digital signage 7400 includes a display unit 7000 provided along the curved surface of the column 7401.

[0428] In Figure 18E and Figure 18F the display device of one embodiment of the present invention can be used for the display unit 7000. Thus, an electronic device with high reliability can be realized.

[0429] The larger the display unit 7000 is, the more information can be provided at one time. The larger the display unit 7000 is, the more likely it is to attract people's attention. For example, the advertising effect can be improved.

[0430] As Figure 18E and Figure 18F shown, the digital signage 7300 or the digital signage 7400 can preferably be linked with an information terminal device 7311 such as a smartphone carried by a user or the information terminal device 7411 through wireless communication.

[0431] Figures 19A to 19G The electronic device shown in includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), connection terminals 9006, a sensor 9007 (the sensor has a function of measuring the following factors: force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, inclination, vibration, odor or infrared rays), a microphone 9008, etc.

[0432] Figures 19A to 19G The electronic device shown in has various functions. For example, it can have the following functions: a function of displaying various information (static images, dynamic images, text images, etc.) on the display unit; a function of a touch panel; a function of displaying a calendar, date or time, etc.; a function of controlling and processing through the use of various software (programs); a function of performing wireless communication; a function of reading out programs or data stored in a storage medium and processing them; etc.

[0433] Next, the electronic device shown in will be described in detail. Figures 19A to 19G The electronic device shown in .

[0434] Figure 19A is a perspective view showing a portable information terminal 9171. The portable information terminal 9171 can be used as a smartphone, for example. Note that in the portable information terminal 9171, a speaker 9003, connection terminals 9006, a sensor 9007, etc. can also be provided. In addition, as the portable information terminal 9171, text or image information can be displayed on its multiple surfaces. In Figure 19AAn example of displaying three icons 9050 is shown. Additionally, information 9051 shown as a rectangle with a dashed line can be displayed on other surfaces of the display unit 9001. As an example of the information 9051, information such as a prompt for receiving an email, SNS, phone call, etc.; the title of an email or SNS, etc.; the sender's name of an email or SNS, etc.; date; time; battery level; and radio wave intensity, etc. can be cited. Alternatively, an icon 9050, etc. can be displayed at the position where the information 9051 is displayed.

[0435] Figure 19B It is a perspective view showing the portable information terminal 9172. The portable information terminal 9172 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example where the information 9052, the information 9053, and the information 9054 are respectively displayed on different surfaces is shown. For example, in a state where the portable information terminal 9172 is placed in an upper body pocket, the user can confirm the information 9053 displayed at a position seen from above the portable information terminal 9172.

[0436] Figure 19C It is a perspective view showing the tablet terminal 9173. The tablet terminal 9173 can execute various application software such as a mobile phone, reading and editing of emails and articles, playing music, network communication, computer games, etc. The tablet terminal 9173 includes a display unit 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front surface of the housing 9000, an operation key 9005 serving as an operation button on the left side surface of the housing 9000, and a connection terminal 9006 on the bottom surface.

[0437] Figure 19D It is a perspective view showing the watch-type portable information terminal 9200. The portable information terminal 9200 can be used as, for example, a smart watch (registered trademark). Additionally, the display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. Furthermore, the portable information terminal 9200 can perform hands-free calls, for example, by communicating with a headset capable of wireless communication. Moreover, by using the connection terminal 9006, the portable information terminal 9200 can perform data transmission with other information terminals or be charged. Charging can also be performed by wireless power supply.

[0438] Figures 19E to 19G It is a perspective view showing the foldable portable information terminal 9201. Additionally, Figure 19E It is a perspective view of the state where the portable information terminal 9201 is unfolded, Figure 19G It is a perspective view of the folded state, Figure 19F It is from Figure 19E the state and Figure 19GA perspective view of an intermediate state when converting from one of the states to another. The portable information terminal 9201 has good portability in the folded state, and has strong display readability in the unfolded state because it has a large display area with seamless splicing. The display unit 9001 included in the portable information terminal 9201 is supported by three housings 9000 connected by a hinge 9055. The display unit 9001 can be bent, for example, in a range where the radius of curvature is 0.1 mm or more and 150 mm or less.

[0439] This embodiment can be appropriately combined with other embodiments or examples. In addition, in this specification, when multiple structural examples are shown in one embodiment, the structural examples can be appropriately combined. [Reference Signs]

[0440] 100A: Display device, 100B: Display device, 100C: Display device, 100E: Display device, 100D: Display device, 100: Insulator, 101a: First electrode, 101b: First electrode, 101c: First electrode, 101d: First electrode, 101R: First electrode, 101G: First electrode, 101B: First electrode, 101: First electrode, 102: Second electrode, 103a: EL layer, 103B: EL layer, 103b: EL layer, 103Bf: Organic compound film, 103c: EL layer, 103d: EL layer, 103G: EL layer, 103Gf: Organic compound film, 103R: EL layer, 103Rf: Organic compound film, 103: EL layer, 110B: Sub-pixel, 110G: Sub-pixel, 110R: Sub-pixel, 110: Sub-pixel, 111a: Hole injection layer, 111b: Hole injection layer, 111c: Hole injection layer, 111d: Hole injection layer, 111: Hole injection layer, 112: Hole transport layer, 112a: Hole transport layer, 112b: Hole transport layer, 112c_1: Hole transport layer, 112c_2: Hole transport layer, 112d_1: Hole transport layer, 112d_2: Hole transport layer, 112R: Conductive layer, 112B: Conductive layer, 113: Light-emitting layer, 113a: Light-emitting layer, 113b: Light-emitting layer, 113c_1: Light-emitting layer, 113c_2: Light-emitting layer, 113d_1: Light-emitting layer, 113d_2: Light-emitting layer, 114: Electron transport layer, 114a: Electron transport layer, 114b: Electron transport layer, 114c_1: Electron transport layer, 114c_2: Electron transport layer, 114d_1: Electron transport layer, 114d_2: Electron transport layer, 115: Electron injection layer, 115a: Electron injection layer, 115b: Electron injection layer, 115c: Electron injection layer, 115d: Electron injection layer, 116: Intermediate layer, 116c: Intermediate layer, 116d: Intermediate layer, 117: P-type layer, 117c: P-type layer, 117d: P-type layer, 118: Electron relay layer, 118c: Electron relay layer, 118d: Electron relay layer, 119: N-type layer, 119c: N-type layer, 119d: N-type layer, 120: Substrate, 122: Resin layer, 125f: Inorganic insulating film, 125: Inorganic insulating layer, 126R: Conductive layer, 126B: Conductive layer, 127a: Insulating layer, 127f: Insulating film, 127: Insulating layer, 128: Layer, 129R: Conductive layer, 129B: Conductive layer, 130a: Light-emitting device, 130B: Light-emitting device, 130b: Light-emitting device, 130c: Light-emitting device, 130d: Light-emitting device, 130G: Light-emitting device, 130R: Light-emitting device, 130: Light-emitting device, 131: Protective layer, 132B: Coloring layer, 132G: Coloring layer, 132R: Coloring layer, 140: Connection portion, 141: Region142: Adhesive layer, 151B: Conductive layer, 151C: Conductive layer, 151f: Conductive film, 151G: Conductive layer, 151R: Conductive layer, 151: Conductive layer, 152B: Conductive layer, 152C: Conductive layer, 152f: Conductive film, 152G: Conductive layer, 152R: Conductive layer, 152: Conductive layer, 153: Insulating layer, 155: Common electrode, 156B: Insulating layer, 156C: Insulating layer, 156f: Insulating film, 156G: Insulating layer, 156R: Insulating layer, 156: Insulating layer, 157: Light-shielding layer, 158B: Sacrificial layer, 158Bf: Sacrificial film, 158G: Sacrificial layer, 158Gf: Sacrificial film, 158R: Sacrificial layer, 158Rf: Sacrificial film, 159B: Mask layer, 159Bf: Mask film, 159G: Mask layer, 159Gf: Mask film, 159R: Mask layer, 159Rf: Mask film, 166: Conductive layer, 171: Insulating layer, 172: Conductive layer, 173: Insulating layer, 174: Insulating layer, 175: Insulating layer, 176: Plug, 177: Pixel section, 178: Pixel, 179: Conductive layer, 190B: Resist mask, 190G: Resist mask, 190R: Resist mask, 191: Resist mask, 201: Transistor, 204: Connection part, 205: Transistor, 211: Insulating layer, 213: Insulating layer, 214: Insulating layer, 215: Insulating layer, 221: Conductive layer, 222a: Conductive layer, 222b: Conductive layer, 223: Conductive layer, 224B: Conductive layer, 224C: Conductive layer, 224G: Conductive layer, 224R: Conductive layer, 231: Semiconductor layer, 240: Capacitor, 241: Conductive layer, 242: Connection layer, 243: Insulating layer, 245: Conductive layer, 254: Insulating layer, 255: Insulating layer, 256: Plug, 261: Insulating layer, 271: Plug, 280: Display module, 281: Display section, 282: Circuit section, 283a: Pixel circuit, 283: Pixel circuit section, 284a: Pixel, 284: Pixel section, 285: Terminal section, 286: Wiring section, 290: FPC, 291: Substrate, 292: Substrate, 301: Substrate, 310: Transistor, 311: Conductive layer, 312: Low-resistance region, 313: Insulating layer, 314: Insulating layer, 315: Element isolation layer, 351: Substrate, 352: Substrate, 353: FPC, 354: IC, 355: Wiring, 356: Circuit, 501: First electrode, 511: First light-emitting unit, 511c: First light-emitting unit, 511d: First light-emitting unit, 502: Second electrode, 512: Second light-emitting unit, 512c: Second light-emitting unit, 512d: Second light-emitting unit, 700A: Electronic device, 700B: Electronic device, 721: Housing, 723: Wearing part, 727: Headphone part, 750: Headphone, 751: Display panel, 753: Optical member756: Display area, 757: Frame, 758: Nose pad, 800A: Electronic device, 800B: Electronic device, 820: Display unit, 821: Housing, 822: Communication unit, 823: Wearing unit, 824: Control unit, 825: Imaging unit, 827: Headphone unit, 832: Lens, 6500: Electronic device, 6501: Housing, 6502: Display unit, 6503: Power button, 6504: Button, 6505: Speaker, 6506: Microphone, 6507: Camera, 6508: Light source, 6510: Protection member, 6511: Display panel, 6512: Optical member, 6513: Touch sensor panel, 6515: FPC, 6516: IC, 6517: Printed circuit board, 6518: Battery, 7000: Display unit, 7100: Television device, 7151: Remote operator, 7171: Housing, 7173: Bracket, 7200: Notebook personal computer, 7211: Housing, 7212: Keyboard, 7213: Pointing device, 7214: External connection port, 7300: Digital signage, 7301: Housing, 7303: Speaker, 7311: Information terminal device, 7400: Digital signage, 7401: Column, 7411: Information terminal device, 9000: Housing, 9001: Display unit, 9002: Camera, 9003: Speaker, 9005: Operation key, 9006: Connection terminal, 9007: Sensor, 9008: Microphone, 9050: Icon, 9051: Information, 9052: Information, 9053: Information, 9054: Information, 9055: Hinge, 9171: Portable information terminal, 9172: Portable information terminal, 9173: Tablet terminal, 9200: Portable information terminal, 9201: Portable information terminal,

Claims

1. A light-emitting device, comprising: A first electrode; A second electrode; And An organic compound layer, Wherein the organic compound layer is located between the first electrode and the second electrode, The organic compound layer includes a light-emitting layer, an electron transport layer, and an electron injection layer, The electron transport layer is located between the light-emitting layer and the electron injection layer, The electron transport layer is in contact with the electron injection layer, The electron injection layer has a function of blocking holes, And the electron transport layer is a bipolar layer.

2. A light-emitting device, comprising: A first electrode; A second electrode; And An organic compound layer, Wherein the organic compound layer is located between the first electrode and the second electrode, The organic compound layer includes a light-emitting layer, an electron transport layer, and an electron injection layer, The electron transport layer is located between the light-emitting layer and the electron injection layer, The electron transport layer is in contact with the electron injection layer, The electron injection layer has a function of blocking holes, And the electron transport layer is a layer containing an organic compound having electron transport properties and an organic compound having hole transport properties.

3. A light-emitting device, comprising: A first electrode; A second electrode; And An organic compound layer, Wherein the organic compound layer is located between the first electrode and the second electrode, The organic compound layer includes a light-emitting layer, an electron transport layer, and an electron injection layer, The electron transport layer is located between the light-emitting layer and the electron injection layer, The electron transport layer is in contact with the electron injection layer, The electron injection layer contains an organic compound having a strong basicity with a pKa of 8 or more, And the electron transport layer contains an organic compound having electron transport properties and an organic compound having hole transport properties.

4. The light-emitting device according to claim 3, Wherein the HOMO energy level of the organic compound having hole transport properties is -5.9 eV or more and -5.0 eV or less.

5. The light-emitting device according to claim 3, Wherein the LUMO energy level of the organic compound having electron transport properties is -3.15 eV or more and -2.50 eV or less.

6. The light-emitting device according to claim 3, Wherein the organic compound having a strong basicity with a pKa of 8 or more has a guanidine skeleton.

7. The light-emitting device according to claim 3, Wherein the organic compound having a strong basicity with a pKa of 8 or more has a 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine skeleton.

8. The light-emitting device according to claim 3, Wherein the organic compound having a strong basicity with a pKa of 8 or more does not have an electron transport skeleton.

9. The light-emitting device according to claim 3, Wherein the organic compound having a strong basicity with a pKa of 8 or more has a guanidine skeleton and does not have an electron transport skeleton.

10. The light-emitting device according to claim 3, Wherein the electron injection layer further contains an organic compound having second electron transport properties.

11. The light-emitting device according to claim 10, The organic compound having a strong basicity with a pKa of 8 or more does not have an electron-donating property with respect to the organic compound having the second electron-transporting property.

12. The light-emitting device according to any one of claims 1 to 11, The spin density obtained by measuring the electron injection layer using electron spin resonance method is 1×10 17 spins / cm 3 or less.

Images