Light-emitting device

Abstract

To provide a light-emitting device that is driven at low voltage.SOLUTION: A light-emitting device includes a first electrode 101, a second electrode 102, and an organic compound layer 103 in this order on a first insulating layer 1000. The second electrode 102 and the organic compound layer 103 are apart from at least one of the second electrode 102 and the organic compound layer 103 of other light-emitting devices that are adjacent to the light-emitting device. When viewed from a direction substantially perpendicular to a surface where the first electrode 101 of the first insulating layer 1000 is formed, the outline of the second electrode 102 and the outline of the organic compound layer 103 coincide substantially. The organic compound layer 103 includes a light-emitting layer 113 and an electron injection layer 115. The electron injection layer 115 includes metal or a metal compound, a first organic compound, and a second organic compound. The first organic compound has a π-electron deficient heteroaromatic ring. The second organic compound is a particular organic compound having two or more heteroaromatic rings.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] One embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (for example, a touch sensor), an input / output device (for example, a touch panel), a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] Display devices have been developed for a variety of applications in recent years. For example, applications of large display devices include home television devices (also called televisions or television receivers), digital signage (electronic billboards), and public information displays (PIDs), while applications of small display devices include smartphones and tablet terminals equipped with touch panels.

[0004] At the same time, there is also a demand for higher resolution display devices. Devices requiring high-resolution display devices include, for example, devices for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR).

[0005] As display elements for use in display devices, the development of light-emitting devices (also referred to as light-emitting elements) has been actively promoted. Light-emitting devices (also referred to as EL devices or EL elements) utilizing the electroluminescence (hereinafter referred to as EL) phenomenon, particularly organic EL devices that mainly use organic compounds, are suitable for display devices because they have features such as being easily thin and lightweight, being capable of high-speed response to input signals, and being capable of being driven by a DC constant voltage power supply.

[0006] In order to obtain a light-emitting device with higher resolution using an organic EL device, research is being conducted into patterning of organic layers by photolithography using photoresist, etc., instead of vapor deposition using a metal mask. By using photolithography, it is possible to obtain a high-resolution display device with an interval of several μm between organic compound layers (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2018-521459 Summary of the Invention [Problem to be solved by the invention]

[0008] It has long been known that exposure to atmospheric components such as water and oxygen can affect the initial characteristics and reliability of the cathode and organic compound layers of organic EL devices, and so it has been common practice to handle them in an inert gas atmosphere or a near-vacuum. In particular, alkali metals, alkaline earth metals, or their compounds are often used for the electron injection layer, but these metals and compounds are highly reactive with water and oxygen, and when the surface of the organic compound layer is exposed to the atmosphere, they quickly deteriorate and no longer function as an electron injection layer.

[0009] However, as described above, in the process of processing by photolithography, the organic EL device needs to be exposed to the atmosphere.

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

[0011] Alternatively, one embodiment of the present invention has an object to provide a novel light-emitting device manufactured through a photolithography process. Alternatively, another embodiment of the present invention has an object to provide a light-emitting device manufactured through a photolithography process and having good emission efficiency. Alternatively, one embodiment of the present invention has an object to provide a light-emitting device manufactured through a photolithography process. Alternatively, another embodiment of the present invention has an object to provide a light-emitting device manufactured through a photolithography process and having good emission efficiency.

[0012] Another object of one embodiment of the present invention is to provide a novel light-emitting device that can be used in a high-resolution display device. Another object of another embodiment of the present invention is to provide a light-emitting device that can be used in a high-resolution display device and has high emission efficiency. Another object of one embodiment of the present invention is to provide a light-emitting device that can be used in a high-resolution display device. Another object of another embodiment of the present invention is to provide a light-emitting device that can be used in a high-resolution display device and has high emission efficiency.

[0013] Another object of another embodiment of the present invention is to provide a highly reliable display device.Another object of another embodiment of the present invention is to provide a high-definition display device.Another object of another embodiment of the present invention is to provide a high-definition display device.

[0014] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description in the specification, drawings, and claims. [Means for solving the problem]

[0015] One embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, and an organic compound layer formed on a first insulating layer, in which the first electrode is formed in contact with the first insulating layer, the organic compound layer is located between the first electrode and the second electrode, the second electrode and the organic compound layer are separated from at least one of the second electrodes and organic compound layers of a plurality of other light-emitting devices adjacent to the light-emitting device, and when viewed from a direction approximately perpendicular to the surface of the first insulating layer on which the first electrode is formed, the outline of the second electrode and the outline of the organic compound layer approximately coincide with each other. The organic compound layer has a light-emitting layer and an electron injection layer, and the electron injection layer has a metal or metal compound, a first organic compound, and a second organic compound, the first organic compound has a π-electron-deficient heteroaromatic ring, the second organic compound has two or more heteroaromatic rings that are bonded to or fused with each other and have a total of three or more heteroatoms, and the second organic compound is an organic compound that has the function of interacting with the metal or metal compound in a multidentate manner via two or more of the three or more heteroatoms.

[0016] In one embodiment of the above invention, the organic compound layer is a light-emitting device having a P-type layer between the electron injection layer and the second electrode, and the P-type layer has a third organic compound having hole transport properties and a fourth organic compound or metal oxide having at least one of a halogen group and a cyano group.

[0017] In one embodiment of the invention, the second organic compound is a light-emitting device having a function of interacting with a metal or metal compound in a bidentate or tridentate manner via two or more of the three or more heteroatoms.

[0018] One aspect of the present invention is a light-emitting device among a plurality of light-emitting devices included in a light-emitting device group having a first electrode group formed on the same insulating surface, a second electrode group facing the first electrode group, and a first layer group located between the first electrode group and the second electrode group, wherein the light-emitting device has a first electrode, a second electrode, and a first layer, the first electrode being one of the first electrode group, and the first electrode being independent for each of the plurality of light-emitting devices, the first layer being one of the first layer group, and the first layer being independent for each of the plurality of light-emitting devices, the second electrode being one of the second electrode group, and the second electrode being independent for each of the plurality of light-emitting devices, and the second electrode and the first layer being a first layer overlapping a first electrode, the first layer having a light-emitting layer and an electron-injection layer, the electron-injection layer having a metal or metal compound, a first organic compound, and a second organic compound, the first organic compound having a π-electron-deficient heteroaromatic ring, the second organic compound having two or more heteroaromatic rings that are bonded or fused to each other and have a total of three or more heteroatoms, the second organic compound being an organic compound that has the function of interacting with the metal or metal compound in a multidentate manner via two or more of the three or more heteroatoms, and the distance between the first layer of the light-emitting device and the first layer of another light-emitting device adjacent to the light-emitting device is 0.5 μm or more and 5 μm or less.

[0019] In one embodiment of the above invention, the first layer is a light-emitting device having a P-type layer between the electron injection layer and the second electrode, and the P-type layer has a third organic compound having hole-transporting properties and a fourth organic compound or metal oxide having at least one of a halogen group and a cyano group.

[0020] In one embodiment of the invention, the second organic compound is a light-emitting device having a function of interacting with a metal or metal compound in a bidentate or tridentate manner via two or more of the three or more heteroatoms.

[0021] In one embodiment of the above invention, the light-emitting device has an outline of the second electrode and an outline of the first layer that are substantially aligned when viewed from a direction substantially perpendicular to the insulating surface.

[0022] In one embodiment of the above invention, the light-emitting device has an end portion of the second electrode in a cross section and an end portion of the first layer in a cross section that are aligned in a direction substantially perpendicular to the insulating surface.

[0023] One embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, and an organic compound layer formed on a first insulating layer, in which the first electrode is formed in contact with the first insulating layer, the organic compound layer is located between the first electrode and the second electrode, the second electrode and the organic compound layer are separated from at least one of the second electrodes and organic compound layers of a plurality of other light-emitting devices adjacent to the light-emitting device, an outline of the second electrode and an outline of the organic compound layer are approximately the same when viewed from a direction approximately perpendicular to a surface of the first insulating layer on which the first electrode is formed, and the organic compound layer has a light-emitting layer and an electron-injection layer, in which the electron-injection layer has a metal or a metal compound, a first organic compound, and a second organic compound, in which the first organic compound has a π-electron-deficient heteroaromatic ring, and the second organic compound is an organic compound represented by General Formula (G1-1).

[0024] [ka]

[0025] In general formula (G1-1), A 1 , A 2 and A 3 each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms; A 1 , A 2 and A 3 may be fused together to form a condensed ring.

[0026] In one embodiment of the above invention, the organic compound layer has a P-type layer between the electron injection layer and the second electrode, and the P-type layer has a third organic compound having hole transport properties, and a fourth organic compound or metal oxide having at least one of a halogen group and a cyano group.

[0027] One embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, and an organic compound layer formed on a first insulating layer, in which the first electrode is formed in contact with the first insulating layer, the organic compound layer is located between the first electrode and the second electrode, the second electrode and the organic compound layer are separated from at least one of a plurality of other light-emitting devices adjacent to the light-emitting device, an outline of the second electrode and an outline of the organic compound layer are approximately consistent when viewed from a direction approximately perpendicular to a surface of the first insulating layer on which the first electrode is formed, and the organic compound layer has a light-emitting layer and an electron-injection layer, in which the electron-injection layer has a metal or a metal compound, a first organic compound, and a second organic compound, in which the first organic compound has a π-electron-deficient heteroaromatic ring, and the second organic compound is an organic compound represented by General Formula (G1-2).

[0028] [ka]

[0029] In general formula (G1-2), A 1 , and A 2 each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms; A 1 , and A 2 may form a condensed ring with each other, A 1 has two or more nitrogen atoms.

[0030] In one embodiment of the above invention, the organic compound layer has a P-type layer between the electron injection layer and the second electrode, and the P-type layer has a third organic compound having hole transport properties, and a fourth organic compound or metal oxide having at least one of a halogen group and a cyano group.

[0031] In one embodiment of the invention, the heteroaromatic ring is a π-electron deficient heteroaromatic ring.

[0032] In one embodiment of the above invention, the heteroaromatic ring is a light-emitting device including at least one of a pyridine ring, a diazine ring (a pyrazine ring, a pyrimidine ring, a pyridazine ring), a triazine ring, an azole ring (an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring), and a triazole ring.

[0033] In one embodiment of the invention, at least one of the heteroaromatic rings of the second organic compound includes a diazine ring (pyrazine ring, pyrimidine ring, pyridazine ring) or a triazine ring. Alternatively, in one embodiment of the invention, the heteroaromatic rings of the second organic compound include a total of three or more pyridine rings.

[0034] In one embodiment of the invention, the first organic compound has an electron-donating group, and the electron-donating group is at least one of an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group.

[0035] In one embodiment of the invention, the light-emitting device is one in which the first organic compound has an acid dissociation constant pKa of at least 8. In another embodiment of the invention, the light-emitting device is one in which the first organic compound has a phenanthroline ring.

[0036] In one embodiment of the invention, the second organic compound has a glass transition temperature Tg of 100° C. or higher, and the lowest unoccupied molecular orbital (LUMO) level of the second organic compound is lower than the LUMO level of the first organic compound.

[0037] In one embodiment of the invention, the light-emitting device is one in which the metal belongs to Group 1, Group 3, Group 11, or Group 13 in the periodic table.

[0038] In one embodiment of the invention, the electron injection layer of the light-emitting device is a mixture of a metal, a second organic compound, and a first organic compound, and the electron injection layer is a stack of a layer containing a metal and a layer containing the second organic compound or the first organic compound.

[0039] Alternatively, another embodiment of the present invention is a light-emitting device having a plurality of light-emitting devices, each of which is any one of the light-emitting devices described above, and each of the plurality of light-emitting devices has an organic compound layer including a light-emitting layer and an electron-injection layer between a first electrode and a second electrode, and the second electrode and the organic compound layer included in each of the plurality of light-emitting devices are independent from each other among the plurality of light-emitting devices.

[0040] Another embodiment of the present invention is a display module including the above-described light-emitting device and at least one of a connector and an integrated circuit.

[0041] Another embodiment of the present invention is an electronic device including the above-described light-emitting device and at least one of a housing, a battery, a camera, a speaker, and a microphone. [Effects of the Invention]

[0042] According to one embodiment of the present invention, a novel light-emitting device can be provided. According to another embodiment of the present invention, a light-emitting device having high efficiency can be provided. According to another embodiment of the present invention, a light-emitting device having high reliability can be provided. According to another embodiment of the present invention, a light-emitting device having high efficiency and reliability can be provided.

[0043] According to one embodiment of the present invention, a novel light-emitting device manufactured through a photolithography process can be provided. According to another embodiment of the present invention, a light-emitting device manufactured through a photolithography process and having high efficiency can be provided. According to one embodiment of the present invention, a light-emitting device manufactured through a photolithography process and having high reliability can be provided. According to another embodiment of the present invention, a light-emitting device manufactured through a photolithography process and having high emission efficiency and reliability can be provided.

[0044] According to one embodiment of the present invention, a novel light-emitting device that can be used in a high-resolution display device can be provided. According to another embodiment of the present invention, a light-emitting device that can be used in a high-resolution display device and has high emission efficiency can be provided. According to one embodiment of the present invention, a light-emitting device that can be used in a high-resolution display device and has high emission efficiency and reliability can be provided. According to another embodiment of the present invention, a light-emitting device that can be used in a high-resolution display device and has high emission efficiency and reliability can be provided.

[0045] According to another embodiment of the present invention, a highly reliable display device can be provided. According to another embodiment of the present invention, a high-definition display device can be provided. According to another embodiment of the present invention, a high-definition and highly reliable display device can be provided.

[0046] Alternatively, 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.

[0047] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief explanation of the drawings]

[0048] [Figure 1] 1A to 1C are diagrams showing a light-emitting device. [Figure 2] Figure 2 shows the analysis results of the spin density distribution in the ground state of the composite material. [Figure 3] Figure 3 shows the results of an electrostatic potential map analysis of the composite material in its ground state. [Figure 4] 4(A) and 4(B) are diagrams showing a light-emitting device. [Figure 5] 5(A) and 5(B) are a top view and a cross-sectional view of the light-emitting device. [Figure 6] 6A to 6E are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 7] 7A and 7B are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 8] 8A to 8D are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 9] 9A to 9C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 10] 10A to 10C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 11] 11A and 11B are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 12] 12(A) and 12(B) are perspective views showing configuration examples of a display module. [Figure 13] 13(A) and 13(B) are cross-sectional views showing examples of the configuration of a display device. [Figure 14] FIG. 14 is a perspective view showing a configuration example of a display device. [Figure 15] FIG. 15 is a cross-sectional view showing an example of the configuration of a display device. [Figure 16] FIG. 16 is a cross-sectional view showing an example of the configuration of a display device. [Figure 17]Fig. 17(A) is a cross-sectional view showing an example of the configuration of a display device, and Fig. 17(B) and Fig. 17(C) are top views showing an example of the configuration of a display device. [Figure 18] FIG. 18 is a cross-sectional view showing an example of the configuration of a display device. [Figure 19] Fig. 19(A) is a cross-sectional view showing an example of the configuration of a display device, and Fig. 19(B) and Fig. 19(C) are top views showing an example of the configuration of a display device. [Figure 20] 20A to 20D are diagrams showing examples of electronic devices. [Figure 21] 21A to 21F are diagrams showing examples of electronic devices. [Figure 22] 22A to 22G are diagrams showing examples of electronic devices. [Figure 23] 23A to 23G are diagrams showing examples of pixel layouts. [Figure 24] FIG. 24 is a diagram illustrating the configuration of a light-emitting device. [Figure 25] FIG. 25 is a diagram illustrating the luminance-current density characteristics of a light-emitting device. [Figure 26] FIG. 26 is a diagram illustrating the luminance-voltage characteristics of a light-emitting device. [Figure 27] FIG. 27 is a diagram illustrating the current efficiency-current density characteristics of a light-emitting device. [Figure 28] FIG. 28 is a diagram illustrating the current density-voltage characteristics of a light-emitting device. [Figure 29] FIG. 29 is a diagram illustrating the electroluminescence spectrum of the light-emitting device. DETAILED DESCRIPTION OF THE INVENTION

[0049] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes can be made in form and detail without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0050] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. In addition, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0051] (Embodiment 1) One method widely used for forming organic semiconductor films into a predetermined shape is vacuum deposition using a metal mask (mask deposition). However, with the recent trend toward higher density and finer definition, mask deposition is approaching its limit for further finer definition due to various reasons, including issues with alignment accuracy and spacing with the substrate. On the other hand, by processing the shape of organic semiconductor films using photolithography, it is expected that organic semiconductor devices with more precise patterns will be realized. Furthermore, because photolithography is easier to process on a larger area than mask deposition, research into processing organic semiconductor films using photolithography is underway.

[0052] It has also long been known that exposure to atmospheric components such as water and oxygen can affect the initial characteristics or reliability of the organic compound layers and cathodes in organic EL devices, and it has been common knowledge that they should be handled in an inert gas atmosphere or a near-vacuum atmosphere.

[0053] In particular, alkali metals or alkaline earth metals, or their compounds (hereinafter also referred to as Li compounds, etc.), may be used in the electron injection layer of light-emitting devices. However, these Li compounds, etc., are highly reactive with water or oxygen, and they deteriorate rapidly when exposed to the atmosphere, resulting in a significant decrease in electron injection properties. Furthermore, even when other metals with a small work function are used in the cathode, exposure to water, oxygen, etc. may also decrease electron injection properties, resulting in a significant increase in driving voltage.

[0054] However, the photolithography process described above requires that the light-emitting device be exposed to the atmosphere during fabrication. Furthermore, the photolithography process involves the use of various chemicals and a cleaning process, creating harsh conditions that accelerate degradation.

[0055] Therefore, when the cathode and organic compound layer are processed by photolithography, the electron injection properties of the cathode and electron injection layer may be significantly reduced. As a result, organic EL devices processed by photolithography have a significantly increased driving voltage, making it difficult to obtain good characteristics.

[0056] To avoid this degradation, photolithography can be performed before the formation of the electron injection layer and cathode, and then the electron injection layer and cathode are formed afterward. However, performing photolithography after the formation of both electrodes minimizes the number of steps required for the photolithography process and offers significant cost benefits. Furthermore, the organic compound layer is significantly less likely to come into contact with chemicals and the atmosphere, achieving performance similar to that of a light-emitting device fabricated without exposure to the atmosphere.

[0057] Therefore, one embodiment of the present invention provides a light-emitting device having a first electrode, an organic compound layer, and a second electrode from the substrate side, which is manufactured by forming the second electrode and then performing a photolithography process, and has good characteristics.

[0058] 1A is a schematic diagram of a light-emitting device according to one embodiment of the present invention. The light-emitting device includes a first electrode 101 over an insulator 1000 and an organic compound layer (also referred to as an EL layer) 103 between the first electrode 101 and a second electrode 102. The organic compound layer 103 includes at least a light-emitting layer 113 and an electron-injection layer 115. The light-emitting layer 113 contains a light-emitting substance and emits light when a voltage is applied between the first electrode 101 and the second electrode 102.

[0059] 1(A), the organic compound layer 103 preferably has functional layers such as a hole injection layer 111, a hole transport layer 112, and an electron transport layer 114 in addition to the light-emitting layer 113 and the electron injection layer 115. The organic compound layer 103 may also include functional layers other than those described above, such as a hole blocking layer, an exciton blocking layer, and an intermediate layer. Conversely, any of the layers described above may not be provided.

[0060] As described above, if the high reactivity of alkali metal compounds and the like used in the electron injection layer is one of the factors that cause the layer to react sensitively to processes such as exposure to the atmosphere, etching, and cleaning, and thus to deteriorate, it is thought that if a less reactive substance can be used in place of the alkali metal compounds and the like, it would be possible to suppress an increase in driving voltage even after processing by photolithography.

[0061] Among metal compounds, metal oxides (except for alkali metal oxides) are generally more stable than alkali metal compounds, making them easier to handle. Furthermore, because metal oxides are stable, they are also materials that deteriorate relatively little even when exposed to the atmosphere. However, because metal oxides are stable, it is difficult to obtain the same properties as alkali metal compounds in conventional light-emitting devices, even when they are used in place of alkali metal compounds in the electron injection layer. Therefore, it has not been possible to obtain organic EL devices with properties suitable for practical use.

[0062] Therefore, in one embodiment of the present invention, an organic EL device having good characteristics can be obtained even after a photolithography process involving exposure of the organic compound layer to the atmosphere by using, as the electron-injection layer 115, a metal or a metal compound, a first organic compound having a π-electron-deficient heteroaromatic ring, and a second organic compound having two or more heteroaromatic rings that are bonded to or fused with each other and have three or more heteroatoms in total.

[0063] With this structure, the first organic compound functions as an electron donor to the second organic compound, and the first organic compound, the metal, and the second organic compound interact to form a donor level (a Singly Occupied Molecular Orbital (SOMO) level or a Highest Occupied Molecular Orbital (HOMO) level). The interaction between the first organic compound, the metal, and the second organic compound raises the donor level (the SOMO level or the HOMO level) to a high energy level, thereby reducing the barrier for electron injection from the electron injection layer to the electron transport layer. Furthermore, this interaction allows smooth injection and transport of electrons from the electron injection layer 115 to the electron transport layer 114, enabling the fabrication of a light-emitting device with a low drive voltage.

[0064] The LUMO and HOMO levels of organic compounds are generally estimated by CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, etc. When comparing values ​​between different compounds, it is preferable to use values ​​estimated by the same measurement.

[0065] The SOMO level is an orbital derived from the unpaired electrons of a metal, and when the metal interacts with the first and second organic compounds, it can also be distributed in the orbitals of the first and second organic compounds. In other words, the electron orbitals of the metal and the organic compounds interact with each other.

[0066] An organic compound containing many atoms capable of interacting can interact more stably with a metal. Therefore, the second organic compound used in one embodiment of the present invention is preferably a material that interacts with a metal in a bidentate, tridentate, or higher polydentate coordination. An organic compound that interacts with a metal in a polydentate coordination is stabilized when interacting with a metal, and therefore can form an electron injection layer that is resistant to oxygen and water in the atmosphere, as well as water and chemical solutions used in photolithography processes.

[0067] The interacting atom may be a heteroatom having an unshared electron pair in an organic compound. Examples include oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P), with nitrogen being preferred. Nitrogen has high electronegativity and therefore easily interacts with metals. Furthermore, nitrogen can form conjugated bonds in organic compounds, so using nitrogen in a molecule, particularly in a heteroaromatic ring, can result in an organic compound with high carrier transport properties. It is more preferable that the heteroaromatic ring is an even-numbered ring, such as a six- or eight-membered ring. With this configuration, the unshared electron pair on the nitrogen is not involved in conjugation, making it more likely to interact with metals.

[0068] The interaction between the metal or metal compound, the first organic compound, and the second organic compound forms a donor level (SOMO level or HOMO level), reducing the electron injection barrier to the electron transport layer and allowing smooth injection and transport of electrons from the electron injection layer to the electron transport layer. The heteroaromatic ring contained in the second organic compound is preferably a π-electron-deficient heteroaromatic ring. This structure allows the second organic compound to have electron transport properties and smoothly inject and transport electrons from the electron injection layer to the electron transport layer. Furthermore, when the second organic compound has two or more heteroaromatic rings that are bonded or fused to each other and have a total of three or more nitrogen atoms, the LUMO level of the second organic compound can be lower than that of the first organic compound. Using a material with a lower LUMO level than the first organic compound for the second organic compound stabilizes the interaction between the metal or metal compound, the first organic compound, and the second organic compound.

[0069] The second organic compound preferably has a π-electron-deficient heteroaromatic ring having an unshared electron pair. This structure allows for stable interaction with a metal or metal compound. The second organic compound preferably has two or more π-electron-deficient heteroaromatic rings having an unshared electron pair, and is a material that interacts with a metal in a multidentate (bidentate or more) coordination. Organic compounds that interact with a metal in a multidentate (bidentate or more) coordination are stabilized when interacting with the metal.

[0070] In addition, it is preferable that the first organic compound has an electron-donating substituent. This structure allows the first organic compound to have high HOMO and LUMO levels, thereby increasing the difference between the LUMO levels of the first organic compound and the second organic compound. Therefore, the interaction between the metal or metal compound, the first organic compound, and the second organic compound is more stable.

[0071] As a result, the first organic compound and the second organic compound can be stabilized when they interact with each other, which enables smooth injection and transport of electrons from the electron injection layer to the adjacent electron transport layer even after a photolithography process that involves exposing the EL layer to the atmosphere. This makes it possible to fabricate a light-emitting device using a photolithography process that suppresses an increase in driving voltage, has high luminous efficiency, and is highly reliable.

[0072] Furthermore, metals with low work functions, such as alkali metals and alkaline earth metals, and their compounds are highly reactive with oxygen or water. Therefore, when used in light-emitting devices processed by lithography, they can cause a decrease in light-emitting efficiency, an increase in driving voltage, a decrease in driving life, and the occurrence of shrinkage (non-light-emitting regions at the ends of the light-emitting part), which may lead to a decrease in the characteristics or reliability of the light-emitting device.

[0073] On the other hand, in one embodiment of the present invention, even when an alkali metal, an alkaline earth metal, or a compound thereof is used, the first organic compound having a π-electron-deficient heteroaromatic ring and the second organic compound having two or more heteroaromatic rings, the two or more heteroaromatic rings being bonded to or fused with each other and having three or more heteroatoms in total, are stabilized by mutual interaction, and therefore it is possible to form an electron injection layer that is resistant to oxygen and water in the atmosphere, as well as to water and chemical solutions used in lithography processes.

[0074] The use of an alkali metal, an alkaline earth metal, or a compound thereof as the metal of one embodiment of the present invention is preferable because it can increase the energy of a donor level (SOMO level or HOMO level) formed by mutual interaction between a first organic compound having a π-electron-deficient heteroaromatic ring and a second organic compound having two or more heteroaromatic rings in which the two or more heteroaromatic rings are bonded to or fused with each other and have three or more heteroatoms in total. This can reduce the barrier for electron injection from the electron-injection layer to the electron-transport layer, thereby enabling the formation of a structure in which electrons are smoothly injected and transported from the electron-injection layer to the electron-transport layer.

[0075] Furthermore, transition metals (metal elements of Groups 3 to 11) and metal elements of Groups 12 to 14 among typical metals have low reactivity with oxygen and water in the atmosphere, as well as with water and chemicals used in lithography processes. Therefore, when used in light-emitting devices, they are less susceptible to deterioration by water and oxygen, which is a concern when metals with low work functions are used. On the other hand, these metals are stable and have low electron injection properties, which can cause a decrease in the luminous efficiency of light-emitting devices, an increase in driving voltage, a decrease in driving life, etc.

[0076] The electron-injection layer according to one embodiment of the present invention includes a first organic compound having a π-electron-deficient heteroaromatic ring and a second organic compound having two or more heteroaromatic rings, the two or more heteroaromatic rings being bonded or fused to each other, and having three or more heteroatoms in total. The first organic compound and the second organic compound interact with each other to form a donor level (SOMO level or HOMO level). That is, the electron-injection barrier from the electron-injection layer to the electron-transport layer is reduced, allowing electrons to be smoothly injected and transported from the electron-injection layer to the electron-transport layer. Furthermore, the electron-injection layer is resistant to oxygen and water in the atmosphere, as well as water and chemicals used in lithography processes. Therefore, one embodiment of the present invention can provide a light-emitting device with excellent moisture resistance, water resistance, oxygen resistance, and chemical resistance, a low driving voltage, and high emission efficiency.

[0077] <Analysis of interactions between metals and organic compounds using quantum chemical calculations> Here, an analysis was performed by quantum chemical calculations on the case where a metal, a first organic compound having an electron-donating property and an unshared electron pair, and a second organic compound having an electron-transporting property interact with each other.

[0078] [Estimation of interactions between metals and organic compounds] Here, we performed quantum chemical calculations to analyze the spin density and electrostatic potential (ESP) of a metal-containing first organic compound having a π-electron-deficient heteroaromatic ring and a second organic compound having two or more heteroaromatic rings, where the two or more heteroaromatic rings are bonded or fused together, resulting in a total of three or more heteroatoms. The first organic compound was 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviated as Pyrrd-Phen), the second organic compound was 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as 6,6'(P-Bqn)2BPy), and the metal was lithium (Li).

[0079] The quantum chemistry calculation program used was Gaussian09. Calculations were performed on an SGI8600 computer manufactured by HPE. The most stable structures in the ground state of the first and second organic compounds, as well as the composite of the first and second organic compounds and a metal, were calculated using density functional theory (DFT). The basis set used was 6-311G(d,p), and the functional used was B3LYP. The total energy in DFT is expressed as the sum of potential energy, electrostatic energy between electrons, electron kinetic energy, and exchange-correlation energy, which includes all complex interactions between electrons. DFT approximates the exchange-correlation interaction with a functional (a function of a function) of a single-electron potential expressed in terms of electron density, resulting in highly accurate calculations.

[0080] Figure 2 shows the analysis results of the spin density distribution in the ground state of the composite material of the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)2BPy), and a metal (Li). The spheres in the figure represent the atoms that make up the compound, and the clouds around the atoms have a density value of 0.0004e / a0 in atomic units. 3 (e is the elementary charge (1e=1.60218×10 -19 C), a0 is the Bohr radius (1a0=5.29177×10 -11 The spin density distribution is shown when the ground state of the first organic compound (Pyrrd-Phen) and the ground state of the second organic compound (6,6'(P-Bqn)2BPy) are singlet ground states, so no spin density distribution is observed.

[0081] In one embodiment of the present invention, in the doublet ground state of a composite material comprising a first organic compound (Pyrrd-Phen), a second organic compound (6,6'(P-Bqn)BPy), and a metal (Li), the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)BPy), and the metal (Li) interact with each other, and the metal (Li) coordinates to nitrogen atoms having lone electron pairs (nitrogen atoms (N) at positions 1 and 10) in the 1,10-phenanthroline ring of the first organic compound (Pyrrd-Phen) and to nitrogen atoms having lone electron pairs in the pyridine ring and benzo[h]quinazoline ring of the second organic compound (6,6'(P-Bqn)BPy), thereby stabilizing the composite material and forming it. Therefore, as shown in Figure 2, it can be seen that the spin originating from the unpaired electron of the metal (Li) is localized in the second organic compound (6,6'(P-Bqn)2BPy). Furthermore, no spin density distribution is observed in the metal (Li). This indicates that the second organic compound (6,6'(P-Bqn)2BPy) is in a radical anion state due to the interaction between the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)2BPy), and the metal (Li).

[0082] Next, Figure 3 shows the results of analyzing the electrostatic potential map in the ground state of a composite of the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)2BPy), and a metal (Li). The spheres in the figure represent the atoms that make up the compound, and the cloud-like matter around the atoms has a density value of 0.0004e / a0 in atomic units. 3This figure shows the electrostatic potential in the electron density distribution when the electron density is 1 / 2. The electrostatic potential is the interaction energy between a positive point charge with a unit charge and the electron distribution of the molecule. The electrostatic potential map shows the electrostatic potential on the isoelectron density surface using color, with regions with negative electrostatic potential shown in red and regions with positive electrostatic potential shown in blue. This indicates that atoms in regions with negative electrostatic potential have a negative charge, and atoms in regions with positive electrostatic potential have a positive charge. However, since Figure 3 is a grayscale image, the dark red areas (i.e., regions with negative electrostatic potential) are surrounded by dotted lines, and the dark blue areas (i.e., regions with positive electrostatic potential) are surrounded by dashed lines to indicate regions with negative and positive electrostatic potential.

[0083] In one embodiment of the present invention, in the doublet ground state of a composite material comprising a first organic compound (Pyrrd-Phen), a second organic compound (6,6'(P-Bqn)BPy), and a metal (Li), the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)BPy), and the metal (Li) interact with each other, and the metal (Li) coordinates to nitrogen atoms having lone electron pairs (nitrogen atoms (N) at positions 1 and 10) in the 1,10-phenanthroline ring of the first organic compound (Pyrrd-Phen) and to nitrogen atoms having lone electron pairs in the pyridine ring and benzo[h]quinazoline ring of the second organic compound (6,6'(P-Bqn)BPy), thereby stabilizing the composite material and forming it. As a result, as shown in Figure 3, it can be seen that the positive electrostatic potential is mainly distributed between the metal (Li) and the first organic compound (Pyrrd-Phen), while the negative electrostatic potential is mainly distributed between the second organic compound (6,6'(P-Bqn)2BPy). It can also be seen that the electrostatic potential of the nitrogen atoms with lone electron pairs in the pyridine ring and benzo[h]quinazoline ring of the second organic compound (6,6'(P-Bqn)2BPy) is negative, while the electrostatic potential of the metal (Li) is positive. The Mulliken partial charge of the Li atom was +0.691e in atomic units.

[0084] [Estimation of SOMO levels or stabilization energies] Next, we performed quantum chemical calculations to estimate the stabilization energy and the SOMO level formed when a metal, a first organic compound having a π-electron-deficient heteroaromatic ring, and a second organic compound having two or more heteroaromatic rings, where the two or more heteroaromatic rings are bonded or fused to each other and have a total of three or more heteroatoms, interact with each other.

[0085] The quantum chemistry calculation program used was Gaussian09. Calculations were performed on an HPE SGI8600. First, the ground states of the first organic compound, the second organic compound, and the metal were calculated using density functional theory (DFT) to determine the most stable structures in the ground states of the first organic compound-metal composite, the second organic compound-metal composite, and the first organic compound, the second organic compound-metal composite, and the first organic compound, the second organic compound-metal composite. The basis functions used were 6-311G(d,p) and LanL2DZ, and the functional used was B3LYP. Next, the stabilization energy was calculated from the difference between the total energy of the organic compound-metal composite and the sum of the total energy of the organic compound alone and the total energy of the metal alone. That is, (stabilization energy) = (total energy of the organic compound-metal composite) - (total energy of the organic compound alone) - (total energy of the metal alone).

[0086] The calculations were performed on a composite material using lithium (Li) as the metal, 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviated as Pyrrd-Phen) as the first organic compound, and 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as 6,6'(P-Bqn)2BPy) as the second organic compound. The results are shown below. For comparison, calculations were performed on a composite material using lithium (Li) as the metal, pyrrd-phen as the first organic compound, and 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (NBphen) instead of 6,6'(P-Bqn)BPy as the second organic compound. The results are also shown for a composite material using lithium (Li) and pyrrd-phen, a composite material using lithium (Li) and 6,6'(P-Bqn)BPy, and a composite material using lithium (Li) and NBphen. Note that 6,6'(P-Bqn)BPy is a second organic compound that contains two or more heteroaromatic rings, which are bonded or fused together, resulting in a total of three or more heteroatoms. On the other hand, NBphen is an organic compound having two or more heteroaromatic rings that are bonded or fused to each other, but have a total of less than three heteroatoms.

[0087] [Table 1]

[0088] [Table 2]

[0089] As can be seen from the table above, the stabilization energy of the composite material of lithium (Li), the first organic compound (Pyrrd-Phen), and the second organic compound (6,6'(P-Bqn)2BPy) according to one embodiment of the present invention has a large negative absolute value. This indicates that the energy is more stable when the organic compound interacts with a metal than when the organic compound does not interact with a metal. The SOMO level formed in this case is higher than the HOMO levels of the first organic compound (Pyrrd-Phen) and the second organic compound (6,6'(P-Bqn)2BPy) and has a small difference from their LUMO levels, making it preferable for excellent electron injection properties. Note that the energy levels of the SOMO level, HOMO level, and LUMO level in the table are calculated values ​​and may differ in absolute value from actual measurements.

[0090] On the other hand, although not as strong as the composite material of lithium (Li), the first organic compound (Pyrrd-Phen), and the second organic compound (6,6'(P-Bqn)2BPy) described above, the composite material of lithium (Li), the first organic compound (Pyrrd-Phen), and NBphen also has a negative stabilization energy, meaning that when the organic compound interacts with a metal, the energy is more stable than when the organic compound does not interact with the metal.

[0091] Furthermore, the composite material of lithium (Li) and the first organic compound (Pyrrd-Phen) has a negative stabilization energy, and a composite material having a second organic compound in addition to the composite material is more stable.

[0092] Furthermore, as shown in Table 1, the composite material of lithium (Li) and the second organic compound (6,6'(P-Bqn)2BPy) has a low SOMO level of -2.88 eV. On the other hand, the composite material containing lithium (Li) and the second organic compound (6,6'(P-Bqn)2BPy) as well as the first organic compound (Pyrrd-Phen) has a high SOMO level of -2.32 eV, resulting in excellent electron injection properties. Furthermore, the composite material of lithium (Li) and the second organic compound (6,6'(P-Bqn)2BPy) has a stabilization energy of -3.07 eV, while the composite material of lithium (Li) and the second organic compound (6,6'(P-Bqn)2BPy) as well as the first organic compound (Pyrrd-Phen) has a stabilization energy of -3.79 eV, making it more stable.

[0093] Furthermore, as shown in Table 1, the composite material of lithium (Li) and NBphen has a low SOMO level of -2.96 eV. On the other hand, the composite material containing lithium (Li), NBphen, and the first organic compound (Pyrrd-Phen) has a high SOMO level of -2.35 eV, and therefore has excellent electron injection properties. Furthermore, the composite material of lithium (Li) and NBphen has a stabilization energy of -2.31 eV, while the composite material containing lithium (Li), NBphen, and the first organic compound (Pyrrd-Phen) has a stabilization energy of -3.67 eV, making it stable.

[0094] That is, a composite material of one embodiment of the present invention, which includes a metal, a first organic compound having a π-electron-deficient heteroaromatic ring, and a second organic compound having two or more heteroaromatic rings that are bonded to or fused with each other and have three or more heteroatoms in total, is stable and has excellent electron-injection properties, and is therefore suitable for an electron-injection layer.

[0095] Next, the results of calculations for composite materials using metals belonging to Groups 11 and 13, specifically silver (Ag) and indium (In), as the metals, Pyrrd-Phen as the first organic compound, and 4',4""-(1,4-phenylene)bis(2,2':6',2"-terpyridine) (abbreviation: tPy2P) and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tzn) as the second organic compound are shown in the table below. For comparison, the results of calculations for composite materials using silver (Ag) and indium (In) as the metals are shown in the table below. The results of calculations for a composite material using (In) with Pyrrd-Phen as the first organic compound and NBphen as the second organic compound are also shown. Note that tPy2P and 2Py3Tzn are second organic compounds that have two or more heteroaromatic rings that are bonded or fused to each other and have a total of three or more heteroatoms. On the other hand, NBphen is an organic compound that has two or more heteroaromatic rings that are bonded or fused to each other but have a total of less than three heteroatoms.

[0096] [Table 3]

[0097] [Table 4]

[0098] As shown in the table above, the composite material of one embodiment of the present invention, which is made of a metal belonging to Group 11 or Group 13, a first organic compound, and a second organic compound, has a large stabilization energy and a stable structure, which is preferable. Furthermore, the SOMO level formed in this case is high, which is preferable because it has excellent electron injection properties.

[0099] Considering the manufacturing process of light-emitting devices, the EL layer of a light-emitting device, particularly the electron injection layer, is generally formed by vacuum deposition. In this case, it is preferable to use a material that can be easily vacuum-deposited, i.e., a material with a low melting point. Metals of Group 11 and Group 13 elements have low melting points and are therefore suitable for vacuum deposition. Furthermore, metals of Group 11 and Group 13 elements are preferred because they are stable to oxygen and water in the atmosphere. Furthermore, vacuum deposition is preferred because it allows for easy mixing of metal atoms with organic compounds.

[0100] Ag and In can also be used as cathode materials. Using the same material for the electron injection layer and the cathode is preferred because it simplifies the fabrication of light-emitting devices and reduces the manufacturing costs of light-emitting devices.

[0101] From the above, it can be seen that a combination of a first organic compound having a π-electron-deficient heteroaromatic ring, a metal, and a second organic compound having two or more heteroaromatic rings, the two or more heteroaromatic rings being bonded or fused to each other and having a total of three or more heteroatoms, interacts with each other, causing the first organic compound and the metal to function as an electron donor for the second organic compound. In one embodiment of the present invention, by using this combination of materials for an electron injection layer, an electron injection layer having good electron injection properties and resistance to oxygen and water in the atmosphere, as well as water and chemical solutions used in lithography processes, can be formed, thereby enabling a light-emitting device with reduced driving voltage and high emission efficiency to be obtained.

[0102] ≪Electron injection layer≫ As shown in FIG. 1(A), the electron-injection layer 115 is provided between the second electrode 102, which is a cathode, and the light-emitting layer 113, and includes a metal or a metal compound, a first organic compound having a π-electron-deficient heteroaromatic ring, and a second organic compound having two or more heteroaromatic rings, which are bonded to or fused with each other and have three or more heteroatoms in total.

[0103] <Metal or metal compound> The metal or metal compound may be a typical metal or transition metal, or a compound thereof, such as a metal oxide, a metal nitride, a metal oxynitride in which nitrogen is added to a metal oxide, or a metal nitride oxide in which oxygen is added to a metal nitride.

[0104] Typical metals that can be used include alkali metals (Group 1 elements) such as Li, Na, K, and Cs, alkaline earth metals (Group 2 elements) such as Mg, Ca, and Ba, Group 12 elements such as Zn, earth metals (Group 13 elements) such as Al and In, and Group 14 elements such as Sn, or compounds thereof.

[0105] By using an alkali metal, an alkaline earth metal, or a compound thereof as the metal, the donor level formed by mutual interaction with the first organic compound and the second organic compound can be set to a high energy level, and electrons can be smoothly injected and transported from the electron injection layer to the electron transport layer, which is preferable because it is possible to provide a light-emitting device that has a low driving voltage and emits light with high efficiency.

[0106] Examples of transition metals that can be used include Group 3 elements including lanthanides such as Y, Eu, and Yb, Group 7 elements such as Mn, Group 8 elements such as Fe, Group 9 elements such as Co, Group 10 elements such as Ni and Pt, and Group 11 elements such as Cu, Ag, and Au, as well as compounds thereof. Transition metals are preferred because they have low reactivity with components in the atmosphere such as water and oxygen.

[0107] Among the above, it is more preferable to use a metal belonging to an odd group (Group 1, Group 3, Group 5, Group 7, Group 9, Group 11, or Group 13). Among these odd group transition metals, metals having one electron (unpaired electron) in the outermost orbital are particularly preferable because they easily form a SOMO with the first organic compound.

[0108] In addition, metals with low melting points that can be formed into films by vacuum deposition are preferred because they can easily form mixed layers with organic compounds. Specifically, for example, metals of Group 11 and Group 13 elements have low melting points and are therefore suitable for vacuum deposition. In addition, metals of Group 11 and Group 13 elements are preferred because they are stable to oxygen and water in the atmosphere.

[0109] <First organic compound> The first organic compound can be an organic compound having a π-electron-deficient heteroaromatic ring. Furthermore, in order for the first organic compound to interact with a metal and function as an electron donor (electron donor) to the second organic compound, the π-electron-deficient heteroaromatic ring preferably has an unshared electron pair, and the unshared electron pair preferably has electron-donating properties. That is, the first organic compound preferably has a basic π-electron-deficient heteroaromatic ring. Furthermore, nitrogen has high electronegativity and therefore easily interacts with metals. Furthermore, nitrogen can form conjugated bonds in organic compounds. Therefore, using nitrogen in the molecule, particularly in the heteroaromatic ring, can result in an organic compound with high carrier transport properties. Therefore, the first organic compound preferably has a nitrogen-containing heteroaromatic ring. Furthermore, the heteroaromatic ring is more preferably an even-numbered ring, such as a six- or eight-membered ring. With this configuration, the unshared electron pair on the nitrogen is not involved in conjugation, making it more likely to interact with metals. In addition, the first organic compound preferably has electron transport properties to smoothly inject and transport electrons from the electron injection layer to the electron transport layer. Specifically, for example, the first organic compound preferably has a pyridine ring.

[0110] Furthermore, a material in which the first organic compound has two or more π-electron-deficient heteroaromatic rings having unshared electron pairs, and the two or more π-electron-deficient heteroaromatic rings are bonded or fused to each other, is preferred. This stabilizes the electron injection layer when the metal or metal compound interacts with the first organic compound and the second organic compound in a bidentate or multidentate coordination, making it possible to form an electron injection layer that is resistant to deterioration even after a photolithography process involving exposure to the atmosphere. Specifically, for example, the first organic compound preferably has a heteroaromatic ring containing two or more pyridine rings. Among these, organic compounds having a bipyridine skeleton are preferred because their nitrogen atoms readily coordinate with metals and therefore readily interact with metals or metal compounds.

[0111] Furthermore, phenanthroline rings are preferred because they are rigid and highly stable. In particular, organic compounds having a 1,10-phenanthroline ring are preferred because the two nitrogen atoms contained therein can coordinate to metals, making them more likely to interact with metals or metal compounds.

[0112] The first organic compound may have a structure in which multiple phenanthroline rings are linked via a single bond or a divalent group. Specific examples of the divalent group include an alkylene group and an arylene group.

[0113] An alkylene group is a divalent group formed by removing two hydrogen atoms from an alkane. Specific examples of alkylene groups include divalent groups formed by removing one hydrogen atom from the specific alkyl groups described below.

[0114] An arylene group is a divalent group obtained by removing two hydrogen atoms from an aromatic hydrocarbon. Specific examples thereof include divalent groups having a structure in which one hydrogen atom has been removed from the specific examples of aryl groups described below. The arylene group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0115] In addition, it is preferable that the first organic compound has an electron-donating substituent. This allows the first organic compound to have high HOMO and LUMO levels, thereby increasing the difference between the LUMO levels of the first organic compound and the LUMO level of the second organic compound, making it possible to form an electron injection layer that is more stable when interacting with a metal or metal compound, the first organic compound, and the second organic compound, and that is less susceptible to deterioration even after a photolithography process involving exposure to the atmosphere.

[0116] Furthermore, it is more preferable to use an organic compound having a phenanthroline ring with an electron-donating group as the first organic compound. In particular, introducing an electron-donating group into the 1,10-phenanthroline ring can increase the electron density of the phenanthroline ring and improve the efficiency of interaction with metals. Furthermore, it is preferable to have an electron-donating group at at least one of the 4- and 7-positions of the 1,10-phenanthroline ring. Introducing an electron-donating group into the 4- and 7-positions can increase the electron density of the nitrogen atoms at the 1- and 10-positions, which are located para to the 4- and 7-positions. Furthermore, it is possible to increase the electron density around the nitrogen atoms at the 1- and 10-positions while avoiding steric crowding around them. Therefore, it is preferable because it facilitates interaction with metals.

[0117] Specific examples of the electron-donating group include an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group. However, the electron-donating group that is preferable for introduction into a π-electron-deficient heteroaromatic ring such as a phenanthroline ring is not limited to these. Any group that can increase the electron density of a π-electron-deficient heteroaromatic ring such as a phenanthroline ring by introducing it into the π-electron-deficient heteroaromatic ring can be used as the electron-donating group. Furthermore, the electron-donating group may be introduced into a π-electron-deficient heteroaromatic ring such as a phenanthroline ring via an arylene group such as a phenylene group, and the arylene group is preferably a p-phenylene group.

[0118] Alkyl groups are groups that are part of alkanes (C n H2n+2 ) represents a monovalent group obtained by removing one hydrogen atom from the alkyl group. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a neohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, and a 2,3-dimethylbutyl group.

[0119] The alkoxy group refers to a monovalent group in which an alkyl group is bonded to an oxygen atom. Specific examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentyloxy, isopentyloxy, sec-pentyloxy, tert-pentyloxy, neopentyloxy, n-hexyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, and neohexyloxy.

[0120] An aryloxy group refers to a monovalent group having an aryl group bonded to an oxygen atom. An aryl group refers to a monovalent group obtained by removing one hydrogen atom from one of the carbon atoms forming the ring of a monocyclic or polycyclic aromatic compound. Specific examples of aryloxy groups include phenoxy, o-tolyloxy, m-tolyloxy, p-tolyloxy, mesityloxy, o-biphenyloxy, m-biphenyloxy, p-biphenyloxy, 1-naphthyloxy, 2-naphthyloxy, and 2-fluorenyloxy. The aryloxy group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0121] The alkylamino group is a monovalent group formed by removing one hydrogen atom from the nitrogen atom of a primary or secondary amine having one or two alkyl groups bonded to the nitrogen atom. Specific examples of the alkylamino group include a dimethylamino group and a diethylamino group.

[0122] An arylamino group is a monovalent group formed by removing one hydrogen atom from the nitrogen atom of a primary amine or secondary amine having one or two aryl groups bonded to the nitrogen atom. Specific examples of the arylamino group include a diphenylamino group, a bis(α-naphthyl)amino group, and a bis(m-tolyl)amino group. The arylamino group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0123] An amino group having both an alkyl group and an aryl group bonded to a nitrogen atom can be called either an alkylamino group or an arylamino group. Specific examples of such amino groups include an N-methyl-N-phenylamino group.

[0124] The heterocyclic amino group refers to a monovalent group obtained by removing one hydrogen atom from one of the nitrogen atoms forming the ring of a heterocyclic amine. Here, the heterocyclic amine refers to a monocyclic or polycyclic heterocyclic compound in which at least one of the atoms forming the ring is a nitrogen atom to which a hydrogen atom is bonded. Specific examples of the heterocyclic amino group include groups represented by the following structural formulas (R-1) to (R-26). The heterocyclic amino group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0125] [ka]

[0126] In addition, when the heterocyclic amino group has aromaticity, the unshared electron pair of the nitrogen atom contributes to aromaticity, and the electron donating ability to the phenanthroline ring may be reduced compared to when the unshared electron pair of the nitrogen atom does not contribute to aromaticity.Therefore, among the above-mentioned heterocyclic amino groups, heterocyclic amino groups in which the unshared electron pair of the nitrogen atom does not contribute to aromaticity are more preferred.Specifically, groups represented by structural formula (R-1), (R-2), (R-3), (R-4), (R-5), (R-8), (R-9), (R-10), (R-12), (R-14), (R-15), (R-16), (R-17) or (R-21) are more preferred as electron donating groups. Among these, groups represented by structural formula (R-3), (R-4), (R-8) or (R-21) are preferred because they have high electron donating properties and can further increase the electron density of the phenanthroline ring.

[0127] Specific examples of the electron-donating group include groups represented by the following structural formulas (R-27) and (R-28).

[0128] [ka]

[0129] The organic compound having a π-electron-deficient heteroaromatic ring that can be used as the first organic compound may have both the above-mentioned electron-donating group and other substituents. In addition to the above-mentioned electron-donating group, specific examples of substituents that can be introduced into the π-electron-deficient heteroaromatic ring include aryl groups. Specific examples of aryl groups include phenyl groups, o-tolyl groups, m-tolyl groups, p-tolyl groups, mesityl groups, o-biphenyl groups, m-biphenyl groups, p-biphenyl groups, 1-naphthyl groups, 2-naphthyl groups, and 2-fluorenyl groups. The aryl group may further have a substituent, and specific examples of the substituent include alkyl groups, alkoxy groups, and phenyl groups.

[0130] The first organic compound may have a structure in which multiple phenanthroline rings are linked via a single bond or a divalent group. Specific examples of the divalent group include an alkylene group and an arylene group.

[0131] Specific examples of organic compounds having a π-electron-deficient heteroaromatic ring that can be used as the first organic compound are shown in structural formulas (100) to (112). Note that the organic compounds that can be used as the first organic compound are not limited to these.

[0132] [ka]

[0133] Structural formula (100) is 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviated as Pyrrd-Phen). Structural formula (103) is 4,7-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline (abbreviated as 4,7hpp2Phen). Structural formula (105) is 2,2'-(1,3-phenylene)bis[9-(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline] (abbreviated as mhppPhen2P). Structural formula (106) is 2-(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-9-phenyl-1,10-phenanthroline (abbreviated as 9Ph-2hppPhen). Structural formula (107) is 2,9-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline (abbreviated as 2,9hpp2Phen). Structural formula (111) is 4,7-di(2,3,3a,4,5,6,7,7a-octahydro-1H-isoindol-2-yl)-1,10-phenanthroline (abbreviated as Hid2Phen). Structural formula (112) is 4,7-bis[4-(1-pyrrolidinyl)phenyl]-1,10-phenanthroline (abbreviation: PrdP2Phen).

[0134] It is preferable that the minimum negative value of the electrostatic potential (ESP) of the first organic compound is small (a large absolute negative value), as this increases the stability of the interaction with the metal. In organic compounds having a π-electron-deficient heteroaromatic ring, the electrostatic potential around the nitrogen atom of the π-electron-deficient heteroaromatic ring tends to be negative. However, by introducing an electron-donating group into the π-electron-deficient heteroaromatic ring, the electrostatic potential around the nitrogen atom of the π-electron-deficient heteroaromatic ring can be further reduced (the absolute negative value can be increased). The electrostatic potential is the interaction energy between a positive point charge with a unit charge and the electron distribution of the molecule. The value of the electrostatic potential also varies depending on the threshold of the electron density distribution. To increase the efficiency of the interaction with the metal, it is preferable that the minimum value of the electrostatic potential of the first organic compound is smaller (more negative) than the minimum value of the electrostatic potential of a phenanthroline ring without a substituent. Specifically, it is preferable to set the threshold of the electron density distribution in the atomic unit system to 0.0004 e / a0 3 The minimum value of the electrostatic potential is -0.085E h (E h is the Hartree energy (1E h =27.211 eV) or less is preferred, -0.090E h It is more preferable that the threshold of the electron density distribution is 0.003e / a0 or less. 3 The minimum value of the electrostatic potential is -0.12E h Less than or equal to -0.13E is preferable h The following is even more preferred:

[0135] <<Estimation of properties of the first organic compound by quantum chemical calculations>> The minimum value of the electrostatic potential (ESP) of an organic compound that can be used for the first organic compound described above was estimated by quantum chemical calculation.

[0136] Gaussian09 was used as the quantum chemistry calculation program. Calculations were performed using an SGI8600 manufactured by HPE. The most stable structure of the first organic compound in its ground state was calculated using density functional theory (DFT). 6-311G(d,p) was used as the basis function, and B3LYP was used as the functional.

[0137] The table below shows the analysis results of the electrostatic potential in the ground state of the first organic compound. The electrostatic potential is the interaction energy between a positive point charge with a unit charge and the electron distribution of the molecule. The value of the electrostatic potential also changes depending on the threshold of the electron density distribution. In the table below, the threshold of the electron density distribution in the atomic unit system is set to 0.0004e / a0 3 or 0.003e / a0 3 The electrostatic potential in the electron density distribution when

[0138] [Table 5]

[0139] The organic compounds represented by structural formulas (101) to (107), structural formula (111), and structural formula (112) in the table, which are shown as organic compounds that can be used for the first organic compound, and the structural formulas of Bphen, mPPhen2P, NBphen, and Phen are shown below.

[0140] [ka]

[0141] From the above table, the organic compounds represented by the structural formulas (100) to (103), the structural formula (111), and the structural formula (112) have an electron density distribution threshold of 0.0004e / a0 in the atomic unit system. 3 When this is done, the minimum value of ESP is -0.085E hOn the other hand, the minimum value of ESP of the organic compounds represented by the structural formulas (104) to (107) is −0.085E h It turned out to be larger.

[0142] The organic compounds represented by structural formulas (100) to (103), structural formula (111), and structural formula (112) have electron-donating groups at the 4- and 7-positions of the 1,10-phenanthroline ring, and therefore exhibit the most favorable values.

[0143] The organic compound represented by structural formula (104) has electron-donating groups at the 4th and 7th positions of the 1,10-phenanthroline ring, and the electron-donating group is an N-carbazolyl group. In the N-carbazolyl group, the unshared electron pair of the nitrogen atom contributes to aromaticity, so compared to groups in which the unshared electron pair of the nitrogen atom does not contribute to aromaticity, the electron-donating ability to the phenanthroline ring is reduced, making it difficult to lower the minimum ESP value, resulting in the above results.

[0144] The organic compounds represented by structural formulas (105) to (107) have electron-donating groups at the 2- and 9-positions of the 1,10-phenanthroline ring. The electron-donating groups introduced at the 2- and 9-positions have low electron-donating properties toward the nitrogen atoms at the 1- and 10-positions of the phenanthroline ring. Therefore, the electron-donating groups on the 1,10-phenanthroline ring are preferably at the 4- and 7-positions.

[0145] It is more preferable that the LUMO level of the second organic compound is lower than that of the first organic compound. This makes it easier for the donor level formed by the first organic compound and the metal to donate electrons to the second organic compound. It is also preferable that the second organic compound has electron transport properties, and for this reason, it is also preferable that the LUMO level of the second organic compound is lower than that of the first organic compound.

[0146] For example, the LUMO level of the first organic compound is preferably -3.0 eV or more and -2.0 eV or less, and more preferably -2.7 eV or more and -2.0 eV or less. The LUMO level of the second organic compound is preferably -3.0 eV or more and -2.0 eV or less, and more preferably -3.0 eV or more and -2.5 eV or less. This facilitates electron donation from the donor level formed by the first organic compound and the metal to the second organic compound. This also facilitates electron transport by the second organic compound.

[0147] The HOMO and LUMO levels of organic compounds are generally estimated by CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, etc. When comparing values ​​between different compounds, it is preferable to use values ​​estimated by the same measurement.

[0148] Furthermore, when the first organic compound has high basicity, it can significantly reduce the hole transport property in the electron injection layer by interacting with holes, thereby preventing holes from being transported from the electron injection layer to the electron transport layer, which is preferable, and thus allows for an efficient light-emitting device to be obtained. Specifically, the acid dissociation constant pKa of the first organic compound is preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more.

[0149] If the acid dissociation constant pKa of an organic compound is unknown, the acid dissociation constant pKa of each skeleton of the organic compound can be investigated, and the largest acid dissociation constant pKa selected from these can be regarded as the acid dissociation constant pKa of the organic compound.

[0150] Alternatively, the acid dissociation constant may be calculated. For example, the acid dissociation constant pKa can be calculated using the following calculation method.

[0151] The initial molecular structure of each molecule used as a calculation model is the most stable structure (singlet ground state) obtained from first-principles calculations.

[0152] The first-principles calculations were performed using Schrödinger's quantum chemistry calculation software, Jaguar, to calculate the most stable structure in the singlet ground state using density functional theory (DFT). The basis set used was 6-31G**, and the functional was B3LYP-D3. The structure used for the quantum chemistry calculations was sampled using Schrödinger's Maestro GUI, with conformational analysis performed using mixed torsional / low-mode sampling.

[0153] For pKa calculations, one or more atoms of each molecule are designated as basic sites, and a Macro Model is used to search for the stable structure of the protonated molecule in water. A conformational search is performed using the OPLS2005 force field, and the lowest energy conformer is used. Using the Jaguar pKa calculation module, the structure is optimized with B3LYP / 6-31G*, followed by a single-point calculation with cc-pVTZ(+), and the pKa value is calculated using empirical corrections for functional groups. For molecules with one or more atoms designated as basic sites, the largest value obtained is used as the pKa value. The obtained pKa value is shown below.

[0154] The acid dissociation constant pKa of 2,9hpp2Phen is 13.35, the acid dissociation constant pKa of 4,7hpp2Phen is 13.42, the acid dissociation constant pKa of Pyrrd-Phen is 11.23, the acid dissociation constant pKa of mPPhen2P is 5.16, the acid dissociation constant pKa of NBphen is 5.59, and the acid dissociation constant pKa of Bphen is 5.62.

[0155] <Second organic compound> The electron injection layer contains, in addition to a metal or metal compound and a first organic compound, a second organic compound having two or more heteroaromatic rings bonded or fused to each other, the two or more heteroaromatic rings having a total of three or more heteroatoms, and the second organic compound has the function of interacting with the metal or metal compound in a multidentate manner via two or more of the three or more heteroatoms.

[0156] The inclusion of the second organic compound can improve heat resistance, electron transport properties, etc. In one embodiment of the present invention, when the π-electron-deficient heteroaromatic ring contained in the first organic compound is a first π-electron-deficient heteroaromatic ring and the π-electron-deficient heteroaromatic ring contained in the second organic compound is a second π-electron-deficient heteroaromatic ring, it is preferable that the first π-electron-deficient heteroaromatic ring and the second π-electron-deficient heteroaromatic ring include different rings.

[0157] Furthermore, as the second π-electron-deficient heteroaromatic ring, a heteroaromatic ring having an azole skeleton (imidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), a heteroaromatic ring having a pyridine skeleton, a heteroaromatic ring having a diazine skeleton, or a heteroaromatic ring having a triazine skeleton is preferred, and a diazine ring (pyrazine ring, pyrimidine ring, pyridazine ring) or a triazine ring is particularly preferred because of its electrochemical stability and high electron transport property.

[0158] For example, the organic compound used for the second organic compound may be an organic compound represented by the following general formula (G1-1).

[0159] [ka]

[0160] In the above general formula (G1-1), A 1 , A 2 and A 3 each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms; A 1 , A 2 and A 3 may be fused together to form a condensed ring.

[0161] The organic compound represented by general formula (G1-1) has a conjugated double bond in which N atoms on a heteroaromatic ring are arranged in the order of NCCN, and has the function of interacting with metals at a tridentate or higher level. Organic compounds with such a structure easily interact with metals, and are therefore suitable for use in electron injection layers.

[0162] In the above general formula (G1-1), A 1 , A 2 and A 3 Examples of the substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula (I) include heteroaromatic rings having a pyridine skeleton (pyridine ring, quinoline ring, isoquinoline ring, naphthyridine ring, bipyridine ring, phenanthridine ring, phenanthroline ring, anthridine ring, azafluoranthene ring), heteroaromatic rings having a diazine skeleton (pyrazine ring, pyrimidine ring, pyridazine ring, quinoxaline ring, benzoquinoxaline ring, dibenzoquinoxaline ring, quinazoline ring, benzoquinazoline ring, phthalazine ring, cinnoline ring, pteridine ring, phenazine ring), heteroaromatic rings having a triazine skeleton, heteroaromatic rings having an azole skeleton (imidazole ring, benzimidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), etc., provided that A 1 , A 2 and A 3 The substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula A is not limited to these. 1 , A 2 and A 3 may form a condensed ring with each other. For example, A 1 and A 2 may be bonded to each other to form a phenanthroline ring.

[0163] As the organic compound used for the second organic compound, an organic compound represented by the following general formula (G2-1) can be used.

[0164] [ka]

[0165] In general formula (G2-1), X 1 ~X 6 each independently represents carbon (C) or nitrogen (N), and carbon (C) has hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; and R1 to R4 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms. Or, in general formula (G2-1), X 1 ~X 6 may be bonded to each other directly or via a carbon atom to form a condensed ring.

[0166] It is more preferable that the organic compound having a tridentate or higher dentate structure and the ability to interact with metals, such as the organic compound represented by general formula (G2-1), has at least one heteroaromatic ring having a pyridine skeleton, a heteroaromatic ring having a diazine skeleton, or a heteroaromatic ring having a triazine skeleton. These rings have excellent electrochemical stability, allowing for the provision of highly reliable light-emitting devices. Furthermore, their excellent electron transport properties allow for the provision of light-emitting devices with reduced driving voltages.

[0167] As the organic compound used for the second organic compound, an organic compound represented by the following general formula (G3-1) can be used.

[0168] [ka]

[0169] In general formula (G3-1), X 1 ~X 4each independently represents carbon (C) or nitrogen (N), carbon (C) has hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R1 to R6 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0170] As the organic compound that can be used for the second organic compound, an organic compound represented by the following general formula (G4-1) can be used.

[0171] [ka]

[0172] In general formula (G4-1), X 1 ~X 5 each independently represent carbon (C) or nitrogen (N), carbon (C) has hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R1 to R5 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0173] Organic compounds having a pyridine skeleton are preferred because they have a high LUMO level. 1 and X 2When represents carbon, the organic compound has a pyridine skeleton, and therefore can form a composite material with a high SOMO level when interacting with a metal. That is, an organic compound that has a pyridine ring and the ability to interact at a tridentate or higher level can form an electron injection layer with high electron injection properties by interacting with a metal.

[0174] In addition, organic compounds having a diazine skeleton or a triazine skeleton are preferred because they are electrochemically stable and have high electron transport properties. 1 and X 2 When at least one of represents nitrogen, the organic compound has a diazine skeleton or a triazine skeleton, and therefore can form a stable composite material with high electron transport properties when interacting with a metal. That is, an organic compound having a diazine ring or a triazine ring and a function of interacting at a tridentate or higher level can form a highly reliable electron injection layer by interacting with a metal.

[0175] Furthermore, for example, an organic compound represented by the following general formula (G1-2) can be used as the second organic compound.

[0176] [ka]

[0177] In the general formula (G1-2), A1 and A2 each independently represent a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, A1 and A2 may form a fused ring with each other, and A1 has two or more nitrogen atoms.

[0178] The organic compound represented by general formula (G1-2) has a conjugated double bond in which N atoms on a heteroaromatic ring are arranged in the order of NCCN, and has the function of interacting with metals at a bidentate or higher level. Organic compounds with such a structure easily interact with metals, and are therefore suitable for use in electron injection layers.

[0179] In the above general formula (G1-2), A 1 Examples of the substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula (I) include heteroaromatic rings having a diazine skeleton (pyrazine ring, pyrimidine ring, pyridazine ring, quinoxaline ring, benzoquinoxaline ring, dibenzoquinoxaline ring, quinazoline ring, benzoquinazoline ring, phthalazine ring, cinnoline ring, pteridine ring, phenazine ring), heteroaromatic rings having a triazine skeleton, and heteroaromatic rings having an azole skeleton (imidazole ring, benzimidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), etc. 2 Examples of the substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula (I) include heteroaromatic rings having a pyridine skeleton (pyridine ring, quinoline ring, isoquinoline ring, naphthyridine ring, bipyridine ring, phenanthridine ring, phenanthroline ring, anthridine ring, azafluoranthene ring), heteroaromatic rings having a diazine skeleton (pyrazine ring, pyrimidine ring, pyridazine ring, quinoxaline ring, benzoquinoxaline ring, dibenzoquinoxaline ring, quinazoline ring, benzoquinazoline ring, phthalazine ring, cinnoline ring, pteridine ring, phenazine ring), heteroaromatic rings having a triazine skeleton, heteroaromatic rings having an azole skeleton (imidazole ring, benzimidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), etc., provided that A 1 and A 2 The substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula A is not limited to these. 1 , and A 2 may form a condensed ring with each other. For example, A 1 and A 2 may be bonded to each other to form a pyrazinoquinoxaline ring.

[0180] As the organic compound used for the second organic compound, an organic compound represented by the following general formula (G2-2) can be used.

[0181] [ka]

[0182] In general formula (G2-2), X 1 ~X 4 at least one of represents nitrogen (N), and the others each independently represent carbon (C) or nitrogen (N), and carbon (C) has hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms, and R1 to R4 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms. 1 ~X 4 may be bonded to each other directly or via a carbon atom to form a condensed ring.

[0183] It is more preferable that the organic compound having the function of interacting with metals at a bidentate or higher level, such as the organic compound represented by general formula (G2-2), has a heteroaromatic ring having a diazine skeleton or a heteroaromatic ring having a triazine skeleton. These rings have excellent electrochemical stability, allowing for the provision of highly reliable light-emitting devices. Furthermore, their excellent electron transport properties allow for the provision of light-emitting devices with reduced driving voltages.

[0184] As the organic compound used for the second organic compound, an organic compound represented by the following general formula (G3-2) can be used.

[0185] [ka]

[0186] In general formula (G3-2), one of X1 and X2 represents nitrogen (N), and the other represents carbon (C) or nitrogen (N), carbon (C) has hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms, and R1 to R6 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0187] Furthermore, as an organic compound that can be used for the second organic compound, an organic compound represented by the following general formula (G4-2) can be used.

[0188] [ka]

[0189] In general formula (G4-2), X 1 ~X 3 at least one of represents nitrogen (N), and the others each independently represent carbon (C) or nitrogen (N), where carbon (C) has a hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R1 to R5 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0190] Organic compounds having a pyridine skeleton are preferred because they have a high LUMO level. 1 and X 2and X represented by general formula (G3-2) 1 When represents carbon, the organic compound has a pyridine skeleton, and therefore can form a composite material with a high SOMO level when interacting with a metal. That is, an organic compound that has a pyridine ring and the ability to interact at a bidentate or higher level can form an electron injection layer with high electron injection properties by interacting with a metal.

[0191] In addition, organic compounds having a diazine skeleton or a triazine skeleton are preferred because they are electrochemically stable and have high electron transport properties. 1 and X 2 and X represented by general formula (G3-2) 1 When represents nitrogen, the organic compound has a diazine skeleton or a triazine skeleton, and therefore can form a stable composite material with high electron transport properties when interacting with a metal. That is, an organic compound having a diazine ring or a triazine ring and having the function of interacting at a bidentate or higher level can form a highly reliable electron injection layer by interacting with a metal.

[0192] Specific examples of the organic compound used for the second organic compound and the organic compound having a heteroaromatic ring of the above general formulae (G1-1) to (G4-2) are shown below.

[0193] [ka]

[0194] [ka]

[0195] In addition, examples of substituents that can be applied to the above general formulae (G1-1) to (G4-2) include alkyl groups having 1 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, aryl groups having 6 to 30 carbon atoms, arylene groups having 6 to 30 carbon atoms, and heteroaryl groups having 1 to 30 carbon atoms. Some or all of the hydrogen atoms may be deuterium. In addition, the groups that can be applied to the above general formulae are not limited to the following specific examples.

[0196] Specific examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a neohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, a 2,3-dimethylbutyl group, and a 1-ethylhexyl group.

[0197] Specific examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a methylcyclobutyl group, a cyclopentyl group, a methylcyclopentyl group, an isopropylcyclopentyl group, a tert-butylcyclopropyl group, a cyclohexyl group, a methylcyclohexyl group, an isopropylcyclohexyl group, a tert-butylcyclohexyl group, a cycloheptyl group, a methylcycloheptyl group, an isopropylcycloheptyl group, a cyclooctyl group, a methylcyclooctyl group, an isopropylcyclohexyl group, a cyclononyl group, a methylcyclononyl group, a cyclodecyl group, and an adamantyl group.

[0198] Specific examples of the aryl group having 6 to 30 carbon atoms include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a mesityl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a 1-naphthyl group, a 2-naphthyl group, a fluorenyl group, a 9,9-dimethylfluorenyl group, a spirobifluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, etc. When the aryl group having 6 to 30 carbon atoms has a substituent, examples of the substituent include an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a phenyl group, etc.

[0199] Specific examples of the arylene group having 6 to 30 carbon atoms include a phenylene group, a biphenyl-diyl group, a naphthalene-diyl group, a fluorene-diyl group, an acenaphthene-diyl group, an anthracene-diyl group, a phenanthrene-diyl group, a terphenyl-diyl group, a triphenylene-diyl group, a tetracene-diyl group, a benzanthracene-diyl group, a pyrene-diyl group, and a spirobi[9H-fluorene]-diyl group. When the arylene group having 6 to 30 carbon atoms has a substituent, examples of the substituent include an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a phenyl group.

[0200] The heteroaryl group having 1 to 30 carbon atoms represents a monovalent group obtained by removing one hydrogen atom from one of the carbon atoms constituting the ring of a monocyclic or polycyclic heteroaromatic compound having 1 to 30 carbon atoms. Specific examples of the heteroaryl group having 1 to 30 carbon atoms include a 1,3,5-triazin-2-yl group, a 1,2,4-triazin-3-yl group, a pyrimidin-4-yl group, a pyrazin-2-yl group, a 2-pyridyl group, a 3-pyridyl group, a 4-pyridyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, an indenocarbazolyl group, and a dibenzocarbazolyl group. When the heteroaryl group has a substituent, examples of the substituent include an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a phenyl group.

[0201] Specific examples of the organic compound used for the second organic compound and the organic compounds represented by the above general formulae (G1-1) to (G4-2) are shown below.

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] It is more preferable that the LUMO level of the second organic compound is lower than that of the first organic compound. This makes it easier for the donor level formed by the first organic compound and the metal or metal compound to donate electrons to the second organic compound. It is also preferable that the second organic compound has electron transport properties, and for this reason, it is also preferable that the LUMO level of the second organic compound is lower than that of the first organic compound.

[0206] The second organic compound preferably has a LUMO level of -3.2 eV to -2.0 eV, more preferably -3.1 eV to -2.0 eV, and even more preferably -3.0 eV to -2.5 eV, while the first organic compound preferably has a LUMO level of -3.0 eV to -2.0 eV, and even more preferably -2.7 eV to -2.0 eV.

[0207] This facilitates electron donation to the second organic compound from the donor level formed by the first organic compound and the metal or metal compound, and also facilitates electron transport by the second organic compound.

[0208] In one embodiment of the present invention, the LUMO level of the second organic compound is lower than the LUMO level of the first organic compound and is preferably at least 0.60 eV lower than the LUMO level of the first organic compound, more preferably at least 0.50 eV lower than the LUMO level of the first organic compound and at most 0.20 eV lower than the LUMO level of the first organic compound, and more preferably at least 0.50 eV lower than the LUMO level of the first organic compound and at most 0.25 eV lower than the LUMO level of the first organic compound. It is more preferable that the LUMO level is at least 0.50 eV lower than the LUMO level of the organic compound and at most 0.30 eV lower than the LUMO level of the first organic compound, more preferably at least 0.50 eV lower than the LUMO level of the first organic compound and at most 0.35 eV lower than the LUMO level of the first organic compound, and even more preferably at least 0.50 eV lower than the LUMO level of the first organic compound and at most 0.40 eV lower than the LUMO level of the first organic compound.

[0209] That is, when the LUMO level of the first organic compound is "LUMO1 (eV)" and the LUMO level of the second organic compound is "LUMO2 (eV)", it is preferable that LUMO2 satisfies the following formula. LUMO1-0.50≦LUMO2≦LUMO1-0.20

[0210] More preferably, LUMO2 satisfies the following formula: LUMO1-0.50≦LUMO2≦LUMO1-0.25

[0211] More preferably, LUMO2 satisfies the following formula: LUMO1-0.50≦LUMO2≦LUMO1-0.30

[0212] More preferably, LUMO2 satisfies the following formula: LUMO1-0.50≦LUMO2≦LUMO1-0.35

[0213] More preferably, LUMO2 satisfies the following formula: LUMO1-0.50≦LUMO2≦LUMO1-0.40

[0214] When LUMO2 is in the above range, the light-emitting device according to one embodiment of the present invention can have excellent characteristics such as low driving voltage, regardless of whether or not it undergoes a photolithography process involving exposure of the EL layer to the atmosphere, and can also have excellent reliability.

[0215] The second organic compound may be an organic compound having electron transport properties. The organic compound having electron transport properties may have an electron mobility of 1×10 or more at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes.

[0216] The number of carbon atoms in the second organic compound is preferably from 25 to 100. By setting the number of carbon atoms in this range, the organic compound can be made to have excellent sublimation properties, and therefore thermal decomposition of the organic compound can be suppressed during vacuum deposition, resulting in good material usage efficiency.

[0217] The second organic compound is preferably an organic compound having a glass transition temperature Tg of 100° C. or higher. This allows the electron injection layer to have good heat resistance and be resistant to crystallization. Therefore, the organic compound layer can be made resistant to crystallization even when part of it is processed by lithography.

[0218] Furthermore, the second organic compound can be an organic compound having an acid dissociation constant pKa of less than 4. This can reduce the solubility of the second organic compound in water, thereby increasing the resistance to water and chemicals used in the lithography process.

[0219] Compared with the solubility in water of organic compounds having an acid dissociation constant pKa of 4 or greater, the solubility in water of organic compounds having an acid dissociation constant pKa of less than 4 is low. Furthermore, compared with the case where an organic compound having an acid dissociation constant pKa of 4 or greater is used as the second organic compound, using an organic compound having an acid dissociation constant pKa of less than 4 as the second organic compound can improve the water resistance of the electron injection layer. Furthermore, during the manufacturing process, defects such as peeling of the electron injection layer from other layers can be suppressed. This can suppress defects that cause defects in light-emitting devices.

[0220] If the acid dissociation constant pKa of an organic compound is unknown, the acid dissociation constant pKa of each skeleton of the organic compound can be investigated, and the largest acid dissociation constant pKa selected from these can be regarded as the acid dissociation constant pKa of the organic compound.

[0221] Furthermore, the first layer contains a second organic compound in addition to the metal or metal compound and the first organic compound, which allows for efficient interaction between the materials, which can be confirmed by measuring the spin density using electron spin resonance (ESR).

[0222] For example, the spin density measured by ESR of a film containing a metal or metal compound and a first organic compound is preferably higher than the spin density measured by ESR of a film containing a metal or metal compound and a second organic compound.Furthermore, the spin density measured by ESR of a film containing a metal or metal compound, a first organic compound, and a second organic compound is preferably higher than the spin density measured by ESR of a film containing only two of the materials, the metal or metal compound, the first organic compound, and the second organic compound, and in this case, it can be confirmed that the interaction between the materials is occurring efficiently.

[0223] More specifically, the film containing the metal or metal compound and the first organic compound has a spin density of 5×10 due to a signal observed in the vicinity of a g value of 2.00 by electron spin resonance. 16 spins / cm 3 More preferably, 1×10 17 spins / cm 3 More preferably, 1×10 18 spins / cm 3 More preferably, 1×10 19 spins / cm 3 More preferably, 1×10 20 spins / cm 3 In such a case, it can be confirmed that an interaction between the materials occurs efficiently in the layer having a combination of a metal or a metal compound and a first organic compound. Alternatively, a film containing a metal or a metal compound, a first organic compound, and a second organic compound may have a spin density of 5×10 or less resulting from a signal observed in the vicinity of a g-value of 2.00 by electron spin resonance.16 spins / cm 3 More preferably, 1×10 17 spins / cm 3 More preferably, 1×10 18 spins / cm 3 More preferably, 1×10 19 spins / cm 3 More preferably, 1×10 20 spins / cm 3 or more is preferable. In such a case, it can be confirmed that in a layer having a combination of a metal or metal compound, a first organic compound, and a second organic compound, the interaction between the materials occurs more efficiently than in a layer having only two of these materials. In this case, for a mixed film containing a metal or metal compound and a second organic compound, the spin density resulting from a signal observed in the vicinity of a g-value of 2.00 by electron spin resonance spectroscopy is 2×10 16 spins / cm 3 For a mixed film containing the first organic compound and the second organic compound, the spin density resulting from a signal observed in the vicinity of a g-value of 2.00 by electron spin resonance is 2 × 10 or less. 16 spins / cm 3 The following is the result.

[0224] In the first layer, the molar ratio of the metal or metal compound to the first organic compound (or the sum of the first organic compound and the second organic compound) is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.5 to 2. Alternatively, the volume ratio is preferably 0.01 to 0.3, more preferably 0.02 to 0.2, and even more preferably 0.05 to 0.1. Having a first layer containing the metal or metal compound and the first organic compound (or the first organic compound and the second organic compound) in such a ratio can provide an electron injection layer with good electron injection properties. Furthermore, although the second organic compound does not necessarily have to be used, when a second organic compound is used, the volume ratio of the first organic compound to the second organic compound is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.5 to 2. By mixing the first organic compound and the second organic compound in such a ratio, an electron injection layer having good electron transport properties can be provided. Furthermore, by using an organic compound having a high Tg and good thermal properties as the second organic compound, it is possible to provide an organic EL device having good reliability.

[0225] The thickness of the first layer is preferably 2 nm to 20 nm, more preferably 5 nm to 10 nm. When the first layer has a laminate structure of a metal or metal compound layer and a layer containing a first organic compound, the thickness of the metal or metal compound layer is preferably 0.1 nm to 5 nm, more preferably 0.2 nm to 2 nm. When the first layer has a laminate structure of a metal or metal compound layer and a layer containing a first organic compound, the thickness of the layer containing the first organic compound is preferably 2 nm to 20 nm, more preferably 5 nm to 10 nm.

[0226] By using the second organic compound, a composite material in which a metal, a first organic compound, and a second organic compound are mixed can function well, and a light-emitting device exhibiting high luminous efficiency can be provided.

[0227] <Second electrode> The second electrode is an electrode paired with the first electrode, and the light-emitting device has the previously formed first electrode, the second electrode, and an organic compound layer located between the first electrode and the second electrode. Preferably, the organic compound layer has a light-emitting layer and an electron-injection layer, and the electron-injection layer is located between the light-emitting layer and the second electrode, and the electron-injection layer and the second electrode are in contact with each other.

[0228] The second electrode is preferably made of a conductive metal oxide such as indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide (ITSO), indium zinc oxide, or indium oxide containing tungsten oxide and zinc oxide (IWZO). Other examples include metal materials such as gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti), aluminum (Al), yttrium (Y), zirconium (Zr), tantalum (Ta), silver (Ag), and magnesium (Mg), as well as alloys containing these metal materials. Alternatively, nitrides of metal materials (e.g., titanium nitride) can be used. These materials are less likely to be deteriorated by the photolithography process, and therefore it is possible to obtain a light-emitting device with good characteristics even after the photolithography process.

[0229] Note that by forming the second electrode with a light-transmitting property, the device can be a top-emission light-emitting device that emits light from the second electrode side. In the case of a bottom-emission light-emitting device, the second electrode is preferably an electrode with high visible light reflectance (40% to 100%, preferably 70% to 100%).

[0230] In addition, some of these materials have a high work function and are therefore difficult to use as a cathode. However, in one embodiment of the present invention, a light-emitting device with good characteristics can be provided by using a second electrode and an electron-injection layer having the above structure.

[0231] Thus, by using an electron-injection layer containing a metal or metal compound, a first organic compound, and a second organic compound having two or more heteroaromatic rings bonded or fused to each other, where the two or more heteroaromatic rings have a total of three or more heteroatoms, in an organic EL device according to one embodiment of the present invention, it is possible to realize an organic EL device that exhibits excellent characteristics even after a process of exposing the organic compound layer to the atmosphere after forming a second electrode. That is, by applying the configuration of one embodiment of the present invention, it is possible to realize an organic EL device with excellent characteristics that is fabricated by a photolithography method that includes a process of exposing the organic compound layer to the atmosphere. Specifically, it is possible to form an electron-injection layer that is resistant to oxygen and water in the atmosphere, as well as water and chemical solutions used in the lithography process. Therefore, one embodiment of the present invention can provide a light-emitting device that has excellent moisture resistance, water resistance, oxygen resistance, and chemical resistance, a low driving voltage, and excellent luminous efficiency.

[0232] This makes it possible to provide a display device with extremely high definition and excellent characteristics.

[0233] Note that the light-emitting device of one embodiment of the present invention is particularly suitable for a light-emitting device that has undergone a photolithography process. However, a light-emitting device that has not undergone a photolithography process is also highly stable against the atmosphere, which improves yield and contributes to cost reduction by eliminating the need for stricter atmosphere control during the manufacturing process.

[0234] (Embodiment 2) In this embodiment, a light-emitting device according to one embodiment of the present invention will be described in detail.

[0235] 1A is a schematic diagram of a light-emitting device of one embodiment of the present invention. The light-emitting device has a first electrode 101 provided over an insulator 1000, and an organic compound layer 103 between the first electrode 101 and a second electrode 102. The organic compound layer 103 includes at least a light-emitting layer 113 and an electron-injection layer 115. The light-emitting layer 113 is a layer containing a light-emitting substance, and the light-emitting device of one embodiment of the present invention emits light when a voltage is applied between the first electrode 101 and the second electrode 102.

[0236] 1(A), the organic compound layer 103 preferably has functional layers such as a hole injection layer 111, a hole transport layer 112, and an electron transport layer 114 in addition to the light-emitting layer 113 and the electron injection layer 115. The organic compound layer 103 may also include functional layers other than those described above, such as a hole blocking layer, an exciton blocking layer, and an intermediate layer. Conversely, any of the layers described above may not be provided.

[0237] Furthermore, the electron injection layer 115 contains, in addition to the metal or metal compound and the first organic compound described in Embodiment 1, a second organic compound having two or more heteroaromatic rings bonded to or fused with each other, and the two or more heteroaromatic rings having a total of three or more heteroatoms. The specific configuration of the electron injection layer 115 has been described in detail in Embodiment 1, so a repeated description will be omitted.

[0238] The first electrode 101 and the second electrode 102 may be formed as a single layer structure or a laminated layer structure.

[0239] Note that the light-emitting device of one embodiment of the present invention is processed after the second electrode 102 is formed by photolithography. Therefore, as shown in Figure 1A, an edge of the second electrode 102 in a cross section and an edge of the organic compound layer 103 in a cross section are aligned in a direction approximately perpendicular to a surface of the insulator 1000. The edge of the second electrode and the edge of the organic compound layer may be located inside the edge of the first electrode as shown in Figures 1A and 1B, or may be located outside the first electrode as shown in Figure 1C.

[0240] The first electrode 101 is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or higher). Specific examples include indium oxide-tin oxide, indium oxide-tin oxide (ITSO: Indium Tin Silicon Oxide) containing silicon or silicon oxide, indium oxide-zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are usually formed by sputtering, but they may also be formed by applying a sol-gel method. For example, indium oxide-zinc oxide can be formed by sputtering using a target containing indium oxide and 1 to 20 wt% zinc oxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) can also be formed by sputtering using a target containing indium oxide and 0.5 to 5 wt% tungsten oxide and 0.1 to 1 wt% zinc oxide. Other examples of materials that can be used for the first electrode 101 include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti), aluminum (Al), and nitrides of metal materials (e.g., titanium nitride). The first electrode 101 may also be a stack of these materials. For example, a film in which Al, Ti, and ITSO are stacked in this order on Ti is preferable because it has good reflectivity, is highly efficient, and enables high resolution of several thousand ppi. Alternatively, graphene can be used for the first electrode 101. Note that by using a composite material capable of forming the hole injection layer 111 (described later) as a layer in contact with the first electrode 101 (typically, a hole injection layer), it becomes possible to select an electrode material regardless of the work function.

[0241] The hole injection layer 111 is provided in contact with the first electrode 101 and has the function of facilitating injection of holes into the organic compound layer 103. The hole injection layer 111 can be formed of a phthalocyanine-based compound or complex compound such as phthalocyanine (abbreviation: HPc) or copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 4,4′-bis(N-{4-[N′-(3-methylphenyl)-N′-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene) / (polystyrenesulfonic acid) (abbreviation: PEDOT / PSS).

[0242] Alternatively, the hole injection layer 111 may be formed of a substance having electron acceptor properties. Examples of the substance having acceptor properties include organic compounds having an electron-withdrawing group (such as a halogen group or a cyano group), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are preferred because of their thermal stability. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups, cyano groups, etc.) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds described above, metal oxides, particularly transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide, can be used as the substance having acceptor properties.

[0243] The hole-injection layer 111 is preferably formed using a composite material containing the above-mentioned material having an acceptor property and an organic compound having a hole-transport property.

[0244] As the organic compound having hole transport properties used in the composite material, various organic compounds can be used, such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.). Note that the organic compound having hole transport properties used in the composite material can be 1×10 -6 cm 2 Preferably, the organic compound has a hole mobility of 1 / Vs or more. The organic compound having hole transport properties used in the composite material is preferably a compound having a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the fused aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. Furthermore, as the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferred, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to the above ring is preferred.

[0245] Such organic compounds having hole-transporting properties preferably have a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. It is preferable that these organic compounds having hole-transporting properties are substances having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of light-emitting devices with long lifetimes.

[0246] Specific examples of organic compounds having hole transport properties as described above include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzylamine (abbreviation: BnfBB1BP), and N,N-bis(4-biphenyl)benzylamine (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]-4-amino-p-terphenyl] ]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβ NB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-Diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl] 4'-[4'-(3-phenyl-9H-carbazol-9-yl)biphenyl-4-yl]-4''-phenyltriphenylamine (abbreviated as TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviated as αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviated as αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviated as YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)furan N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N- Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4' -[4-(9-phenylfluoren-9-yl)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'- Di(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-fluoren]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis( Examples of such amines include N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine.

[0247] Other aromatic amine compounds that can be used as materials having hole transport properties include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0248] By forming the hole injection layer 111, the hole injection property becomes good, and a light emitting device with a low driving voltage can be obtained.

[0249] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film.

[0250] The hole transport layer 112 is formed by containing an organic compound having a hole transport property. -6 cm 2 It is preferable that the hole mobility is / Vs or more.

[0251] Examples of the material having hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'- (9-Phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), Compounds with an aromatic amine skeleton, such as 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), 9,9'-Bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviated as BisBPCz), 9,9'-Bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviated as BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-Bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1"-terf phenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3 '-9H,9'H-Bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-9'-[1,1':3',1"-taphe compounds having a carbazole skeleton such as [4-yl-3,3'-9H,9'H-bicarbazole]; compounds having a thiophene skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV);Examples of the compounds include compounds having a furan skeleton, such as 4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the compounds mentioned above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. Note that the substances listed as materials having hole transport properties used in the composite material of the hole injection layer 111 can also be suitably used as materials for the hole transport layer 112.

[0252] The light-emitting layer 113 is a layer containing a light-emitting material, and preferably contains a light-emitting material and a host material. The light-emitting layer may also contain other materials. It may also be a laminate of two or more layers with different compositions.

[0253] The light-emitting material may be a fluorescent material, a phosphorescent material, a material that exhibits thermally activated delayed fluorescence (TADF), or any other light-emitting material.

[0254] Examples of materials that can be used as fluorescent materials in the light-emitting layer include the following: In addition, fluorescent materials other than these can also be used.

[0255] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N,N',N'-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviated as DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA) , 9,10-bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyra N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), Name: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB),6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b]naphtho]] Examples include N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviated as 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds, such as pyrenediamine compounds 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred due to their high hole-trapping properties and excellent luminous efficiency and reliability.

[0256] In addition, 5,9-diphenyl-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (abbreviation: DABNA1), 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-3-amine (abbreviation: DABNA2), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: DABNA3), Amine (abbreviation: DPhA-tBu4DABNA), 2,12-di(tert-butyl)-N,N,5,9-tetra(4-tert-butylphenyl)-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin (abbreviation: Me-tBu4DABNA), N 7 ,N 7 ,N 13 ,N 13 Fused heteroaromatic compounds containing nitrogen and boron, such as 5,9,11,15-octaphenyl-5H,9H,11H,15H-[1,4]benzazaborino[2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[3,2-b]phenazaborine-7,13-diamine (abbreviation: ν-DABNA) and 2-(4-tert-butylphenyl)benz[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc), are particularly suitable for use as compounds having a diazaboranaphthoanthracene skeleton, since they have a narrow emission spectrum and can emit blue light with good color purity.

[0257] In addition to these, 9,10,11-tris[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-G), 9,11-bis[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-Y) and the like can be preferably used.

[0258] When a phosphorescent material is used as the light-emitting material in the light-emitting layer, examples of materials that can be used include the following.

[0259] Organometallic iridium compounds with a 4H-triazole skeleton, such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]) and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]). complexes, organometallic iridium complexes with 1H-triazole skeletons such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), fac-tris[1-( [2,6-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} organometallic iridium complexes with an imidazole skeleton such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]), organometallic complexes with a benzimidazolidene skeleton such as bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ] Organometallic iridium complexes with phenylpyridine derivatives bearing electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviated as FIracac), are compounds that exhibit blue phosphorescence and have an emission peak in the wavelength range from 450 nm to 520 nm.

[0260] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6- Organometallic iridium complexes with a pyrimidine skeleton, such as (2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and tris(2-phenylpyridinato-N,C 2’) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’)iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mbfpypy-d3)]), [2-d3- Methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy-d3)]), [2-(4-d3-methyl-5-phenyl-2-pyridinyl-κN2)phenyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mdppy)]), and rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These compounds mainly exhibit green phosphorescence, with an emission peak in the wavelength range of 500 to 600 nm. Organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they are remarkably superior in reliability and luminous efficiency.

[0261] and organometallic iridium complexes having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]). Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’) iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III), and (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III). In addition to iridium complexes, platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated as PtOEP) and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviated as [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviated as [Eu(TTA)3(Phen)]) are compounds that exhibit red phosphorescence, with peak emission in the wavelength range from 600 to 700 nm. Organometallic iridium complexes with a pyrazine skeleton also exhibit excellent red chromaticity.

[0262] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0263] TADF materials include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also available are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), all of which are shown in the following structural formulas.

[0264] [ka]

[0265] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), and Heterocyclic compounds having one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the electron-donating ability of the π-electron-rich heteroaromatic ring and the electron-accepting ability of the π-electron-deficient heteroaromatic ring are both enhanced, thereby reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0266] [ka]

[0267] TADF materials are materials with a small difference between the S1 and T1 levels, and have the ability to convert triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) using a small amount of thermal energy, allowing for efficient generation of a singlet excited state. Triplet excitation energy can also be converted into light emission.

[0268] Furthermore, exciplexes (also known as exciplexes), which form an excited state with two types of substances, have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0269] The phosphorescence spectrum observed at low temperatures (for example, 77 K to 10 K) can be used as an indicator of the T1 level. For a TADF material, when a tangent line is drawn at the base of the fluorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the S1 level, and a tangent line is drawn at the base of the phosphorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0270] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0271] As the host material of the light-emitting layer, various carrier transport materials such as a material having an electron transport property and / or a material having a hole transport property, and the above-mentioned TADF material can be used.

[0272] Preferred materials having hole transport properties include organic compounds having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring containing at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton, and more specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is fused to one of these rings.

[0273] Such organic compounds having hole-transporting properties preferably have a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. It is preferable that these organic compounds having hole-transporting properties are substances having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of light-emitting devices with long lifetimes.

[0274] 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-fluoren]-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 (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PC Aromatic amines such as 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviated as PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviated as PCBASF) Compounds with a carbazole skeleton, such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), and 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable materials include compounds having a thiophene skeleton, such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. The organic compounds listed as examples of materials having hole transport properties for the hole transport layer can also be used.

[0275] Preferred examples of the material having electron transport properties include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), and organic compounds having a π-electron-deficient heteroaromatic ring. Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include organic compounds containing a heteroaromatic ring having an azole skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, organic compounds containing a heteroaromatic ring having a diazine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton.

[0276] Among these, organic compounds containing a heteroaromatic ring having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reduced driving voltage. In addition, benzofuropyrimidine skeletons, benzothienopyrimidine skeletons, benzofuropyrazine skeletons, and benzothienopyrazine skeletons are preferred because of their high acceptor properties and high reliability.

[0277] 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-oxadiazole- Organic compounds with an azole skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), 3,5-bis[3-(9H-carbazole-9-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), )phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10 -phenanthroline (abbreviation: mTpPPhen), 2-phenyl-9-(2-triphenylenyl)-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: PnNPhen), 2-[4-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen), and other organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl phenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated as 9mDBtBPNf pr), 9-[3'-(dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated as 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviated as 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviated as 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviated as 4,6mCzP2Pm), 9,9'-[pyrimidinyl benzofuro[3,2-d]pyrimidine (abbreviated as 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviated as 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2, 6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviated as 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9 -yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (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, such as 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d] 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-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 Rubazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl Phenyl-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'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3 Examples of suitable organic compounds include those containing a heteroaromatic ring with a triazine skeleton, such as -[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn) and 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Organic compounds containing a heteroaromatic ring with a diazine skeleton, organic compounds containing a heteroaromatic ring with a pyridine skeleton, and organic compounds containing a heteroaromatic ring with a triazine skeleton are preferred due to their high reliability. In particular, organic compounds containing a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring with a triazine skeleton have high electron transport properties and contribute to reduced driving voltage.

[0278] The TADF materials that can be used as host materials are the same as those listed above. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted to singlet excitation energy through reverse intersystem crossing, and the energy is then transferred to the light-emitting material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0279] This is very effective when the luminescent material is a fluorescent luminescent material. In this case, in order to obtain high luminous efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. In addition, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent luminescent material.

[0280] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, as this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0281] Furthermore, to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, carrier recombination is preferred in the TADF material. Furthermore, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to triplet excitation energy in the fluorescent material. To achieve this, the fluorescent material preferably has a protecting group around the luminophore (the skeleton responsible for light emission) of the fluorescent material. The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples include alkyl groups with 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups with 3 to 10 carbon atoms, and trialkylsilyl groups with 3 to 10 carbon atoms. Multiple protecting groups are even more preferred. Substituents without a π bond have poor carrier transport properties, allowing for increased distance between the TADF material and the luminophore of the fluorescent material without significantly affecting carrier transport or carrier recombination. Here, the term "luminophore" refers to the atomic group (skeleton) responsible for light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of such luminophores include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton. In particular, fluorescent materials having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0282] When a fluorescent emitting substance is used as the emitting substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as a host material for a fluorescent emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. As a substance having an anthracene skeleton to be used as a host material, a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferred due to its chemical stability. Furthermore, host materials having a carbazole skeleton are preferred because of their enhanced hole injection and transport properties. However, host materials containing a benzocarbazole skeleton, in which a benzene ring is further condensed to a carbazole skeleton, are even more preferred because their HOMO level is approximately 0.1 eV higher than that of a carbazole skeleton, facilitating hole insertion. In particular, host materials containing a dibenzocarbazole skeleton are preferred because their HOMO level is approximately 0.1 eV higher than that of a carbazole skeleton, facilitating hole insertion, and also exhibiting excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that, from the viewpoint of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'- 9-(1-naphthyl)-10-(4-(2-naphthyl)phenyl)anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)benzo Examples include zo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0283] The host material may be a mixture of multiple substances, and when a mixture of host materials is used, it is preferable to mix a material having electron-transporting properties with a material having hole-transporting properties. By mixing a material having electron-transporting properties with a material having hole-transporting properties, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole-transporting properties to the material having electron-transporting properties (material having hole-transporting properties:material having electron-transporting properties) may be 1:19 to 19:1.

[0284] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0285] Furthermore, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, using this structure is also preferable because it reduces the driving voltage.

[0286] At least one of the materials forming the exciplex may be a phosphorescent material, which allows efficient conversion of triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0287] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the hole-transporting material is equal to or higher than the HOMO level of the electron-transporting material. It is also preferable that the LUMO level of the hole-transporting material is equal to or higher than the LUMO level of the electron-transporting material. The LUMO and HOMO levels of the materials can be derived from the electrochemical properties (reduction potential and oxidation potential) of the materials measured by cyclic voltammetry (CV).

[0288] The formation of exciplexes can be confirmed by, for example, comparing the emission spectra of a hole-transporting material, an electron-transporting material, and a mixed film of these materials and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL can also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response.

[0289] The electron transport layer 114 is a layer containing a substance having an electron transport property. The material having an electron transport property is a material having an electron mobility of 1×10 or more at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can be used as long as they have a higher electron transporting property than holes. Note that the organic compound is preferably an organic compound having a π-electron-deficient heteroaromatic ring. The organic compound having a π-electron-deficient heteroaromatic ring is preferably one or more of, for example, an organic compound having a heteroaromatic ring with an azole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0290] The organic compounds having electron transport properties that can be used in the electron transport layer 114 include the organic compounds having electron transport properties in the light-emitting layer 113 and the organic compounds listed as organic compounds that can be used as the second organic compound in the electron injection layer 115 in Embodiment 1. Among these, organic compounds containing a heteroaromatic ring with a diazine skeleton, an organic compound containing a heteroaromatic ring with a pyridine skeleton, and an organic compound containing a heteroaromatic ring with a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and an organic compound containing a heteroaromatic ring with a triazine skeleton have high electron transport properties and contribute to reduced driving voltage. Among these, organic compounds having a phenanthroline skeleton, such as mTpPPhen, PnNPhen, and mPPhen2P, are preferred, and organic compounds having a phenanthroline dimer structure, such as mPPhen2P, are more preferred because of their excellent stability.

[0291] The electron transport layer preferably contains an organic compound having an acid dissociation constant pKa of less than 4 and having electron transport properties.

[0292] The electron transport layer 114 may have a laminated structure. When the electron transport layer 114 has a laminated structure, a layer in contact with the light-emitting layer 113 may function as a hole-blocking layer. When the electron transport layer in contact with the light-emitting layer is made to function as a hole-blocking layer, it is preferable to use a material whose HOMO level is lower by 0.5 eV or more than the HOMO level of the material contained in the light-emitting layer.

[0293] The 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 therefore, a repeated description will be omitted.

[0294] The second electrode 102 is preferably formed in contact with the electron-injection layer 115. The structure of the second electrode has been described in detail in Embodiment 1, and therefore, repeated description will be omitted.

[0295] When the second electrode 102 is formed using a material that is transparent to visible light, a light-emitting device can be obtained that emits light from the second electrode 102 side, and when the first electrode 101 is formed using a material that is transparent to visible light, a light-emitting device can be obtained that emits light from the first electrode 101 side.

[0296] The conductive material constituting the second electrode 102 can be formed into a film by a dry method such as a vacuum deposition method or a sputtering method, an inkjet method, a spin coating method, etc. Alternatively, the second electrode 102 may be formed by a wet method using a sol-gel method, or may be formed by a wet method using a paste of a metal material.

[0297] In the case of a top-emission light-emitting device, the light extraction efficiency can be improved by forming a capping layer by evaporating an organic compound on the second electrode. The capping layer may have a single-layer structure or a multilayer structure. In the case of a multilayer structure, the light extraction efficiency can be further improved by using organic compounds with different refractive indices.

[0298] In addition, various methods, whether dry or wet, can be used to form the organic compound layer 103. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, spin coating, or the like may be used.

[0299] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0300] 1B , a P-type layer 117 may be provided to protect the electron-injection layer 115 when a deposition method that significantly damages a base, such as a sputtering method, is used to form the second electrode 102. The P-type layer 117 can be formed using the composite material described above as a material that can be used for the hole-injection layer 111. Transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide are more robust than organic compounds, and therefore, by using them as a substance having acceptor properties for the P-type layer, damage during the formation of the second electrode 102 can be prevented.

[0301] Although not shown, an electron relay layer may be provided between the electron injection layer 115 and the P-type layer 117. The electron relay layer contains at least a substance having electron transport properties and has the function of preventing interaction between the electron injection layer 115 and the P-type layer 117 and smoothly transferring electrons. The LUMO level of the substance having electron transport properties contained in the electron relay layer is preferably between the LUMO level of the acceptor substance in the P-type layer 117 and the LUMO level of the substance contained in the layer of the electron transport layer 114 that is in contact with the electron injection layer 115. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer is −5.0 eV or higher, preferably −5.0 eV or higher and −3.0 eV or lower. The substance having electron transport properties used in the electron relay layer is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand. Specific examples of the substance having electron transport properties that can be used in the electron relay layer include diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA-F6), perylene tetracarboxylic acid derivatives such as 3,4,9,10-perylene tetracarboxylic diimide (abbreviation: PTCDI) and 3,4,9,10-perylene tetracarboxylic-bis-benzimidazole (abbreviation: PTCBI), (C60-Ih)[5,6]fullerene (abbreviation: C60), and (C70-D5h)[5,6]fullerene (abbreviation: C70). Furthermore, a compound having a heterophane skeleton, which is a cyclophane skeleton containing a heterocycle, can be used, and as such a compound, for example, a phthalocyanine compound such as phthalocyanine (abbreviation: H2Pc) can be used.Metal phthalocyanines containing copper, zinc, cobalt, iron, chromium, nickel, etc., such as copper phthalocyanine (abbreviated as CuPc), zinc phthalocyanine (abbreviated as ZnPc), cobalt phthalocyanine (abbreviated as CoPc), iron phthalocyanine (abbreviated as FePc), tin phthalocyanine (abbreviated as SnPc), tin oxide phthalocyanine (abbreviated as SnOPc), titanium oxide phthalocyanine (abbreviated as TiOPc), and vanadium oxide phthalocyanine (abbreviated as VOPc), and their derivatives can also be used. Phthalocyanine-based metal complexes, such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine are particularly preferred.

[0302] The thickness of the electron relay layer is preferably 1 nm or more and 10 nm or less, more preferably 2 nm or more and 5 nm or less.

[0303] Next, an embodiment of a light-emitting device having a structure in which a plurality of light-emitting units are stacked (also referred to as a stacked device or a tandem device) will be described with reference to FIG. 1(C). This light-emitting device has a plurality of light-emitting units between a first electrode 101 and a cathode. One light-emitting unit has a structure substantially similar to that of the organic compound layer 103 shown in FIG. 1(A). In other words, the light-emitting device shown in FIG. 1(C) is a light-emitting device having a plurality of light-emitting units, and the light-emitting device shown in FIG. 1(A) can be said to be a light-emitting device having one light-emitting unit.

[0304] In FIG. 1(C), a first light-emitting unit 511 and a second light-emitting unit 512 are stacked between a first electrode 501 and a second electrode 502, and an intermediate layer 513 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 correspond to the first electrode 101 and the second electrode 102 in FIG. 1(A), respectively, and the same materials as those described in the description of FIG. 1(A) can be applied to them. The layer structures of the first light-emitting unit 511 and the second light-emitting unit 512 may be the same or different. The materials constituting the layers of the first light-emitting unit 511 and the second light-emitting unit 512 may be the same or different.

[0305] The intermediate layer 513 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 between the first electrode 501 and the second electrode 502. That is, in FIG. 1C, when a voltage is applied so that the potential of the first electrode 101 is higher than the potential of the cathode, the intermediate layer 513 injects electrons into the first light-emitting unit 511 and injects holes into the second light-emitting unit 512.

[0306] Intermediate layer 513 includes a charge generation layer. The charge generation layer also includes at least a P-type layer 117. P-type layer 117 is preferably formed using the composite material listed above as a material that can be used to form hole injection layer 111. P-type layer 117 may also be formed by laminating a film containing an acceptor material and a film containing a hole transport material, both of which are materials that form the composite material. By applying a potential to P-type layer 117, electrons are injected into electron transport layer 114 and holes are injected into the cathode, causing the light-emitting device to operate.

[0307] In addition, it is preferable that the intermediate layer 513 includes, in addition to the P-type layer 117, either or both of an electron relay layer 118 and an N-type layer 119.

[0308] The electron relay layer 118 has the same configuration as the electron relay layer mentioned in the description of FIG. 1(B), and therefore a repeated description will be omitted.

[0309] The N-type layer 119 can be made of a material with high electron injection properties, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0310] When the N-type layer 119 is formed containing a substance having an electron-transporting property and a donor substance, the donor substance can be an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof (an alkali metal compound (including an oxide such as lithium oxide, a halide, or a carbonate such as lithium carbonate or cesium carbonate), an alkaline earth metal compound (including an oxide, a halide, or a carbonate), or a rare earth metal compound (including an oxide, a halide, or a carbonate)), or an organic compound such as tetrathianaphthacene (abbreviation: TTN), nickelocene, or decamethylnickelocene. Note that the substance having an electron-transporting property can be formed using the same material as the material for forming the electron-transporting layer 114 described above.

[0311] Alternatively, instead of N-type layer 119, a layer containing the metal compound described as being used for the electron injection layer in Embodiment 1 and an organic compound having a phenanthroline ring with an electron-donating group may be formed at the same position as N-type layer 119. Even with this configuration, a tandem light-emitting device with excellent characteristics can be fabricated.

[0312] When the surface of the light-emitting unit facing the first electrode 101 is in contact with the intermediate layer 513, the charge generation layer of the intermediate layer 513 can also function as the hole injection layer of the light-emitting unit, so the light-emitting unit does not need to be provided with a hole injection layer. When the surface of the light-emitting unit facing the cathode is in contact with the intermediate layer 513, the intermediate layer 513 can also function as the electron injection layer of the light-emitting unit, so the light-emitting unit does not need to be provided with an electron injection layer.

[0313] 1C illustrates a light-emitting device having two light-emitting units, but the present invention can be applied to a light-emitting device having three or more stacked light-emitting units. By disposing a plurality of light-emitting units between a pair of electrodes and separating them with an intermediate layer 513, as in the light-emitting device according to this embodiment, high-luminance light emission can be achieved while maintaining a low current density, and an element with a long life can be realized. Furthermore, a light-emitting device that can be driven at a low voltage and consumes low power can be realized.

[0314] Furthermore, by configuring each light-emitting unit to emit a different light color, the light-emitting device as a whole can emit light of a desired color. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light as a whole by obtaining red and green light from the first light-emitting unit and blue light from the second light-emitting unit.

[0315] Each layer and electrode, such as the organic compound layer 103, the first light-emitting unit 511, the second light-emitting unit 512, and the intermediate layer 513, can be formed by, for example, an evaporation method (including a vacuum evaporation method), a droplet discharge method (also called an inkjet method), a coating method, a gravure printing method, etc. They may also contain a low-molecular-weight material, a medium-molecular-weight material (including an oligomer and a dendrimer), or a polymer material.

[0316] FIG. 4A shows two adjacent light-emitting devices (light-emitting device 130a and light-emitting device 130b) included in a display device of one embodiment of the present invention.

[0317] The light-emitting device 130a has an organic compound layer 103a between a first electrode 101a on an insulating layer 175 and an opposing second electrode 102a, and the organic compound layer 103a has an electron injection layer 115a. The organic compound layer 103a has a configuration 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, but may have a different stacked structure.

[0318] The light-emitting device 130b has an organic compound layer 103b between a first electrode 101b on an insulating layer 175 and an opposing second electrode 102b, and the organic compound layer 103b has an electron injection layer 115b. The organic compound layer 103b has a configuration 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, but may have a different stacked structure.

[0319] The configurations of the electron injection layer 115a and the second electrode 102a in the light-emitting device 130a, and the configurations of the electron injection layer 115b and the second electrode 102b in the light-emitting device 130b are preferably the same as those described in the first embodiment.

[0320] The organic compound layer 103a and the organic compound layer 103b, and the second electrode 102a and the second electrode 102b are processed by photolithography after the films to be the second electrodes 102a and 102b are formed, and therefore are independent from each other. A light-emitting device according to one embodiment of the present invention can have good characteristics even when processed by photolithography after the films to be the second electrodes 102a and 102b are formed.

[0321] The edge (outline) of the second electrode 102a and the edge (outline) of the organic compound layer 103a are processed by photolithography, so they are roughly aligned in the vertical direction relative to the substrate. The edge (outline) of the second electrode 102b and the edge (outline) of the organic compound layer 103b are processed by photolithography, so they are roughly aligned in the vertical direction relative to the substrate.

[0322] Furthermore, since the organic compound layer 103a is processed by photolithography, a gap d exists between the organic compound layer 103a and the organic compound layer 103d. Furthermore, since the organic compound layer is processed by photolithography, the distance between the first electrode 101c and the first electrode 101d can be made smaller than that when mask vapor deposition is performed, and can be set to 0.5 μm or more and 5 μm or less.

[0323] FIG. 4(B) shows two adjacent tandem light-emitting devices (light-emitting device 130c, light-emitting device 130d) fabricated by photolithography.

[0324] The light-emitting device 130c has an organic compound layer 103c between a first electrode 101c and a second electrode 102c on an insulating layer 175. The organic compound layer 103c has a structure in which a first light-emitting unit 501c and a second light-emitting unit 502c are stacked with an intermediate layer 116c sandwiched therebetween. Note that although an example in which two light-emitting units are stacked is shown in FIG. 4(B), a structure in which three or more light-emitting units are stacked may also be used. 4(B), the first light-emitting unit 501c includes a hole injection layer 111c, a first hole transport layer 112c_1, a first light-emitting layer 113c_1, and a first electron transport layer 114c_1, the intermediate layer 116c includes a P-type layer 117c, an electron relay layer 118c, and an N-type layer 119c, and the second light-emitting unit 502c 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 115c. The electron relay layer 118c may or may not be present.

[0325] The light-emitting device 130d has an organic compound layer 103d between a first electrode 101d and a second electrode 102d on an insulating layer 175. The organic compound layer 103d has a structure in which a first light-emitting unit 501d and a second light-emitting unit 502d are stacked with an intermediate layer 116d sandwiched therebetween. Note that although an example in which two light-emitting units are stacked is shown in FIG. 4(B), a structure in which three or more light-emitting units are stacked may also be used. 4(B), the first light-emitting unit 501d 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, and the second light-emitting unit 502d 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 115d. The electron relay layer 118d is optional.

[0326] In the light-emitting devices 130c and 130d, the electron injection layers 115c and 115d, and the second electrodes 102c and 102d preferably have the structures described in the first embodiment.

[0327] Note that the organic compound layer 103c and the organic compound layer 103d are independent from each other because they are processed by photolithography after the films to be the second electrodes 102c and 102d are formed. A light-emitting device according to one embodiment of the present invention can have good characteristics even when processed by photolithography after the films to be the second electrodes 102c and 102d are formed.

[0328] The edges (outlines) of the second electrode 102c and the organic compound layer 103c are processed by photolithography, so they are roughly aligned in the vertical direction relative to the substrate. The edges (outlines) of the second electrode 102d and the organic compound layer 103d are processed by photolithography, so they are roughly aligned in the vertical direction relative to the substrate.

[0329] Furthermore, since the organic compound layer 103c is processed by photolithography, a gap d exists between the organic compound layer 103c and the organic compound layer 103d. Furthermore, since the organic compound layer is processed by photolithography, the distance between the first electrode 101c and the first electrode 101d can be made smaller than that when mask vapor deposition is performed, and can be set to 0.5 μm or more and 5 μm or less.

[0330] Since the second electrodes 102a and 102b, or the second electrodes 102c and 102d, are independent of each other, it is preferable to form an auxiliary electrode 105 to apply a voltage to the multiple second electrodes included in the light-emitting device. The auxiliary electrode 105 is preferably formed after forming an insulating layer 106 between the second electrodes 102a and 102b or between the light-emitting devices 130c and 130d to prevent short-circuiting of the organic compound layer or the first electrode. The insulating layer 106 is preferably formed using an organic insulating material. The auxiliary electrode 105 can be made of a material that can be used for the second electrode.

[0331] In the light-emitting device of one embodiment of the present invention, the organic compound layer is processed by photolithography, and therefore, the light-emitting device can be processed with sufficient precision to fabricate a high-resolution display device. Furthermore, since the lithography process can be performed on the electron injection layer far from the light-emitting layer without contamination by alkali metals, the light-emitting device can have excellent characteristics. As described above, the light-emitting device of one embodiment of the present invention having such a structure can realize a high-resolution display device and can have excellent characteristics.

[0332] In a light-emitting device according to one embodiment of the present invention, the second electrode and the organic compound layer are processed simultaneously by photolithography after the formation of the second electrode. Therefore, when viewed from a direction substantially perpendicular to the surface of the insulating layer on which the first electrode is formed, the contours of the layers included in the organic compound layer substantially coincide with each other. Furthermore, the end of the cross section of the second electrode and the end of the cross section of the first layer are aligned in a direction substantially perpendicular to the surface of the insulating layer on which the first electrode is formed. In this specification, "aligned" and "substantially coincident" mean that, in contacting layers A and B, the deviation between the contour A of layer A and the contour B of layer B is within 5% of the width of the organic compound layer on a line perpendicular to the contours of the compared portions. Furthermore, "substantially perpendicular" means an angle of 85° to 95°.

[0333] The structure of this embodiment mode can be used in appropriate combination with other structures.

[0334] (Embodiment 3) In this embodiment, a mode in which a light-emitting device of one embodiment of the present invention is used as a display element of a display device will be described.

[0335] As shown in FIGS. 5(A) and 5(B), a plurality of light-emitting devices 130 are formed on an insulating layer 175 to form a display device.

[0336] The display device has a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 has a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0337] In this specification and the like, when describing matters common to, for example, the subpixels 110R, 110G, and 110B, they may be referred to as the subpixels 110. When describing matters common to other components distinguished by alphabets, they may also be described using symbols without the alphabets.

[0338] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. This allows a full-color image to be displayed in the pixel section 177. In this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are described as an example, but combinations of sub-pixels of other colors may also be used. The number of sub-pixels is not limited to three, and may be four or more. Examples of four sub-pixels include sub-pixels of four colors: R, G, B, and white (W); sub-pixels of four colors: R, G, B, and yellow (Y); and sub-pixels of R, G, B, and infrared (IR).

[0339] In this specification, the row direction may be referred to as the X direction, and the column direction may be referred to as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly.

[0340] 5A shows an example in which sub-pixels of different colors are arranged side by side in the X direction, and sub-pixels of the same color are arranged side by side in the Y direction. Note that sub-pixels of different colors may also be arranged side by side in the Y direction, and sub-pixels of the same color may also be arranged side by side in the X direction.

[0341] The layout of the sub-pixels is not limited to this, and various other arrangements are possible, such as a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, a pentile arrangement, etc. Fig. 23 shows an example of a layout of the sub-pixels.

[0342] An S-stripe arrangement is applied to the pixel 178 shown in Fig. 23(A). The pixel 178 shown in Fig. 23(A) is composed of three subpixels: a subpixel 110R, a subpixel 110G, and a subpixel 110B.

[0343] The pixel 178 shown in FIG. 23(B) includes a subpixel 110R having a generally trapezoidal or triangular top surface shape with rounded corners, a subpixel 110G having a generally trapezoidal or triangular top surface shape with rounded corners, and a subpixel 110B having a generally rectangular or hexagonal top surface shape with rounded corners. The subpixel 110R has a larger light-emitting area than the subpixel 110G. Thus, the shape and size of each subpixel can be determined independently. For example, the more reliable the light-emitting device, the smaller the size of the subpixel.

[0344] The Pentile arrangement is applied to the pixels 124a and 124b shown in Fig. 23(C). Fig. 23(C) shows an example in which the pixel 124a having the subpixel 110R and the subpixel 110G and the pixel 124b having the subpixel 110G and the subpixel 110B are arranged alternately.

[0345] 23(D) to 23(F) are arranged in a delta configuration. Pixel 124a has two subpixels (subpixel 110R and subpixel 110G) in the top row (first row) and one subpixel (subpixel 110B) in the bottom row (second row). Pixel 124b has one subpixel (subpixel 110B) in the top row (first row) and two subpixels (subpixel 110R and subpixel 110G) in the bottom row (second row).

[0346] Figure 23(D) is an example in which each sub-pixel has an approximately rectangular top surface shape with rounded corners, Figure 23(E) is an example in which each sub-pixel has a circular top surface shape, and Figure 23(F) is an example in which each sub-pixel has an approximately hexagonal top surface shape with rounded corners.

[0347] In Figure 23(F), each subpixel is arranged inside a densely arranged hexagonal region. Each subpixel is arranged so that it is surrounded by six other subpixels when focusing on one subpixel. Furthermore, subpixels that emit light of the same color are arranged so that they are not adjacent to each other. For example, when focusing on subpixel 110R, three subpixels 110G and three subpixels 110B are arranged alternately to surround it.

[0348] 23(G) shows an example in which subpixels of each color are arranged in a zigzag pattern. Specifically, when viewed from above, the positions of the upper sides of two subpixels aligned in the row direction (for example, subpixels 110R and 110G, or subpixels 110G and 110B) are misaligned.

[0349] 23(A) to 23(G), it is preferable that the subpixel 110R be the subpixel R that emits red light, the subpixel 110G be the subpixel G that emits green light, and the subpixel 110B be the subpixel B that emits blue light. Note that the configuration of the subpixels is not limited to this, and the colors that the subpixels emit and their order can be determined appropriately. For example, the subpixel 110G may be the subpixel R that emits red light, and the subpixel 110R may be the subpixel G that emits green light.

[0350] In the case of a so-called stripe arrangement as shown in Figures 5(A) and 23(G), the second electrodes 102 of light-emitting devices that emit the same light color can be formed continuously. In this case, even if processing is performed by photolithography after forming the second electrodes 102, voltage can be applied to each light-emitting device without the auxiliary electrodes 105. If processing by photolithography results in a configuration in which the second electrodes 102 are independent for each light-emitting device, it is preferable to form the auxiliary electrodes 105.

[0351] A connection portion 140 may be provided outside the pixel portion 177, and a region 141 may be provided. The region 141 is provided between the pixel portion 177 and the connection portion 140. The region 141 is provided with an organic compound layer 103. Furthermore, the connection portion 140 is provided with a conductive layer 151C.

[0352] 5A shows an example in which the region 141 and the connection portion 140 are located on the right side of the pixel portion 177, but the positions of the region 141 and the connection portion 140 are not particularly limited. The region 141 and the connection portion 140 may be singular or plural.

[0353] Fig. 5(B) is an example of a cross-sectional view taken along dashed line A1-A2 in Fig. 5(A). As shown in Fig. 5(A), 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 have openings that reach the conductive layer 172, and a plug 176 is provided to fill the opening.

[0354] In the pixel section 177, the light-emitting device 130 is provided on the insulating layer 175 and the plug 176. A protective layer 131 is provided to cover the light-emitting device 130. The substrate 120 is bonded to the protective layer 131 by a resin layer 122. Preferably, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are provided between adjacent light-emitting devices 130.

[0355] The insulating layer 127 can be made of acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, or precursors of these resins. The organic resin layer 180 can also be made of organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin.

[0356] Furthermore, a photosensitive resin can be used for the insulating layer 127. The photosensitive resin may be a photoresist. The photosensitive resin may be a positive-type material or a negative-type material.

[0357] The insulating layer 127 may contain a material that absorbs visible light. For example, the insulating layer 127 itself may be made of a material that absorbs visible light, or the insulating layer 127 may contain a pigment that absorbs visible light. For example, the insulating layer 127 may be made of a resin that can be used as a color filter that transmits red, blue, or green light and absorbs other light, or a resin that contains carbon black as a pigment and functions as a black matrix.

[0358] 5B shows multiple cross sections of the inorganic insulating layer 125 and the insulating layer 127, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are connected to one another when the display device is viewed from above. That is, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are insulating layers having openings over the first electrodes.

[0359] 5(B) shows light emitting device 130R, light emitting device 130G, and light emitting device 130B. Light emitting device 130R, light emitting device 130G, and light emitting device 130B emit light of different colors. For example, light emitting device 130R can emit red light, light emitting device 130G can emit green light, and light emitting device 130B can emit blue light. Light emitting device 130R, light emitting device 130G, or light emitting device 130B may also emit other visible light or infrared light.

[0360] The display device of one embodiment of the present invention can be, for example, a top-emission type that emits light in the direction opposite to the substrate on which the light-emitting device is formed. Note that the display device of one embodiment of the present invention may also be a bottom-emission type.

[0361] The light-emitting device 130R has the configuration described in Embodiments 1 and 2. It has a first electrode 101R (pixel electrode) composed of a conductive layer 151R and a conductive layer 152R, an organic compound layer 103R on the first electrode 101R, and a second electrode 102R on the organic compound layer 103R. The electron injection layer, which is the outermost layer of the organic compound layer 103R, and the second electrode 102R have the configurations described in Embodiments 1 and 2. This configuration can suppress damage to the light-emitting layer or active layer during the photolithography process, and can provide a light-emitting device 130R with good film quality and electrical characteristics.

[0362] The light-emitting device 130G has the configuration described in Embodiments 1 and 2. It includes a first electrode 101G (pixel electrode) composed of a conductive layer 151G and a conductive layer 152G, an organic compound layer 103G on the first electrode 101G, and a second electrode 102G on the organic compound layer 103G. The electron injection layer, which is the outermost layer of the organic compound layer 103G, and the second electrode 102G have the configurations described in Embodiments 1 and 2. This configuration can suppress damage to the light-emitting layer or active layer during the photolithography process, and can provide a light-emitting device 130G with good film quality and electrical characteristics.

[0363] The light-emitting device 130B has the configuration described in Embodiments 1 and 2. It has a first electrode 101B (pixel electrode) composed of a conductive layer 151B and a conductive layer 152B, an organic compound layer 103B on the first electrode 101B, and a second electrode 102B on the organic compound layer 103B. The electron injection layer, which is the outermost layer of the organic compound layer 103B, and the second electrode 102B have the configurations described in Embodiments 1 and 2. This configuration can suppress damage to the light-emitting layer or active layer during the photolithography process, and can provide a light-emitting device 130B with good film quality and electrical characteristics.

[0364] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independent island-like layers for each light-emitting device or each emitted color. It is preferable that the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B do not overlap with each other. By providing the organic compound layer 103 in an island-like shape for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in a high-resolution display device. This prevents crosstalk, enabling a display device with extremely high contrast to be realized. In particular, a display device with high current efficiency at low brightness can be realized.

[0365] The second electrodes 102R, 102G, and 102B are isolated in an island shape for each light-emitting device or for each row of the same emitted light color. It is preferable that the second electrodes 102R, 102G, and 102B do not overlap with each other.

[0366] It is preferable to form the auxiliary electrode 105 on the second electrode 102 after forming the insulating layer 127 to cover the side surface of the light-emitting device 130, because this makes it easier to supply a voltage to the second electrode 102. The auxiliary electrode 105 can be made of, for example, a metal material. 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), magnesium (Mg), and the like, as well as alloys containing appropriate combinations of these metals, can also be used.

[0367] The auxiliary electrode 105 may be formed of an oxide containing one or more selected from the group consisting of indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, it is preferable to use a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. When the light-emitting device 130 is a top-emission light-emitting device, it is preferable to use a light-transmitting conductive metal oxide as the auxiliary electrode 105.

[0368] The island-shaped organic compound layer 103 is formed by forming an organic compound film, forming the second electrode 102, and processing the organic compound film and the second electrode 102 by photolithography. Since the electron-injection layer and the second electrode of the light-emitting device of one embodiment of the present invention have the structures described in Embodiment 1, even when the second electrode 102 is formed and then processed by photolithography, the light-emitting device can have favorable characteristics in which an increase in driving voltage is suppressed. Furthermore, by forming the second electrode 102 and then processing it by photolithography, an inexpensive and reliable light-emitting device can be obtained.

[0369] In the display device of one embodiment of the present invention, the first electrode 101 (pixel electrode) of the light-emitting device preferably has a stacked-layer structure. For example, in the example shown in FIG. 5B, the first electrode 101 of the light-emitting device 130 has a stacked-layer structure of a conductive layer 151 (conductive layer 151R, conductive layer 151G, conductive layer 151B) provided on the insulating layer 171 side and a conductive layer 152 (conductive layer 152R, conductive layer 152G, conductive layer 152B) provided on the organic compound layer side.

[0370] For example, a metal material can be used for the conductive layer 151. Specifically, metals such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), neodymium (Nd), and the like, as well as alloys containing appropriate combinations of these metals, can also be used.

[0371] The conductive layer 152 can be formed using an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, it is preferable to use a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. In particular, indium tin oxide containing silicon has a large work function, for example, a work function of 4.0 eV or more, and therefore can be suitably used for the conductive layer 152.

[0372] The conductive layer 151 may have a stacked structure of multiple layers containing different materials, and the conductive layer 152 may have a stacked structure of multiple layers containing different materials. In this case, the conductive layer 151 may include a layer containing a material that can be used for the conductive layer 152, such as a conductive oxide, or the conductive layer 152 may include a layer containing a material that can be used for the conductive layer 151, such as a metal material. For example, when the conductive layer 151 has a stacked structure of two or more layers, a layer in contact with the conductive layer 152 can be a layer containing a material that can be used for the conductive layer 152.

[0373] 5B, the conductive layer 151 has a tapered edge. Specifically, the conductive layer 151 preferably has a tapered edge with a taper angle of less than 90°. In this case, the conductive layer 152 provided along the side surface of the conductive layer 151 also has a tapered edge. By tapering the side surface of the conductive layer 152, coverage of the organic compound layer 103 provided along the side surface of the conductive layer 152 can be improved.

[0374] The ends of the conductive layers 151 and 152 may not be tapered, that is, may be substantially vertical. Preferably, the ends of the organic compound layer 103 are located inside the first electrode 101. In this case, leakage current through the organic compound layer 103 can be reduced, and a display device with low driving voltage and excellent display performance can be obtained.

[0375] In the display device of one embodiment of the present invention, the light-emitting device 130 has the structure described in Embodiments 1 and 2, and therefore can be a highly reliable light-emitting device.

[0376] Next, an example of a method for manufacturing a display device having the structure shown in FIG. 5A will be described with reference to FIGS.

[0377] [Production method example 1] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, or the like.

[0378] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by wet film formation methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0379] Furthermore, when processing the thin films that constitute the display device, they can be processed using, for example, photolithography.

[0380] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, and ArF laser light. Exposure may also be performed using immersion exposure techniques. Extreme ultraviolet (EUV) light or X-rays may also be used as light for exposure. An electron beam may also be used instead of light for exposure.

[0381] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0382] 6(A), an insulating layer 171 is formed on a substrate (not shown). Subsequently, conductive layers 172 and 179 are formed on the insulating layer 171, and an insulating layer 173 is formed on the insulating layer 171 so as to cover the conductive layers 172 and 179. Subsequently, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

[0383] The substrate may be a substrate having heat resistance at least sufficient to withstand subsequent heat treatment, such as a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, a single crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate made of silicon germanium, or an SOI substrate.

[0384] 6A, openings are formed in the insulating layers 175, 174, and 173, reaching the conductive layer 172. Then, plugs 176 are formed to fill the openings.

[0385] 6A, a conductive film 151f, which will later become the conductive layers 151R, 151G, 151B, and 151C, and a conductive film 152f, which will later become the conductive layers 152R, 152G, 152B, and 152C, are formed on the plug 176 and the insulating layer 175. The conductive film 151f can be formed of, for example, a metal material. The conductive film 152f can be formed of, for example, an oxide containing one or more elements selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon.

[0386] 6A, a resist mask 191 is formed over the conductive film 152f. The resist mask 191 can be formed by applying a photosensitive material (photoresist), exposing it to light, and developing it.

[0387] 6B, for example, the conductive film 151f and the conductive film 152f are removed from regions that do not overlap with the resist mask 191. As a result, the conductive layer 151 and the conductive layer 152 are formed.

[0388] 6(C), the resist mask 191 is removed. The resist mask 191 can be removed by ashing using oxygen plasma, for example.

[0389] Next, as shown in FIG. 6(D), an insulating film 156f, which will later become insulating layers 156R, 156G, 156B, and 156C, is formed on conductive layer 152R, conductive layer 152G, conductive layer 152B, conductive layer 152C, and insulating layer 175.

[0390] The insulating film 156f can be an inorganic insulating film such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, or an insulating nitride oxide film, for example, a silicon oxynitride film.

[0391] Subsequently, as shown in FIG. 6(E), the insulating film 156f is processed to form an insulating layer 156R, an insulating layer 156G, an insulating layer 156B, and an insulating layer 156C.

[0392] 7(A), the organic compound film 103Rf is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the insulating layer 175. Note that, as shown in FIG. 7(A), the organic compound film 103Rf is not formed on the conductive layer 152C.

[0393] 7(A), a conductive film 102Rf serving as a second electrode is formed on the organic compound film 103Rf, and then a sacrificial film 158Rf and a mask film 159Rf are formed on the conductive film 102Rf. By forming the sacrificial film 158Rf and the mask film 159Rf on the organic compound film 103Rf via the conductive film 102Rf, 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.

[0394] When the second electrode 102 is an electrode from which light is extracted, the conductive film 102Rf is preferably made of a material that is transparent to visible light. For example, the reflectance of visible light is 20% or more and 80% or less, preferably 40% or more and 70% or less, and the resistivity is 1×10 -2 Examples of such a conductive material include a material with a resistivity of Ω·cm or less. When a material with low light transmittance, such as a metal or alloy, is used for the conductive film 102Rf, it may be formed to a thickness that allows visible light to pass through (for example, a thickness of 1 nm to 10 nm). Specifically, in addition to an oxide conductor layer typified by ITO, it includes an oxide semiconductor layer or an organic conductor layer containing an organic substance. Examples of organic conductor layers containing an organic substance include a layer containing a composite material obtained by mixing an organic compound and an electron donor (donor), and a layer containing a composite material obtained by mixing an organic compound and an electron acceptor (acceptor). The resistivity of the transparent conductive layer is preferably 1×10 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0395] The conductive film 102Rf can be formed by a dry method such as a vacuum deposition method or a sputtering method, an inkjet method, a spin coating method, or the like. Alternatively, the conductive film 102Rf may be formed by a wet method using a sol-gel method, or by a wet method using a metal material paste. In particular, the conductive film 102Rf formed on and in contact with the organic compound film 103Rf is preferably formed by a method that causes less damage to the organic compound film 103Rf. For example, the ALD method or the vacuum deposition method is preferable.

[0396] The sacrificial film 158Rf and the mask film 159Rf are provided as needed. For example, if the conductive film 102Rf can sufficiently protect the organic compound film 103Rf, the mask film 159Rf can be formed on the conductive film 102Rf, thereby eliminating the step of forming the sacrificial film 158Rf. Furthermore, if the etching selectivity between the organic compound film 103Rf and the conductive film 102Rf and between the conductive film 102Rf and the sacrificial film 158Rf are both sufficiently large, the sacrificial film 158Rf can be used as a mask, and the step of forming the mask film 159Rf may be omitted.

[0397] The sacrificial film 158Rf is made of a film that is highly resistant to the processing conditions of the organic compound film 103Rf, specifically, a film that has a high etching selectivity with respect to the organic compound film 103Rf.The mask film 159Rf is made of a film that has a high etching selectivity with respect to the sacrificial film 158Rf.

[0398] The conductive film 102Rf, the sacrificial film 158Rf, and the mask film 159Rf are preferably formed at a temperature lower than the heat resistance temperature of the organic compound film 103Rf. The substrate temperature during the formation of the sacrificial film 158Rf and the mask film 159Rf is typically 100° C. to 200° C., preferably 100° C. to 150° C., and more preferably 100° C. to 120° C. The light-emitting device of one embodiment of the present invention includes the first compound, and therefore can provide a display device with good display quality even after a heating step at a higher temperature.

[0399] It is preferable to use a film that can be removed by wet etching or dry etching for the sacrificial film 158Rf and the mask film 159Rf.

[0400] It is preferable that the sacrificial film 158Rf has a denser film quality than the mask film 159Rf. For example, the ALD method or the vacuum deposition method is more preferable than the sputtering method.

[0401] The sacrificial film 158Rf and the mask film 159Rf may each be made of one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, an inorganic insulating film, or the like.

[0402] The sacrificial film 158Rf and the mask film 159Rf can be made of metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metal materials. It is particularly preferable to use a low-melting-point material such as aluminum or silver. Using a metal material capable of blocking ultraviolet rays for one or both of the sacrificial film 158Rf and the mask film 159Rf is preferable because it can prevent the organic compound film 103Rf from being irradiated with ultraviolet rays during pattern exposure, thereby suppressing deterioration of the organic compound film 103Rf.

[0403] Furthermore, the sacrificial film 158Rf and the mask film 159Rf can be made of metal oxides such as In-Ga-Zn oxide, indium oxide, In-Zn oxide, In-Sn oxide, indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), and indium tin oxide containing silicon, respectively.

[0404] In addition, in the above metal oxide, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used instead of gallium.

[0405] The sacrificial film 158Rf and the mask film 159Rf are preferably made of a semiconductor material such as silicon or germanium, which has a high affinity with the semiconductor manufacturing process, or a compound containing the semiconductor material.

[0406] Moreover, various inorganic insulating films can be used for the sacrificial film 158Rf and the mask film 159Rf, respectively. In particular, an oxide insulating film is preferable because it has higher adhesion to the organic compound film 103Rf than a nitride insulating film.

[0407] 7A, a resist mask 190R is formed. The resist mask 190R can be formed by applying a photosensitive material (photoresist) and then exposing and developing it.

[0408] The resist mask 190R is provided in a position overlapping with the conductive layer 152R. The resist mask 190R is preferably provided also in a position overlapping with the conductive layer 152C, which can prevent the conductive layer 152C from being damaged during the manufacturing process of the display device.

[0409] 7(B), a resist mask 190R is used to remove part of the mask film 159Rf to form a mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. The resist mask 190R is then removed. The mask layer 159R is used as a mask (also referred to as a hard mask) to remove part of the sacrificial film 158Rf and the conductive film 102Rf to form a sacrificial layer 158R and a second electrode 102R.

[0410] By using the wet etching method, damage to the organic compound film 103Rf can be reduced when processing the conductive film 102Rf, the sacrificial film 158Rf, and the mask film 159Rf compared to when using the dry etching method. When using the wet etching method, it is preferable to use an acid aqueous solution such as a developer, an alkaline aqueous solution such as a tetramethylammonium hydroxide aqueous solution (TMAH), or a chemical solution using dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture of these.

[0411] Furthermore, when dry etching is used to process the sacrificial film 158Rf and the conductive film 102Rf, deterioration of the organic compound film 103Rf can be suppressed by not using a gas containing oxygen as the etching gas.

[0412] The resist mask 190R can be removed in the same manner as the resist mask 191.

[0413] 7(B), the organic compound film 103Rf is processed to form the organic compound layer 103R. For example, the mask layer 159R and the sacrificial layer 158R are used as hard masks to remove a part of the conductive film 102Rf and a part of the organic compound film 103Rf, thereby forming the organic compound layer 103R.

[0414] 7B, a stacked structure of the organic compound layer 103R, the second electrode 102R, the sacrificial layer 158R, and the mask layer 159R remains on the conductive layer 152R. Also, the conductive layers 152G and 152B are exposed.

[0415] The organic compound film 103Rf is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0416] When dry etching is used, deterioration of the organic compound film 103Rf can be suppressed by not using an oxygen-containing gas as the etching gas.

[0417] Alternatively, an etching gas containing oxygen may be used. The etching rate can be increased by using an etching gas containing oxygen. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate. This can reduce damage to the organic compound film 103Rf. Furthermore, problems such as adhesion of reaction products generated during etching can be reduced.

[0418] When dry etching is used, it is preferable to use a gas containing one or more of H, CF, C, F, SF, CHF, Cl, H, O, BCl, or Group 18 elements such as He and Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of these elements and oxygen as the etching gas. Alternatively, oxygen gas may be used as the etching gas.

[0419] Subsequently, as shown in FIG. 8A, an organic compound film 103Gf, which will later become the organic compound layer 103G, and a conductive film 102Gf, which will later become the second electrode 102G, are formed.

[0420] The organic compound film 103Gf can be formed by a method similar to that used to form the organic compound film 103Rf. The organic compound film 103Gf can have the same structure as the organic compound film 103Rf. The conductive film 102Gf can be formed by a method similar to that used to form the conductive film 102Rf. The conductive film 102Gf can have the same structure as the conductive film 102Rf.

[0421] Next, as shown in FIG. 8A, a sacrificial film 158Gf and a mask film 159Gf are formed in this order. Then, a resist mask 190G is formed. The materials and forming methods of the sacrificial film 158Gf and the mask film 159Gf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and forming methods of the resist mask 190G are the same as those applicable to the resist mask 190R.

[0422] The resist mask 190G is provided in a position overlapping with the conductive layer 152G.

[0423] 8(B), a resist mask 190G is used to remove a portion of the mask film 159Gf to form a mask layer 159G. The mask layer 159G remains on the conductive layer 152G. The resist mask 190G is then removed. Next, using the mask layer 159G as a mask, a portion of the sacrificial film 158Gf and a portion of the conductive film 102Gf are removed to form a sacrificial layer 158G and a second electrode 102G. Next, the organic compound film 103Gf is processed to form an organic compound layer 103G.

[0424] Subsequently, as shown in FIG. 8C, an organic compound film 103Bf and a conductive film 102Bf that will later become the second electrode 102B are formed.

[0425] The organic compound film 103Bf can be formed by a method similar to that used to form the organic compound film 103Rf. The organic compound film 103Bf can have the same structure as the organic compound film 103Rf. The conductive film 102Bf can be formed by a method similar to that used to form the conductive film 102Rf. The conductive film 102Bf can have the same structure as the conductive film 102Rf.

[0426] 8(C), a sacrificial film 158Bf and a mask film 159Bf are formed in this order. Then, a resist mask 190B is formed. The materials and forming methods of the sacrificial film 158Bf and the mask film 159Bf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and forming methods of the resist mask 190B are the same as those applicable to the resist mask 190R.

[0427] The resist mask 190B is provided in a position overlapping with the conductive layer 152B.

[0428] 8(D), a resist mask 190B is used to remove a portion of the mask film 159Bf to form a mask layer 159B. The mask layer 159B remains on the conductive layer 152B. The resist mask 190B is then removed. Using the mask layer 159B as a mask, a portion of the sacrificial film 158Bf and a portion of the conductive film 102Bf are removed to form the sacrificial layer 158B and the second electrode 102B. The organic compound film 103Bf is then processed to form the organic compound layer 103B. For example, using the mask layer 159B and the sacrificial layer 158B as a hard mask, a portion of the organic compound film 103Bf is removed to form the organic compound layer 103B.

[0429] 8D, a stacked structure of the organic compound layer 103B, the second electrode 102B, the sacrificial layer 158B, and the mask layer 159B remains on the conductive layer 152B, and the mask layers 159R and 159G are exposed.

[0430] Note that the side surfaces of the stacked structure of the organic compound layer 103R and the second electrode 102R, the stacked structure of the organic compound layer 103G and the second electrode 102G, and the stacked structure of the organic compound layer 103B and the second electrode 102B are preferably perpendicular or approximately perpendicular to the surface on which the layers are to be formed. For example, the angle formed between the surface on which the layers are to be formed and these side surfaces is preferably 60 degrees or more and 90 degrees or less.

[0431] As described above, the distance between adjacent layers among the stacked structures of the organic compound layer 103R and the second electrode 102R, the stacked structure of the organic compound layer 103G and the second electrode 102G, and the stacked structure of the organic compound layer 103B and the second electrode 102B formed using a photolithography method can be narrowed to 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. Here, the distance can be defined, for example, as the distance between adjacent opposing ends of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B. By narrowing the distance between the island-shaped organic compound layers in this way, a display device with high definition and a large aperture ratio can be provided. Furthermore, the distance between the first electrodes of adjacent light-emitting devices can also be narrowed, for example, to 10 μm or less, 8 μm or less, 5 μm or less, 3 μm or less, or 2 μm or less. The distance between the first electrodes of adjacent light-emitting devices is preferably 2 μm or more and 5 μm or less.

[0432] Subsequently, as shown in FIG. 9(A), it is preferable to remove the mask layers 159R, 159G, and 159B.

[0433] When the light-emitting devices are arranged in a stripe configuration as shown in FIG. 23(G), the second electrode 102 can be formed as a continuous layer for light-emitting devices emitting the same light. In this case, the auxiliary electrode 105 (described later) does not need to be formed. Therefore, in the case of bottom emission, the mask layer 159 does not need to be removed, and the process can proceed to the process of FIG. 11(B) after the process of FIG. 8(D). In the case of top emission, if the sacrificial layer 158 and the mask layer 159 are light-transmitting, they do not need to be removed, and the process can proceed to the process of FIG. 11(B) after the process of FIG. 8(D). If they are not light-transmitting, it is preferable to remove the sacrificial layer 158 and the mask layer 159. After removing the sacrificial layer 158 and / or the mask layer 159 (after the process of FIG. 9(A)), the process can proceed to the process of FIG. 11(B).

[0434] The mask layer removal process can be performed using the same method as the mask film processing process. In particular, by using a wet etching method, damage to the organic compound layer 103 during the mask layer removal can be reduced compared to when a dry etching method is used.

[0435] The mask layer may also be removed by dissolving it in a polar solvent such as water or alcohol, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0436] After removing the mask layer, a drying treatment may be performed to remove water adsorbed on the surface. For example, a heat treatment can be performed in an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced pressure atmosphere is preferred because it allows drying at a lower temperature.

[0437] Subsequently, as shown in FIG. 9(B), an inorganic insulating film 125f is formed.

[0438] Subsequently, as shown in FIG. 9(C), an insulating film 127f, which will later become the insulating layer 127, is formed on the inorganic insulating film 125f.

[0439] The substrate temperature when forming the inorganic insulating film 125f and the insulating film 127f is preferably 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher, and 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower, respectively.

[0440] As the inorganic insulating film 125f, it is preferable to form an insulating film having a thickness of 3 nm or more, 5 nm or more, or 10 nm or more, and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less within the above substrate temperature range.

[0441] The inorganic insulating film 125f is preferably formed by, for example, the ALD method. The ALD method is preferable because it can reduce film formation damage and form a film with high coverage. The inorganic insulating film 125f is preferably formed as an aluminum oxide film by, for example, the ALD method.

[0442] The insulating film 127f is preferably formed by the wet film formation method described above. The insulating film 127f is preferably formed by, for example, spin coating using a photosensitive material, more specifically, using a photosensitive resin composition containing an acrylic resin.

[0443] Subsequently, exposure is performed to expose a part of the insulating film 127f to visible light or ultraviolet light. The insulating layer 127 is formed in a region sandwiched between any two of the conductive layers 152R, 152G, and 152B, and around the conductive layer 152C.

[0444] The exposed region of the insulating film 127f can control the width of the insulating layer 127 to be formed later. In this embodiment, the insulating layer 127 is processed so as to have a portion overlapping the upper surface of the conductive layer 151.

[0445] The light used for exposure preferably contains i-line (wavelength 365 nm), and may contain at least one of g-line (wavelength 436 nm) and h-line (wavelength 405 nm).

[0446] Subsequently, as shown in FIG. 10(A), development is carried out to remove the exposed area of ​​the insulating film 127f, thereby forming the insulating layer 127a.

[0447] 10(B), an etching process is performed using the insulating layer 127a as a mask to remove a portion of the inorganic insulating film 125f. If the sacrificial layer 158 is left, the thicknesses of the sacrificial layers 158R, 158G, and 158B are reduced. This results in the inorganic insulating layer 125 being formed below the insulating layer 127a. Furthermore, the surfaces of the thin portions of the sacrificial layers 158R, 158G, and 158B are exposed. Hereinafter, the etching process using the insulating layer 127a as a mask may be referred to as the first etching process.

[0448] The first etching process can be performed by dry etching or wet etching. Note that if the inorganic insulating film 125f is formed using the same material as the sacrificial layers 158R, 158G, and 158B, the first etching process can be performed all at once, which is preferable. Furthermore, if the sacrificial layer 158 is not formed, the surfaces of the second electrode 102R, the second electrode 102B, and the second electrode 102G are exposed by the first etching process.

[0449] When dry etching is performed, it is preferable to use a chlorine-based gas. Examples of chlorine-based gases that can be used include Cl2, BCl3, SiCl4, and CCl4, either singly or in combination. Furthermore, oxygen gas, hydrogen gas, helium gas, and argon gas can be added to the chlorine-based gas, either singly or in combination. For example, if the sacrificial layer 158 is left, dry etching can be used to form thin-film regions of the sacrificial layers 158R, 158G, and 158B with good in-plane uniformity.

[0450] The dry etching apparatus may be a dry etching apparatus having a high-density plasma source, such as an inductively coupled plasma (ICP) etching apparatus, or a capacitively coupled plasma (CCP) etching apparatus having parallel plate electrodes.

[0451] Furthermore, it is preferable to perform the first etching process by wet etching. By using the wet etching method, damage to the structure to be processed can be reduced compared to when using the dry etching method. For example, the wet etching can be performed using an alkaline solution. For example, TMAH, which is an alkaline solution, can be used for wet etching of an aluminum oxide film. Alternatively, an acid solution containing fluoride can also be used. In this case, the wet etching can be performed by the paddle method. Note that if the inorganic insulating film 125f is formed using the same material as the sacrificial layers 158R, 158G, and 158B, the above etching process can be performed all at once, which is preferable.

[0452] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, and the etching process is stopped when the film thicknesses become thin. In this way, by leaving the corresponding sacrificial layers 158R, 158B, and 158G on the second electrodes 102R, 102B, and 102G, it is possible to prevent the structure including the organic compound layer 103 from being damaged in a subsequent process.

[0453] Next, the entire substrate is exposed to visible light or ultraviolet light, and the insulating layer 127a is preferably irradiated with the energy density of 0 mJ / cm. 2 Larger, 800mJ / cm 2 It is preferable that the dose is 0 mJ / cm or less, and 2 Larger, 500mJ / cm 2It is more preferable to perform the following. By performing such exposure after development, the transparency of the insulating layer 127a can be improved in some cases. Furthermore, the substrate temperature required for heat treatment to transform the insulating layer 127a into a tapered shape in a later step can be reduced in some cases.

[0454] Here, the presence of a barrier insulating layer against oxygen (e.g., an aluminum oxide film, etc.) as sacrificial layer 158R, sacrificial layer 158G, and sacrificial layer 158B can reduce the diffusion of oxygen into second electrode 102R, second electrode 102B, and second electrode 102G, or the decrease in conductivity due to metal oxidation.

[0455] Next, heat treatment (also referred to as post-baking) is performed. By performing the heat treatment, the insulating layer 127a can be transformed into the insulating layer 127 having tapered side surfaces (FIG. 10C). The heat treatment is performed at a temperature lower than the upper temperature limit of the organic compound layer. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., more preferably 70° C. to 130° C. The heating atmosphere may be an air atmosphere or an inert gas atmosphere. The heating atmosphere may be an atmospheric pressure atmosphere or a reduced-pressure atmosphere. This can improve adhesion between the insulating layer 127 and the inorganic insulating layer 125 and also improve the corrosion resistance of the insulating layer 127.

[0456] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, and the sacrificial layers 158R, 158G, and 158B are left in a reduced thickness state, thereby preventing the processed structure including the organic compound layer 103 from being damaged and deteriorated in the heat treatment, thereby improving the reliability of the light-emitting device.

[0457] 11(A), an etching process is performed using the insulating layer 127 as a mask. If the sacrificial layer 158 is left, portions of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B are removed. As a result, openings are formed in the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, respectively, and the upper surfaces of the second electrode 102R, the second electrode 102B, the second electrode 102G, and the conductive layer 152C are exposed. Note that, hereinafter, this etching process may be referred to as a second etching process.

[0458] If the sacrificial layer 158 is not formed, the surfaces of the second electrode 102R, the second electrode 102B, and the second electrode 102G are exposed by the first etching process, and therefore the second etching process described below can be omitted.

[0459] The end of inorganic insulating layer 125 is covered with insulating layer 127. Furthermore, if sacrificial layer 158 is left, part of the end of sacrificial layer 158G (specifically, the tapered portion formed by the first etching process) is covered with insulating layer 127, and the tapered portion formed by the second etching process is exposed.

[0460] The second etching process is performed by wet etching. By using wet etching, damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be reduced compared to when dry etching is used. Wet etching can be performed using, for example, an alkaline solution or an acidic solution. It is preferable to use an aqueous solution so that the organic compound layer 103 does not dissolve.

[0461] 11(B), an auxiliary electrode 105 is formed on the second electrode 102R, the second electrode 102B, the second electrode 102G, the conductive layer 152C, and the insulating layer 127. The auxiliary electrode 105 can be formed by a method such as sputtering or vacuum deposition.

[0462] 11(B), a protective layer 131 is formed on the auxiliary electrode 105. The protective layer 131 can be formed by a method such as vacuum deposition, sputtering, CVD, or ALD.

[0463] Subsequently, the substrate 120 is attached over the protective layer 131 using the resin layer 122, whereby a display device can be manufactured. As described above, in the method for manufacturing a display device of one embodiment of the present invention, the insulating layer 156 (insulating layer 156R, insulating layer 156G, insulating layer 156B) is provided so as to have a region overlapping with a side surface of the conductive layer 151, and the conductive layer 152 is formed so as to cover the conductive layer 151 and the insulating layer 156. This can increase the yield of the display device and suppress the occurrence of defects.

[0464] As described above, in the manufacturing method of a display device according to one embodiment of the present invention, the island-shaped organic compound layers 103R, 103G, and 103B are formed by forming films over the entire surface and then processing them, rather than using a fine metal mask. This allows the island-shaped layers to be formed with uniform thicknesses. This allows a high-resolution display device or a display device with a high aperture ratio to be realized. Furthermore, even when the resolution or aperture ratio is high and the distance between subpixels is extremely short, the organic compound layers 103R, 103G, and 103B can be prevented from contacting each other in adjacent subpixels. Therefore, leakage current between subpixels can be suppressed. This prevents crosstalk and realizes a display device with extremely high contrast. Furthermore, even in a display device including tandem light-emitting devices fabricated by photolithography, a display device with excellent characteristics can be provided.

[0465] (Fourth embodiment) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0466] The display device of the present embodiment can be a high-definition display device, and can therefore be used as a display unit for information terminals (wearable devices) such as wristwatches and bracelets, as well as for wearable devices that can be worn on the head, such as VR devices such as head-mounted displays (HMDs) and AR devices such as glasses.

[0467] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproducing devices.

[0468] [Display module] 12A shows a perspective view of a display module 280. The display module 280 has a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A, and may be either a display device 100B or a display device 100E, which will be described later.

[0469] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel unit 284 (described later) can be viewed.

[0470] 12(B) is a perspective view schematically showing the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0471] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of Fig. 12(B). The various configurations described in the previous embodiments can be applied to the pixel 284a. Fig. 12(B) shows an example in which the pixel 284a has the same configuration as the pixel 178 shown in Fig. 5.

[0472] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0473] One pixel circuit 283a is a circuit that controls the driving of a plurality of elements included in one pixel 284a.

[0474] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a gate line driver circuit and a source line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0475] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may be mounted on the FPC 290.

[0476] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby making it possible to extremely increase the aperture ratio (effective display area ratio) of the display unit 281.

[0477] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as HMDs or glasses-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so that even if the display unit is enlarged with the lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this and can be suitably used in electronic devices having relatively small display units.

[0478] [Display device 100A] The display device 100A shown in FIG. 13A 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.

[0479] The substrate 301 corresponds to the substrate 291 in FIGS. 12A and 12B. The transistor 310 has a channel formation region in the substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities and functions as a source or drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0480] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0481] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0482] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 located therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0483] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0484] An insulating layer 255 is provided to cover the capacitor 240, an insulating layer 174 is provided on the insulating layer 255, and an insulating layer 175 is provided on the insulating layer 174. Light-emitting device 130R, light-emitting device 130G, and light-emitting device 130B are provided on the insulating layer 175. An insulator is provided in the region between adjacent light-emitting devices.

[0485] Insulating layer 156R is provided to have a region overlapping with a side surface of conductive layer 151R, insulating layer 156G is provided to have a region overlapping with a side surface of conductive layer 151G, and insulating layer 156B is provided to have a region overlapping with a side surface of conductive layer 151B. Furthermore, conductive layer 152R is provided to cover conductive layer 151R and insulating layer 156R, conductive layer 152G is provided to cover conductive layer 151G and insulating layer 156G, and conductive layer 152B is provided to cover conductive layer 151B and insulating layer 156B. Note that insulating layer 156 does not necessarily have to be provided.

[0486] The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B are electrically connected to one of the source and drain of the transistor 310 via an insulating layer 243, an insulating layer 255, an insulating layer 174, a plug 256 embedded in the insulating layer 175, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261. Various conductive materials can be used for the plug.

[0487] Furthermore, a protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B via an auxiliary electrode 105. A substrate 120 is bonded to the protective layer 131 by a resin layer 122. For details of the components from the light-emitting devices 130 to the substrate 120, refer to embodiment 3. The substrate 120 corresponds to the substrate 292 in FIG. 12(A).

[0488] Fig. 13(B) is a modified example of the display device 100A shown in Fig. 13(A). The display device shown in Fig. 13(B) has a colored layer 132R, a colored layer 132G, and a colored layer 132B, and the light-emitting device 130 has an area where it overlaps with one of the colored layer 132R, the colored layer 132G, and the colored layer 132B. In the display device shown in Fig. 13(B), the light-emitting device 130 can emit, for example, white light. Furthermore, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light.

[0489] [Display device 100B] FIG. 14 shows a perspective view of the display device 100B, and FIG. 15 shows a cross-sectional view of the display device 100B.

[0490] The display device 100B has a configuration in which a substrate 352 and a substrate 351 are bonded together. In Fig. 14, the substrate 352 is indicated by a dashed line.

[0491] The display device 100B has a pixel portion 177, a connection portion 140, a circuit 356, wiring 355, etc. Fig. 14 shows an example in which an IC 354 and an FPC 353 are mounted on the display device 100B. Therefore, the configuration shown in Fig. 14 can also be called a display module having the display device 100B, an IC (integrated circuit), and an FPC. Here, a display device having a connector such as an FPC attached to a substrate, or a display device having an IC mounted on the substrate, is called a display module.

[0492] The connection section 140 is provided outside the pixel section 177. There may be one or more connection sections 140. The connection section 140 electrically connects the common electrode of the light-emitting device and the conductive layer, and can supply a potential to the common electrode.

[0493] The circuit 356 can be, for example, a scanning line driver circuit.

[0494] The wiring 355 has a function of supplying signals and power to the pixel portion 177 and the circuit 356. The signals and power are input to the wiring 355 from the outside via the FPC 353 or from the IC 354.

[0495] 14 shows an example in which an IC 354 is provided on a substrate 351 by a COG (Chip On Glass) method or a COF (Chip on Film) method. The IC 354 may be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 100B and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by, for example, a COF method.

[0496] FIG. 15 shows an example of a cross section of the display device 100C, taken along a line including a part of the region including the FPC 353, a part of the circuit 356, a part of the pixel portion 177, and a part of the connection portion 140. In FIG.

[0497] [Display device 100C] The display device 100C shown in Figure 15 has, between a substrate 351 and a substrate 352, a transistor 201, a transistor 205, a light-emitting device 130R that emits red light, a light-emitting device 130G that emits green light, and a light-emitting device 130B that emits blue light, etc.

[0498] For details of the light emitting devices 130R, 130G, and 130B, refer to the first embodiment or the second embodiment.

[0499] Light-emitting device 130R has conductive layer 224R, conductive layer 151R on conductive layer 224R, and conductive layer 152R on conductive layer 151R. Light-emitting device 130G has conductive layer 224G, conductive layer 151G on conductive layer 224G, and conductive layer 152G on conductive layer 151G. Light-emitting device 130B has conductive layer 224B, conductive layer 151B on conductive layer 224B, and conductive layer 152B on conductive layer 151B.

[0500] The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. An end of the conductive layer 151R is located outside an end of the conductive layer 224R. An insulating layer 156R is provided to have a region in contact with a side surface of the conductive layer 151R, and a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R.

[0501] Conductive layer 224G, conductive layer 151G, conductive layer 152G, and insulating layer 156G in light-emitting device 130G, and conductive layer 224B, conductive layer 151B, conductive layer 152B, and insulating layer 156B in light-emitting device 130B are similar to conductive layer 224R, conductive layer 151R, conductive layer 152R, and insulating layer 156R in light-emitting device 130R, and therefore detailed description thereof will be omitted.

[0502] Recesses are formed in the conductive layers 224R, 224G, and 224B so as to cover the openings provided in the insulating layer 214. A layer 128 is buried in the recesses.

[0503] Layer 128 has the function of filling in recesses in conductive layer 224R, conductive layer 224G, and conductive layer 224B and planarizing the surface. Conductive layers 151R, 151G, and 151B, which are electrically connected to conductive layer 224R, conductive layer 224G, and conductive layer 224B, are provided on conductive layer 224R, conductive layer 224G, and conductive layer 224B and layer 128. Therefore, the regions overlapping with the recesses in conductive layer 224R, conductive layer 224G, and conductive layer 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixel.

[0504] The layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be used for the layer 128 as appropriate. In particular, the layer 128 is preferably formed using an insulating material, and is particularly preferably formed using an organic insulating material. For example, the organic insulating materials that can be used for the insulating layer 127 described above can be used for the layer 128.

[0505] A protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B via an auxiliary electrode 105. The protective layer 131 and the substrate 352 are bonded together via an adhesive layer 142. A light-shielding layer 157 is provided on the substrate 352. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting device 130. In FIG. 15, the space between the substrates 352 and 351 is filled with the adhesive layer 142, thereby applying a solid sealing structure. Alternatively, the space may be filled with an inert gas (nitrogen, argon, etc.), thereby applying a hollow sealing structure. In this case, the adhesive layer 142 may be provided so as not to overlap with the light-emitting devices. Alternatively, the space may be filled with a resin different from the frame-shaped adhesive layer 142.

[0506] 15 shows an example in which connecting portion 140 has conductive layer 224C obtained by processing the same conductive film as conductive layers 224R, 224G, and 224B, conductive layer 151C obtained by processing the same conductive film as conductive layers 151R, 151G, and 151B, and conductive layer 152C obtained by processing the same conductive film as conductive layers 152R, 152G, and 152B. Also shown in FIG. 15 is an example in which insulating layer 156C is provided so as to have a region overlapping with a side surface of conductive layer 151C.

[0507] The display device 100C is a top-emission type. Light emitted by the light-emitting device is emitted toward the substrate 352. The substrate 352 is preferably made of a material that is highly transparent to visible light. The pixel electrode contains a material that reflects visible light, and the counter electrode (second electrode 102) and auxiliary electrode 105 contain a material that transmits visible light.

[0508] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 351 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0509] The insulating layers 211, 213, and 215 are each preferably formed using an inorganic insulating film.

[0510] The insulating layer 214, which functions as a planarizing layer, is preferably an organic insulating layer.

[0511] The transistor 201 and the transistor 205 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a conductive layer 222a and a conductive layer 222b functioning as a source and a drain, a semiconductor layer 231, an insulating layer 213 functioning as a gate insulating layer, and a conductive layer 223 functioning as a gate.

[0512] A connection portion 204 is provided in a region of the substrate 351 where the substrate 352 does not overlap. In the connection portion 204, a source electrode or a drain electrode of the transistor 201 is electrically connected to the FPC 353 via a conductive layer 166 and a connection layer 242. The conductive layer 166 has an example of a stacked structure including a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. The conductive layer 166 is exposed on the top surface of the connection portion 204. This allows the connection portion 204 and the FPC 353 to be electrically connected via the connection layer 242.

[0513] It is preferable to provide a light-shielding layer 157 on the surface of the substrate 352 facing the substrate 351. The light-shielding layer 157 can be provided between adjacent light-emitting devices, on the connection section 140, on the circuit 356, etc. Also, various optical members can be arranged on the outside of the substrate 352.

[0514] The substrate 351 and the substrate 352 can be made of the same material as can be used for the substrate 120 .

[0515] The adhesive layer 142 can be made of a material that can be used for the resin layer 122 .

[0516] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0517] [Display device 100D] The display device 100D shown in FIG. 16 differs from the display device 100C shown in FIG. 15 mainly in that it is a bottom-emission display device.

[0518] Light emitted from the light emitting device is emitted toward the substrate 351. It is preferable that a material with high transparency to visible light is used for the substrate 351. On the other hand, the light transparency of the material used for the substrate 352 is not an issue.

[0519] A light-shielding layer 317 is preferably formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205. Figure 16 shows an example in which the light-shielding layer 317 is provided over the substrate 351, the insulating layer 153 is provided over the light-shielding layer 317, and the transistors 201, 205, etc. are provided over the insulating layer 153.

[0520] Light emitting device 130R includes conductive layer 112R, conductive layer 126R on conductive layer 112R, and conductive layer 129R on conductive layer 126R.

[0521] Light emitting device 130B includes conductive layer 112B, conductive layer 126B on conductive layer 112B, and conductive layer 129B on conductive layer 126B.

[0522] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are each made of a material that is highly transparent to visible light. The second electrode 102 is preferably made of a material that reflects visible light.

[0523] Although the light emitting device 130G is not shown in FIG. 16, the light emitting device 130G is also provided.

[0524] In addition, although FIG. 16 and other figures show an example in which the top surface of the layer 128 has a flat portion, the shape of the layer 128 is not particularly limited.

[0525] [Display device 100D2] The display device 100D2 shown in Fig. 17(A) is an example of a bottom-emission type display device that differs from the display device 100D shown in Fig. 16. The display device 100D2 differs from the display device 100D in that it has an organic resin layer 180. Note that in the drawing, the reference numerals of the same components as those in Fig. 16 may be omitted, and the description in Fig. 16 can be referred to for details.

[0526] 17(B) shows a top view layout of pixel 178 (pixel 178a and pixel 178b) having subpixels 110 (subpixels 110R, 110G, and 110B), and Fig. 17(C) shows a top view of organic resin layer 180 in a region where subpixels 110R and 110G of pixel 178 are formed. Note that the distance between light-shielding layers 317 is 110Rw in the light-emitting region of subpixel 110R.

[0527] As shown in FIG. 17(A), the organic resin layer 180 is provided on the insulating layer 214. As shown in the region surrounded by the dashed line in FIG. 17(A) and in FIG. 17(C), the organic resin layer 180 has curved recesses 181 (recesses 181a and 181b) at least in the region where the subpixels are formed. The recesses 181 may be provided outside the light-emitting region, such as recess 181c. By providing recess 181c, light emitted in the region overlapping with the light-shielding layer 317 or light traveling to the region overlapping with the light-shielding layer 317 is refracted and can be extracted from the light-emitting region, thereby improving the light-emitting efficiency.

[0528] A plurality of recesses 181 may be formed in a matrix. Recesses 181a and 181b may be provided in contact with each other, or may have a flat surface between them.

[0529] Although the upper surface shape of the recess is shown as a hexagon (FIG. 17(C)) and the cross-sectional shape is shown as a semicircle (FIG. 17(A)), other shapes may be used as needed. For example, the upper surface shape of the recess may be a polygon such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any of these polygons with rounded corners, an ellipse, or a circle.

[0530] An insulating layer containing an organic material can be used as the organic resin layer 180. For example, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, precursors of these resins, etc. can be used as the organic resin layer 180. Alternatively, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used as the organic resin layer 180.

[0531] Furthermore, a photosensitive resin can be used as the organic resin layer 180. A photoresist can be used as the photosensitive resin. The photosensitive resin can be a positive type material or a negative type material.

[0532] The organic resin layer 180 may contain a material that absorbs visible light. For example, the organic resin layer 180 itself may be made of a material that absorbs visible light, or the organic resin layer 180 may contain a pigment that absorbs visible light. For example, the organic resin layer 180 may be made of a resin that can be used as a color filter that transmits red, blue, or green light and absorbs other light, or a resin that contains carbon black as a pigment and functions as a black matrix.

[0533] In addition, a first electrode 101 is provided on the organic resin layer 180, an organic compound layer 103 is provided on the first electrode 101, and a second electrode 102 is provided on the organic compound layer 103. Ends of the first electrode 101, the organic compound layer 103, and the second electrode 102 may be covered with an insulating layer 127.

[0534] Furthermore, the first electrode 101 formed on the organic resin layer 180 has a recess similar to the recess of the organic resin layer 180. Furthermore, the organic compound layer 103 formed on the first electrode 101 has a recess similar to the recess of the first electrode 101. Furthermore, the second electrode 102 formed on the organic compound layer 103 has a recess similar to the recess of the organic compound layer 103. Furthermore, the auxiliary electrode 105 formed on the second electrode 102 has a recess similar to the recess of the second electrode 102. That is, the recesses of the organic resin layer 180, the first electrode 101, the organic compound layer 103, the second electrode 102, and the auxiliary electrode 105 overlap one another.

[0535] In addition, a second electrode 102 is provided over the organic compound layer 103 and the insulating layer 127, and an auxiliary electrode 105 is provided over the second electrode 102. A protective layer 131 is provided over the auxiliary electrode 105, and the auxiliary electrode 105 is bonded to a substrate 352 with an adhesive layer 142 interposed therebetween.

[0536] Although light emitting device 130G and light emitting device 130B are not shown in FIG. 17, light emitting device 130G and light emitting device 130B are also provided.

[0537] The light-emitting device according to one embodiment of the present invention, which includes the organic resin layer 180 as described above, has the structure described in Embodiment 1 or 2. As a result, an organic semiconductor device with low driving voltage and excellent characteristics can be provided.

[0538] [Display device 100E] The display device 100E shown in FIG. 18 is a modification of the display device 100C shown in FIG. 15, and differs from the display device 100C mainly in that it has colored layers 132R, 132G, and 132B.

[0539] In the display device 100E, the light-emitting device 130 has an area that overlaps one of the colored layer 132R, the colored layer 132G, and the colored layer 132B. The colored layer 132R, the colored layer 132G, and the colored layer 132B can be provided on the surface of the substrate 352 facing the substrate 351. An end of the colored layer 132R, an end of the colored layer 132G, and an end of the colored layer 132B can overlap the light-shielding layer 157.

[0540] In the display device 100E, for example, the colored layer 132R transmits red light, the colored layer 132G transmits green light, and the colored layer 132B transmits blue light. The display device 100E may be configured such that the colored layers 132R, 132G, and 132B are provided between the protective layer 131 and the adhesive layer 142.

[0541] [Display device 100E2] The display device 100E2 shown in Fig. 19 is a modified example of the display device 100E shown in Fig. 18, and has microlenses 182 on the colored layers 132R, 132G, and 132B. Note that in the figure, the reference numerals of the same components as those in Fig. 18 may be omitted, and the description in Fig. 18 can be referred to for details.

[0542] 19(B) shows a top view layout of a pixel 178 (pixel 178a and pixel 178b) having subpixels 110 (subpixels 110R, 110G, and 110B), and FIG. 19(C) shows a top view of a microlens 182 in a region where the subpixels 110R and 110G of the pixel 178 are formed. The region where the auxiliary electrode 105 and the organic compound layer 103 contact each other has a width 110Gw in the light-emitting region of the subpixel 110G.

[0543] 19(A) has a planarization film 143 provided on a protective layer 131, and colored layers 132R, 132G, and 132B provided on the planarization film 143. A planarization film 144 is provided so as to cover the colored layers 132R, 132G, and 132B. A microlens 182 is provided on the planarization film 144.

[0544] As shown in FIG. 19C, the microlens 182 may be provided for each sub-pixel in a region where the sub-pixel is formed.

[0545] 19(C), the top surface shape of the microlens 182 is shown as a hexagon, but other shapes may be used as needed. For example, the top surface shape of the recess may be a polygon such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any of these polygons with rounded corners, an ellipse, or a circle.

[0546] The microlenses 182 can be formed using the same material as the organic resin layer 180 .

[0547] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0548] (Embodiment 5) In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0549] The electronic devices of this embodiment include the display device of one embodiment of the present invention in their display portions. The display device of one embodiment of the present invention has high display performance and can easily achieve high definition and high resolution. Therefore, the display device of one embodiment of the present invention can be used in the display portions of various electronic devices.

[0550] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0551] In particular, the display device of one embodiment of the present invention can have high resolution and can therefore be suitably used in electronic devices having a relatively small display area. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices (head-mounted displays), eyeglass-type AR devices, and MR devices.

[0552] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0553] An example of a wearable device that can be worn on the head will be described with reference to FIGS. 20(A) to 20(D).

[0554] The electronic device 700A shown in Figure 20(A) and the electronic device 700B shown in Figure 20(B) each have a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0555] The display device of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device can be highly reliable.

[0556] The electronic device 700A and the electronic device 700B can each project an image displayed on the display panel 751 onto a display area 756 of the optical member 753. Because the optical member 753 is translucent, the user can see the image displayed in the display area superimposed on a transmitted image visible through the optical member 753.

[0557] Electronic device 700A and electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, electronic device 700A and electronic device 700B may each be provided with an acceleration sensor such as a gyro sensor, thereby detecting the orientation of the user's head and displaying an image corresponding to that orientation in display area 756.

[0558] The communication unit has a wireless communication device, and can supply, for example, a video signal via the wireless communication device. Note that instead of or in addition to the wireless communication device, a connector to which a cable through which a video signal and a power supply potential can be connected may be provided.

[0559] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0560] The housing 721 may be provided with a touch sensor module.

[0561] Various touch sensors can be used as the touch sensor module. For example, various types of touch sensors can be used, such as a capacitance type, a resistive film type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, or an optical type. In particular, it is preferable to use a capacitance type or an optical type sensor in the touch sensor module.

[0562] The electronic device 800A shown in Figure 20(C) and the electronic device 800B shown in Figure 20(D) each have a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0563] The display device of one embodiment of the present invention can be applied to the display portion 820. Therefore, the electronic device can be highly reliable.

[0564] Display unit 820 is provided inside housing 821 at a position that can be viewed through lens 832. Also, by displaying different images on the pair of display units 820, it is possible to perform a three-dimensional display using parallax.

[0565] It is preferable that electronic device 800A and electronic device 800B each have a mechanism that allows the left and right positions of lens 832 and display unit 820 to be adjusted so that they are optimally positioned according to the position of the user's eyes.

[0566] The wearing part 823 allows the user to wear the electronic device 800A or the electronic device 800B on the head.

[0567] The imaging unit 825 has a function of acquiring external information. Data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used for the imaging unit 825. Furthermore, multiple cameras may be provided to support multiple angles of view, such as telephoto and wide angle.

[0568] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone.

[0569] The electronic device 800A and the electronic device 800B may each have an input terminal to which a cable can be connected for supplying a video signal from a video output device or the like and power for charging a battery provided in the electronic device.

[0570] The electronic device of one embodiment of the present invention may have a function of wirelessly communicating with the earphone 750 .

[0571] 20B includes earphone unit 727. A part of the wiring connecting earphone unit 727 and a control unit may be disposed inside housing 721 or attachment unit 723.

[0572] 20(D) includes an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be configured to be connected to each other by wire.

[0573] As described above, the electronic devices of one embodiment of the present invention are preferably either glasses-type devices (such as the electronic devices 700A and 700B) or goggle-type devices (such as the electronic devices 800A and 800B).

[0574] An electronic device 6500 shown in FIG. 21A is a portable information terminal that can be used as a smartphone.

[0575] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display portion 6502 has a touch panel function.

[0576] The display device of one embodiment of the present invention can be applied to the display portion 6502. Therefore, the electronic device can be highly reliable.

[0577] FIG. 21B is a schematic cross-sectional view including the end portion of the housing 6501 on the microphone 6506 side.

[0578] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0579] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0580] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0581] A flexible display manufactured using one embodiment of the present invention can be applied to the display panel 6511. Therefore, 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 thereon while keeping the thickness of the electronic device small. In addition, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0582] 21C shows an example of a television set. A television set 7100 includes a display portion 7000 built in a housing 7171. Here, the housing 7171 is supported by a stand 7173.

[0583] The display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can be highly reliable.

[0584] The television set 7100 shown in FIG. 21C can be operated using an operation switch provided on a housing 7171 and a separate remote control 7151.

[0585] 21D shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214. A display portion 7000 is incorporated in the housing 7211.

[0586] The display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can be highly reliable.

[0587] 21(E) and 21(F) show an example of digital signage.

[0588] 21E includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0589] 21F shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0590] 21E and 21F, the display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can have high reliability.

[0591] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0592] Furthermore, as shown in Figures 21(E) and 21(F), it is preferable that the digital signage 7300 or the digital signage 7400 be able to wirelessly communicate with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user.

[0593] The electronic devices shown in Figures 22(A) to 22(G) have a housing 9000, a display portion 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone 9008, etc.

[0594] 22(A) to 22(G) have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to control processing by various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc.

[0595] The electronic devices shown in FIGS. 22A to 22G will be described in detail below.

[0596] FIG. 22A is a perspective view showing a mobile information terminal 9171. The mobile information terminal 9171 can be used as, for example, a smartphone. Note that the mobile information terminal 9171 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, or the like. The mobile information terminal 9171 can display text and image information on multiple surfaces thereof. FIG. 22A shows an example in which three icons 9050 are displayed. Information 9051 indicated by a dashed rectangle can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notification of an incoming email, SNS, phone call, etc., the title of the email or SNS, the sender's name, the date and time, the remaining battery level, and radio wave intensity. Alternatively, the icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0597] 22B is a perspective view of a mobile information terminal 9172. The mobile information terminal 9172 has a function of displaying information on three or more surfaces of the display portion 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position where the mobile information terminal 9172 can be observed from above while the mobile information terminal 9172 is placed in a breast pocket of clothes.

[0598] 22C is a perspective view of a tablet terminal 9173. The tablet terminal 9173 is capable of executing various applications such as mobile phone calls, e-mails, document browsing and creation, music playback, internet communication, and computer games. The tablet terminal 9173 has a display portion 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front side of a housing 9000, operation keys 9005 as operation buttons on the left side of the housing 9000, and a connection terminal 9006 on the bottom.

[0599] 22D is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display portion 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also p...

Claims

1. A light-emitting device having a first electrode, a second electrode, and an organic compound layer formed on a first insulating layer, the first electrode is formed in contact with the first insulating layer, the organic compound layer is located between the first electrode and the second electrode, the second electrode and the organic compound layer are separated from at least one of the second electrodes and the organic compound layers of a plurality of other light-emitting devices adjacent to the light-emitting device; when viewed from a direction substantially perpendicular to a surface of the first insulating layer on which the first electrode is formed, an outline of the second electrode and an outline of the organic compound layer substantially coincide with each other; the organic compound layer has a light-emitting layer and an electron injection layer, the electron injection layer comprises a metal or a metal compound, a first organic compound, and a second organic compound; the first organic compound has a π-electron-deficient heteroaromatic ring, the second organic compound has two or more heteroaromatic rings, two or more of the heteroaromatic rings are bonded to or fused with each other and have a total of three or more heteroatoms; A light-emitting device, wherein the second organic compound is an organic compound having a function of interacting with the metal or the metal compound in a multidentate manner by two or more of the three or more heteroatoms.

2. In claim 1, the organic compound layer has a P-type layer between the electron injection layer and the second electrode, The P-type layer comprises a third organic compound having a hole transporting property, and a fourth organic compound having at least one of a halogen group and a cyano group, or a metal oxide.

3. In claim 1 or claim 2, A light-emitting device, wherein the second organic compound has a function of interacting with the metal or metal compound in a bidentate or tridentate manner via two or more of the three or more heteroatoms.

4. a first electrode group formed on the same insulating surface; a second electrode group facing the first electrode group; a first layer group located between the first electrode group and the second electrode group, The light emitting device comprises: a first electrode, a second electrode, and a first layer; The first electrode is one of the first electrode group, the first electrode is independent for each of the plurality of light-emitting devices; the first layer is one of the first group of layers, the first layer is independent for each of the plurality of light-emitting devices; The second electrode is one of the second electrode group, the second electrode is independent for each of the plurality of light-emitting devices; the second electrode and the first layer overlap the first electrode; the first layer has a light-emitting layer and an electron-injecting layer, the electron injection layer comprises a metal or a metal compound, a first organic compound, and a second organic compound; the first organic compound has a π-electron-deficient heteroaromatic ring, the second organic compound has two or more heteroaromatic rings, two or more of the heteroaromatic rings are bonded to or fused with each other and have a total of three or more heteroatoms; the second organic compound is an organic compound having a function of interacting with the metal or the metal compound in a multidentate manner via two or more of the three or more heteroatoms, A light-emitting device, wherein the distance between the first layer of the light-emitting device and a first layer of another light-emitting device adjacent to the light-emitting device is 0.5 μm or more and 5 μm or less.

5. In claim 4, the first layer has a P-type layer between the electron injection layer and the second electrode; The P-type layer comprises a third organic compound having a hole transporting property, and a fourth organic compound having at least one of a halogen group and a cyano group, or a metal oxide.

6. In claim 4 or claim 5, A light-emitting device, wherein the second organic compound has a function of interacting with the metal or metal compound in a bidentate or tridentate manner via two or more of the three or more heteroatoms.

7. In claim 4 or claim 5, When viewed from a direction substantially perpendicular to the insulating surface, the outline of the second electrode and the outline of the first layer substantially coincide with each other.

8. In claim 4 or claim 5, A light-emitting device, wherein an end portion of the second electrode in a cross section and an end portion of the first layer in a cross section are aligned in a direction substantially perpendicular to the insulating surface.

9. A light-emitting device having a first electrode, a second electrode, and an organic compound layer formed on a first insulating layer, the first electrode is formed in contact with the first insulating layer, the organic compound layer is located between the first electrode and the second electrode, the second electrode and the organic compound layer are separated from at least one of the second electrodes and the organic compound layers of a plurality of other light-emitting devices adjacent to the light-emitting device; when viewed from a direction substantially perpendicular to a surface of the first insulating layer on which the first electrode is formed, an outline of the second electrode and an outline of the organic compound layer substantially coincide with each other; the organic compound layer has a light-emitting layer and an electron injection layer, the electron injection layer comprises a metal or a metal compound, a first organic compound, and a second organic compound; the first organic compound has a π-electron-deficient heteroaromatic ring, The light-emitting device, wherein the second organic compound is an organic compound represented by general formula (G1-1). 【Chemical 1】 (In general formula (G1-1), A １ , A ２ and A ３ each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms; A １ , A ２ and A ３ may be mutually condensed to form a ring.)

10. In claim 9, the organic compound layer has a P-type layer between the electron injection layer and the second electrode, The P-type layer comprises a third organic compound having a hole transporting property, and a fourth organic compound having at least one of a halogen group and a cyano group, or a metal oxide.

11. A light-emitting device having a first electrode, a second electrode, and an organic compound layer formed on a first insulating layer, the first electrode is formed in contact with the first insulating layer, the organic compound layer is located between the first electrode and the second electrode, the second electrode and the organic compound layer are separated from at least one of a plurality of other light-emitting devices adjacent to the light-emitting device; when viewed from a direction substantially perpendicular to a surface of the first insulating layer on which the first electrode is formed, an outline of the second electrode and an outline of the organic compound layer substantially coincide with each other; the organic compound layer has a light-emitting layer and an electron injection layer, the electron injection layer comprises a metal or a metal compound, a first organic compound, and a second organic compound; the first organic compound has a π-electron-deficient heteroaromatic ring, The light-emitting device, wherein the second organic compound is an organic compound represented by general formula (G1-2). 【Chemistry 2】 (In general formula (G1-2), A １ , and A ２ each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms; A １ , and A ２ may be mutually condensed to form a ring, and A １ has two or more nitrogen atoms.

12. In claim 11, the organic compound layer has a P-type layer between the electron injection layer and the second electrode, The P-type layer comprises a third organic compound having a hole transporting property, and a fourth organic compound having at least one of a halogen group and a cyano group, or a metal oxide.

13. In any one of claims 1, 2, 4, 5, and 9 to 12, The light-emitting device, wherein the heteroaromatic ring is a π-electron deficient heteroaromatic ring.

14. In any one of claims 1, 2, 4, 5, and 9 to 12, The heteroaromatic ring includes at least one of a pyridine ring, a diazine ring (a pyrazine ring, a pyrimidine ring, a pyridazine ring), a triazine ring, an azole ring (an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring), and a triazole ring.

15. In any one of claims 1, 2, 4, 5, and 9 to 12, A light-emitting device, wherein at least one of the heteroaromatic rings of the second organic compound includes a diazine ring (a pyrazine ring, a pyrimidine ring, or a pyridazine ring) or a triazine ring.

16. In any one of claims 1, 2, 4, 5, and 9 to 12, a light-emitting device, wherein the heteroaromatic ring of the second organic compound includes a total of three or more pyridine rings;

17. 13. The light-emitting device according to claim 1, wherein the first organic compound has an electron-donating group.

18. In claim 17, The light-emitting device, wherein the electron-donating group is at least one of an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group.

19. In any one of claims 1, 2, 4, 5, and 9 to 12, The first organic compound has an acid dissociation constant pKa of 8 or more.

20. In any one of claims 1, 2, 4, 5, and 9 to 12, The light-emitting device, wherein the first organic compound has a phenanthroline ring.

21. In any one of claims 1, 2, 4, 5, and 9 to 12, The second organic compound has a glass transition temperature Tg of 100° C. or higher.

22. In any one of claims 1, 2, 4, 5, and 9 to 12, A light-emitting device, wherein the LUMO level of the second organic compound is lower than the LUMO level of the first organic compound.

23. In any one of claims 1, 2, 4, 5, and 9 to 12, The light-emitting device, wherein the metal belongs to Group 1, 3, 11 or 13 of the periodic table.

24. In any one of claims 1, 2, 4, 5, and 9 to 12, the electron injection layer is a mixture of the metal, the second organic compound, and the first organic compound.

25. In any one of claims 1, 2, 4, 5, and 9 to 12, a light-emitting device, wherein the electron injection layer is a stack of a layer containing the metal and a layer containing the second organic compound or the first organic compound.

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