Compound, light-emitting element including the same, display device, and lighting device

Abstract

The object of this invention is to provide organic EL devices with excellent luminous efficiency and longevity. This invention relates to compounds represented by the following general formula (1) or (2). (X) 1 For CR 12 Or a nitrogen atom. X 2 and X 3 Each independently for CR 13 Or nitrogen atoms. Y is CR 14 R 15 NR 16 Oxygen or sulfur atoms. R 1 ~R 16 Each is independently selected from the group consisting of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups. Among them, R 1 ~R 7 The two adjacent groups in, and R 8 ~R 11 and R 13 The two adjacent groups in the formula are groups represented by the following general formula (3). )(X 4 ~X 16 Each independently for CR 17 Or a nitrogen atom. R 17 The group is selected from the group consisting of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups. Among them, X 4 ~X 6 One of them, X 7 ~X 11 One of them, and X 12 ~X 16 One of them is a nitrogen atom. L 1 (Substituted or unsubstituted aryl group, or substituted or unsubstituted heteroaryl group. n is 0 or 1.)

Description

Technical Field

[0001] This invention relates to compounds, light-emitting elements using the same, display devices, and lighting devices. Background Technology

[0002] Organic electroluminescent (OLED) devices are light-emitting devices that have an anode, a cathode, and an organic layer between them, and that emit light using electrical energy. In recent years, OLED devices have been steadily being used in television and smartphone displays, among other applications. However, many technical challenges remain with existing OLED devices. Among these, achieving a balance between high-efficiency light emission and long lifespan has become a significant challenge.

[0003] As compounds for solving the above problems, terpyridine dimers with specific heteroaryl groups (e.g., see Patent Document 1), terpyridine dimers with an anthracene skeleton (e.g., see Patent Document 2), terpyridine dimers with a pyrene skeleton (e.g., see Patent Document 3), etc., have been developed to date.

[0004] Existing technical documents Patent documents Patent Document 1: Korean Patent Application Publication No. 2018-0031224 Patent Document 2: International Publication No. 2009 / 107651 Patent Document 3: International Publication No. 2012 / 173073 Summary of the Invention

[0005] The problem that the invention aims to solve According to the techniques described in Patent Documents 1 to 3, organic EL devices with improved luminous efficiency, low-voltage drive capability, and excellent durability can be obtained. However, in recent years, the requirements for luminous efficiency and durability of organic EL devices have gradually increased, demanding technologies that can simultaneously achieve higher luminous efficiency and longer lifespan.

[0006] In view of the problems of the prior art, the present invention aims to provide an organic EL element with excellent luminous efficiency and longevity.

[0007] Methods for solving problems To address the aforementioned issues, the present invention employs the following configuration.

[0008] [1] Compounds represented by the following general formula (1) or (2): [Chemical Formula 1] X 1 For CR 12 Or nitrogen atom, X 2 and X3 Each independently for CR 13 Or nitrogen atoms, Y is CR 14 R 15 NR 16 Oxygen or sulfur atoms, R 1 ~R 16 Each is independently selected from the group consisting of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups, wherein R 1 ~R 7 The two adjacent groups in, and R 8 ~R 11 and R 13 The two adjacent groups in the formula are groups represented by the following general formula (3); [Chemical Formula 2] X 4 ~X 16 Each independently for CR 17 Or nitrogen atom, R 17 The group selected is composed of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups, wherein X 4 ~X 6 One of them, X 7 ~X 11 One of them, and X 12 ~X 16 One of them is a nitrogen atom, L 1 For substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, n is 0 or 1.

[0009] [2] The compound as described in [1], wherein the group represented by the aforementioned general formula (3) is the group represented by the following general formula (4): [Chemical Formula 3] In general formula (4), X 7 ~X 9 X 12 ~X 14 and L 1 X in general formula (3) 7 ~X 9 X 12 ~X 14 and L 1 It is the same, where X 7 ~X 9 One of them, and X 12~X 14 One of them is a nitrogen atom, and n is 0 or 1.

[0010] [3] The compounds as described in [1] or [2], wherein the compounds represented by the aforementioned general formula (1) or (2) are compounds represented by the following general formulas (5) to (7): [Chemical Formula 4] In general formulas (5) to (7), X 1 X 7 ~X 9 X 12 ~X 14 Y and R 3 ~R 11 X in general formulas (1) to (3) 1 X 7 ~X 9 X 12 ~X 14 Y and R 3 ~R 11 It is the same, where X 7 ~X 9 One of them, and X 12 ~X 14 One of them is a nitrogen atom, L 2 ~L 5 Each is independently a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, where n is 0 or 1.

[0011] [4] The compound as described in any one of [1] to [3], wherein the compound represented by the aforementioned general formula (1) or (2) is the compound represented by the aforementioned general formula (2), and Y is an oxygen atom or a sulfur atom.

[0012] [5] The compound as described in any one of [1] to [4], wherein n is 1, L 1 It is a phenylene oxide.

[0013] [6] A light-emitting element having at least an electron transport layer and a light-emitting layer between an anode and a cathode and emitting light using electrical energy, wherein the electron transport layer contains any one of the compounds described in [1] to [5].

[0014] [7] The light-emitting element as described in [6], wherein the aforementioned electron transport layer further contains alkali metal atoms, rare earth metal atoms or copper group atoms.

[0015] [8] A light-emitting element having at least a charge-generating layer and a light-emitting layer between an anode and a cathode and emitting light using electrical energy, wherein the charge-generating layer contains any one of the compounds described in [1] to [5].

[0016] [9] The light-emitting element as described in [8], wherein the aforementioned charge-generating layer further contains a phenanthroline derivative.

[0017]

[10] The light-emitting element as described in [8] or [9], wherein the aforementioned charge-generating layer further contains alkali metal atoms, rare earth metal atoms or copper group atoms.

[0018]

[11] The light-emitting element as described in [8] or [9], wherein the aforementioned charge-generating layer further contains alkali metal atoms, wherein the aforementioned alkali metal atoms are Li.

[0019]

[12] The light-emitting element as described in [8] or [9], wherein the aforementioned charge-generating layer further contains rare earth metal atoms, wherein the aforementioned rare earth metal atoms are Yb.

[0020]

[13] A light-emitting element having at least an electron injection layer and a light-emitting layer between an anode and a cathode and emitting light using electrical energy, wherein the electron injection layer contains any one of the compounds described in [1] to [5].

[0021]

[14] The light-emitting element as described in

[13] , wherein the aforementioned electron injection layer further contains alkali metal atoms, rare earth metal atoms or copper group atoms.

[0022]

[15] A display device comprising a light-emitting element containing any one of [1] to [5].

[0023]

[16] A lighting device comprising a light-emitting element containing any one of the compounds described in [1] to [5].

[0024] Invention Effects According to the present invention, organic EL elements with excellent luminous efficiency and long lifespan can be provided. Detailed Implementation

[0025] Hereinafter, preferred embodiments of the compound, light-emitting element, display device, and lighting device according to the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments and can be implemented with various modifications depending on the purpose and application.

[0026] (Compounds represented by general formula (1) or (2)) The compounds involved in the embodiments of the present invention are compounds represented by general formula (1) or (2).

[0027] [Chemical Formula 5] X 1 For CR 12 Or a nitrogen atom. X2 and X 3 Each independently for CR 13 Or nitrogen atoms. Y is CR 14 R 15 NR 16 Oxygen or sulfur atoms. R 1 ~R 16 Each is independently selected from the group consisting of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups. Among them, R 1 ~R 7 The two adjacent groups in, and R 8 ~R 11 and R 13 The two adjacent groups in the formula are groups represented by the following general formula (3).

[0028] [Chemical Formula 6] X 4 ~X 16 Each independently for CR 17 Or a nitrogen atom. R 17 The group is selected from the group consisting of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups. Among them, X 4 ~X 6 One of them, X 7 ~X 11 One of them, and X 12 ~X 16 One of them is a nitrogen atom. L 1 It can be a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. n is 0 or 1.

[0029] In all the groups mentioned above, the hydrogen atom can also be a deuterium atom. The same applies to the substituents, compounds, or parts thereof described below.

[0030] When referred to as "substituted or unsubstituted," "unsubstituted" means that a hydrogen atom or a deuterium atom is substituted. The same applies to the compounds or parts thereof described below when referred to as "substituted or unsubstituted."

[0031] The term "aryl" can refer to aromatic hydrocarbon groups such as phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, benzo[9,10]fluorenyl, dibenzo[9,10]fluorenyl, phenanthryl, anthracene, benzo[9,10]phenanthryl, benzo[9,10]fluorenyl, dibenzo[9,10]anthryl, peryl, and helicenyl.

[0032] The number of cyclic atoms is not particularly limited, but is preferably in the range of 6 to 40, more preferably in the range of 6 to 30. Among these, phenyl is preferred.

[0033] The term "arylene" can refer to, for example, aromatic hydrocarbon groups such as phenylene, biphenylene, terphenylene, naphthylene, fluorene, benzo[9,10]phenanthyl, benzo[9,10]fluorenyl, benzo[9,10]fluorenyl, benzo[9,10]fluorenyl, perylene, and helicalyl. Here, the divalent bonds of the arylene group are linked to the same conjugated system. The number of ring atoms is not particularly limited, but is preferably in the range of 6 to 40, more preferably in the range of 6 to 30. Among these, phenylene and biphenylene are preferred.

[0034] The term "heteroaryl" refers to, for example, cyclic aromatic groups containing atoms other than carbon in one or more rings, such as pyridyl, furanyl, thiopheneyl, quinolinyl, isoquinolinyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, naphridinyl, cinolinyl, phthalazinyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothiopheneyl, indolyl, dibenzofuranyl, dibenzothiopheneyl, carbazoyl, benzocarbazoyl, carbazoyl, indolocarbazoyl, benzofuranocarbazoyl, benzothiophenocarbazoyl, dihydroindocarbazoyl, benzoquinolinyl, acridineyl, dibenzoacridyl, benzoimidazoyl, imidazopyridyl, benzooxazolyl, benzothiazoyl, phenanthrolinel, etc. The term "naphthidyl" refers to any one of 1,5-naphthidyl, 1,6-naphthidyl, 1,7-naphthidyl, 1,8-naphthidyl, 2,6-naphthidyl, and 2,7-naphthidyl. The number of cyclic atoms is not particularly limited, but is preferably in the range of 3 to 40, more preferably in the range of 3 to 30. Among these, pyridyl is particularly preferred.

[0035] The term "heteroaryl" can refer to, for example, pyridinyl, furanyl, thiopheneyl, quinolineyl, isoquinolineyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, naphridinyl, cinnamyl, phthalazinyl, quinoxalinyl, quinoxalinyl, benzofuranyl, benzothiopheneyl, indoleyl, dibenzofuranyl, dibenzothiopheneyl, carbazolyl, and benzo[] Cyclic aromatic groups having atoms other than carbon in one or more rings, such as carbazolyl, carbamolyl, indole-carbazolyl, benzofuran-carbazolyl, benzothiophene-carbazolyl, dihydroindobenzocarbazolyl, benzoquinolinel, acridinel, dibenzoacrididine, benzimidazolyl, imidazopyridyl, benzoxazolyl, benzothiazolyl, and phenanthrolinel. The term "naphthidyl" refers to any one of 1,5-naphthidyl, 1,6-naphthidyl, 1,7-naphthidyl, 1,8-naphthidyl, 2,6-naphthidyl, and 2,7-naphthidyl. Here, the divalent bonds of the heteroaryl group are linked to the same conjugated system. The number of ring atoms is not particularly limited, but is preferably in the range of 5 to 40, more preferably in the range of 5 to 30.

[0036] The term "alkyl" refers to, for example, saturated aliphatic hydrocarbon groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl. The number of carbon atoms in the alkyl group is not particularly limited, but from the perspective of ease of acquisition and cost, it is preferably 1 to 20, more preferably 1 to 8. The number of carbon atoms referred to here also includes the number of carbon atoms contained in the substituents bonded to the alkyl group; the same applies to other substituents for which a specific number of carbon atoms is specified.

[0037] The term alkoxy refers to, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, etc., alkyl groups bonded to oxygen. The number of carbon atoms in an alkoxy group is not particularly limited, but considering ease of acquisition and cost, it is generally 1 to 20, more preferably 1 to 8.

[0038] As conventional compounds containing nitrogen-containing aromatic heterocycles and polycyclic aromatic hydrocarbons, for example, compounds X, Y and Z represented by the following formulas are shown in Patent Documents 1 to 3.

[0039] [Chemical Formula 7] However, even when these compounds are used as materials for organic EL devices in electron injection layers, electron transport layers, or charge generation layers, they have not yet achieved sufficient performance to meet the characteristics required in recent years. Therefore, there is a need for compounds that can further improve performance in terms of luminous efficiency and lifetime.

[0040] For example, compounds like compound X, which have substituents in a dibenzofuran skeleton with terpyridine skeletons in adjacent positions, have high crystallinity due to the dibenzofuran skeleton, which causes an increase in sublimation temperature. When these compounds are deposited together with metals to form a film, there is a problem of reduced film stability and operability.

[0041] Compounds Y and Z, which have two terpyridine skeletons in non-adjacent positions within a polycyclic aromatic skeleton, have the problem of reduced film stability when deposited together with metals, due to the strong intermolecular hydrogen bonds from terpyridine, in addition to the influence of the structure obtained by the fusion of more than three rings.

[0042] The inventors of this application focused on the effects of the terpyridine skeleton in their improved research, specifically investigating the placement of structures with the terpyridine skeleton within the parent skeleton at specific positions. The terpyridine skeleton is a substituent with high electron transport capacity and strong coordination to metal atoms.

[0043] Compounds represented by general formula (1) or (2) have appropriately sized fused ring structures as the parent skeleton with a terpyridine skeleton, thus giving the compounds moderate crystallinity and thermal stability, and suppressing the rise in sublimation temperature, which also improves operability. In addition, the group represented by general formula (3) represents a terpyridine skeleton, which can endow the compounds with large electron transport and coordination to metal atoms.

[0044] Furthermore, as mentioned above, compounds with multiple terpyridine skeletons generally exhibit high crystallinity due to the strong intermolecular hydrogen bonds from terpyridine, which may lead to a decrease in film stability and operability. However, in this invention, by making R in the compound represented by general formula (1) 1 ~R 7 In the two adjacent groups in the compound represented by general formula (2), R 8 ~R 11 and R 13 The two adjacent groups in the formula (3) are the groups represented by the above general formula. Thus, due to the steric hindrance between the adjacent terpyridine skeletons, the excessive increase in crystallinity can be suppressed even though there are multiple terpyridine skeletons.

[0045] Considering the ease of obtaining the compound, R is preferred. 1 ~R 13 Each is independently selected from the group consisting of hydrogen atom, methyl, cyano and phenyl, more preferably hydrogen atom.

[0046] Y is preferably an oxygen atom or a sulfur atom. This is because, in this case, the electron density of the compound increases, thus making the coordination to the metal atom stronger.

[0047] By making L 1 The above-mentioned groups, thus sandwiching L 1 The groups on both sides of the compound become more easily conjugated. Therefore, the electron transport capacity of the compound becomes greater. From the viewpoint of having moderate crystallinity, improving film stability, and further enhancing the durability of the light-emitting element, L... 1 Preferably, it is phenylene. Particularly preferred is that n is 1, L 1 It is a phenylene oxide.

[0048] In general formula (3), X 4 Nitrogen atoms are preferred. This is because, in this case, by placing the nitrogen atom in the center of the terpyridine skeleton, the coordination to the metal atom becomes stronger. In particular, when the group represented by general formula (3) is the group represented by general formula (4) below, the coordination to the metal atom of the compound is further enhanced, and therefore preferred.

[0049] [Chemical Formula 8] In general formula (4), X 7 ~X 9 X 12 ~X 14 and L 1 X in general formula (3) 7 ~X 9 X 12 ~X 14 and L 1 They are the same. Among them, X 7 ~X 9 One of them, and X 12 ~X 14 One of them is a nitrogen atom. n is 0 or 1.

[0050] From the viewpoint of ease of obtaining and operability of the compound, it is more preferable for the compound represented by general formula (1) or (2) to be the compound represented by the following general formulas (5) to (7).

[0051] [Chemical Formula 9] In general formulas (5) to (7), X 1 X 7 ~X 9 X 12 ~X 14 Y and R 3 ~R 11X in general formulas (1) to (3) 1 X 7 ~X 9 X 12 ~X 14 Y and R 3 ~R 11 They are the same. Among them, X 7 ~X 9 One of them, and X 12 ~X 14 One of them is a nitrogen atom. L 2 ~L 5 Each is independently a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. n is 0 or 1.

[0052] From the viewpoint of suppressing crystallization and improving the stability of the film, the molecular weight of the compound represented by general formula (1) or (2) is preferably 590 or more. On the other hand, from the viewpoint of improving the processability during sublimation purification and vapor deposition, the molecular weight of the compound represented by general formula (1) or (2) is preferably 800 or less.

[0053] As compounds represented by general formula (1) or (2), examples include the compounds shown below. It should be noted that the following are examples, and even compounds other than those explicitly described herein, as long as they are represented by general formula (1) or (2), may be used in the same way.

[0054] [Chemical Formula 10] [Chemical Formula 11] [Chemical Formula 12] [Chemical Formula 13] [Chemical Formula 14] [Chemical Formula 15] [Chemical Formula 16] [Chemical Formula 17] [Chemical Formula 18] [Chemical Formula 19] [Chemical Formula 20] [Chemical Formula 21] [Chemical Formula 22] [Chemical Formula 23] [Chemical Formula 24] Compounds represented by general formula (1) or (2) can be synthesized using known synthetic methods. Examples of synthetic methods include, for instance, the coupling reaction of terpyridineboronic acid derivatives with dihaloarylene or dihaloheteroarylene derivatives, but are not limited thereto.

[0055] Compounds represented by general formula (1) or (2) are preferably used in any layer of a light-emitting element. As described later, compounds represented by general formula (1) or (2) are suitable for use in hole injection layers, hole transport layers, light-emitting layers, electron transport layers, protective films (capping layers) of electrodes, etc., in light-emitting elements. By using materials represented by general formula (1) or (2) in any layer of a light-emitting element, light-emitting elements with excellent luminous efficiency and longevity can be provided.

[0056] (Light-emitting element) The light-emitting element according to embodiments of the present invention has an anode and a cathode, and an organic layer between the anode and the cathode, the organic layer emitting light using electrical energy. In the following description, such a light-emitting element is sometimes referred to as an "organic EL element".

[0057] Regarding the layer structure between the anode and cathode in an organic EL element, in addition to the structure formed solely by the light-emitting layer, other stacked structures can be cited, such as: 1) light-emitting layer / electron transport layer, 2) hole transport layer / light-emitting layer, 3) hole transport layer / light-emitting layer / electron transport layer, 4) hole injection layer / hole transport layer / light-emitting layer / electron transport layer, 5) hole transport layer / light-emitting layer / electron transport layer / electron injection layer, 6) hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer, and 7) hole injection layer / hole transport layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer.

[0058] Alternatively, multiple of the above-mentioned layers can be stacked in series with an intermediate layer between them. The intermediate layer is also commonly referred to as an intermediate electrode, intermediate conductive layer, charge generation layer, electron extraction layer, connecting layer, or intermediate insulating layer, and can be made of known materials. Specific examples of the series type include, for example, 8) hole transport layer / light emission layer / electron transport layer / charge generation layer / hole transport layer / light emission layer / electron transport layer, and 9) hole injection layer / hole transport layer / light emission layer / electron transport layer / electron injection layer / charge generation layer / hole injection layer / hole transport layer / light emission layer / electron transport layer / electron injection layer, in which a charge generation layer is included as an intermediate layer between the anode and the cathode.

[0059] Furthermore, each of the aforementioned layers can be either a single layer or a multilayer, and can also be doped. In particular, it is preferable that the electron injection layer and charge generation layer be metal-doped layers, which can improve electron transport capability and the ability to inject electrons into adjacent layers. In addition, besides the aforementioned layers, a protective layer (capping layer) may also be provided, which can further improve luminous efficiency by utilizing optical interference effects.

[0060] The compound represented by general formula (1) or (2) can be used in any of the above-mentioned layers in an organic EL element, but is particularly suitable for use in an electron transport layer, a charge generation layer, or an electron injection layer. As a light-emitting element according to an embodiment of the present invention, the following configurations are preferred: a configuration having at least an electron transport layer and a light-emitting layer between an anode and a cathode, and containing a compound represented by general formula (1) or (2) in the electron transport layer; a configuration having at least a charge generation layer and a light-emitting layer between an anode and a cathode, and containing a compound represented by general formula (1) or (2) in the charge generation layer; and a configuration having at least an electron injection layer and a light-emitting layer between an anode and a cathode, and containing a compound represented by general formula (1) or (2) in the electron injection layer.

[0061] In the light-emitting element according to embodiments of the present invention, the anode and cathode serve to supply sufficient current for the element to emit light, and it is desirable that at least one of them is transparent or semi-transparent in order to extract the light. Typically, the anode formed on the substrate is a transparent electrode.

[0062] (Substrate) To ensure the mechanical strength of the organic EL element, it is preferable to form the organic EL element on a substrate. Examples of substrates include glass substrates such as soda-lime glass and alkali-free glass, and plastic substrates. The thickness of the glass substrate only needs to be sufficient to ensure mechanical strength; 0.5 mm or more is sufficient. Regarding the glass material, it is preferable to have low ion leaching, and alkali-free glass is preferred. Furthermore, commercially available soda-lime glass with a barrier coating such as SiO2 can also be used.

[0063] (anode) The material used for the anode is preferably capable of efficiently injecting holes into the organic layer. Furthermore, it is preferably transparent or translucent to extract light. Examples of materials used for the anode include conductive metal oxides such as zinc oxide, tin oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, and chromium; inorganic conductive substances such as copper iodide and copper sulfide; and conductive polymers such as polythiophene, polypyrrole, and polyaniline. Among these, ITO glass and NESA glass are preferred. These electrode materials can be used individually or in combination, either layered or mixed.

[0064] (cathode) The material used for the cathode is not particularly limited as long as it can efficiently inject electrons into the light-emitting layer. Examples of materials for the cathode include metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys of these metals with low work function metals such as lithium, sodium, potassium, calcium, and magnesium, or multilayer laminations. Among these, aluminum, silver, and magnesium are preferred as main components considering factors such as resistivity, ease of film fabrication, film stability, and luminous efficiency. Magnesium and silver are more preferred as main components considering ease of electron injection into the electron transport layer and electron injection layer.

[0065] (Protective layer) To protect the cathode, a protective layer (capping layer) is preferably stacked on the cathode. The material constituting the protective layer (capping material) is not particularly limited; examples include metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium; alloys using these metals; inorganic materials such as silicon dioxide, titanium dioxide, and silicon nitride; and organic polymers such as polyvinyl alcohol, polyvinyl chloride, and hydrocarbon-based polymers. Additionally, compounds represented by general formula (1) can also be used as capping materials. However, when the organic EL element is a structure that extracts light from the cathode side (top-emitting structure), the capping material preferably has light transmittance in the visible light region.

[0066] (hole injection layer) The hole injection layer is a layer inserted between the anode and the hole transport layer. The hole injection layer can be a single layer or multiple layers stacked together; both are acceptable. When a hole injection layer exists between the hole transport layer and the anode, lower voltage driving is possible, and the lifespan is improved. Furthermore, the carrier balance of the device is improved, and the luminous efficiency is also increased, making this a preferred option.

[0067] The material used for the hole injection layer can be any known material. Examples include benzidine derivatives, materials known as starburst arylamines, triarylamine derivatives, biscarbazole derivatives, pyrazoline derivatives, uranyl compounds, fluorene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, and other heterocyclic compounds; as well as polymeric materials such as polycarbonate, styrene derivatives, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, and polysilane having the aforementioned monomers on their side chains. From the viewpoint of smoothly injecting and transporting holes from the anode to the hole transport layer, benzidine derivatives, starburst arylamine materials, and fluorene compounds are more preferred.

[0068] These materials can be used alone or in combination of two or more materials. Alternatively, multiple materials can be stacked to form a hole injection layer. Furthermore, the aforementioned effects are more significantly achieved when the hole injection layer is composed solely of an acceptor compound, or when an acceptor compound is doped into the hole injection material described above; therefore, this is preferred. An acceptor compound, when used as a monolayer, is a material that forms a charge-transfer complex with the adjacent hole transport layer; when used in combination, it is a material that forms a charge-transfer complex with the material constituting the hole injection layer. Using such a material improves the conductivity of the hole injection layer, further reducing the device's driving voltage and improving luminous efficiency and lifetime.

[0069] Known materials can be used as acceptor compounds. Examples include metal chlorides, metal oxides such as molybdenum oxide, charge-transfer complexes, organic compounds containing nitro, cyano, halogen, or trifluoromethyl groups within the molecule, quinone compounds, acid anhydride compounds, and fullerenes. Among these, metal oxides and cyano-containing compounds are easy to process and readily vapor-deposit, thus readily achieving the aforementioned effects, and are therefore preferred. In either the case where the hole injection layer is composed solely of the acceptor compound, or in the case where the hole injection layer is doped with the acceptor compound, the hole injection layer can be a single layer or multiple layers stacked together.

[0070] (Hole transport layer) The hole transport layer is the layer that transports holes injected from the anode to the light-emitting layer. The hole transport layer can be a single layer or composed of multiple layers stacked together.

[0071] Materials used for the hole transport layer can be exemplified as materials for the hole injection layer. From the viewpoint of smoothly injecting and transporting holes into the light-emitting layer, triarylamine derivatives and benzidine derivatives are more preferred.

[0072] (Emitting layer) Regarding the light-emitting layer, it can be a single layer or multiple layers, formed separately from light-emitting materials (main material and dopant material). These can be mixtures of main material and dopant material, a single main material, or a mixture of two main materials and one dopant material; any of these are permissible. That is, regarding the light-emitting element in the embodiments of the present invention, in each light-emitting layer, only the main material or the dopant material may emit light, or both the main material and the dopant material may emit light. From the viewpoint of efficiently utilizing electrical energy and obtaining light emission with high color purity, the light-emitting layer is preferably obtained from a mixture of main material and dopant material. Furthermore, the main material and dopant material can each be one type, or a combination of multiple types; any of these are permissible. The dopant material can be included entirely in the main material or partially; any of these are permissible. The dopant material can be stacked or dispersed; any of these are permissible. The dopant material allows for control over the emission color. From the viewpoint of suppressing concentration quenching, the amount of dopant material relative to the main material is preferably 30% by weight or less, more preferably 20% by weight or less. In terms of doping methods, it can be formed by co-evaporation with the host material, but it can also be pre-mixed with the host material and then evaporated simultaneously.

[0073] Known materials can be used as luminescent materials. For example, examples include fused ring derivatives such as anthracene and pyrene, metal chelate oxinoid compounds such as tris(8-hydroxyquinoline)aluminum, bis(styrene)-anthracene derivatives, bis(styrene)-benzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, violet ketone derivatives, cyclopentadiene derivatives, thiadiazopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indole-carbazole derivatives, polyphenylene ethylene derivatives, poly(p-phenylene) derivatives, polythiophene derivatives, and polymers such as poly(p-phenylene)-ethylene derivatives, etc.

[0074] The host material in a luminescent material does not need to be limited to a single compound; multiple compounds can be mixed and used. Alternatively, they can be layered. Known materials can be used as the host material. Without specific limitations, examples include compounds with fused aryl rings such as naphthalene, anthracene, phenanthrene, pyrene, benzo[a], tetraphenylene, tri-o-benzene, perylene, fluoranthene, fluorene, and indene, as well as their derivatives; aromatic amine derivatives such as N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine; metal chelate compounds such as tris(8-hydroxyquinoline)aluminum(III); bis(styrene) derivatives such as styreneylbenzene derivatives; tetraphenylbutadiene derivatives; indene derivatives; coumarin derivatives; oxadiazole derivatives; pyrrolopyridine derivatives; violetone derivatives; cyclopentadiene derivatives; pyrrolopyrrole derivatives; thiadiazopyridine derivatives; dibenzofuran derivatives; carbazole derivatives; indolecarbazole derivatives; triazine derivatives; polyphenyleneethylene derivatives; poly(p-phenylene) derivatives; polyfluorene derivatives; polyvinylcarbazole derivatives; and polythiophene derivatives, etc. Among them, metal chelated oxazone compounds, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, indole-carbazole derivatives, triazine derivatives, tri-o-benzylene derivatives, etc. are preferably used as the main body when the light-emitting layer is used for triplet emission (phosphorescence).

[0075] Examples of dopants used in luminescent materials include compounds with aryl rings, their derivatives, compounds with heteroaryl rings, their derivatives, stilbene derivatives, aminostyryl derivatives, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, piracene derivatives, aldehyde azide derivatives, pyrrole methylene derivatives, diketopyrrolo[3,4-c]pyrrole derivatives, coumarin derivatives, azole derivatives, their metal complexes, aromatic amine derivatives, and compounds represented by the following general formula (8). Among these, dopants containing a diamine skeleton and dopants containing a fluoranthene skeleton can further improve luminescence efficiency, and compounds represented by the following general formula (8) can further improve luminescence efficiency and durability.

[0076] [Chemical Formula 25] In general formula (8), the Za ring, Zb ring, and Zc ring are each independently a substituted or unsubstituted aryl ring with 6 to 30 cyclic carbon atoms or a substituted or unsubstituted heteroaryl ring with 5 to 30 cyclic carbon atoms. It is preferred that the Za ring, Zb ring, and Zc ring are each independently a substituted or unsubstituted aryl ring with 6 to 30 cyclic carbon atoms. 1 and Z 2 Each can be independently an oxygen atom, NRa (a nitrogen atom with a substituent Ra), or a sulfur atom, Z 1In the case of NRa, it can bond with a Za ring or a Zb ring to form a ring, or it can not form a ring. 2 In the case of NRa, it can bond with the Zb or Zc ring to form a ring, or it may not form a ring. Ra is independently an aryl group with 6 to 30 cyclic carbon atoms (substituted or unsubstituted), a heteroaryl group with 5 to 30 cyclic carbon atoms (substituted or unsubstituted), or an alkyl group with 1 to 30 cyclic carbon atoms (substituted or unsubstituted). Preferably, Z... 1 and Z 2 All are NRa, where Ra is an aryl group with 6 to 30 substituted or unsubstituted cyclic carbon atoms. Z 3 It can be a boron atom, a phosphorus atom, SiRb (a silicon atom with a substituent Rb), P=O, or P=S. Each Rb can be an aryl group with 6 to 30 substituted or unsubstituted cyclic carbon atoms, a heteroaryl group with 5 to 30 substituted or unsubstituted cyclic carbon atoms, or an alkyl group with 1 to 30 substituted or unsubstituted carbon atoms. 3 Boron atoms are preferred.

[0077] Of all the groups described above, the preferred substituents for substitution are alkyl, cycloalkyl, heterocyclic, alkenyl, cycloalkenyl, alkynyl, aryl, heteroaryl, hydroxyl, thiol, alkoxy, alkylthio, aryl ether, aryl thioether, halogen, cyano, aldehyde, acyl, carboxyl, ester, amide, acyl, sulfonyl, sulfonate, sulfonamide, amino, nitro, silyl, siloxane, boronyl, and oxo. Furthermore, these substituents can also be replaced by the substituents described above.

[0078] As alkyl, alkoxy, aryl and heteroaryl, examples of substituents in general formula (1) or (2) can be cited.

[0079] The term cycloalkyl refers to, for example, saturated alicyclic hydrocarbon groups such as cyclopropyl, cyclohexyl, norbornyl, and adamantyl, which may or may not have substituents. The number of carbon atoms in the ring is not particularly limited, but is preferably in the range of 3 to 20.

[0080] The term "heterocyclic group" refers to, for example, an aliphatic ring such as a pyran ring, piperidine ring, or cyclic amide ring, which contains atoms other than carbon within the ring. It may or may not contain substituents. The number of ring atoms is not particularly limited, but is preferably in the range of 3 to 20.

[0081] The term alkenyl refers to, for example, unsaturated aliphatic hydrocarbon groups containing double bonds such as vinyl, allyl, and butadienyl, which may or may not have substituents. The number of carbon atoms in an alkenyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0082] The term "cycloalkenyl" refers to, for example, unsaturated alicyclic hydrocarbon groups containing double bonds such as cyclopentenyl, cyclopentadienyl, and cyclohexenyl. These groups may or may not have substituents.

[0083] The term alkynyl, for example, refers to an unsaturated aliphatic hydrocarbon group containing a triple bond, such as ethynyl, which may or may not have substituents. The number of carbon atoms in the alkynyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0084] Furthermore, in a substituted phenyl group, if each of the two adjacent carbon atoms of the phenyl group has a substituent, these substituents can form a ring structure with each other. The resulting group, depending on its structure, can be equivalent to any one or more of the following: "substituted phenyl group", "aryl group with a structure obtained by fusion of two or more rings", and "heteroaryl group with a structure obtained by fusion of two or more rings".

[0085] An alkylthio group is a group obtained by replacing the oxygen atom in the ether bond of an alkoxy group with a sulfur atom. Alkylthio groups may or may not have substituents. The number of carbon atoms in an alkylthio group is not particularly limited, but is preferably in the range of 1 to 20.

[0086] The term "aryl ether group" refers to a functional group, such as phenoxy, to which an aromatic hydrocarbon group is bonded via an ether bond. It may or may not have substituents. The number of carbon atoms in an aryl ether group is not particularly limited, but is preferably in the range of 6 to 40.

[0087] The term "aryl thioether group" refers to a functional group obtained by replacing the oxygen atom in the ether bond of an aryl ether group with a sulfur atom. It may or may not have substituents. There is no particular limitation on the number of carbon atoms in an aryl thioether group, but it is preferably in the range of 6 to 40.

[0088] The term halogen refers to fluorine, chlorine, bromine, or iodine.

[0089] The term acyl group refers to functional groups such as acetyl, propionyl, benzoyl, and acryloyl, which are bonded to alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or heteroaryl groups via a carbonyl group. It may or may not have substituents. The number of carbon atoms in the acyl group is not particularly limited, but is preferably 2 to 40, more preferably 2 to 30.

[0090] The term "ester group" refers to a functional group formed by bonding alkyl, cycloalkyl, aryl, or heteroaryl groups via ester bonds. It may or may not have substituents. The number of carbon atoms in the ester group is not particularly limited, but is preferably in the range of 1 to 20. More specifically, examples include methyl ester groups such as methoxycarbonyl, ethyl ester groups such as ethoxycarbonyl, propyl ester groups such as propoxycarbonyl, butyl ester groups such as butoxycarbonyl, isopropyl ester groups such as isopropoxymethoxycarbonyl, hexyl ester groups such as hexoxycarbonyl, and phenyl ester groups such as phenoxycarbonyl, etc.

[0091] The term "amide group" refers to a functional group formed by bonding alkyl, cycloalkyl, aryl, or heteroaryl groups via amide bonds. It may or may not have substituents. The number of carbon atoms in the amide group is not particularly limited, but is preferably in the range of 1 to 20. More specifically, examples include methylamide, ethylamide, propylamide, butylamide, isopropylamide, hexylamide, and phenylamide.

[0092] The term sulfonyl group refers to, for example, a functional group formed by bonding alkyl, cycloalkyl, aryl, heteroaryl, etc., via a -S (=O)2- bond. It may or may not have substituents. The number of carbon atoms in the sulfonyl group is not particularly limited, but is preferably in the range of 1 to 20.

[0093] The term "sulfonate group" refers to a functional group formed by the bonding of alkyl, cycloalkyl, aryl, or heteroaryl groups via a sulfonate bond. It may or may not have substituents. Here, a sulfonate bond refers to a bond formed by replacing the carbonyl group (-C(=O)-) of an ester bond with a sulfonyl group (-S(=O)2-). The number of carbon atoms in the sulfonate group is not particularly limited, but is preferably in the range of 1 to 20.

[0094] The term "sulfonamide group" refers to a functional group formed by bonding alkyl, cycloalkyl, aryl, or heteroaryl groups via a sulfonamide bond. It may or may not have substituents. Here, the sulfonamide bond refers to a bond formed by replacing the carbonyl group (-C(=O)-) of an ester bond with a sulfonyl group (-S(=O)2-). The number of carbon atoms in the sulfonamide group is not particularly limited, but is preferably in the range of 1 to 20.

[0095] The amino group may or may not have substituents. The number of carbon atoms in the amino group is not particularly limited, but is preferably in the range of 2 to 50, more preferably in the range of 6 to 40, and particularly preferably in the range of 6 to 30.

[0096] The term silyl group refers to a functional group bonded with substituted or unsubstituted silicon atoms. Examples include alkylsilyl groups such as trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, propyldimethylsilyl, and vinyldimethylsilyl, as well as arylsilyl groups such as phenyldimethylsilyl, tert-butyldiphenylsilyl, triphenylsilyl, and trinaphthylsilyl. Silyyl groups may or may not have substituents. The number of carbon atoms in a silyl group is not particularly limited, but is preferably in the range of 1 to 30.

[0097] The term siloxane refers to silicon compound groups formed by ether bonds, such as trimethylsiloxane. Siloxane groups may or may not have substituents.

[0098] Boronyl groups may or may not have substituents.

[0099] As a compound represented by general formula (8), for example, the following examples can be cited.

[0100] [Chemical Formula 26] In embodiments of the present invention, it is preferable that the light-emitting layer of the light-emitting element contains a triplet light-emitting material.

[0101] The dopant used as the emissive layer for triplet emission (phosphorescence) is preferably a metal coordination compound containing at least one metal selected from the group consisting of iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re). The ligand preferably has a nitrogen-containing aromatic heterocycle such as a phenylpyridine backbone, a phenylquinoline backbone, or a carbene backbone. However, this is not a limitation, and an appropriate complex can be selected based on the desired emission color, element performance, and relationship with the host compound. Specifically, examples include tris(2-phenylpyridyl)iridium complex, tris{2-(2-thienyl)pyridyl}iridium complex, tris{2-(2-benzothienyl)pyridyl}iridium complex, tris(2-phenylbenzothiazole)iridium complex, tris(2-phenylbenzoxazole)iridium complex, tribenzoquinone iridium complex, bis(2-phenylpyridyl)(acetylacetone)iridium complex, bis{2-(2-thienyl)pyridyl}iridium complex, bis{2-(2-benzothienyl)pyridyl}(acetylacetone)iridium complex, and bis(2-phenylbenzothiazole)(acetylacetone)iridium complex. Complexes, including bis(2-phenylbenzoxazole)(acetylacetone)iridium complexes, dibenzoquinone(acetylacetone)iridium complexes, bis{2-(2,4-difluorophenyl)pyridyl}(acetylacetone)iridium complexes, tetraethylporphyrin platinum complexes, {tris(thiophenecarboxyltrifluoroacetone)mono(1,10-phenanthroline)} europium complexes, {tris(thiophenecarboxyltrifluoroacetone)mono(4,7-diphenyl-1,10-phenanthroline)} europium complexes, {tris(1,3-diphenyl-1,3-propanedione)mono(1,10-phenanthroline)} europium complexes, and triacetylacetone terbium complexes, etc. Furthermore, phosphorescent dopants described in Japanese Patent Application Laid-Open No. 2009-130141 are preferred. Iridium complexes or platinum complexes are preferred as they can further improve luminescence efficiency.

[0102] The aforementioned triplet luminescent materials used as dopant materials can be contained in the luminescent layer in a single form, or two or more can be mixed together. When using two or more triplet luminescent materials, the total weight of the dopant materials relative to the host material is preferably 30% by weight or less, more preferably 20% by weight or less.

[0103] There are no particular limitations on the preferred host and dopant in triplet luminescent systems. Specifically, the following examples can be cited.

[0104] [Chemical Formula 27] [Chemical Formula 28] Furthermore, it is preferable that the luminescent layer contains a thermally activated delayed fluorescence (TADF) material. TADF is explained on pages 87-103 of "The Cutting Edge of Organic EL" (edited by Chinatsu Adachi and Hiroshi Fujimoto, published by CMC). This document explains that by bringing the energy levels of the excited singlet and excited triplet states of the fluorescent luminescent material close together, a reverse energy transfer from the normally low-probability excited triplet state to the excited singlet state is generated with high efficiency, resulting in thermally activated delayed fluorescence (TADF). Furthermore, Figure 5 in this document illustrates the generation mechanism of delayed fluorescence. The emission of delayed fluorescence can be confirmed using transition PL (PhotoLuminescence) measurements.

[0105] Thermally activated delayed fluorescence (TADF) materials are also commonly referred to as TADF materials. TADF materials can be materials exhibiting TADF as a single material or materials exhibiting TADF as a combination of multiple materials. When the material has multiple components, it can be used as a mixture or as a layer stacked from the various materials. Known materials can be used as TADF materials. Examples include, but are not limited to, benzonitrile derivatives, triazine derivatives, disulfoxide derivatives, carbazole derivatives, indolocarbazole derivatives, dihydrophenazine derivatives, thiazole derivatives, and oxadiazole derivatives.

[0106] In devices containing TADF material in the light-emitting layer, it is preferable to further include a fluorescent dopant in the light-emitting layer. This is because the TADF material converts triplet excitons into singlet excitons, which are then received by the fluorescent dopant, thereby achieving higher luminous efficiency and longer lifetime.

[0107] (Electron transport layer) In this invention, the electron transport layer is a layer that further transports electrons after they are injected from the cathode. For the electron transport layer, high electron injection efficiency and efficient transport of the injected electrons are desirable. Therefore, the material constituting the electron transport layer is preferably a substance with high electron affinity, high electron mobility, excellent stability, and low likelihood of generating impurities that could become traps during manufacturing and use. Especially when the film is stacked in thick layers, low molecular weight compounds can crystallize, leading to film degradation. Therefore, to ensure a stable film, compounds with a molecular weight of 400 or higher are preferred. However, considering the balance between hole and electron transport, as long as the electron transport layer primarily functions to efficiently prevent holes from the anode from flowing to the cathode side without recombination, the effect of improving luminous efficiency is equivalent to that of a material with high electron transport capability, even if it is composed of a material with relatively low electron transport capability. Therefore, in the electron transport layer of the present invention, the hole blocking layer, which can effectively prevent hole movement, is also included as a synonymous layer. The hole blocking layer and the electron transport layer can be made of separate materials or can be made by stacking multiple materials.

[0108] Known materials can be used as electron transport materials for the electron transport layer. Examples include fused polycyclic aromatic derivatives, styrene-based aromatic ring derivatives, quinone derivatives, phosphorus oxide derivatives, hydroxyquinoline complexes, benzo[a]hydroxyquinoline complexes, hydroxyazole complexes, methylimine complexes, cycloheptatrienolone metal complexes, and flavonol metal complexes. From the perspective of further reducing the driving voltage and obtaining higher efficiency luminescence, compounds composed of elements selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus, and having a heteroaryl ring structure containing electron-accepting nitrogen, are preferred.

[0109] The term "electron-accepting nitrogen" here refers to a nitrogen atom that has formed multiple bonds with neighboring atoms. Because nitrogen atoms have high electronegativity, these multiple bonds exhibit electron-accepting properties. Therefore, aromatic heterocycles containing electron-accepting nitrogen possess high electron affinity. Electron transport materials containing electron-accepting nitrogen readily accept electrons from cathodes with high electron affinity, enabling driving at lower voltages. Furthermore, the increased supply of electrons to the luminescent layer and the higher recombination probability further enhance luminous efficiency.

[0110] Examples of heteroaryl rings containing electron-accepting nitrogen include triazine rings, pyridine rings, pyrazine rings, pyrimidine rings, quinoline rings, quinoxaline rings, quinazoline rings, naphthidine rings, pyrimidine rings, benzoquinoline rings, phenanthrene rings, imidazole rings, oxazole rings, oxadiazole rings, triazole rings, thiazole rings, thiadiazole rings, benzoxazole rings, benzothiazole rings, benzimidazole rings, and phenanthrenemidazole rings.

[0111] Examples of compounds having these heteroaryl ring structures include, for example, pyridine derivatives, triazine derivatives, quinazoline derivatives, pyrimidine derivatives, benzimidazole derivatives, benzoxazole derivatives, benzothiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligopyridine derivatives, and naphthidine derivatives. From the viewpoint of electron transport capability, imidazole derivatives, oxadiazole derivatives, triazole derivatives, triazine derivatives, pyrimidine derivatives, phenanthroline derivatives, benzoquinoline derivatives, bipyridine derivatives, terpyridine derivatives, and naphthidine derivatives are preferred.

[0112] Furthermore, if these derivatives have a fused polycyclic aromatic skeleton, the glass transition temperature is increased and the electron mobility is also increased, which can further reduce the driving voltage of the organic EL device, and is therefore preferred. In addition, considering further improvement in device durability, ease of synthesis, and easy availability of raw materials, the fused polycyclic aromatic skeleton is more preferably a fluoranthene skeleton, anthracene skeleton, pyrene skeleton, or phenanthroline skeleton.

[0113] There are no particular limitations on preferred electron transport materials, but the following examples can be cited.

[0114] [Chemical Formula 29] [Chemical Formula 30] In addition, compounds represented by general formula (1) or (2) also have high electron transport properties and exhibit excellent properties as electron transport layers, and are therefore preferred.

[0115] The aforementioned electron transport materials can be used alone, or two or more of the aforementioned electron transport materials can be mixed together, or one or more other electron transport materials can be mixed into the aforementioned electron transport materials.

[0116] The electron transport layer may also contain donor materials. Here, the so-called donor material is a compound that facilitates electron injection from the cathode or electron injection layer to the electron transport layer by improving the electron injection barrier, thereby further improving the conductivity of the electron transport layer.

[0117] As a donor material, from the viewpoint of improving electron transport characteristics by having a low work function, it is preferable to contain alkali metal atoms, alkaline earth metal atoms, or rare earth metal atoms. Among these, from the viewpoint of further reducing the driving voltage of organic ELs, it is more preferable to contain alkali metal atoms, rare earth metal atoms, or copper group atoms.

[0118] Furthermore, since vacuum deposition is easy and has excellent processability, the donor material is more preferably an inorganic salt or a complex of metal and organic matter than a metallic element. Further, considering ease of atmospheric treatment and the ability to easily adjust the addition concentration, a complex of metal and organic matter is more preferred. Examples of inorganic salts include oxides, nitrides, fluorides, and carbonates. Preferred examples of organic compounds in complexes include hydroxyquinoline, benzo[a]hydroxyquinoline, pyridylphenol, flavonols, hydroxyimidazo[a]pyridine, hydroxybenzo[a]azole, and hydroxytriazole. Among these, alkali metal-organic complexes are preferred from the viewpoint of further reducing the driving voltage of organic EL elements. Further, from the viewpoint of ease of synthesis and thermal stability, lithium-organic complexes are more preferred, and lithium hydroxyquinoline (Liq), which is relatively inexpensive, is particularly preferred.

[0119] The ionization potential of the electron transport layer is not particularly limited, but is preferably 5.6 eV or more and 8.0 eV or less, and more preferably 5.6 eV or more and 7.0 eV or less.

[0120] The methods for forming the above-mentioned layers constituting organic EL elements are not particularly limited to resistance heating evaporation, electron beam evaporation, sputtering, molecular stacking, coating, etc. Generally, from the perspective of element characteristics, resistance heating evaporation or electron beam evaporation is preferred.

[0121] (Electron injection layer) In this invention, an electron injection layer may also be provided between the cathode and the electron transport layer. Typically, the electron injection layer is inserted to facilitate the injection of electrons from the cathode into the electron transport layer. In the case of insertion, a compound having a heteroaryl ring structure containing electron-accepting nitrogen may be used, or a layer containing the aforementioned donor material may be used.

[0122] Furthermore, inorganic materials such as insulators and semiconductors can be used in the electron injection layer; known materials can be employed. By using these materials, short circuits in organic EL devices can be suppressed, and electron injection performance can be improved.

[0123] As such an insulator, it is preferably at least one metal compound selected from the group consisting of alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides.

[0124] Furthermore, complexes of organic compounds and metals are also suitable for use. When an organic-metal complex is used in the electron injection layer, the film thickness can be easily adjusted. Preferred examples of organic compounds in organometallic complexes include hydroxyquinoline, benzo[a]hydroxyquinoline, pyridylphenol, flavonols, hydroxyimidazopyridine, hydroxybenzoazole, and hydroxytriazole.

[0125] Furthermore, layers containing compounds represented by general formula (1) or (2) are also preferred because they exhibit high electron injection capability and excellent properties as electron injection layers. Further, it is preferred that the electron injection layer contains compounds represented by general formula (1) or (2), and alkali metal atoms, rare earth metal atoms, or copper group atoms. In this case, the driving voltage can be further reduced, and the durability life can be further improved.

[0126] (charge generation layer) The charge generation layer in this invention is typically formed as a double layer; specifically, it can be used as a pn junction charge generation layer comprising an n-type charge generation layer and a p-type charge generation layer. Regarding the aforementioned pn junction charge generation layer, by applying a voltage to the organic EL element, charge is generated, or the charge is separated into holes and electrons, which are then injected into the light-emitting layer via a hole transport layer and an electron transport layer. Specifically, in an organic EL element with stacked light-emitting layers, the charge generation layer functions as an intermediate layer. The n-type charge generation layer supplies electrons to the first light-emitting layer located on the anode side, and the p-type charge generation layer supplies holes to the second light-emitting layer located on the cathode side. Therefore, the luminous efficiency in an organic EL element with multiple stacked light-emitting layers can be further improved, the driving voltage can be reduced, and the lifespan of the element can also be further improved.

[0127] The n-type charge generation layer is formed from an n-type dopant and a host material, which can be made from conventional materials. For example, alkali metals, alkaline earth metals, or rare earth metals can be used as the n-type dopant. Additionally, compounds with nitrogen-containing aromatic heterocycles, such as phenanthroline derivatives and oligopyridine derivatives, can be used as the host material. In particular, compounds represented by general formula (1) or (2) and phenanthroline derivatives exhibit excellent properties as the host material for the aforementioned n-type charge generation layer, and are therefore preferred.

[0128] As a way to generate a charge layer, it is preferable to contain a phenanthroline derivative in addition to the compound represented by general formula (1) or (2). Examples of phenanthroline derivatives include the following compounds.

[0129] [Chemical Formula 31] As a method of generating a charge layer, it is preferable to contain alkali metal atoms, copper group atoms, or rare earth metal atoms in addition to the compounds represented by general formula (1) or (2). Li is particularly preferred as an alkali metal atom. Ag is particularly preferred as a copper group atom. Yb is particularly preferred as a rare earth metal atom.

[0130] As a way of generating a charge layer, it is also preferred that, in addition to the compounds represented by general formula (1) or (2), the compounds contain phenanthrene derivatives and alkali metal atoms, copper group atoms or rare earth metal atoms.

[0131] The p-type charge generation layer is formed from a p-type dopant and a host material, both of which can be conventional materials. For example, tetrafluoro-7,7,8,8-tetracyanoquinone dimethane (F4-TCNQ), tetracyanoquinone dimethane derivatives, axialene derivatives, iodine, FeCl3, FeF3, SbCl5, etc., can be used as p-type dopants. Axylene derivatives are preferred as p-type dopants. Arylamine derivatives are preferred as the host material.

[0132] The thickness of the organic layer varies depending on the resistance value of the luminescent material, and therefore cannot be limited; it is preferably 1 to 1000 nm. The film thicknesses of the luminescent layer, electron transport layer, and hole transport layer are preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

[0133] The light-emitting element according to embodiments of the present invention has the function of converting electrical energy into light. Here, direct current is mainly used as electrical energy, but pulsed current and alternating current can also be used. There are no particular limitations on the current and voltage values; when considering the power consumption and lifespan of the element, it should be selected in a way that can obtain the maximum brightness using the lowest possible energy.

[0134] The light-emitting elements according to embodiments of the present invention are suitable for use in display devices such as displays that display in a matrix and / or segmented manner. That is, the display device of the present invention includes a light-emitting element containing the compound of the present invention. Furthermore, it is also equally suitable for use in display devices such as displays with optical sensors that are studied in terms of thinness and weight reduction.

[0135] The light-emitting element described in the embodiments of the present invention is suitable for use as a display device such as a monitor in various electronic devices. For example, electronic devices such as portable phones, smartphones, tablet terminals, laptops, and wearable terminals are being researched for power saving and long lifespan, therefore the light-emitting element of the present invention can provide electronic devices with higher durability compared to the past.

[0136] The light-emitting element according to embodiments of the present invention is also preferably used as a backlight for various devices, etc. Backlights are primarily used to improve the visibility of display devices such as displays that do not emit light themselves, and are used in liquid crystal displays, timers, audio devices, automotive panels, display boards, and signs, etc. In particular, the light-emitting element of the present invention is preferably used as a backlight for liquid crystal displays, especially for personal power applications where thinning is being studied, providing a thinner and lighter backlight compared to conventional backlights.

[0137] The light-emitting element according to embodiments of the present invention is also preferably used in various lighting devices. That is, the lighting device of the present invention comprises a light-emitting element containing the compound of the present invention.

[0138] The light-emitting element involved in the embodiments of the present invention can simultaneously achieve high luminous efficiency and high color purity, and can also achieve thinness and light weight. Therefore, it can realize a lighting device with low power consumption, bright light emission color, and high design flexibility.

[0139] Example The present invention will be illustrated below with examples, but the present invention is not limited to these examples.

[0140] Synthesis Example 1: Synthesis of Compound 2 A mixed solution of 15.0 g of 2,3-dibromonaphthalene, 40.7 g of raw material A, 16.6 g of sodium carbonate, 370 mg of bis(diphenylphosphine)ferrocene palladium dichloride, and 520 ml of dimethoxyethane was heated and stirred at 80 °C for 5 hours under a nitrogen atmosphere. After cooling to room temperature, water was added and the mixture was filtered, washed with methanol, and dried under vacuum. The resulting solid was recrystallized in toluene and dried under vacuum to give 27.2 g of compound 2.

[0141] For the obtained compound 2, an oil diffusion pump was used at 1×10 -3 The compound was purified by sublimation at approximately 350°C under a pressure of Pa. The HPLC purity (area %) of compound 1 before and after sublimation purification was 99.9%.

[0142] After sublimation purification, the samples were analyzed by mass spectrometry (MS). 1 The structure of compound 2 was identified by 1H-NMR analysis. The analytical results are shown below.

[0143] MS (m / z): 743 [M+H] + 1 H-NMR (400MHz, DMSO-d6) δ: 8.75-8.71 (m, 8H), 8.66 (d, J=8.0Hz, 4H), 8.14 (s, 2H), 8.11-8. 07 (m, 2H), 8.05-8.01 (m, 4H), 7.93 (d, J=8.0Hz, 4H), 7.64-7.61 (m, 2H), 7.55-7.49 (m, 8H).

[0144] [Chemical Formula 32] Synthesis Example 2: Synthesis of Compound 6 A mixed solution of 16.0 g of 2,3-dibromobenzo[b]thiophene, 2.6 g of raw material B, 17.4 g of sodium carbonate, 380 mg of bis(diphenylphosphine)ferrocene palladium dichloride, and 550 ml of dimethoxyethane was heated and stirred under reflux for 8 hours under a nitrogen atmosphere. After cooling to room temperature, water was added and the mixture was filtered, washed with methanol, and dried under vacuum. The resulting solid was recrystallized in toluene and dried under vacuum to give 25.8 g of compound 6.

[0145] For the obtained compound 6, an oil diffusion pump was used at 1×10 -3 The compound 6 was purified by sublimation at approximately 350°C under a pressure of Pa. The HPLC purity (area %) of compound 6 before and after sublimation purification was 99.9%.

[0146] After sublimation purification, the samples were analyzed by mass spectrometry (MS). 1 The structure of compound 6 was identified by 1H-NMR analysis. The analytical results are shown below.

[0147] MS (m / z): 749 [M+H] + 1 H-NMR (400MHz, DMSO-d6) δ: 8.76-8.71 (m, 2H), 8.66-8.64 (m, 2H), 8.60-8.55 (m, 6H), 8.42 (s, 2H), 8.15-8. 13 (m, 1H), 8.07-8.04 (m, 1H), 8.02-7.96 (m, 4H), 7.89-7.80 (m, 3H), 7.75-7.66 (m, 5H), 7.52-7.46 (m, 6H).

[0148] [Chemical Formula 33] Next, the evaluation methods in each embodiment will be described.

[0149] (Initial drive voltage and voltage rise) At 10mA / cm 2 The components obtained in Examples 1-21 and Comparative Examples 1-8 were subjected to DC drive, and the initial drive voltage was measured. Furthermore, the components were driven at a current density of 10 mA / cm² in an environment with a temperature of 70°C. 2 The driving voltage was measured during 100 hours of DC drive, and the voltage rise compared to the initial driving voltage was calculated.

[0150] In addition, with a brightness of 1000 cd / m² 2The organic EL devices obtained in Examples 22-63 and Comparative Examples 9-24 were lit up, and the initial driving voltage was measured. Further, the initial driving voltage was measured at room temperature with a current density of 10 mA / cm². 2 The driving voltage was measured during 100 hours of constant current driving, and the voltage rise compared to the initial driving voltage was calculated.

[0151] A lower initial driving voltage allows for driving at a lower voltage, thus resulting in excellent luminous efficiency (brightness / power). Furthermore, a smaller voltage rise indicates better durability.

[0152] (External quantum efficiency) With a current density of 10 mA / cm 2 The organic EL elements obtained in Examples 22-63 and Comparative Examples 9-24 were lit up, and the external quantum efficiency was measured and the luminous efficiency was evaluated. The higher the external quantum efficiency, the better the luminous efficiency can be evaluated.

[0153] (Durability) At 10mA / cm 2 A constant current was used to continuously drive the organic EL elements obtained in Examples 22-63 and Comparative Examples 9-24, and the time when the brightness decreased by 20% compared to the initial brightness was measured, which was defined as durability.

[0154] Example 1 As the anode, a glass substrate (manufactured by Geomatec Corporation, 11Ω / □, sputtered) with a 125nm ITO transparent conductive film deposited on it was cut into 38mm × 46mm pieces and etched. The resulting substrate was then ultrasonically cleaned for 15 minutes using "Semico Clean" (registered trademark) 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.), followed by washing with ultrapure water. Prior to component fabrication, the substrate underwent a 1-hour UV-ozone treatment in a vacuum evaporation apparatus, where exhaust was performed until the vacuum level reached 5 × 10⁻⁶. -4 Below Pa. Using a resistance heating method, compound 1 and the dopant metal element Yb were deposited at a deposition rate ratio of 9:1 (compound 1:Yb = 9:1) for 100 nm to form an electron transport layer with a weight ratio of 9:1. Subsequently, 60 nm of aluminum was deposited as the cathode to fabricate a 5 mm × 5 mm square single-charge element. Electron injection, charge generation efficiency, and electron transport properties could be evaluated by measuring the single-charge element. The film thickness referred to here is the value displayed by a quartz oscillating film thickness monitor, which is also common in other embodiments and comparative examples.

[0155] The single-charge element was evaluated using the aforementioned method. The results showed that the initial driving voltage was 0.096V and the voltage rise after 100 hours of driving at 70°C was 0.052V.

[0156] Examples 2-21, Comparative Examples 1-8 As described in Table 1, the compounds, metal elements, and vapor deposition rate ratios of the compounds and metal elements used were varied, but otherwise the same procedure as in Example 1 was followed to fabricate single-charge elements. The results of each example and comparative example are shown in Table 1. It should be noted that compounds 1 to 12 are the compounds shown below.

[0157] [Chemical Formula 34] [Chemical Formula 35] [Table 1] Example 22 As the anode, a glass substrate (manufactured by Geomatec Corporation, 11Ω / □, sputtered) with a 165nm ITO transparent conductive film deposited on it was cut into 38mm × 46mm pieces and etched. The resulting substrate was then ultrasonically cleaned for 15 minutes using "Semico Clean" 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.), followed by rinsing with ultrapure water. Prior to component fabrication, the substrate underwent a 1-hour UV-ozone treatment within a vacuum evaporation apparatus, where exhaust was performed until the vacuum level reached 5 × 10⁻⁶. -4 Below Pa. Using a resistance heating method, a 5 nm layer of P-D1 was first deposited as a hole injection layer, followed by a 50 nm layer of HT-1 as a hole transport layer. Next, as the light-emitting layer, a mixed layer of host material H-1 and dopant material D-1 was deposited to a thickness of 20 nm at a doping concentration of 5% by weight. Next, as the electron transport layer, ET-1 and 2E-1 were deposited to a thickness of 35 nm at a deposition rate ratio of ET-1 to 2E-1 = 1:1. Next, as the electron injection layer, compound 1 and the dopant metal element Yb were deposited to a thickness of 10 nm at a deposition rate ratio of compound 1:Yb = 9:1. Finally, a 60 nm layer of aluminum was deposited as the cathode to fabricate a 5 mm × 5 mm square organic EL device.

[0158] The organic EL device was evaluated using the aforementioned method. The results showed an initial driving voltage of 4.75V, an external quantum efficiency (luminous efficiency) of 4.91%, a lifetime of 810 hours, and a voltage rise of 0.041V after 100 hours of driving at room temperature. It should be noted that P-D1, HT-1, H-1, D-1, ET-1, and 2E-1 are the compounds shown below.

[0159] [Chemical Formula 36] Examples 23-42, Comparative Examples 9-16 As described in Table 2, the compounds, metal elements, and vapor deposition rate ratios of the compounds and metal elements used were varied, but otherwise the organic EL elements were fabricated in the same manner as in Example 22. The results of each example and comparative example are shown in Table 2.

[0160] [Table 2] Example 43 As the anode, a glass substrate (manufactured by Geomatec Corporation, 11Ω / □, sputtered) with a 165nm ITO transparent conductive film deposited on it was cut into 38mm × 46mm pieces and etched. The resulting substrate was then ultrasonically cleaned for 15 minutes using "Semico Clean" 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.), followed by rinsing with ultrapure water. Prior to component fabrication, the substrate underwent a 1-hour UV-ozone treatment within a vacuum evaporation apparatus, where exhaust was performed until the vacuum level reached 5 × 10⁻⁶. -4 Below Pa. Using a resistance heating method, a 5nm p-D1 layer is first deposited as a hole injection layer. Then, a light-emitting unit (first light-emitting unit) comprising a hole transport layer, a light-emitting layer, and an electron transport layer is formed on the hole injection layer.

[0161] Specifically, HT-1 with a thickness of 50 nm is deposited as a hole transport layer. Next, as a light-emitting layer, a mixed layer of host material H-1 and dopant material D-1 is deposited with a doping concentration of 5% by weight to a thickness of 20 nm. Then, as an electron transport layer, ET-1 and 2E-1 are deposited with a deposition rate ratio of ET-1 to 2E-1 = 1:1 to a thickness of 35 nm.

[0162] On the first light-emitting unit, as an N-type charge generation layer, compound 1 and metal element Yb as a dopant are deposited at a deposition rate ratio of compound 1:Yb=9:1 for 10 nm. Then, as a P-type charge generation layer, P-D1 is deposited for 10 nm.

[0163] Next, a charge generation layer is formed, and a second light-emitting unit is formed in the same way as the first light-emitting unit. Then, as an electron injection layer, compound 1 and the metal element Yb as a dopant are deposited at a deposition rate ratio of compound 1:Yb=9:1 for 10 nm. Then, 60 nm of aluminum is deposited as a cathode to fabricate an organic EL element with a size of 5 mm × 5 mm.

[0164] The organic EL device was evaluated using the aforementioned method. The results showed that the initial driving voltage was 9.66V, the external quantum efficiency (luminous efficiency) was 9.60%, the lifetime was 1590 hours, and the voltage rise after 100 hours of driving at room temperature was 0.025V.

[0165] Examples 44–63, Comparative Examples 17–24 As described in Table 3, the compounds used and the vapor deposition rate ratio of the compound to the metal element were varied, but the organic EL element was fabricated in the same manner as in Example 43. The results of each example and comparative example are shown in Table 3.

[0166] [Table 3] Examples 1-21 show the results of obtaining single-charge elements by using compounds represented by general formula (1) or (2) together with Li as an alkali metal element and Yb as a rare earth metal element. On the other hand, Comparative Examples 1-8 show the results of obtaining light-emitting elements by using compounds 10-12 (compounds not represented by general formula (1) or (2)) together with Li as an alkali metal element and Yb as a rare earth metal element. Compared with each comparative example, the initial driving voltage in each example is low and the rise in driving voltage is small. The reason for this is that, compared with compounds 10-12, compounds 1-9 represented by general formula (1) or (2) have high film stability, thus strong coordination stability with alkali metal elements and rare earth metal elements, higher charge generation efficiency and electron transport, thus stable carrier balance and suppression of voltage rise during driving.

[0167] Furthermore, Examples 1-12 show the results of using a compound represented by general formula (1) or (2) and a single-charge element of Yb as a rare earth metal element, while Examples 13-21 show the results of using a single-charge element of Li as an alkali metal element instead of Yb. Based on these results, it can be understood that the compound represented by general formula (1) or (2), when used in conjunction with a rare earth metal element, forms a more stable layer with a lower driving voltage rise.

[0168] Furthermore, Examples 22-42 show the results of applying the organic layers used in Examples 1-21 to the light-emitting element. On the other hand, Comparative Examples 9-16 show the results of applying the organic layers used in Comparative Examples 1-8 to the light-emitting element. Compared with each comparative example, each example shows a lower driving voltage, higher external quantum efficiency, improved durability, and less driving voltage rise. It can be seen that, similar to the results of a single-charge element, the compounds represented by general formula (1) or (2) effectively form a more stable light-emitting element with less driving voltage rise.

[0169] Furthermore, Examples 22-33 show the results of light-emitting elements containing compounds represented by general formula (1) or (2) and Yb as a rare earth metal element, and Examples 34-42 show the results of light-emitting elements containing Li as an alkali metal element instead of Yb. Based on these results, it can be understood that compounds represented by general formula (1) or (2), when used in conjunction with rare earth metal elements, form a more stable layer with a lower driving voltage rise.

[0170] Furthermore, Examples 43-63 show the results of applying the light-emitting elements used in Examples 22-42 to a series-type light-emitting element. On the other hand, Comparative Examples 17-24 show the results of applying the light-emitting elements used in Comparative Examples 9-16 to a series-type light-emitting element. Compared with each comparative example, each example shows a lower driving voltage, higher external quantum efficiency, improved durability, and less driving voltage rise. It can be seen that, similar to the results of the light-emitting elements used in Examples 22-42 and Comparative Examples 13-24, the compound represented by general formula (1) or (2) effectively forms a more stable series-type light-emitting element with less driving voltage rise.

[0171] Furthermore, Examples 43-54 show the results of a tandem light-emitting element containing a compound represented by general formula (1) or (2) and Yb as a rare earth metal element, while Examples 55-63 show the results of a tandem light-emitting element containing Li as an alkali metal element instead of Yb. Based on these results, it can be understood that the compound represented by general formula (1) or (2), when used in conjunction with a rare earth metal element, forms a more stable layer with a lower driving voltage rise.

Claims

1. Compounds represented by the following general formula (1) or (2): [Chemical Formula 1] X 1 For CR 12 Or nitrogen atom, X 2 and X 3 Each independently for CR 13 Or nitrogen atoms, Y is CR 14 R 15 NR 16 Oxygen or sulfur atoms, R 1 ~R 16 Each is independently selected from the group consisting of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups, wherein... R 1 ~R 7 The two adjacent groups in, and R 8 ~R 11 and R 13 The two adjacent groups in the formula are groups represented by the following general formula (3); [Chemical Formula 2] X 4 ~X 16 Each independently for CR 17 Or nitrogen atom, R 17 The group selected is composed of hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted heteroaryl groups, wherein X 4 ~X 6 One of them, X 7 ~X 11 One of them, and X 12 ~X 16 One of them is a nitrogen atom, L 1 For substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, n is 0 or 1.

2. The compound of claim 1, wherein, The group represented by the general formula (3) is the group represented by the following general formula (4): [Chemical Formula 3] In general formula (4), X 7 ~X 9 X 12 ~X 14 and L 1 X in general formula (3) 7 ~X 9 X 12 ~X 14 and L 1 It is the same, where X 7 ~X 9 One of them, and X 12 ~X 14 One of them is a nitrogen atom, and n is 0 or 1.

3. The compound of claim 1, wherein, The compounds represented by general formula (1) or (2) are compounds represented by the following general formulas (5) to (7): [Chemical Formula 4] In general formulas (5) to (7), X 1 X 7 ~X 9 X 12 ~X 14 Y and R 3 ~R 11 X in general formulas (1) to (3) 1 X 7 ~X 9 X 12 ~X 14 Y and R 3 ~R 11 It is the same, where X 7 ~X 9 One of them, and X 12 ~X 14 One of them is a nitrogen atom, L 2 ~L 5 Each is independently a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, where n is 0 or 1.

4. The compound of claim 1, wherein, The compound represented by the general formula (1) or (2) is the compound represented by the general formula (2), where Y is an oxygen atom or a sulfur atom.

5. The compound of claim 1, wherein, n is 1, L 1 It is a phenylene oxide.

6. A light-emitting element, which is a light-emitting element that has at least an electron transport layer and a light-emitting layer between the anode and the cathode and emits light using electrical energy, wherein, The electron transport layer contains the compound according to any one of claims 1 to 5.

7. The light-emitting element as claimed in claim 6, wherein, The electron transport layer also contains alkali metal atoms, rare earth metal atoms, or copper group atoms.

8. A light-emitting element, which is a light-emitting element that has at least a charge-generating layer and a light-emitting layer between the anode and the cathode and emits light using electrical energy, wherein, The charge-generating layer contains the compound according to any one of claims 1 to 5.

9. The light-emitting element as claimed in claim 8, wherein, The charge-generating layer also contains phenanthroline derivatives.

10. The light-emitting element as claimed in claim 8, wherein, The charge-generating layer also contains alkali metal atoms, rare earth metal atoms, or copper group atoms.

11. The light-emitting element as claimed in claim 8, wherein, The charge-generating layer also contains alkali metal atoms, wherein the alkali metal atoms are Li.

12. The light-emitting element as claimed in claim 8, wherein, The charge-generating layer also contains rare earth metal atoms, wherein the rare earth metal atoms are Yb.

13. A light-emitting element, which is a light-emitting element that emits light using electrical energy and has at least an electron injection layer and a light-emitting layer between the anode and the cathode, wherein, The electron-injected layer contains the compound according to any one of claims 1 to 5.

14. The light-emitting element as claimed in claim 13, wherein, The electron injection layer also contains alkali metal atoms, rare earth metal atoms, or copper group atoms.

15. A display device comprising a light-emitting element containing the compound according to any one of claims 1 to 5.

16. A lighting device comprising a light-emitting element containing the compound according to any one of claims 1 to 5.

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