Compound, organic electroluminescent element, display device, and lighting device

Abstract

The present invention provides an organic electroluminescent element excellent in luminous efficacy and service life. The present invention involves a compound represented by general formula (1) or a compound represented by general formula (3).

Description

Compound, organic EL element, display device and lighting device

[0001] The present invention relates to a compound, and an organic EL device, a display device, and a lighting device using the compound.

[0002] In recent years, organic EL elements have been steadily put to practical use, including their use in television and smartphone displays. However, existing organic EL elements still have many technical challenges. One of the biggest challenges is achieving both highly efficient light emission and a long lifespan for organic EL elements.

[0003] To date, compounds that have been developed to solve these problems include phosphine oxide derivatives having a phosphine oxide skeleton and an anthracene skeleton (see, for example, Patent Documents 1 and 2), phosphine oxide derivatives having a dibenzofuran skeleton or a dibenzothiophene skeleton (see, for example, Patent Document 3), phosphine oxide derivatives in which the linking group is substituted with a diphenylphosphine group (see, for example, Patent Document 4), and phosphine oxide derivatives having a bipyridine group and a fused ring structure (see, for example, Patent Document 5).

[0004] Chinese Patent Application Publication No. 112724073 Korean Patent Application Publication No. 10-2020-0103380 Korean Patent Application Publication No. 10-2019-0009704 U.S. Patent Application Publication No. 2019-0019959 Chinese Patent Application Publication No. 111574565

[0005] However, in recent years, the luminous efficiency and durability required of organic EL elements have been increasing, and there is a demand for a technology that can achieve both higher luminous efficiency and a longer lifespan.

[0006] In view of the above problems of the prior art, an object of the present invention is to provide an organic EL element having excellent luminous efficiency and durable life.

[0007] In order to solve the above problems, the present invention has the following features: [1] A compound represented by the following general formula (1):

[0008]

[0009] In general formula (1), R １１ and R１２ are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ is an unsubstituted phenylene group, an unsubstituted naphthylene group, an unsubstituted pyridylene group, an unsubstituted pyridazylene group, an unsubstituted pyrazylene group, or an unsubstituted pyrimidylene group, and L ２ is selected from a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted pyridazylene group, a substituted or unsubstituted pyrazylene group, and a substituted or unsubstituted pyrimidylene group. １３ ~R １６ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １４ and R １５ At least one of the above is a group represented by the following general formula (2).

[0010]

[0011] In general formula (2), X １ ~X ５ are each independently C-R １ ~C-R ５ or a nitrogen atom. １ ~R ５ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １ ~X ５ [2] A compound represented by the following general formula (3):

[0012]

[0013] In general formula (3), R ２１ and R ２２are each independently a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group, and are linked together to form a ring structure. １ is an unsubstituted phenylene group, an unsubstituted naphthylene group, an unsubstituted pyridylene group, an unsubstituted pyridazylene group, an unsubstituted pyrazylene group, or an unsubstituted pyrimidylene group, and L ２ is selected from a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted pyridazylene group, a substituted or unsubstituted pyrazylene group, and a substituted or unsubstituted pyrimidylene group. ２３ ~R ２６ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. ２４ and R ２５ is a group represented by the following general formula (2).

[0014]

[0015] In the general formula (2), X １ ~X ５ are each independently C-R １ ~C-R ５ or a nitrogen atom. １ ~R ５ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １ ~X ５ At least one of R in the general formula (1) is a nitrogen atom. １１ and R １２ are each independently a methyl group, a phenyl group, a naphthyl group, or a pyridyl group. １４ and R １５[5] The compound according to [1] or [3], wherein each of X is independently a group represented by general formula (2). １ ~X ５ wherein one of the groups is a nitrogen atom and the others are methine groups. [6] An organic EL device that emits light in response to electrical energy, having at least an electron transport layer and an emitting layer between an anode and a cathode, wherein the electron transport layer contains the compound according to any one of [1] to [5]. [7] The organic EL device according to [6], wherein the electron transport layer further contains a complex of an alkali metal, a rare earth metal, or an alkali metal with an organic substance. [8] An organic EL device that emits light in response to electrical energy, having at least a charge generation layer and an emitting layer between an anode and a cathode, wherein the charge generation layer contains the compound according to any one of [1] to [5]. [9] The organic EL device according to [8], wherein the charge generation layer further contains a phenanthroline derivative.

[10] The organic EL device according to [8] or [9], wherein the charge generation layer further contains an alkali metal or a rare earth metal.

[11] The organic EL device according to

[10] , wherein the alkali metal is Li.

[12] The organic EL device according to

[10] , wherein the rare earth metal is Yb.

[13] An organic EL device which emits light by electrical energy, and which has at least an electron injection layer and an emitting layer between an anode and a cathode, and the electron injection layer contains the compound according to any one of [1] to [5].

[14] The organic EL device according to

[13] , wherein the electron injection layer further contains an alkali metal or a rare earth metal.

[15] The organic EL device according to any one of [6] to

[14] , wherein the emitting layer contains a compound represented by the following general formula (4):

[0016]

[0017] In the general formula (4), the ring Za, the ring Zb, and the ring Zc are each independently a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroaryl ring having 5 to 30 ring atoms; Z １ and Z ２are each independently an oxygen atom, NRa (a nitrogen atom having a substituent Ra), or a sulfur atom, and Z １ is NRa, it may or may not be bonded to ring A or ring B to form a ring, and Z ２ is NRa, it may or may not form a ring with ring B or ring C; Ra is each independently a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring atoms, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; Y is a boron atom, a phosphorus atom, SiRb (a silicon atom having a substituent Rb), P=O, or P=S; Rb is each independently selected from a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring atoms, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

[16] A display device comprising the organic EL element according to any one of [6] to

[15] .

[17] A lighting device comprising the organic EL element according to any one of [5] to

[15] .

[0018] According to the present invention, an organic EL element having excellent luminous efficiency and durability can be provided.

[0019] Preferred embodiments of the compound, light-emitting element, display device, and lighting device according to the present invention will be described in detail below. However, the present invention is not limited to the following embodiments and can be practiced with various modifications depending on the purpose and application.

[0020] (Compound Represented by General Formula (1)) The compound according to the first embodiment of the present invention is a compound represented by general formula (1).

[0021]

[0022] In general formula (1), R １１ and R １２ are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １is an unsubstituted phenylene group, an unsubstituted naphthylene group, an unsubstituted pyridylene group, an unsubstituted pyridazylene group, an unsubstituted pyrazylene group, or an unsubstituted pyrimidylene group, and L ２ is selected from a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted pyridazylene group, a substituted or unsubstituted pyrazylene group, and a substituted or unsubstituted pyrimidylene group. １３ ~R １６ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １４ and R １５ At least one of the above is a group represented by the following general formula (2).

[0023]

[0024] In general formula (2), X １ ~X ５ are each independently C-R １ ~C-R ５ or a nitrogen atom. １ ~R ５ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １ ~X ５ One of the groups is a nitrogen atom.

[0025] (Compound Represented by General Formula (3)) The compound according to the second embodiment of the present invention is a compound represented by general formula (3).

[0026]

[0027] In general formula (3), R ２１ and R ２２ are each independently a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group, and are linked together to form a ring structure.１ is an unsubstituted phenylene group, an unsubstituted naphthylene group, an unsubstituted pyridylene group, an unsubstituted pyridazylene group, an unsubstituted pyrazylene group, or an unsubstituted pyrimidylene group, and L ２ is selected from a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted pyridazylene group, a substituted or unsubstituted pyrazylene group, and a substituted or unsubstituted pyrimidylene group. ２３ ~R ２６ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. ２４ and R ２５ is the group represented by the above general formula (2) shown in the description of the compound according to the first embodiment.

[0028] The following explanation applies to the compounds according to the first and second embodiments, unless otherwise specified.

[0029] In all of the above groups, a hydrogen atom may be a deuterium atom. The same applies to "substituted or unsubstituted" in the compounds or partial structures thereof described below.

[0030] The alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group, which may or may not have a substituent. The number of carbon atoms in the alkyl group is not particularly limited, but from the standpoint of availability and cost, it is preferably in the range of 1 to 20, more preferably 1 to 8. The number of carbon atoms referred to here includes the number of carbon atoms contained in a substituent bonded to the alkyl group, and the same applies to other substituents that specify the number of carbon atoms.

[0031] The alkoxy group refers to a group in which an alkyl group is bonded to oxygen, such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, or a tert-butoxy group, which may or may not have a substituent. The number of carbon atoms in the alkoxy group is not particularly limited, but from the standpoints of availability and cost, it is usually in the range of 1 to 20, more preferably 1 to 8.

[0032] The aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthryl group, an anthracenyl group, a benzophenanthryl group, a benzanthracenyl group, a chrysenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a benzofluoranthenyl group, a dibenzoanthracenyl group, a perylenyl group, or a helicenyl group. These may or may not have a substituent. Among these, a phenyl group or a biphenyl group is preferred.

[0033] Examples of heteroaryl groups include pyridyl, pyrrole, furanyl, thiophenyl, quinolinyl, isoquinolinyl, pyrazinyl, pyrimidyl, pyridazinyl, triazinyl, naphthyridinyl, cinnolinyl, phthalazinyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothiophenyl, indolyl, dibenzofuranyl, dibenzothiophenyl, benzophosphole, benzophosphole oxide, dibenzophosphole, and dibenzophosphole. It refers to a cyclic aromatic group having one or more atoms other than carbon in the ring, such as an oxide group, a carbazolyl group, a benzocarbazolyl group, a carbolinyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, a dihydroindenocarbazolyl group, a benzoquinolinyl group, an acridinyl group, a dibenzoacridinyl group, an imidazolyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, a naphthazinyl group, or a phenanthrolinyl group, provided that a naphthyridinyl group refers to any of a 1,5-naphthyridinyl group, a 1,6-naphthyridinyl group, a 1,7-naphthyridinyl group, a 1,8-naphthyridinyl group, a 2,6-naphthyridinyl group, and a 2,7-naphthyridinyl group. The heteroaryl group may or may not have a substituent. The number of ring atoms is not particularly limited, but is preferably 3 to 40, more preferably 3 to 30.

[0034] As conventional compounds containing a phosphine oxide skeleton and a nitrogen-containing aromatic heterocyclic group, for example, Patent Documents 1 to 5 disclose compounds U, V, W, X, and Y represented by the following formulas.

[0035]

[0036] However, even when these compounds are used as materials for organic EL devices in the electron injection layer, electron transport layer, or charge generation layer, they still do not provide sufficient performance for the characteristics required in recent years, and therefore, compounds that enable further improvements in performance in terms of luminous efficiency and durability are desired.

[0037] For example, phosphine oxide derivatives having a substituted anthrinyl group, such as compounds U and V, have a large twisted structure due to the bulky nature of the anthrinyl group, which makes it difficult for the groups on both sides of the anthrinyl group to conjugate, resulting in reduced charge transport properties, increased driving voltage, and problems with luminous efficiency and durability.

[0038] Phosphine oxide derivatives having a dibenzofuran skeleton as a linking group, such as Compound W, use a highly electron-accepting dibenzofuran skeleton as a linking group, which inhibits efficient conjugation between the phosphine oxide skeleton and the nitrogen-containing aromatic heterocycle. As a result, charge transport properties are reduced, driving voltage is increased, and there are issues with luminous efficiency and durability.

[0039] In phosphine oxide derivatives such as Compound X, which have a phosphine oxide group as a linking group, the highly electron-accepting phosphine oxide group substitutes for the linking group, inhibiting efficient conjugation between the phosphine oxide skeleton and the nitrogen-containing aromatic heterocycle. As a result, charge transport properties are reduced, driving voltage is increased, and there are issues with luminous efficiency and durability.

[0040] A dibenzophosphole derivative having a bipyridine group, such as compound Y, has a group with a short conjugation length, and therefore has poor charge transport properties, high driving voltage, and problems with luminous efficiency and durability.

[0041] In their investigations into the improvement, the present inventors have focused on the effects of the phosphine oxide skeleton, specific aryl or heteroaryl groups, and linking groups thereto.

[0042] The compound represented by general formula (1) can improve the charge transport property by containing at least one group represented by general formula (2).

[0043] In general formula (1), R １１ and R １２ are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. In this case, the highly reactive phosphorus atom in the phosphine oxide skeleton is substituted, thereby improving the stability of the compound.

[0044] From the viewpoint of improving the film quality stability and further improving the durability life of the light-emitting element, R １１ and R １２ are each independently a methyl group, an ethyl group, a phenyl group, a naphthyl group, or a pyridyl group. １１ and R １２ and are each independently a methyl group, a phenyl group, or a naphthyl group.

[0045] In view of the availability of the compound, in general formula (1), R １３ and R １６ And, R １４ and R １５ Among these, those which are not groups represented by general formula (2) are preferably each independently selected from the group consisting of a hydrogen atom, a methyl group, and a phenyl group, and are more preferably hydrogen atoms from the viewpoint of improving the film quality stability and further improving the durability life of the light-emitting element.

[0046] From the viewpoint of further enhancing the electron transport property and forming a stable layer, in general formula (1), R １４ and R １５ is preferably a group represented by general formula (2). Furthermore, electron mobility is increased, and driving voltage can be reduced.

[0047] On the other hand, the compound represented by formula (3) can improve the charge transport property by containing two groups represented by formula (2).

[0048] In general formula (3), R ２１ and R ２２ are each independently a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group, and are linked together to form a ring structure, which is preferable because the glass transition temperature is improved, the electron mobility is increased, and the driving voltage of the organic EL device can be further reduced.

[0049] In addition, from the viewpoint of improving the film quality stability and further improving the durability life of the light emitting element, R ２１ and R ２２and are each independently a phenyl group or a pyridyl group.

[0050] In view of the availability of the compound, in general formula (3), R ２３ and R ２６ are each independently preferably selected from the group consisting of a hydrogen atom, a methyl group, and a phenyl group, and are more preferably hydrogen atoms from the viewpoint of improving the film stability and further improving the durability of the light-emitting element. ２４ and R ２５ is preferably a substituent represented by general formula (2).

[0051] In the general formulas (1) and (3), L １ is an unsubstituted phenylene group, an unsubstituted naphthylene group, an unsubstituted pyridylene group, an unsubstituted pyridazylene group, an unsubstituted pyrazylene group, or an unsubstituted pyrimidylene group. These groups are preferred because they can improve the stability of the compound without reducing the charge transport property of the compound.

[0052] From the viewpoint of improving the film quality stability and further improving the luminous efficiency and durability life, １ is preferably a phenylene group or a naphthylene group, and L ２ is preferably a phenylene group or a naphthylene group. On the other hand, from the viewpoint of increasing the interaction between the phosphine oxide skeleton and the substituted pyridyl group and further improving the luminous efficiency and the durable life, L ２ is preferably a single bond.

[0053] In addition, X in the general formula (2) １ ~X ５ However, each independently, C-R １ ~C-R ５ Alternatively, a stable layer can be formed by using nitrogen atoms.

[0054] In the general formula (2), X １ ~X ５ Preferably, one of X is a nitrogen atom and the others are methine groups.４ and X ５ It is more preferable that one of the groups is a nitrogen atom and the other is a methine group. By forming a more stable layer, the organic EL device can be driven at a low voltage and have a longer durability life.

[0055] The molecular weight of the compound represented by general formula (1) or general formula (3) is preferably 400 or more from the viewpoint of suppressing crystallization and improving the stability of film quality, while the molecular weight of the compound represented by general formula (1) or general formula (3) is preferably 800 or less from the viewpoint of improving processability during sublimation purification and vapor deposition.

[0056] Examples of the compound represented by general formula (1) include the compounds shown below. Note that the following are merely examples, and compounds other than those explicitly listed here can also be preferably used as long as they are represented by general formula (1).

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] Examples of the compound represented by general formula (3) include the compounds shown below. Note that the following are merely examples, and compounds other than those explicitly listed here can also be preferably used as long as they are represented by general formula (3).

[0085]

[0086]

[0087] The compound represented by general formula (1) or general formula (3) can be synthesized by a known synthesis method, such as, but not limited to, a coupling reaction of an aryl halide derivative with an arylboronic acid derivative using palladium.

[0088] In the present invention, the light-emitting element has an anode, a cathode, and an organic layer interposed between the anode and the cathode, and the organic layer emits light when exposed to electrical energy. In the following description, such a light-emitting element may be referred to as an "organic EL element."

[0089] The layer configuration between the anode and the cathode in the organic EL element may be a configuration consisting of only an emitting layer, or may be a laminate configuration such as 1) emitting layer / electron transport layer, 2) hole transport layer / emitting layer, 3) hole transport layer / emitting layer / electron transport layer, 4) hole injection layer / hole transport layer / emitting layer / electron transport layer, 5) hole transport layer / emitting layer / electron transport layer / electron injection layer, 6) hole injection layer / hole transport layer / emitting layer / electron transport layer / electron injection layer, or 7) hole injection layer / hole transport layer / emitting layer / hole blocking layer / electron transport layer / electron injection layer.

[0090] The organic EL element may be a tandem type in which a plurality of the above-described layered structures are stacked via an intermediate layer. The intermediate layer is generally also called an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, or an intermediate insulating layer, and may be made of a known material. Specific examples of the tandem type include layered structures including a charge generation layer as an intermediate layer between an anode and a cathode, such as 8) hole transport layer / light emitting layer / electron transport layer / charge generation layer / hole transport layer / light emitting layer / electron transport layer, and 9) hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / charge generation layer / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer.

[0091] Each of the above layers may be a single layer or multiple layers, and may be doped. In particular, the electron injection layer and charge generation layer are preferably metal-doped layers doped with a metal, which can improve the electron transport ability and the electron injection ability into adjacent layers. In addition to the above layers, a protective layer (cap layer) may be further provided, which can further improve the luminous efficiency by the optical interference effect. The compound represented by general formula (1) or general formula (3) may be used in any of the above layers in the organic EL device, but is particularly suitable for use in the electron transport layer, charge generation layer, or electron injection layer. As the organic EL element according to the embodiment of the present invention, preferred configurations include a configuration having at least an electron transport layer between an anode and a cathode, and containing a compound represented by general formula (1) or general formula (3) 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 general formula (3) 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 general formula (3) in the electron injection layer.

[0092] In the organic EL element according to the embodiment of the present invention, the anode and cathode have the role of supplying a 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 light. Usually, the anode formed on the substrate is used as the transparent electrode.

[0093] (Substrate) In order to maintain the mechanical strength of the organic EL element, it is preferable to form the organic EL element on a substrate. Examples of the substrate include glass substrates such as soda glass and alkali-free glass, and plastic substrates. The thickness of the glass substrate is sufficient to maintain the mechanical strength, and 0.5 mm or more is sufficient. As for the glass material, it is preferable that the amount of ions eluted from the glass is small, and alkali-free glass is preferable. In addition, SiO ２ Soda lime glass coated with a barrier coating such as the above is also commercially available and can be used.

[0094] (Anode) The material used for the anode is preferably one that can efficiently inject holes into the organic layer. Furthermore, it is preferably transparent or semi-transparent in order 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 may be used alone, or multiple materials may be stacked or mixed together.

[0095] (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 used for the cathode include metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, as well as alloys and multilayer laminates of these metals with low-work-function metals such as lithium, sodium, potassium, calcium, and magnesium. Among these, aluminum, silver, and magnesium are preferred as the main components in terms of electrical resistance, ease of film formation, film stability, and light-emitting efficiency, and magnesium and magnesium are more preferred because they facilitate electron injection into the electron transport layer and the electron injection layer.

[0096] (Protective Layer) For cathode protection, it is preferable to laminate a protective layer (capping layer) on the cathode. The material constituting the protective layer (capping material) is not particularly limited, but examples thereof include metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, alloys using these metals, inorganic substances such as silica, titania, and silicon nitride, and organic polymer compounds such as polyvinyl alcohol, polyvinyl chloride, and hydrocarbon polymer compounds. Compounds represented by general formula (1) can also be used as capping materials. However, when the organic EL element has a device structure in which light is extracted from the cathode side (top emission structure), it is preferable that the capping material be optically transparent in the visible light region.

[0097] (Hole injection layer) The hole injection layer is a layer inserted between the anode and the hole transport layer. The hole injection layer may be a single layer or a laminate of multiple layers. The presence of a hole injection layer between the hole transport layer and the anode is preferable because it not only enables lower voltage driving and improves durability and lifespan, but also improves the carrier balance of the element and the luminous efficiency.

[0098] Known materials can be used for the hole injection layer. Examples include heterocyclic compounds such as benzidine derivatives, starburst arylamine materials, triarylamine derivatives, biscarbazole derivatives, pyrazoline derivatives, stilbene compounds, fluorene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, and porphyrin derivatives, and polymer materials such as polycarbonates and styrene derivatives having the above-mentioned monomers in their side chains, polythiophenes, polyanilines, polyfluorenes, polyvinylcarbazoles, and polysilanes. 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 preferably used.

[0099] These materials may be used alone or in combination of two or more materials. Furthermore, a hole injection layer may be formed by laminating a plurality of materials. Furthermore, it is more preferable that the hole injection layer be composed solely of an acceptor compound or that the hole injection material be doped with an acceptor compound, since the above-described effects are more pronounced. The acceptor compound is a material that forms a charge-transfer complex with the adjacent hole transport layer when used as a single layer film, or with the material constituting the hole injection layer when used as a doped film. The use of such a material improves the conductivity of the hole injection layer, further contributing to a reduction in the driving voltage of the device and further improving the luminous efficiency and durability.

[0100] Known materials can be used as the acceptor compound. Examples include metal chlorides, metal oxides such as molybdenum oxide, charge-transfer complexes, organic compounds having a nitro group, a cyano group, a halogen, or a trifluoromethyl group in the molecule, quinone compounds, acid anhydride compounds, and fullerenes. Among these, metal oxides and cyano group-containing compounds are preferred because they are easy to handle and vapor-deposit, and therefore the above-mentioned effects can be easily obtained. Whether the hole injection layer is composed of an acceptor compound alone or is doped with an acceptor compound, the hole injection layer may be a single layer or may be composed of multiple layers stacked together.

[0101] (Hole Transport Layer) The hole transport layer is a layer that transports holes injected from the anode to the light emitting layer. The hole transport layer may be a single layer or may be configured by laminating multiple layers.

[0102] Materials used for the hole transport layer include those exemplified as materials used for the hole injection layer. From the viewpoint of smoothly injecting and transporting holes to the light emitting layer, triarylamine derivatives and benzidine derivatives are more preferred.

[0103] (Light-Emitting Layer) The light-emitting layer may be a single layer or multiple layers, each formed from light-emitting materials (host material, dopant material). This may be a mixture of a host material and a dopant material, a host material alone, or a mixture of two host materials and one dopant material. That is, in the organic EL device according to the embodiment of the present invention, only the host material or the dopant material may emit light in each light-emitting layer, or both the host 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 composed of a mixture of a host material and a dopant material. Furthermore, the host material and the dopant material may each be one type, or a combination of multiple types. The dopant material may be contained entirely or partially in the host material. The dopant material may be laminated or dispersed. The dopant material can control the emitted color. The amount of the dopant material is preferably 30% by weight or less, more preferably 20% by weight or less, based on the host material, from the viewpoint of suppressing concentration quenching. The doping method can be a co-evaporation method with the host material, or the dopant material may be mixed with the host material in advance and then evaporated simultaneously.

[0104] Known light-emitting materials can be used, including, for example, fused ring derivatives of anthracene, pyrene, and the like, which are known as light-emitting bodies, metal-chelated oxinoid compounds such as tris(8-quinolinolato)aluminum, bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, and polymers such as polyphenylenevinylene derivatives, polyparaphenylene derivatives, and polythiophene derivatives.

[0105] The host material contained in the light-emitting material does not need to be limited to only one compound, and a mixture of multiple compounds may be used. Furthermore, the compounds may be laminated. Known materials can be used as the host material. Examples of the host material include, but are not limited to, compounds having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, and indene, and derivatives thereof; aromatic amine derivatives such as N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine; metal chelated oxinoid compounds such as tris(8-quinolinato)aluminum(III); bisstyryl derivatives such as distyrylbenzene derivatives; Examples of the host include tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, and polymers such as polyphenylenevinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polythiophene derivatives. Among these, preferred examples of the host used when the light-emitting layer exhibits triplet emission (phosphorescence emission) include metal-chelated oxinoid compounds, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, and triphenylene derivatives.

[0106] Examples of dopant materials contained in the light-emitting material include compounds having an aryl ring and derivatives thereof, compounds having a heteroaryl ring and derivatives thereof, distyrylbenzene derivatives, aminostyryl derivatives, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, stilbene derivatives, aldazine derivatives, pyrromethene derivatives, diketopyrrolo[3,4-c]pyrrole derivatives, coumarin derivatives, azole derivatives, metal complexes thereof, aromatic amine derivatives, and compounds represented by the following general formula (4). Among these, dopants containing a diamine skeleton and dopants containing a fluoranthene skeleton can further improve light-emitting efficiency, and compounds represented by the following general formula (4) can further improve light-emitting efficiency and durable life. It is particularly preferable that the light-emitting layer contains a compound represented by the following general formula (4).

[0107]

[0108] In general formula (4), ring Za, ring Zb, and ring Zc are each independently a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroaryl ring having 5 to 30 ring atoms. Ring Za, ring Zb, and ring Zc are each preferably independently a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms. Z １ and Z ２ are each independently an oxygen atom, NRa (a nitrogen atom having a substituent Ra), or a sulfur atom, and Z １ is NRa, it may or may not be bonded to ring Za or ring Zb to form a ring, ２ When NRa is NRa, it may or may not be bonded to the Zb ring or the Zc ring to form a ring. Each Ra is independently a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring atoms, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms. Z １ and Z ２are all NRa, and Ra is preferably a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms. Y is a boron atom, a phosphorus atom, SiRb (a silicon atom having a substituent Rb), P=O, or P=S. Rb is each independently a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring atoms, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms. Y is preferably a boron atom. In all of the above groups, the substituent when substituted is preferably an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, a halogen atom, a cyano group, an aldehyde group, an acyl group, a carboxyl group, an ester group, an amide group, an acyl group, a sulfonyl group, a sulfonate ester group, a sulfonamide group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, or an oxo group. These substituents may further be substituted with the above-mentioned substituents.

[0109] Examples of the alkyl group, alkoxy group, aryl group and heteroaryl group include those exemplified as the substituent in general formula (1).

[0110] The cycloalkyl group refers to a saturated alicyclic hydrocarbon group, such as a cyclopropyl group, a cyclohexyl group, a norbornyl group, or an adamantyl group, which may or may not have a substituent. The number of ring carbon atoms is not particularly limited, but is preferably in the range of 3 to 20.

[0111] The heterocyclic group refers to an aliphatic ring having atoms other than carbon atoms in the ring, such as a pyran ring, a piperidine ring, or a cyclic amide, which may or may not have a substituent. The number of ring atoms is not particularly limited, but is preferably in the range of 3 to 20.

[0112] The alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond, such as a vinyl group, an allyl group, or a butadienyl group, which may or may not have a substituent. The number of carbon atoms in the alkenyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0113] The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond, such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexenyl group, which may or may not have a substituent.

[0114] The alkynyl group refers to an unsaturated aliphatic hydrocarbon group containing a triple bond, such as an ethynyl group, which may or may not have a substituent. The number of carbon atoms in the alkynyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0115] Furthermore, in a substituted phenyl group, when two adjacent carbon atoms in the phenyl group each have a substituent, the substituents may together form a ring structure. The resulting group may correspond to one or more of a "substituted phenyl group," an "aryl group having a structure in which two or more rings are fused," or a "heteroaryl group having a structure in which two or more rings are fused," depending on its structure.

[0116] An alkylthio group is an alkoxy group in which the oxygen atom of the ether bond is replaced with a sulfur atom. The alkylthio group may or may not have a substituent. The number of carbon atoms in the alkylthio group is not particularly limited, but is preferably in the range of 1 to 20.

[0117] The aryl ether group refers to a functional group in which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and may or may not have a substituent. The number of carbon atoms in the aryl ether group is not particularly limited, but is preferably in the range of 6 to 40.

[0118] The aryl thioether group refers to a functional group in which the oxygen atom of the ether bond of an aryl ether group is substituted with a sulfur atom, and may or may not have a substituent. The number of carbon atoms in the aryl thioether group is not particularly limited, but is preferably in the range of 6 to 40.

[0119] Halogen refers to fluorine, chlorine, bromine or iodine.

[0120] The acyl group refers to a functional group in which an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heteroaryl group is bonded via a carbonyl group, such as an acetyl group, a propionyl group, a benzoyl group, or an acrylyl group, and may or may not have a substituent. The number of carbon atoms in the acyl group is not particularly limited, but is preferably 2 to 40, more preferably 2 to 30.

[0121] The ester group refers to a functional group in which, for example, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or the like is bonded via an ester bond, and may or may not have a substituent. The number of carbon atoms in the ester group is not particularly limited, but is preferably in the range of 1 to 20. More specific examples include methyl ester groups such as a methoxycarbonyl group, ethyl ester groups such as an ethoxycarbonyl group, propyl ester groups such as a propoxycarbonyl group, butyl ester groups such as a butoxycarbonyl group, isopropyl ester groups such as an isopropoxymethoxycarbonyl group, hexyl ester groups such as a hexyloxycarbonyl group, and phenyl ester groups such as a phenoxycarbonyl group.

[0122] The amide group refers to a functional group in which, for example, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or the like is bonded via an amide bond, and may or may not have a substituent. The number of carbon atoms in the amide group is not particularly limited, but is preferably in the range of 1 to 20. More specific examples include a methylamide group, an ethylamide group, a propylamide group, a butylamide group, an isopropylamide group, a hexylamide group, and a phenylamide group.

[0123] The sulfonyl group is, for example, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, etc., which is —S(═O) ２ The sulfonyl group represents a functional group bonded via a - bond, and may or may not have a substituent. The number of carbon atoms in the sulfonyl group is not particularly limited, but is preferably in the range of 1 to 20.

[0124] The sulfonate ester group refers to a functional group in which, for example, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or the like is bonded via a sulfonate ester bond, and may or may not have a substituent. Here, the sulfonate ester bond refers to a group in which the carbonyl part of the ester bond, i.e., —C(═O)—, is bonded to the sulfonyl part, i.e., —S(═O) ２ The number of carbon atoms in the sulfonate ester group is not particularly limited, but is preferably in the range of 1 to 20.

[0125] The sulfonamide group refers to a functional group in which, for example, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or the like is bonded via a sulfonamide bond, and may or may not have a substituent. Here, the sulfonamide bond refers to a group in which the carbonyl part of the ester bond, i.e., —C(═O)—, is bonded to the sulfonyl part, i.e., —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.

[0126] The amino group may or may not have a substituent. 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 6 to 40, and particularly preferably 6 to 30.

[0127] The silyl group refers to a functional group to which a substituted or unsubstituted silicon atom is bonded, and examples thereof include alkylsilyl groups such as trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, propyldimethylsilyl, and vinyldimethylsilyl, and arylsilyl groups such as phenyldimethylsilyl, tert-butyldiphenylsilyl, triphenylsilyl, and trinaphthylsilyl. The silyl group may or may not have a substituent. The number of carbon atoms in the silyl group is not particularly limited, but is preferably in the range of 1 to 30.

[0128] The siloxanyl group refers to a silicon compound group bonded via an ether bond, such as a trimethylsiloxanyl group, etc. The siloxanyl group may or may not have a substituent.

[0129] The boryl group may or may not have a substituent.

[0130] Examples of the compound represented by general formula (4) include the following.

[0131]

[0132] In the organic EL device according to the embodiment of the present invention, the light-emitting layer preferably contains a triplet light-emitting material.

[0133] The dopant used when the light-emitting layer emits triplet light (phosphorescence) is preferably a metal complex 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 skeleton, a phenylquinoline skeleton, or a carbene skeleton. However, the dopant is not limited to these, and an appropriate complex is selected based on the required emission color, device performance, and relationship with the host compound. Specifically, tris(2-phenylpyridyl)iridium complexes, tris{2-(2-thiophenyl)pyridyl}iridium complexes, tris{2-(2-benzothiophenyl)pyridyl}iridium complexes, tris(2-phenylbenzothiazole)iridium complexes, tris(2-phenylbenzoxazole)iridium complexes, trisbenzoquinolineiridium complexes, bis(2-phenylpyridyl)(acetylacetonate)iridium complexes, bis{2-(2-thiophenyl)pyridyl}iridium complexes, bis{2-(2-benzothiophenyl)pyridyl}(acetylacetonate)iridium complexes, bis(2-phenylbenzothiazole)(acetylacetonate)iridium complexes, bis(2-phenylbenzothiazole)(acetylacetonate)iridium complexes, Examples of suitable dopants include a bis(2-(2,4-difluorophenyl)pyridyl)(acetylacetonate)iridium complex, a bisbenzoquinoline(acetylacetonate)iridium complex, a bis{2-(2,4-difluorophenyl)pyridyl}(acetylacetonate)iridium complex, a tetraethylporphyrin platinum complex, a {tris(cenoyltrifluoroacetone)mono(1,10-phenanthroline)}europium complex, a {tris(cenoyltrifluoroacetone)mono(4,7-diphenyl-1,10-phenanthroline)}europium complex, a {tris(1,3-diphenyl-1,3-propanedione)mono(1,10-phenanthroline)}europium complex, and a trisacetylacetone terbium complex. Phosphorescent dopants such as those described in JP-A-2009-130141 are also suitable. Iridium complexes or platinum complexes are preferred, as they can further improve luminous efficiency.

[0134] The triplet light-emitting materials used as dopant materials may each be contained alone in the light-emitting layer, or two or more of them may be mixed together. When two or more triplet light-emitting materials are used, the total weight of the dopant materials is preferably 30% by weight or less, more preferably 20% by weight or less, based on the host material.

[0135] Preferred hosts and dopants in triplet light-emitting systems are not particularly limited, but specific examples include the following.

[0136]

[0137]

[0138] It is also preferable that the light-emitting layer contains a thermally activated delayed fluorescent material. Thermally activated delayed fluorescence is discussed on pages 87 to 103 of "State-of-the-art Organic EL" (edited by Adachi Chinaya and Fujimoto Hiroshi, published by CMC Publishing). This document explains that by bringing the energy levels of the excited singlet state and the excited triplet state of a fluorescent material close to each other, reverse energy transfer from the excited triplet state, which normally has a low transition probability, to the excited singlet state occurs with high efficiency, resulting in the expression of thermally activated delayed fluorescence (TADF). Furthermore, Figure 5 in this document explains the mechanism by which delayed fluorescence occurs. The emission of delayed fluorescence can be confirmed by transient PL (Photo Luminescence) measurement.

[0139] Thermally activated delayed fluorescence materials are also commonly referred to as TADF materials. Thermally activated delayed fluorescence materials may be materials that exhibit thermally activated delayed fluorescence using a single material, or may be materials that exhibit thermally activated delayed fluorescence using multiple materials. When multiple materials are used, they may be used as a mixture, or layers made of each material may be stacked. Known materials can be used as thermally activated delayed fluorescence 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.

[0140] It is preferable that a device containing a TADF material in its light-emitting layer further contains a fluorescent dopant in the light-emitting layer, because the TADF material converts triplet excitons into singlet excitons, and the fluorescent dopant accepts the singlet excitons, thereby achieving higher luminous efficiency and longer durability.

[0141] (Electron Transport Layer) In the present invention, the electron transport layer is a layer into which electrons are injected from the cathode and which further transports the electrons. It is desirable for the electron transport layer to have high electron injection efficiency and efficiently transport the injected electrons. Therefore, it is preferable that the material constituting the electron transport layer has high electron affinity, high electron mobility, excellent stability, and is unlikely to generate impurities that become traps during production and use. In particular, when a thick film is laminated, low-molecular-weight compounds are prone to deterioration of film quality due to crystallization, etc., so in order to maintain stable film quality, compounds with a molecular weight of 400 or more are preferred. However, considering the balance between hole and electron transport, if the electron transport layer mainly plays a role in efficiently preventing holes from the anode from flowing to the cathode without recombining, even if the electron transport layer is composed of a material with a relatively low electron transport capacity, the effect of improving luminous efficiency will be equivalent to that of a material with a high electron transport capacity. Therefore, the electron transport layer in the present invention also includes a hole blocking layer that can efficiently block the movement of holes, and the hole blocking layer and the electron transport layer may be formed by a single material or by laminating a plurality of materials.

[0142] Known materials can be used as the electron transport material for the electron transport layer. Examples include condensed polycyclic aromatic derivatives, styryl aromatic ring derivatives, quinone derivatives, phosphorus oxide derivatives, quinolinol complexes, benzoquinolinol complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes, and various metal complexes such as flavonol metal complexes. Compounds containing an electron-accepting nitrogen atom and an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus are preferably used because they can reduce the driving voltage and achieve more efficient light emission.

[0143] The electron-accepting nitrogen referred to here refers to a nitrogen atom that forms a multiple bond with an adjacent atom. Because the nitrogen atom has high electronegativity, the multiple bond has electron-accepting properties. Therefore, aromatic heterocycles containing electron-accepting nitrogen have high electron affinity. Electron-transporting materials containing electron-accepting nitrogen readily accept electrons from a cathode with high electron affinity, enabling operation at lower voltages. Furthermore, the supply of electrons to the light-emitting layer increases, increasing the recombination probability, further improving luminous efficiency.

[0144] Examples of heteroaryl rings containing an electron-accepting nitrogen include a triazine ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a quinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, a pyrimidopyrimidine ring, a benzoquinoline ring, a phenanthroline ring, an imidazole ring, an oxazole ring, an oxadiazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, and a phenanthroimidazole ring.

[0145] Examples of compounds having these heteroaryl ring structures include pyridine derivatives, triazine derivatives, quinazoline derivatives, pyrimidine derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligopyridine derivatives, quinoxaline derivatives, and naphthyridine derivatives. Among these, imidazole derivatives, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, benzoquinoline derivatives, bipyridine derivatives, terpyridine derivatives, and naphthyridine derivatives are preferably used from the viewpoint of electron transport ability.

[0146] Furthermore, when these derivatives have a condensed polycyclic aromatic skeleton, the glass transition temperature is improved, the electron mobility is increased, and the driving voltage of the organic EL device can be further reduced, which is preferable. Furthermore, in consideration of further improving the durability life of the device, ease of synthesis, and ease of availability of raw materials, it is more preferable that the condensed polycyclic aromatic skeleton is a fluoranthene skeleton, an anthracene skeleton, a pyrene skeleton, or a phenanthroline skeleton.

[0147] Preferred electron transport materials are not particularly limited, but specific examples include the following.

[0148]

[0149]

[0150]

[0151] The compounds represented by the general formula (1) or (3) are also preferred because they have high electron transporting properties and exhibit excellent properties as an electron transport layer.

[0152] The electron transport material may be used alone, or two or more of the electron transport materials may be mixed, or one or more other electron transport materials may be mixed with the electron transport material. The electron transport layer may contain a donor material in addition to the electron transport material, preferably the compound represented by formula (1) or (3). The donor material is a compound that improves the electron injection barrier, thereby facilitating electron injection from the cathode or the electron injection layer into the electron transport layer, and further improving the electrical conductivity of the electron transport layer.

[0153] Preferred examples of the donor material include alkali metals, inorganic salts containing alkali metals, complexes of alkali metals and organic substances, alkaline earth metals, inorganic salts containing alkaline earth metals or complexes of alkaline earth metals and organic substances, rare earth metals, and simple substances of Group 11 elements. Preferred examples of alkali metals and rare earth metals include lithium and ytterbium, which have a low work function and are highly effective in improving electron transport ability. Furthermore, a plurality of these metals may be used, or an alloy of these metals may be used.

[0154] Furthermore, because deposition in a vacuum is easy and handling is excellent, inorganic salts or complexes with organic substances are preferred over simple metals. Furthermore, complexes with organic substances are more preferred because they facilitate handling in the atmosphere and allow for easy adjustment of the addition concentration. Examples of inorganic salts include oxides, nitrides, fluorides, and carbonates. Preferable examples of alkali metals or alkaline earth metals include lithium and cesium, from the viewpoint of further reducing the driving voltage. Preferable examples of organic substances in complexes with organic substances include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, and hydroxytriazole. Among these, complexes of alkali metals and organic substances are preferred from the viewpoint of further reducing the driving voltage of organic EL devices. Furthermore, complexes of lithium and organic substances are more preferred from the viewpoints of ease of synthesis and thermal stability, and lithium quinolinol (Liq), which is relatively inexpensive and available, is particularly preferred.

[0155] The ionization potential of the electron transport layer is not particularly limited, but is preferably from 5.6 eV to 8.0 eV, more preferably from 5.6 eV to 7.0 eV.

[0156] (Electron Injection Layer) In the present invention, an electron injection layer may be provided between the cathode and the electron transport layer. Generally, the electron injection layer is inserted for the purpose of assisting the injection of electrons from the cathode to the electron transport layer. In this case, a compound having a heteroaryl ring structure containing electron-accepting nitrogen may be used, or a layer containing the above-mentioned donor material may be used.

[0157] In addition, inorganic insulating or semiconducting materials can be used for the electron injection layer, and known materials can be used. By using these materials, short circuits in the organic EL element can be suppressed and the electron injection property can be improved.

[0158] Such an insulator 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.

[0159] Furthermore, a complex of an organic substance and a metal can also be suitably used. When a complex of an organic substance and a metal is used in the electron injection layer, the film thickness can be easily adjusted. Preferred examples of the organic substance in the organometallic complex include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, and hydroxytriazole.

[0160] In addition, a layer containing a compound represented by general formula (1) or general formula (3) also has high electron injection properties and is therefore preferred because it exhibits excellent properties as an electron injection layer. Furthermore, the compound represented by general formula (1) or general formula (3) is preferably doped with the above-mentioned alkali metal or rare earth metal, which can further reduce the driving voltage and further improve the durability life.

[0161] The electron injection layer preferably contains an alkali metal or a rare earth metal in addition to the compound represented by formula (1) or formula (3). Preferred examples of the alkali metal or rare earth metal include alkali metals such as lithium, sodium, potassium, rubidium, and cesium, which have a low work function and are highly effective in improving electron transport ability, and rare earth metals such as samarium, europium, and ytterbium. More preferred examples of the alkali metal or rare earth metal include lithium and ytterbium, which can further reduce the driving voltage.

[0162] (Charge Generation Layer) The charge generation layer in the present invention generally comprises a double layer, and specifically, can be used as a pn junction charge generation layer comprising an n-type charge generation layer and a p-type charge generation layer. When a voltage is applied to the organic EL element, the pn junction charge generation layer generates charges or separates the charges into holes and electrons, and injects these holes and electrons into the light-emitting layer via the hole transport layer and electron transport layer. Specifically, it functions as an intermediate charge generation layer in an organic EL element in which light-emitting layers are stacked. 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 of an organic EL element in which multiple light-emitting layers are stacked can be further improved, the driving voltage can be reduced, and the durability of the element can be further improved.

[0163] The n-type charge generating layer comprises an n-type dopant and a host, and conventional materials can be used for these. For example, an alkali metal, alkaline earth metal, rare earth metal, or a simple substance of a Group 11 element can be used as the n-type dopant. Furthermore, a compound having a nitrogen-containing aromatic heterocycle, such as a phenanthroline derivative or an oligopyridine derivative, can be used as the host. In particular, the compounds represented by general formula (1) or general formula (3) and phenanthroline derivatives are preferred because they exhibit excellent properties as hosts for the n-type charge generating layer.

[0164] In one embodiment of the charge generating layer, it is preferable to further contain a phenanthroline derivative in addition to the compound represented by formula (1) or (3). Examples of the phenanthroline derivative include the following compounds.

[0165]

[0166]

[0167] In one embodiment of the charge generating layer, it is preferable that the charge generating layer further contains an alkali metal or a rare earth metal in addition to the compound represented by formula (1) or (3). As the alkali metal, Li is particularly preferable. As the rare earth metal, Yb is particularly preferable.

[0168] As one embodiment of the charge generating layer, a structure containing a phenanthroline derivative and an alkali metal or a rare earth metal in addition to the compound represented by formula (1) or (3) is also preferred.

[0169] The p-type charge generation layer is composed of a p-type dopant and a host, and conventional materials can be used for these. For example, p-type dopants include tetrafluorene-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), tetracyanoquinodimethane derivatives, radialene derivatives, iodine, and FeCl. ３ , FeF ３ , SbCl ５ The p-type dopant is preferably a radialene derivative, and the host is preferably an arylamine derivative.

[0170] The thickness of the organic layer is not limited because it depends on the resistance value of the light-emitting substance, but is preferably 1 to 1,000 nm. The thickness of each of the light-emitting layer, electron transport layer, and hole transport layer is preferably 1 nm to 200 nm, more preferably 5 nm to 100 nm.

[0171] The method for forming each of the layers constituting the organic EL element is not particularly limited, and may be resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination, coating, or the like. However, resistance heating evaporation or electron beam evaporation is usually preferred in terms of element characteristics.

[0172] The organic EL element according to the embodiment of the present invention has a function of converting electrical energy into light. While direct current is primarily used as the electrical energy, pulsed current or alternating current can also be used. While there are no particular limitations on the current and voltage values, they should be selected so as to obtain maximum brightness with as little energy as possible, taking into consideration the power consumption and lifespan of the element.

[0173] The organic EL element according to the embodiment of the present invention is suitably used as a display device such as a matrix and / or segment display.

[0174] The organic EL element according to the embodiment of the present invention is also preferably used as a backlight for various devices. Backlights are primarily used for the purpose of improving the visibility of display devices such as non-self-luminous displays, and are used in liquid crystal displays, clocks, audio equipment, automobile panels, display boards, signs, etc. In particular, the organic EL element of the present invention is preferably used as a backlight for liquid crystal displays, particularly for personal computers, which are being considered for thinning, and can provide a backlight that is thinner and lighter than conventional ones.

[0175] The organic EL element according to the embodiment of the present invention is also preferably used in various lighting devices. The organic EL element according to the embodiment of the present invention can achieve both high luminous efficiency and high color purity, and can also be made thin and lightweight, thereby realizing a lighting device that combines low power consumption, vivid luminous color, and high designability.

[0176] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0177] Synthesis Example 1: Synthesis of Compound 7 A mixed solution of 2.67 g of 4'-chloro-terpyridine, 4.04 g of boronic acid ester A, 702 mg of dichlorobis(triphenylphosphinepalladium) dichloride, 200 ml of 2.0 M aqueous potassium phosphate solution, and 500 ml of dimethoxyethane was heated and stirred under reflux for 2 hours under a nitrogen stream. After cooling to room temperature, water was added, the mixture was filtered, washed with methanol, and dried under vacuum. The catalyst was removed from the resulting solid using activated carbon, and the solvent was removed by evaporation. The resulting solid was recrystallized in toluene and then dried under vacuum to obtain 2.4 g of Compound 5.

[0178] The obtained compound 7 was subjected to a 1×10 －３ Sublimation purification was carried out at about 320° C. under a pressure of 100 Pa. The HPLC purity (area % at a measurement wavelength of 254 nm) of Compound 5 before and after sublimation purification was 99.9%.

[0179] After sublimation purification, mass spectrometry (MS) analysis and １ The structure of Compound 7 was identified by H-NMR analysis. The analytical results are shown below. MS (m / z): 510 [M+H] ＋ １ H-NMR (400MHz, DMSO-d6) δ: 9.18 (d, 2H), 9.14 (s, 2H), 8.55 (d, 2H), 7.97 (d, 2H), 7.96 (d, 2H), 7.77 (d, 4H), 7.74 (t, 2H), 7.51 (m, 6H), 7.23 (t, 2H)

[0180]

[0181] Synthesis Example 2: Synthesis of Compound 18 A mixed solution of 2.67 g of 4'-chloro-terpyridine, 4.02 g of boronic acid ester A, 702 mg of dichlorobis(triphenylphosphinepalladium) dichloride, 200 ml of 2.0 M aqueous potassium phosphate solution, and 500 ml of dimethoxyethane was heated and stirred under reflux for 2 hours under a nitrogen stream. After cooling to room temperature, water was added, the mixture was filtered, washed with hexane, and dried under vacuum. The catalyst was removed from the resulting solid using activated carbon, and the solvent was removed by evaporation. The resulting solid was recrystallized from toluene and then dried under vacuum to obtain 2.4 g of Compound 18.

[0182] The obtained compound 18 was subjected to a 1×10 －３ Sublimation purification was carried out at about 320° C. under a pressure of 100 Pa. The HPLC purity (area % at a measurement wavelength of 254 nm) of Compound 7 before and after sublimation purification was 99.9%.

[0183] After sublimation purification, mass spectrometry (MS) analysis and １ The structure of Compound 14 was identified by H-NMR analysis. The analytical results are shown below. MS (m / z): 508 [M+H] ＋ １ H-NMR (400MHz, DMSO-d6) δ: 9.18 (d, 2H), 9.14 (s, 2H), 8.55 (d, 2H), 7.97 (d, 2H), 7.96 (m, 4H), 7.95 (d, 2H), 7.74 (t, 2H), 7.61 (m, 4H), 7.23 (t, 2H)

[0184]

[0185] Next, the evaluation methods used in each example will be described.

[0186] (Driving voltage) The organic EL elements obtained in Examples 1 to 25 and Comparative Examples 1 to 5 were each driven at a luminance of 1000 cd / m ２ The device was then turned on at a current density of 10 mA / cm at room temperature, and the initial driving voltage was measured. ２ The voltage was measured after driving the device at a constant current of 100 hours at 100 volts, and the amount of voltage increase from the initial driving voltage was calculated.

[0187] The organic EL devices obtained in Examples 26 to 105 and Comparative Examples 6 to 20 were each subjected to a current density of 10 mA / cm ２ The device was driven at 1000 V and the initial driving voltage was measured.

[0188] The smaller the initial driving voltage, the lower the driving voltage, and thus the better the luminous efficiency (brightness / power). Also, the smaller the voltage rise, the better the durability.

[0189] (External Quantum Efficiency) The organic EL devices obtained in Examples 1 to 25 and Comparative Examples 1 to 5 were each subjected to a current density of 10 mA / cm ２The 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.

[0190] (Brightness) The organic EL devices obtained in Examples 26 to 105 and Comparative Examples 6 to 20 were each subjected to a current density of 10 mA / cm ２ The luminance was measured and the luminous efficiency was evaluated. The higher the luminance, the better the luminous efficiency.

[0191] (Durability) The organic EL devices obtained in Examples 26 to 105 and Comparative Examples 6 to 20 were each subjected to a current density of 10 mA / cm ２ The time required for the brightness to decrease by 20% from the initial brightness was measured and used as durability. Durability was also evaluated based on the amount of voltage increase in the above (driving voltage).

[0192] Example 1 A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / □, sputtered product) on which a 165 nm ITO transparent conductive film had been deposited as an anode was cut into 38 mm × 46 mm pieces and etched. The resulting substrate was ultrasonically cleaned for 15 minutes using "Semicoclean" 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.) and then washed with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before fabricating the element, and then placed in a vacuum deposition apparatus, and the degree of vacuum in the apparatus was adjusted to 5 × 10. －４ The chamber was evacuated to a pressure of 100 Pa or less. Using a resistance heating method, first, P-D1 was vapor-deposited to a thickness of 5 nm as a hole injection layer, and then HT-1 was vapor-deposited to a thickness of 50 nm as a hole transport layer. Next, a mixed layer of host material H-1 and dopant material D-1 was vapor-deposited to a thickness of 20 nm as an emitting layer so that the doping concentration was 5 wt %. Next, ET-1 and 2E-1 were vapor-deposited to a thickness of 35 nm as an electron transport layer at a vapor deposition rate ratio of ET-1:2E-1 = 1:1. Next, compound 1 and the metal element Li as a dopant were vapor-deposited to a thickness of 10 nm as an electron injection layer at a vapor deposition rate ratio of compound 1:Li = 99:1. Subsequently, aluminum was vapor-deposited to a thickness of 60 nm to form a cathode, and a 5 mm x 5 mm square organic EL device was fabricated.

[0193] When this organic EL device was evaluated by the above-mentioned method, the initial driving voltage was 4.46 V, the external quantum efficiency (luminous efficiency) was 6.48%, the durability life was 735 hours, and the voltage increase after driving for 100 hours at room temperature was 0.091 V. Compounds 1, P-D1, HT-1, H-1, D-1, ET-1, and 2E-1 are the compounds shown below.

[0194]

[0195] Examples 2 to 25, Comparative Examples 1 to 5 Elements were fabricated in the same manner as in Example 1, except that the compounds used were changed as shown in Table 1. The results of each example and comparative example are shown in Table 1. Compounds 2 to 32 are the compounds shown below.

[0196]

[0197]

[0198]

[0199]

[0200]

[0201] Example 26 A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / □, sputtered product) on which a 165 nm ITO transparent conductive film had been deposited as an anode was cut into 38 mm × 46 mm pieces and etched. The resulting substrate was ultrasonically cleaned for 15 minutes using "Semicoclean" 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.) and then washed with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before fabricating the element, and then placed in a vacuum deposition apparatus, and the degree of vacuum in the apparatus was adjusted to 5 × 10. －４ The chamber was evacuated to a pressure of 100 Pa or less. First, P-D1 was vapor-deposited to a thickness of 5 nm as a hole injection layer by resistance heating. Next, an emitting unit (first emitting unit) consisting of a hole transport layer, an emitting layer, and an electron transport layer was formed on the hole injection layer.

[0202] Specifically, HT-1 was deposited to a thickness of 50 nm as a hole transport layer, then a mixed layer of host material H-1 and dopant material D-1 was deposited to a thickness of 20 nm as an emitting layer so that the doping concentration was 5 wt %, and then ET-1 and 2E-1 were deposited to a thickness of 35 nm as an electron transport layer so that the deposition rate ratio of ET-1:2E-1 was 1:1.

[0203] On the first light-emitting unit, Compound 1 and a metal element Yb as a dopant were deposited to a thickness of 10 nm as an n-type charge generation layer so that the deposition rate ratio of Compound 1:Yb was 98:2, and then P-D1 was deposited to a thickness of 10 nm as a p-type charge generation layer.

[0204] Following the charge generation layer, a second light-emitting unit was formed in the same manner as the first light-emitting unit. Then, as an electron injection layer, Compound 1 and a metal element Yb serving as a dopant were vapor-deposited to a thickness of 10 nm at a vapor deposition rate ratio of Compound 1:Yb=98:2, and subsequently, aluminum was vapor-deposited to a thickness of 60 nm to form a cathode, thereby producing an organic EL device having a size of 5 mm × 5 mm.

[0205] When this organic EL element was evaluated by the above-mentioned method, the initial driving voltage was 8.95 V and the luminance was 1627 cd / m ２ The durability was 2016 hours.

[0206] Examples 27 to 79 and Comparative Examples 6 to 15 Organic EL devices were prepared in the same manner as in Example 26, except that the compounds, dopant materials, metal elements, and vapor deposition rate ratios of the compounds and metal elements used were changed as shown in Tables 2 and 3. In Example 51, Compound 1, ET-2, and the metal element Yb were vapor-deposited to a thickness of 10 nm to form an n-type charge generation layer, with the vapor deposition rate ratio of Compound 1:ET-2:Yb=49:49:2. In Example 78, Compound 1, ET-2, and the metal element Li were vapor-deposited to a thickness of 10 nm to form an n-type charge generation layer, with the vapor deposition rate ratio of Compound 1:ET-2:Li=49:49:2. In Examples 52 and 79, a mixed layer of host material H-1 and dopant material D-2 was vapor-deposited to a thickness of 20 nm to form an emitting layer, with a doping concentration of 5 wt %. The results of each Example and Comparative Example are shown in Tables 2 and 3. D-2 and ET-2 are the compounds shown below.

[0207]

[0208]

[0209]

[0210] Example 80 An organic EL device was fabricated in the same manner as in Example 28, except that Compound 1 was used instead of ET-1 in forming the electron transport layer, and that ET-2 was used instead of Compound 1 in forming the n-type charge generation layer. When this organic EL device was evaluated by the above-mentioned method, the initial driving voltage was 8.94 V and the luminance was 1515 cd / m ２ The durability was 2122 hours.

[0211] Examples 81 to 105, Comparative Examples 16 to 20 Organic EL devices were prepared in the same manner as in Example 80, except that the compounds used were changed as shown in Table 4. In Example 105, Compound 1 and ET-2 were deposited as an electron transport layer to a thickness of 35 nm such that the deposition rate ratio of Compound 1:2E-1 was 1:1. The results of each Example and Comparative Example are shown in Table 4.

[0212]

Claims

1. A compound represented by the following general formula (1): (In the general formula (1), R １１ and R １２ are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ is an unsubstituted phenylene group, an unsubstituted naphthylene group, an unsubstituted pyridylene group, an unsubstituted pyridazylene group, an unsubstituted pyrazylene group, or an unsubstituted pyrimidylene group; L ２ is selected from a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted pyridazylene group, a substituted or unsubstituted pyrazylene group, and a substituted or unsubstituted pyrimidylene group. １３ ~R １６ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １４ and R １５ At least one of the above is a group represented by the following general formula (2). (In the general formula (2), X １ ~X ５ are each independently C-R １ ~C-R ５ or a nitrogen atom. １ ~R ５ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １ ~X ５ One of the is a nitrogen atom.) 2. A compound represented by the following general formula (3): (In the general formula (3), R ２１ and R ２２ are each independently a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group, and are linked together to form a ring structure. １ is an unsubstituted phenylene group, an unsubstituted naphthylene group, an unsubstituted pyridylene group, an unsubstituted pyridazylene group, an unsubstituted pyrazylene group, or an unsubstituted pyrimidylene group; L ２ is selected from a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted pyridylene group, a substituted or unsubstituted pyridazylene group, a substituted or unsubstituted pyrazylene group, and a substituted or unsubstituted pyrimidylene group. ２３ ~R ２６ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. ２４ and R ２５ is a group represented by the following general formula (2): (In the general formula (2), X １ ~X ５ are each independently C-R １ ~C-R ５ or a nitrogen atom. １ ~R ５ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, a phosphoryl group, a halogen atom, a cyano group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. １ ~X ５ One of the is a nitrogen atom.) 3. R ​​in the general formula (1) １１ and R １２ The compound according to claim 1 , wherein each of the is independently a methyl group, a phenyl group, a naphthyl group, or a pyridyl group.

4. R in the general formula (1) １４ and R １５ The compound according to claim 1 , wherein each of the groups is independently a group represented by general formula (2):

5. In the general formula (2), X １ ~X ５ The compound according to claim 1 or 2, wherein one of the groups is a nitrogen atom and the others are methine groups.

6. An organic EL element which emits light by electrical energy and which has at least an electron transport layer and a light emitting layer between an anode and a cathode, said electron transport layer containing the compound according to claim 1 or 2.

7. The organic EL device according to claim 6, wherein said electron transport layer further contains a complex of an alkali metal, a rare earth metal or an alkali metal with an organic substance.

8. An organic EL element which emits light by electrical energy and which has at least a charge generating layer and a light emitting layer between an anode and a cathode, said charge generating layer containing the compound according to claim 1 or 2.

9. The organic EL device according to claim 8, wherein said charge generating layer further contains a phenanthroline derivative.

10. The organic electroluminescent device according to claim 8, wherein said charge generating layer further contains an alkali metal or a rare earth metal.

11. The organic electroluminescent device according to claim 10, wherein the alkali metal is Li.

12. The organic EL device according to claim 10, wherein the rare earth metal is Yb.

13. An organic EL element which emits light by electrical energy and which has at least an electron injection layer and a light emitting layer between an anode and a cathode, said electron injection layer containing the compound according to claim 1 or 2.

14. The organic electroluminescent device according to claim 13, wherein the electron injection layer further contains an alkali metal or a rare earth metal.

15. The organic EL device according to claim 6, wherein the light-emitting layer contains a compound represented by the following general formula (4): (In the general formula (4), ring Za, ring Zb and ring Zc are each independently a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroaryl ring having 5 to 30 ring atoms; Z １ and Z ２ are each independently an oxygen atom, NRa (a nitrogen atom having a substituent Ra) or a sulfur atom; Z １ is NRa, it may or may not be bonded to ring A or ring B to form a ring; Z ２ is NRa, it may or may not form a ring by bonding with ring B or ring C; each Ra is independently a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring atoms, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; each Y is a boron atom, a phosphorus atom, SiRb (a silicon atom having a substituent Rb), P=O, or P=S; each Rb is independently selected from a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 30 ring atoms, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

16. A display device comprising the organic EL element according to claim 6.

17. A lighting device comprising the organic EL element according to claim 6.

Images