WO2023058644A1

WO2023058644A1 - Compound, organic el element, display device and lighting device

Info

Publication number: WO2023058644A1
Application number: PCT/JP2022/037096
Authority: WO
Inventors: 徳田貴士; 長尾和真
Original assignee: 東レ株式会社
Priority date: 2021-10-08
Filing date: 2022-10-04
Publication date: 2023-04-13

Abstract

The purpose of the present invention is to provide a compound which enables the achievement of an organic EL element that exhibits excellent heat resistance, while having excellent luminous efficiency and durability life. The present invention provides a compound which has a structure represented by general formula (1). (In general formula (1), each of R1 to R6 independently represents a hydrogen atom or an alkyl group; meanwhile, at least two of the R1 to R6 moieties are alkyl groups; X represents a hydrogen atom, a substituted or unsubstituted aryl group or a heteroaryl group; meanwhile, if these groups are substituted, the substituents are alkyl groups; Y represents a biphenyl group, a terphenyl group, a quarterphenyl group or an L-Z; L represents a divalent linking group that is selected from among those described below, and is bonded at the position of *; and Z represents a substituted or unsubstituted naphthyl group, a phenanthryl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a dimethylfluorenyl group, a diphenylfluorenyl group, a spirobifluorenyl group, a pyridyl group, a pyrimidyl group, a triazinyl group, a bipyridyl group, a terpyridyl group, a quinolinyl group, a quinazolyl group, a carbazolyl group, a carbolinyl group, a dibenzofuranyl group, a dibenzothiophenyl group or a phenanthrolinyl group.)

Description

compound, organic EL device, display device and lighting device

The present invention relates to a phenanthroline derivative having a specific structure, and an organic EL device, display device and lighting device using the same.

In recent years, organic EL elements have been steadily put into practical use, such as being used in TV and smartphone displays. However, existing organic EL devices still have many technical problems. Among them, there are problems in obtaining highly efficient light emission, obtaining a long-life light-emitting element, and obtaining an element excellent in heat resistance.

As compounds for solving these problems, phenanthroline derivatives substituted with a specific phosphine oxide group (see, for example, Patent Document 1), phenanthroline derivatives having an amino group (see, for example, Patent Document 2), and specific Phenanthroline derivatives having an aryl group (see, for example, Patent Document 3), phenanthroline derivatives having a specific arylene group and a heteroaryl group (see, for example, Patent Document 4), compounds having multiple phenanthrolines (see, for example, Patent Document 5), etc. is being developed.

U.S. Patent Application Publication No. 2016/0005980 JP-A-7-82551 Chinese Patent Application Publication No. 105272979 Chinese Patent Application Publication No. 111187201 Japanese Patent Application Laid-Open No. 2004-281390

According to Patent Documents 1 to 5, phenanthroline derivatives having specific aryl groups or heteroaryl groups make it possible to obtain organic EL devices with excellent light-emitting properties. However, in recent years, the characteristics required of organic EL devices have been increasing more and more, and there is a demand for techniques for improving luminous efficiency, durability, and heat resistance of materials.

In view of the problems of the prior art, the object of the present invention is to provide a compound capable of obtaining an organic EL device having excellent heat resistance, luminous efficiency and durable life.

The present invention is as follows.
[1] A compound having a structure represented by the following general formula (1).

In general formula (1), R ¹ to R ⁶ each independently represent a hydrogen atom or an alkyl group. However, at least two of R ¹ to R ⁶ are alkyl groups. X is a hydrogen atom, a substituted or unsubstituted aryl group or heteroaryl group. However, when these groups are substituted, the substituent is an alkyl group. Y is a biphenyl group, terphenyl group, quaterphenyl group, or LZ. However, L is a divalent linking group selected from the following, and is bonded at the position of *. Z is a substituted or unsubstituted naphthyl group, phenanthryl group, pyrenyl group, fluoranthenyl group, triphenylenyl group, dimethylfluorenyl group, diphenylfluorenyl group, spirobifluorenyl group, pyridyl group, pyrimidyl group, triazinyl group, bipyridyl group, terpyridyl group, quinolinyl group, quinazolyl group, carbazolyl group, carbolinyl group, dibenzofuranyl group, dibenzothiophenyl group or phenanthrolinyl group.

[2] The compound according to [1], wherein in the general formula (1), X is a substituted or unsubstituted aryl group or heteroaryl group.
[3] In the general formula (1), Y is LZ, and Z is a substituted or unsubstituted pyridyl group, pyrimidyl group, triazinyl group, bipyridyl group, terpyridyl group or phenanthrolinyl group, [ 1] or the compound according to [2].
[4] The compound according to any one of [1] to [3], wherein in the general formula (1), Y is LZ and Z is an unsubstituted terpyridyl group.
[5] In the general formula (1), X is a substituted or unsubstituted aryl group or heteroaryl group, Y is LZ, and Z is a substituted or unsubstituted phenanthrolinyl group or terpyridyl group The compound according to any one of [1] to [3].
[6] The compound according to any one of [1] to [5], wherein in the general formula (1), Y is LZ and L is a phenylene group.
[7] The compound according to any one of [1] to [6], wherein at least four of R ¹ to R ⁶ in general formula (1) are alkyl groups.
[8] In the general formula (1), X is a phenyl group, Y is LZ, and Z is a phenanthrolinyl group substituted with a phenyl group or an unsubstituted terpyridyl group, [1 ] to the compound according to any one of [7].
[9] A light-emitting device having at least an electron-transporting layer and a light-emitting layer between an anode and a cathode and emitting light by electric energy, wherein the electron-transporting layer is the light-emitting device according to any one of [1] to [8]. An organic EL device containing a compound of
[10] The organic EL device of [9], wherein the electron transport layer further contains an alkali metal complex compound.
[11] A light-emitting device having at least a charge-generating layer and a light-emitting layer between an anode and a cathode and emitting light by electrical energy, wherein the charge-generating layer is the light-emitting element according to any one of [1] to [8]. An organic EL device containing a compound of
[12] The organic EL device of [11], wherein the charge generation layer further contains a phenanthroline dimer.
[13] The organic EL device of [11] or [12], wherein the charge generation layer further contains an alkali metal and/or a rare earth metal.
[14] The organic EL device according to [13], wherein the alkali metal is Li.
[15] The organic EL device according to [13], wherein the rare earth metal is Yb.
[16] A light-emitting device having at least an electron injection layer and a light-emitting layer between an anode and a cathode and emitting light by electric energy, wherein the electron-injection layer is according to any one of [1] to [8]. An organic EL device containing a compound of
[17] A display device comprising the EL device according to any one of [9] to [16].
[18] A lighting device including the EL device according to any one of [9] to [16].

The compound of the present invention has excellent durability. The compound of the present invention can provide an organic EL device excellent in luminous efficiency and durability.

Preferred embodiments of the compound, the organic EL device, the display device, and the 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 carried out with various modifications according to purposes and applications.

(Compound having a structure represented by general formula (1))
A compound that is one embodiment of the present invention has a structure represented by general formula (1).

"Unsubstituted" in the case of "substituted or unsubstituted" means that hydrogen atoms are attached, and "substituted" means that at least a portion of the hydrogen atoms are substituted. . The hydrogen atom may be a deuterium atom. The same applies to "substituted or unsubstituted" in the compounds or partial structures thereof described below.

The alkyl group is, for example, a saturated aliphatic hydrocarbon group such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, which is a substituent may or may not have Also, the hydrogen atom in the alkyl group may be a deuterium atom. Although the number of carbon atoms in the alkyl group is not particularly limited, it is usually in the range of 1 to 20, more preferably 1 to 8 in terms of availability and cost.

An aryl group is, for example, an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a fluorenyl group, a phenanthryl group, a triphenylenyl group, and a terphenyl group. Although the number of carbon atoms in the aryl group is not particularly limited, it is usually in the range of 6 or more and 40 or less.

The heteroaryl group includes, for example, pyridyl group, furanyl group, thiophenyl group, quinolinyl group, isoquinolinyl group, pyrazinyl group, pyrimidyl group, pyridazinyl group, triazinyl group, napthyridinyl group, cinnolinyl group, phthalazinyl group, quinoxalinyl group, quinazolinyl group, benzofuranyl group, benzothiophenyl group, indolyl group, dibenzofuranyl group, dibenzothiophenyl group, carbazolyl group, benzocarbazolyl group, carbolinyl group, indolocarbazolyl group, benzoflocarbazolyl group, benzothienocarba Non-carbon groups such as zolyl, dihydroindenocarbazolyl, benzoquinolinyl, acridinyl, dibenzoacridinyl, benzimidazolyl, imidazopyridyl, benzoxazolyl, benzothiazolyl, phenanthrolinyl, etc. Indicates a cyclic aromatic group having one or more atoms in the ring. Although the number of carbon atoms in the heteroaryl group is not particularly limited, it is preferably in the range of 2 to 40, more preferably in the range of 2 to 30.

As conventional phenanthroline derivatives, for example, Patent Documents 1 to 5 disclose compounds V, W, X, Y, and Z represented by the following formulas.

However, even devices using these compounds as organic EL device materials in the electron injection layer, electron transport layer, or charge generation layer have not yet achieved sufficient performance to meet the characteristics demanded in recent years. , luminous efficiency, durable life, and heat resistance of the material.

For example, compounds in which a phosphine oxide group is substituted for a phenanthrolinyl group, such as compound V, tend to generate impurities during vapor deposition, and there has been a demand for improved heat resistance. In addition, because of its high crystallinity, it tends to crystallize in the device, and there are problems with the driving voltage and durability. A compound in which a phenanthrolinyl group is substituted with an amino group, such as compound W, tends to generate impurities during vapor deposition, and an improvement in heat resistance has been demanded. In addition, having an amino group makes the energy level of the LUMO, which is the electronic conduction level, shallower, lowering the electron transporting ability, increasing the drive voltage of the device, and causing problems in luminous efficiency and durability. Compounds having an anthrylene group, such as compounds X and Y, tend to generate impurities during vapor deposition, and there has been a demand for improved heat resistance. In addition, since the crystallinity is too high due to the high planarity of the phenanthrolinyl group and the linking group, the drive voltage of the device is increased, and there are problems in luminous efficiency and durability. A phenanthrolinyl derivative such as compound Z is likely to react at high temperatures, and further improvement in heat resistance has been desired. In addition, there has been a demand for further improvement in the durable life of the element.

The present inventors paid attention to the substituent effect of the phenanthrolinyl group in the study of the improvement. In general formula (1), R ¹ to R ⁶ are each independently a hydrogen atom or an alkyl group, and at least two of R ¹ to R ⁶ are alkyl groups. When all of R ¹ to R ⁶ are hydrogen atoms, any one of R ¹ to R ⁶ is likely to react when exposed to high temperature conditions, and impurities tend to be generated. When two or more of R ¹ to R ⁶ are alkyl groups, the reaction sites are protected and the reactivity is lowered by the steric repulsion of the alkyl groups, thereby suppressing the generation of impurities due to heat and improving the heat resistance. can be made In general formula (1), at least four of R ¹ to R ⁶ are preferably alkyl groups.

In general formula (1), X is a hydrogen atom, a substituted or unsubstituted aryl group or heteroaryl group. When X is a substituted or unsubstituted aryl group or heteroaryl group, the 2- and 9-positions, which are one of the reaction sites of phenanthroline, can be substituted, so that the durability life of the organic EL device can be further improved. can be done. In particular, when X is a phenyl group, the high coordinating property of the nitrogen atom on the phenanthrolinyl group results in the formation of a more stable layer with higher metal coordinating property when used in a metal-doped layer. can be done. Therefore, the drive voltage can be further reduced, and the durable life can be further improved.

When the aryl group or heteroaryl group of X is substituted, the substituent is an alkyl group. These substituents can further improve the heat resistance of the compound and the durability life of the organic EL device without lowering the charge transport property of the compound.

In general formula (1), Y is a biphenyl group, terphenyl group, quaterphenyl group or LZ. However, L is a divalent linking group selected from the following, and is bonded at the position of *. When Y is one of these substituents, the compound having the structure represented by general formula (1) has a high glass transition temperature, so that the durable life of the organic EL device can be further improved.

Z is a substituted or unsubstituted naphthyl group, phenanthryl group, pyrenyl group, fluoranthenyl group, triphenylenyl group, dimethylfluorenyl group, diphenylfluorenyl group, spirobifluorenyl group, pyridyl group, pyrimidyl group, triazinyl group, bipyridyl group, terpyridyl group, quinolinyl group, quinazolyl group, carbazolyl group, carbolinyl group, dibenzofuranyl group, dibenzothiophenyl group or phenanthrolinyl group. Metal doping when Z is pyridyl, pyrimidyl, triazinyl, bipyridyl, terpyridyl, quinolinyl, quinazolyl, carbazolyl, carbolinyl, dibenzofuranyl, dibenzothiophenyl, phenanthrolinyl When used in a layer, it is preferable because it can form a more stable layer with higher metal coordinating property. When Z is a phenyl group-substituted phenanthrolinyl group or terpyridyl group, this effect is further enhanced. is more preferable because The case where L is a phenylene group is also preferable from the viewpoint of increasing the metal coordinating ability.

Examples of substituents for Z include alkyl groups, aryl groups, and heteroaryl groups. Among these, a methyl group and a phenyl group are preferable.

In general formula (1), Y is LZ, and Z is more preferably a substituted or unsubstituted pyridyl group, pyrimidyl group, triazinyl group, bipyridyl group, terpyridyl group or phenanthrolinyl group.

In general formula (1), it is more preferable that Y is LZ and Z is an unsubstituted terpyridyl group.

In general formula (1), X is a substituted or unsubstituted aryl group or heteroaryl group, Y is LZ, and Z is a substituted or unsubstituted phenanthrolinyl group or terpyridyl group. more preferred.

In general formula (1), it is more preferable that Y is LZ and L is a phenylene group. In general formula (1), it is more preferable that X is a phenyl group, Y is LZ, and Z is a phenyl group-substituted phenanthrolinyl group or an unsubstituted terpyridyl group.

The molecular weight of the compound having the structure represented by general formula (1) is preferably 400 or more from the viewpoint of suppressing crystallization and improving the stability of film quality. On the other hand, the molecular weight of the compound having the structure represented by the general formula (1) is preferably 700 or less from the viewpoint of improving workability during sublimation purification and vapor deposition.

Examples of the compound having the structure represented by the general formula (1) include the compounds shown below. The following are examples, and compounds other than those specified here are preferably used as long as they have a structure represented by the general formula (1).

A compound having a structure represented by general formula (1) can be synthesized by a known synthesis method. Examples of the synthesis method include, but are not limited to, a coupling reaction between an aryl halide derivative and an arylboronic acid derivative using palladium.

A compound having a structure represented by general formula (1) represents a material used in any layer of an organic EL device, and includes a hole injection layer, a hole transport layer, a light emitting layer, an electron Materials used for transport layers and protective films (cap layers) of electrodes are included. The compound having the structure represented by the general formula (1) in the present invention has excellent heat resistance, and by using such a compound in any layer of the organic EL device, the organic EL device has excellent luminous efficiency and durable life. element can be provided.

(Organic EL element)
Next, embodiments of the organic EL element will be described in detail. An organic EL element has an anode, a cathode, and an organic layer interposed between the anode and the cathode, and the organic layer emits light by electric energy.

The layer structure between the anode and the cathode in such an organic EL element includes, in addition to the structure consisting only of the light-emitting layer, 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) positive 7) Layered structure of hole injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer, hole injection layer/hole transport layer/light emitting layer/hole blocking layer/electron transport layer/electron injection layer is mentioned.

Furthermore, a tandem type in which a plurality of the above laminated structures are laminated via an intermediate layer may be used. The intermediate layer is also generally referred to as an intermediate electrode, intermediate conductive layer, charge generation layer, electron withdrawal layer, connection layer, and intermediate insulating layer, and known material configurations can be used. Specific examples of the tandem type include, for example, 8) hole transport layer/light emitting layer/electron transport layer/charge generation layer/hole transport layer/light emitting layer/electron transport layer, 9) hole injection layer/hole transport layer/ A charge-generating layer as an intermediate layer between the anode and the cathode, such as light-emitting layer/electron-transporting layer/electron-injecting layer/charge-generating layer/hole-injecting layer/hole-transporting layer/light-emitting layer/electron-transporting layer/electron-injecting layer. A laminate configuration including:

Also, each of the above layers may be either a single layer or multiple layers, and may be doped. In particular, the electron injection layer and the charge generation layer are preferably metal-doped layers, so that the electron transport ability and the electron injection ability to other adjacent layers can be improved. Moreover, in addition to the above layers, a protective layer (cap layer) may be further provided, and the light emission efficiency can be further improved by the optical interference effect.

The compound having the structure represented by general formula (1) may be used in any of the above layers in the organic EL device, but is particularly preferably used in the electron transport layer, charge generation layer or electron injection layer. The organic EL device of the present invention preferably has at least an electron-transporting layer and a light-emitting layer between an anode and a cathode, and the electron-transporting layer contains a compound having a structure represented by general formula (1). The organic EL device of the present invention has at least a charge-generating layer and a light-emitting layer between an anode and a cathode, and the charge-generating layer contains a compound having a structure represented by general formula (1). is preferred. Further, the organic EL device of the present invention has at least an electron injection layer and a light emitting layer between the anode and the cathode, and the electron injection layer contains a compound having a structure represented by general formula (1). is preferred. A compound having a structure represented by general formula (1) may be contained in two or more layers.

In the organic EL device of the present invention, the anode and cathode have the role of supplying sufficient current for light emission of the device, and at least one of them is preferably transparent or translucent in order to extract light. . Generally, the anode formed on the substrate is used as a transparent electrode.

(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 should be sufficient to maintain the mechanical strength, and a thickness of 0.5 mm or more is sufficient. Regarding the material of the glass, it is preferable that the amount of eluted ions from the glass is small, and alkali-free glass is preferable. In addition, soda-lime glass with a barrier coating such as SiO ₂ is commercially available, and this can also be used.

(anode)
The material used for the anode is preferably capable of efficiently injecting holes into the organic layer. Moreover, it is preferably transparent or translucent in order to take out 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 chloride and copper sulfide, and conductive polymers such as polythiophene, polypyrrole and polyaniline are included. Among these, ITO glass and Nesa glass are preferable. These electrode materials may be used alone, or may be used by laminating or mixing a plurality of materials. The resistance of the transparent electrode should be sufficient to supply a current sufficient for light emission of the device, but from the viewpoint of power consumption of the device, a low resistance is preferable. For example, an ITO substrate with a resistance of 300Ω/square or less functions as an element electrode, but it is now possible to supply a substrate with a resistance of about 10Ω/square, so substrates with a low resistance of 20Ω/square or less are used. is preferred. The thickness of ITO can be arbitrarily selected according to the resistance value, and is usually used in the range of 45 to 300 nm.

(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, or combinations of these metals with low work function metals such as lithium, sodium, potassium, calcium, and magnesium. Examples include alloys and multilayer lamination. Among them, aluminum, silver, and magnesium are preferable as the main component from the viewpoint of electrical resistance, ease of film formation, film stability, luminous efficiency, etc., and electron injection into the electron transport layer and the electron injection layer is easy. Therefore, it is more preferable to be composed of magnesium and silver.

(protective layer)
For cathodic protection, it is preferred to laminate a protective layer (cap layer) on the cathode. The material constituting the protective layer (capping material) is not particularly limited, but examples include metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, alloys using these metals, silica, titania and Inorganic substances such as silicon nitride, and organic polymer compounds such as polyvinyl alcohol, polyvinyl chloride, and hydrocarbon-based polymer compounds are included. In addition, the organic EL element material represented by the general formula (1) can also be used as a capping material. However, when the organic EL element has an element structure (top emission structure) in which light is extracted from the cathode side, the capping material preferably has light transmittance in the visible light region.

(hole injection layer)
A hole-injecting layer is a layer interposed between the anode and the hole-transporting layer. The hole injection layer may be either a single layer or a laminate of a plurality of layers. The presence of a hole injection layer between the hole transport layer and the anode is preferable because it not only enables the device to be driven at a lower voltage and extends the durability life, but also improves the carrier balance of the device and the luminous efficiency.

The material used for the hole injection layer is not particularly limited. -(1-naphthyl)-N-phenylamino)biphenyl (NPD), 4,4'-bis(N,N-bis(4-biphenylyl)amino)biphenyl (TBDB), bis(N,N'-diphenyl- 4-aminophenyl)-N,N-diphenyl-4,4′-diamino-1,1′-biphenyl (TPD232), 4,4′,4″-tris(3-methylphenyl(phenyl) amino)triphenylamine (m-MTDATA), 4,4′,4″-tris(1-naphthyl(phenyl)amino)triphenylamine (1-TNATA), a group of materials called starburst arylamines, triaryl Amine derivatives, bis(N-arylcarbazole), bis(N-alkylcarbazole) and other biscarbazole derivatives, pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrins Heterocyclic compounds such as derivatives, polycarbonates and styrene derivatives having the above-mentioned monomers in side chains, polymer materials such as polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, polysilane, and the like can be mentioned. From the viewpoint of smoothly injecting and transporting holes from the anode to the hole-transporting layer, benzidine derivatives and starburst arylamine-based materials are more preferably used.

These materials may be used alone, or two or more materials may be mixed and used. Alternatively, a hole injection layer may be formed by laminating a plurality of materials. Furthermore, it is more preferable that the hole injection layer is composed of an acceptor compound alone, or that the hole injection material as described above is doped with an acceptor compound, since the above effects can be obtained more remarkably. . The acceptor compound is a material that forms a charge-transfer complex with a material that forms a hole-transport layer in contact with it when used as a single-layer film, and a material that forms a hole-injection layer when it is doped and used. The use of such a material improves the conductivity of the hole injection layer, contributes to lowering the drive voltage of the device, and can further improve the luminous efficiency and durable life.

Examples of acceptor compounds include metal chlorides such as iron (III) chloride, aluminum chloride, gallium chloride, indium chloride, and antimony chloride; metal oxides such as molybdenum oxide, vanadium oxide, tungsten oxide, and ruthenium oxide; Charge transfer complexes such as 4-bromophenyl)aminium hexachloroantimonate (TBPAH), organic compounds having a nitro group, cyano group, halogen or trifluoromethyl group in the molecule, quinone compounds, acid anhydride compounds, fullerenes etc. Among these, metal oxides and cyano group-containing compounds are preferable because they are easy to handle and easy to vapor-deposit, so that the above effects can be easily obtained. In either case where the hole injection layer is composed of an acceptor compound alone or where the hole injection layer is doped with an acceptor compound, the hole injection layer may be a single layer, A plurality of layers may be laminated and configured.

(Hole transport layer)
The hole-transporting layer is a layer that transports holes injected from the anode to the light-emitting layer. The hole transport layer may be either a single layer or a laminate of a plurality of layers.

Materials used for the hole transport layer include those exemplified as materials used for the hole injection layer. A triarylamine derivative and a benzidine derivative are more preferable from the viewpoint of injecting and transporting holes smoothly into the light-emitting layer.

(Light emitting layer)
The light-emitting layer may be either a single layer or multiple layers, each formed of a light-emitting material (host material, dopant material), which may be a mixture of the host material and the dopant material, or the host material alone. , or a mixture of two host materials and one dopant material. That is, in the organic EL element of the present invention, only the host material or the dopant material may emit light, or both the host material and the dopant material may emit light in each light emitting layer. From the viewpoint of efficient use of electrical energy and obtaining light emission with high color purity, the light-emitting layer is preferably made of a mixture of a host material and a dopant material. Moreover, the host material and the dopant material may be of one kind or a combination of a plurality of them. The dopant material may be contained entirely or partially in the host material. The dopant material can be either layered or dispersed. Dopant materials can control the emission color. From the viewpoint of suppressing the concentration quenching phenomenon, the amount of the dopant material is preferably 30% by weight or less, more preferably 20% by weight or less, relative to the host material. The doping method can be formed by a co-evaporation method with a host material, but it may be pre-mixed with the host material and then vapor-deposited at the same time.

Examples of light-emitting materials include condensed ring derivatives such as anthracene and pyrene, which are known as light emitters, metal chelated oxinoid compounds such as tris(8-quinolinolato)aluminum, bisstyryl derivatives such as bisstyryl anthracene 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, Examples include polymers such as polyphenylene vinylene derivatives, polyparaphenylene derivatives, polythiophene derivatives, and the like.

The host material contained in the light-emitting material need not be limited to one type of compound, and a mixture of multiple compounds may be used. Moreover, you may laminate|stack and use it. Host materials include, but are not limited to, naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, compounds having condensed aryl rings such as indene, derivatives thereof, N,N'-dinaphthyl- aromatic amine derivatives such as N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine, metal chelated oxinoid compounds such as tris(8-quinolinato)aluminum (III), distyrylbenzene derivatives, etc. bisstyryl derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole Examples include derivatives, triazine derivatives, and polymers such as polyphenylenevinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polythiophene derivatives. Among them, the host used when the emitting layer performs triplet emission (phosphorescence emission) includes metal chelated oxinoid compounds, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, triphenylene derivatives, and the like. is preferably used.

Dopant materials contained in the light-emitting material include, for example, compounds having an aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, fluoranthene, triphenylene, perylene, fluorene, and indene, and derivatives thereof (eg, 2-(benzothiazole-2- yl)-9,10-diphenylanthracene and 5,6,11,12-tetraphenylnaphthacene), furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9'-spirobisilafluorene, benzothiophene , benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, compounds having a heteroaryl ring such as thioxanthene and their derivatives, distyrylbenzene derivatives, 4,4'-bis( 2-(4-diphenylaminophenyl)ethenyl)biphenyl, aminostyryl derivatives such as 4,4'-bis(N-(stilben-4-yl)-N-phenylamino)stilbene, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, stilbene derivatives, aldazine derivatives, pyrromethene derivatives, diketopyrrolo[3,4-c]pyrrole derivatives, 2,3,5,6-1H,4H-tetrahydro-9-(2′-benzothiazolyl)quinolidino[9,9a, coumarin derivatives such as 1-gh]coumarin, azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole, metal complexes thereof, N,N'-diphenyl-N,N'-di(3- and aromatic amine derivatives such as methylphenyl)-4,4'-diphenyl-1,1'-diamine. Among these, a dopant containing a diamine skeleton and a dopant containing a fluoranthene skeleton can further improve the luminous efficiency, thereby further improving the luminous efficiency and durability life.

In the organic EL device of the present invention, the light-emitting layer preferably contains a triplet light-emitting material.

Iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re A metal complex compound containing at least one metal selected from the group consisting of ) is preferred. The ligand preferably has a nitrogen-containing aromatic heterocycle such as a phenylpyridine skeleton, phenylquinoline skeleton, or carbene skeleton. However, it is not limited to these, and an appropriate complex is selected from the required emission color, device performance, and relationship with the host compound. Specifically, tris(2-phenylpyridyl)iridium complex, tris{2-(2-thiophenyl)pyridyl}iridium complex, tris{2-(2-benzothiophenyl)pyridyl}iridium complex, tris(2-phenyl benzothiazole)iridium complex, tris(2-phenylbenzoxazole)iridium complex, trisbenzoquinolineiridium complex, bis(2-phenylpyridyl)(acetylacetonate)iridium complex, bis{2-(2-thiophenyl)pyridyl}iridium complex, bis{2-(2-benzothiophenyl)pyridyl}(acetylacetonato)iridium complex, bis(2-phenylbenzothiazole)(acetylacetonato)iridium complex, bis(2-phenylbenzoxazole)(acetylacetonato) nate) iridium complex, bisbenzoquinoline (acetylacetonato) iridium complex, bis {2-(2,4-difluorophenyl)pyridyl} (acetylacetonato) iridium complex, tetraethylporphyrin platinum complex, {tris(senoyltrifluoroacetone) ) mono (1,10-phenanthroline)} europium complex, {tris (senoyltrifluoroacetone) mono (4,7-diphenyl-1,10-phenanthroline)} europium complex, {tris (1,3-diphenyl-1, 3-propanedione)mono(1,10-phenanthroline)}europium complex, trisacetylacetoneterbium complex and the like. Phosphorescent dopants described in JP-A-2009-130141 are also preferably used. An iridium complex or a platinum complex is preferable, and can further improve the luminous efficiency.

The above triplet light-emitting materials used as dopant materials may be contained in the light-emitting layer alone, or may be used in combination of two or more. 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, relative to the host material.

Preferable hosts and dopants in the triplet emission system are not particularly limited, but specific examples include the following.

It is also preferable that the light emitting layer contains a thermally activated delayed fluorescence material. The heat-activated delayed fluorescence is explained on pages 87 to 103 of "State-of-the-Art Organic EL" (edited by Chihaya Adachi and Hiroshi Fujimoto, published by CMC Publishing). In the literature, by bringing the energy levels of the excited singlet state and the excited triplet state close to each other, the reverse energy transfer from the excited triplet state, which normally has a low transition probability, to the excited singlet state is high. It is explained that it occurs efficiently and thermally activated delayed fluorescence (TADF) is expressed. Furthermore, FIG. 5 in the document explains the generation mechanism of delayed fluorescence. Emission of delayed fluorescence can be confirmed by transient PL (Photo Luminescence) measurement.

Thermally activated delayed fluorescence materials are also generally called TADF materials. The thermally activated delayed fluorescence material may be a single material that exhibits thermally activated delayed fluorescence, or a plurality of materials that exhibit thermally activated delayed fluorescence. When a plurality of materials are used, they may be used as a mixture, or may be used by stacking layers of each material. A known material can be used as the thermally activated delayed fluorescence material. Examples include, but are not limited to, benzonitrile derivatives, triazine derivatives, disulfoxide derivatives, carbazole derivatives, indolocarbazole derivatives, dihydrophenazine derivatives, thiazole derivatives, oxadiazole derivatives and the like.

In the element in which the TADF material is contained in the light-emitting layer, it is preferable that the light-emitting layer further contains a fluorescent dopant. This is because triplet excitons are converted into singlet excitons by the TADF material, and the singlet excitons are received by the fluorescent dopant, thereby achieving higher luminous efficiency and longer durability.

(Electron transport layer)
In the present invention, the electron transport layer is a layer into which electrons are injected from the cathode and which transports the electrons. The electron transport layer is desired to have high electron injection efficiency and efficiently transport the injected electrons. Therefore, the material constituting the electron transport layer is preferably a substance that has high electron affinity, high electron mobility, excellent stability, and does not easily generate trapping impurities during production and use. In particular, in the case of laminating a thick film, a compound having a molecular weight of 400 or more is preferable in order to maintain a stable film quality, because a low-molecular-weight compound tends to crystallize and deteriorate the film quality. However, considering the transport balance of holes and electrons, if the electron transport layer mainly plays a role of efficiently preventing the holes from the anode from flowing to the cathode side without recombination, the electron transport Even if it is made of a material that does not have a very high ability, the effect of improving the luminous efficiency is equivalent to that of a material that has a high electron transport ability. Therefore, the electron-transporting layer in the present invention includes a hole-blocking layer that can efficiently block the movement of holes. may be configured.

Examples of electron transport materials used in the electron transport layer include condensed polycyclic aromatic derivatives such as naphthalene and anthracene, styryl aromatic ring derivatives such as 4,4′-bis(diphenylethenyl)biphenyl, anthraquinone and diphenoquinone. quinone derivatives, phosphorus oxide derivatives, quinolinol complexes such as tris(8-quinolinolato)aluminum (III), benzoquinolinol complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes and flavonol metal complexes. A heteroaryl ring structure composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus and containing an electron-accepting nitrogen can be used to further reduce the driving voltage and obtain more efficient light emission. It is preferable to use a compound having

The electron-accepting nitrogen here means a nitrogen atom that forms a multiple bond with an adjacent atom. Due to the high electronegativity of the nitrogen atom, the multiple bond has electron-accepting properties. Therefore, heteroaromatic rings containing electron-accepting nitrogen have high electron affinities. An electron-transporting material having electron-accepting nitrogen makes it easier to accept electrons from a cathode having a high electron affinity, and can be driven at a lower voltage. In addition, more electrons are supplied to the light-emitting layer and the probability of recombination is increased, so that the light emission efficiency is further improved.

Heteroaryl rings containing electron-accepting nitrogen include, for example, triazine ring, pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, quinazoline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, oxadiazole ring, triazole ring, thiazole ring, thiadiazole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, phenanthroimidazole ring and the like.

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 such as bipyridine and terpyridine, quinoxaline derivatives and naphthyridine derivatives. Among others, imidazole derivatives such as tris(N-phenylbenzimidazol-2-yl)benzene, oxadiazole derivatives such as 1,3-bis[(4-tert-butylphenyl)1,3,4-oxadiazolyl]phenylene, triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole, phenanthroline derivatives such as bathocuproine and 1,3-bis(1,10-phenanthrolin-9-yl)benzene, 2,2' - benzoquinoline derivatives such as bis(benzo[h]quinolin-2-yl)-9,9'-spirobifluorene, 2,5-bis(6'-(2',2''-bipyridyl))-1, bipyridine derivatives such as 1-dimethyl-3,4-diphenylsilole, terpyridine derivatives such as 1,3-bis(4′-(2,2′:6′2″-terpyridinyl))benzene, bis(1-naphthyl) Naphthyridine derivatives such as -4-(1,8-naphthyridin-2-yl)phenylphosphine oxide are preferably used from the viewpoint of electron transport ability.

In addition, 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, considering the durability of the device, the ease of synthesis, and the availability of raw materials, the condensed polycyclic aromatic skeleton is preferably a fluoranthene skeleton, anthracene skeleton, a pyrene skeleton, or a phenanthroline skeleton. more preferred.

Preferable electron-transporting materials are not particularly limited, but specific examples include the following.

A compound having a structure represented by general formula (1) is also preferable because it has a high electron-transporting property and exhibits excellent properties as an electron-transporting layer.

The electron-transporting material may be used alone, or two or more of the electron-transporting materials may be mixed and used, or one or more other electron-transporting materials may be mixed with the electron-transporting material. I do not care. Moreover, you may contain a donor compound. Here, the donor compound is a compound that facilitates the injection of electrons from the cathode or the electron injection layer into the electron transport layer by improving the electron injection barrier and further improves the electrical conductivity of the electron transport layer.

Preferable examples of the donor compound include an alkali metal, an inorganic salt containing an alkali metal, a complex of an alkali metal and an organic substance, an alkaline earth metal, an inorganic salt containing an alkaline earth metal, or a mixture of an alkaline earth metal and an organic substance. complexes, rare earth metals, and the like. Preferred examples of alkali metals, alkaline earth metals, and rare earth metals 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 magnesium, calcium, cerium, and barium. and alkaline earth metals such as samarium, europium, and ytterbium. A plurality of these metals may be used, or an alloy of these metals may be used.

In addition, it is preferably in the form of an inorganic salt or a complex with an organic substance, rather than a single metal, because vapor deposition in a vacuum is easy and handling is excellent. Furthermore, it is more preferable to be in the state of a complex with an organic substance in terms of facilitating handling in the atmosphere and facilitating adjustment of the addition concentration. Examples of inorganic salts include oxides and nitrides such as LiO and Li ₂ O, fluorides such as LiF, NaF and KF, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Rb ₂ CO ₃ , Carbonates such as Cs ₂ CO ₃ and the like are included. Preferred examples of alkali metals or alkaline earth metals include lithium and cesium from the viewpoint that the driving voltage can be further reduced. Preferable examples of the organic matter in the complex with the organic matter include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, and hydroxytriazole. Among them, a complex of an alkali metal and an organic substance is preferable from the viewpoint that the driving voltage of the organic EL device can be further reduced. That is, it is preferred that the electron transport layer further contains an alkali metal complex compound. Furthermore, as the alkali metal complex compound, a complex of lithium and an organic substance is more preferable from the viewpoint of ease of synthesis and thermal stability, and lithium quinolinol (Liq), which is available at a relatively low cost, is particularly preferable.

Although the ionization potential of the electron transport layer is not particularly limited, it is preferably 5.6 eV or more and 8.0 eV or less, more preferably 5.6 eV or more and 7.0 eV or less.

The method of forming each layer constituting the organic EL element is not particularly limited, such as resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, and coating method. is preferred.

(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 into the electron transport layer. , a layer containing the above-described donor material may be used.

In addition, inorganic materials such as insulators and semiconductors can also be used for the electron injection layer. By using these materials, the short circuit of the organic EL element can be suppressed and the electron injection properties can be improved.

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.

Specifically, preferred alkali metal chalcogenides include, for example, _Li2O , _Na2S and _Na2Se . Preferred alkaline earth metal chalcogenides also include, for example, CaO, BaO, SrO, BeO, BaS and CaSe. Preferred alkali metal halides include, for example, LiF, NaF, KF, LiCl, KCl and NaCl. Preferred examples of halides of alkaline earth metals include fluorides such as CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ and BeF ₂ , and halides other than fluorides.

Furthermore, a complex of an organic substance and a metal is also preferably used. When a complex of an organic substance and a metal is used for the electron injection layer, the film thickness can be easily adjusted. Preferable examples of organic substances in organometallic complexes include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, and hydroxytriazole.

A layer containing a compound having a structure represented by general formula (1) is also preferable because it has high electron injection properties and exhibits excellent properties as an electron injection layer. Further, the compound represented by the general formula (1) is preferably doped with the above alkali metal or rare earth metal, so that the driving voltage can be further reduced and the durability life can be further improved.

(Charge generating layer)
The charge generation layer in the present invention generally consists of a double layer, and specifically can be used as a pn junction type charge generation layer consisting of an n-type charge generation layer and a p-type charge generation layer. The pn junction charge generation layer generates charges or separates the charges into holes and electrons when a voltage is applied in the organic EL element, and converts these holes and electrons into holes and electrons. It is injected into the light-emitting layer via the transport layer. Specifically, it functions as an intermediate charge generation layer in an organic EL device having a stack of light-emitting layers. The n-type charge-generating layer supplies electrons to the first light-emitting layer on the anode side, and the p-type charge-generating layer supplies holes to the second light-emitting layer on the cathode side. Therefore, it is possible to further improve the luminous efficiency of the organic EL element in which a plurality of light-emitting layers are laminated, reduce the driving voltage, and further improve the durable life of the element.

The n-type charge generation layer consists of an n-type dopant and a host, and conventional materials can be used for these. For example, alkali metals, alkaline earth metals, or rare earth metals can be used as n-type dopants. Among them, it is preferable that the charge generation layer further contains an alkali metal and/or a rare earth metal. Preferably the alkali metal is Li. It is preferred that the rare earth metal is Yb. As a host, compounds having a nitrogen-containing aromatic heterocycle such as phenanthroline derivatives and oligopyridine derivatives can be used. In particular, the compound having the structure represented by the general formula (1) and the phenanthroline dimer exhibit excellent properties as a host for the n-type charge generation layer, and they may be used in combination. Among them, it is preferable that the charge generation layer further contains a phenanthroline dimer. Preferable phenanthroline dimers are not particularly limited, but specific examples are given below.

The p-type charge generation layer consists of a p-type dopant and a host, which can be conventional materials. For example, p-type dopants include tetrafluor-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), tetracyanoquinodimethane derivatives, radialene derivatives, iodine, FeCl ₃ , FeF ₃ , SbCl ₅ etc. can be used. Preferred p-type dopants are radialene derivatives. Preferred hosts are arylamine derivatives.

The thickness of the organic layer depends on the resistance value of the light-emitting substance and cannot be limited, but is preferably 1 to 1000 nm. Each of the light-emitting layer, the electron transport layer, and the hole transport layer preferably has a film thickness of 1 nm or more and 200 nm or less, more preferably 5 nm or more and 100 nm or less.

The organic EL element of the present invention has the function of converting electrical energy into light. Here, direct current is mainly used as electric energy, but pulse current and alternating current can also be used. There are no particular restrictions on the current value and voltage value, but considering the power consumption and life of the device, it should be selected so that the maximum luminance can be obtained with the lowest possible energy.

The organic EL element of the present invention is suitable for use as a display device such as a matrix and/or segment display. That is, the display device of the present invention includes the organic EL element of the present invention.

The organic EL element of the present invention is also preferably used as a backlight for various devices. Backlights are mainly 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 devices, automobile panels, display boards, signs, and the like. In particular, the organic EL device of the present invention is preferably used for liquid crystal displays, especially for backlights for personal computers, for which thinning is being considered, and it is possible to provide thinner and lighter backlights than conventional ones.

The organic EL device of the present invention is also preferably used as various lighting devices. The organic EL device of the present invention can achieve both high luminous efficiency and high color purity, and can be made thinner and lighter. A combined lighting device can be realized. That is, the lighting device of the present invention includes the organic EL element of the present invention.

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

First, the evaluation method in each example will be explained.

(Heat-resistant)
After measuring the HPLC purity (area % at a measurement wavelength of 254 nm) for the compounds used in each example and comparative example, the ampoule was sealed in a vacuum-exchanged ampule and held in an oven at 385° C. for 150 hours. After that, the temperature was returned to room temperature, and the HPLC purity of the sample was determined in the same manner. The smaller the change in purity before and after the heat resistance test, the better the heat resistance can be evaluated.

(drive voltage)
The organic EL devices obtained in Examples 17 to 32 and Comparative Examples 6 to 10 were lit at a luminance of 1000 cd/m ² and the initial drive voltage was measured.

Further, the organic EL devices obtained in Examples 33 to 64 and Comparative Examples 11 to 20 were each driven at a current density of 10 mA/cm ² and the initial driving voltage was measured.

　The lower the initial drive voltage, the lower the voltage that can be driven, so it can be evaluated as having excellent luminous efficiency (luminance/power).

(external quantum efficiency)
The organic EL devices obtained in Examples 17 to 32 and Comparative Examples 6 to 10 were lit at a current density of 10 mA/cm ² , and the external quantum efficiency was measured to evaluate the luminous efficiency. It can be evaluated that the higher the external quantum efficiency, the better the luminous efficiency.

(Luminance)
The organic EL devices obtained in Examples 33 to 64 and Comparative Examples 11 to 20 were lit at 10 mA/cm ² , luminance was measured, and luminous efficiency was evaluated. It can be evaluated that the higher the luminance, the better the luminous efficiency.

(durable life)
The organic EL devices obtained in Examples 17 to 32 and Comparative Examples 6 to 10 were driven at room temperature at a constant current density of 10 mA/cm ² for 100 hours, and the voltage was measured. was calculated. It can be evaluated that the smaller the amount of voltage rise, the better the durability life.

The organic EL devices obtained in Examples 17 to 64 and Comparative Examples 6 to 20 were continuously driven at a constant current of 10 mA/cm ² , and the time required for the luminance to decrease by 20% from the initial luminance was measured. It can be evaluated that the longer the time to decrease, the better the durability life.

Example 1
To a mixed solution of 4.0 g of bromobenzene and 26 ml of tetrahydrofuran was added dropwise 17.4 ml of n-butyllithium (1.6 M hexane solution) at 0° C. under a nitrogen stream. After stirring at 0°C for 1 hour, it was added dropwise at 0°C to a mixed solution of 5.0 g of 3,4,7,8-tetramethyl-1,10-phenanthroline and 40 ml of tetrahydrofuran. After cooling to room temperature, the reaction solution was extracted with dichloromethane, leaving 100 ml of solvent and evaporated. After adding 10.0 g of manganese dioxide to the obtained solution and stirring at room temperature for 4 hours, magnesium sulfate was added and filtered, and the solvent was removed by evaporation. The obtained solid was purified by silica gel column chromatography, and the solid obtained by removing the solvent by evaporation was vacuum-dried to obtain 6.4 g of Intermediate A.

Next, 8.4 ml of n-butyl lithium (1.6 M hexane solution) was added dropwise at 0°C to a mixed solution of 3.4 g of 1,3-dibromobenzene and 30 ml of tetrahydrofuran under a nitrogen stream. After stirring at 0°C for 1 hour, it was added dropwise at 0°C to a mixed solution of 3.8 g of intermediate A and 30 ml of tetrahydrofuran. After cooling to room temperature, the reaction solution was extracted with dichloromethane, leaving 100 ml of solvent and evaporated. After adding 8.0 g of manganese dioxide to the obtained solution and stirring at room temperature for 4 hours, magnesium sulfate was added and filtered, and the solvent was removed by evaporation. The obtained solid was purified by silica gel column chromatography, and the solid obtained by removing the solvent by evaporation was dried in vacuum to obtain 2.9 g of Intermediate B.

Next, a mixed solution of 1.0 g of intermediate B, 0.62 g of 3,5-diphenylphenylboronic acid, 50 mg of dichlorobis(triphenylphosphinepalladium) dichloride, 5 ml of 1.5 M tripotassium phosphate aqueous solution, and 20 ml of dimethoxyethane, The mixture was heated and stirred for 7 hours under reflux under a nitrogen stream. After cooling to room temperature, water was added, filtered, washed with methanol, and dried in vacuum. The catalyst was removed from the obtained solid using activated carbon, and the solid obtained by removing the solvent by evaporation was washed with toluene and methanol, and then vacuum-dried to obtain 0.6 g of Compound 1.

The resulting compound 1 was purified by sublimation at about 320° C. under a pressure of 1×10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area % at a measurement wavelength of 254 nm) of Compound 1 before and after sublimation purification was both 99.9%.

After purification by sublimation, the structure of compound 1 was identified by mass spectrum (MS) analysis and ¹ H-NMR analysis. The analysis results are shown below.
MS (m/z): 617 [M+H] ⁺
¹ H-NMR (400 MHz, CDCl ₃ ) δ: 7.95-8.11 (m, 3H), 7.55-7.88 (m, 12H), 7.27-7.48 (m, 9H) 2.77 (s, 6H), 2.53 (s, 6H).

When the heat resistance was evaluated by the method described above, the HPLC purity was 99% both before and after the heat resistance test.

Example 2
To a mixed solution of 3.2 g of 1,4-dibromobenzene and 20 ml of tetrahydrofuran was added dropwise 7.8 ml of n-butyl lithium (1.6 M hexane solution) at 0° C. under a nitrogen stream. After stirring at 0°C for 1 hour, it was added dropwise at 0°C to a mixed solution of 2.6 g of 3,4,7,8-tetramethyl-1,10-phenanthroline and 20 ml of tetrahydrofuran. After cooling to room temperature, the reaction solution was extracted with dichloromethane, leaving 100 ml of solvent and evaporated. After adding 5.0 g of manganese dioxide to the obtained solution and stirring at room temperature for 4 hours, magnesium sulfate was added and filtered, and the solvent was removed by evaporation. The obtained solid was purified by silica gel column chromatography, and the solid obtained by removing the solvent by evaporation was dried in vacuum to obtain 3.5 g of Intermediate C.

Next, a mixed solution of 1.6 g of Intermediate C, 1.8 g of boronate ester BA, 80 mg of dichlorobis(triphenylphosphinepalladium) dichloride, 7 ml of 1.5 M tripotassium phosphate aqueous solution, and 40 ml of 1,4-dioxane was passed under a nitrogen stream. The mixture was heated and stirred under reflux for 3 hours. After cooling to room temperature, water was added, filtered, washed with methanol, and dried in vacuum. The catalyst was removed from the obtained solid using activated charcoal, and the solid obtained by removing the solvent by evaporation was washed with toluene and methanol, and then vacuum-dried to obtain 1.1 g of Compound 2.

The resulting compound 2 was purified by sublimation at about 360° C. under a pressure of 1×10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area % at a measurement wavelength of 254 nm) of compound 2 before and after sublimation purification was both 99.9%.

After purification by sublimation, the structure of compound 2 was identified by mass spectrum (MS) analysis and ¹ H-NMR analysis. The analysis results are shown below.
MS (m/z): 620 [M+H] ⁺
¹ H-NMR (400 MHz, CDCl ₃ ) δ: 8.93 (s, 1H), 8.82 (s, 2H), 8.72-8.76 (m, 2H), 8.69 (d, 2H) , J=7.6 Hz), 8.64 (s, 1H, J=2.0 Hz), 8.66 (d, 2H, J=5.6 Hz) 7.85-7.92 (m, 3H), 7.74-7.83 (m, 5H), 7.62 (t, 1H, J=8.0Hz), 7.34-7.37 (m, 2H), 2.78 (s, 3H), 2.69 (s, 3H), 2.54 (s, 3H), 2.52 (s, 3H).

Examples 3-19, Comparative Examples 1-5
Heat resistance was evaluated in the same manner as in Example 1 except that the compounds listed in Table 1 were used. Table 1 shows the results of each example and comparative example. Compounds 1 to 24 are compounds shown below.

Example 20
A glass substrate (manufactured by Geomatec, 11Ω/□, sputtered product) on which an ITO transparent conductive film of 165 nm was deposited as an anode was cut into 38 mm×46 mm and etched. The obtained substrate was ultrasonically cleaned for 15 minutes using "Semico Clean" 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.) and then cleaned with ultrapure water. This substrate was treated with UV-ozone for 1 hour immediately before manufacturing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus reached 5×10 ⁻⁴ Pa or less. HAT-CN ₆ 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 by resistance heating. Next, as a light-emitting layer, a mixed layer of host material H-1 and dopant material D-1 was deposited to a thickness of 20 nm with a doping concentration of 5% by weight. Next, as an electron transport layer, ET-1 and 2E-1 were vapor-deposited to a thickness of 35 nm so that the vapor deposition rate ratio was ET-1 and 2E-1=1:1. Next, as an electron injection layer, Compound 1 and a metal element Li as a dopant were vapor-deposited to a thickness of 10 nm at a vapor deposition rate ratio of Compound 1:Li=99:1. After that, aluminum was vapor-deposited to a thickness of 60 nm to form a cathode, and an organic EL element of 5 mm×5 mm square was produced.

When this organic EL device was evaluated by the method described above, the initial drive voltage was 4.35 V, the external quantum efficiency (luminous efficiency) was 5.55%, the durability life was 980 hours, and the lifespan was 980 hours when driven at room temperature for 100 hours. The amount of voltage increase was 0.014V. HAT-CN ₆ , HT-1, H-1, D-1, ET-1 and 2E-1 are compounds shown below.

Examples 21-38, Comparative Examples 6-10
An organic EL device was produced in the same manner as in Example 20, except that the compounds used were changed as shown in Table 2. Table 2 shows the results of each example and comparative example.

Example 39
A glass substrate (manufactured by Geomatec, 11Ω/□, sputtered product) on which an ITO transparent conductive film of 165 nm was deposited as an anode was cut into 38 mm×46 mm and etched. The obtained substrate was ultrasonically cleaned for 15 minutes using "Semico Clean" 56 (trade name, manufactured by Furuuchi Chemical Co., Ltd.) and then cleaned with ultrapure water. This substrate was treated with UV-ozone for 1 hour immediately before manufacturing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus reached 5×10 ⁻⁴ Pa or less. First, HAT-CN ₆ was vapor-deposited to 5 nm as a hole injection layer by a resistance heating method. Next, a light-emitting unit (first light-emitting unit) was formed on the hole-injection layer, comprising a hole-transporting layer, a light-emitting layer, and an electron-transporting layer.

Specifically, HT-1 was vapor-deposited to a thickness of 50 nm as a hole transport layer, and then a mixed layer of host material H-1 and dopant material D-1 was formed as a light-emitting layer with a doping concentration of 5% by weight. Then, as an electron transport layer, ET-1 and 2E-1 were deposited to a thickness of 35 nm so that the deposition rate ratio of ET-1 and 2E-1 was 1:1. vapor-deposited on.

On the first light-emitting unit, as an N-type charge generation layer, compound 1 and a metal element Li as a dopant were deposited to a thickness of 10 nm at a deposition rate ratio of compound 1:Li=99:1. , HAT-CN ₆ was evaporated to 10 nm as a P-type charge generation layer.

Following the charge generation layer, a second light-emitting unit was formed in the same manner as the first light-emitting unit. After that, as an electron injection layer, compound 1 and a dopant metal element Li were vapor-deposited to a thickness of 10 nm at a vapor deposition rate ratio of compound 1:Li=99:1. A 5 mm square organic EL device was produced.

When this organic EL device was evaluated by the method described above, the initial drive voltage was 8.81 V, the luminance was 1610 cd/m ² , and the endurance life was 2400 hours.

Examples 40-60, Comparative Examples 11-15
An organic EL device was produced in the same manner as in Example 39, except that the compounds and metal elements used were changed as shown in Table 3. Table 3 shows the results of each example and comparative example.

Example 61
Same as Example 33 except that Compound 1 was used instead of ET-1 in the formation of the electron transport layer, and ET-2 was used instead of Compound 1 in the formation of the N-type charge generation layer. Then, an organic EL device was produced. ET-2 is a compound shown below.

When this organic EL device was evaluated by the method described above, the initial drive voltage was 8.83 V, the luminance was 1600 cd/m ² , and the endurance life was 2410 hours.

Examples 62-79, Comparative Examples 16-20
An organic EL device was produced in the same manner as in Example 61, except that the compounds used were changed as shown in Table 4. Table 4 shows the results of each example and comparative example.

Claims

A compound having a structure represented by the following general formula (1).

(In general formula (1), R 1 to R 6 are each independently a hydrogen atom or an alkyl group. However, at least two of R 1 to R 6 are alkyl groups. X is a hydrogen atom. , a substituted or unsubstituted aryl or heteroaryl group, provided that the substituent when these groups are substituted is an alkyl group, Y is a biphenyl group, a terphenyl group, a quaterphenyl group, or an L —Z, where L is a divalent linking group selected from the following and bonded at the position of *, Z is a substituted or unsubstituted naphthyl group, phenanthryl group, pyrenyl group, or fluoranthenyl group , triphenylenyl group, dimethylfluorenyl group, diphenylfluorenyl group, spirobifluorenyl group, pyridyl group, pyrimidyl group, triazinyl group, bipyridyl group, terpyridyl group, quinolinyl group, quinazolyl group, carbazolyl group, carbonyl group, a dibenzofuranyl group, a dibenzothiophenyl group, or a phenanthrolinyl group.)
2. The compound according to claim 1, wherein in the general formula (1), X is a substituted or unsubstituted aryl group or heteroaryl group.
Claim 1, wherein in the general formula (1), Y is LZ, and Z is a substituted or unsubstituted pyridyl group, pyrimidyl group, triazinyl group, bipyridyl group, terpyridyl group or phenanthrolinyl group. Compound as described.
The compound according to claim 1, wherein in the general formula (1), Y is LZ and Z is an unsubstituted terpyridyl group.
In the general formula (1), X is a substituted or unsubstituted aryl group or heteroaryl group, Y is LZ, and Z is a substituted or unsubstituted phenanthrolinyl group or terpyridyl group. Item 1. A compound according to Item 1.
2. The compound according to claim 1, wherein in the general formula (1), Y is LZ and L is a phenylene group.
2. The compound according to claim 1, wherein at least four of R 1 to R 6 in said general formula (1) are alkyl groups.
2. The formula (1) according to claim 1, wherein X is a phenyl group, Y is LZ, and Z is a phenyl group-substituted phenanthrolinyl group or an unsubstituted terpyridyl group. compound.
An organic EL device comprising at least an electron-transporting layer and a light-emitting layer between an anode and a cathode and emitting light by electric energy, wherein the electron-transporting layer contains the compound according to claim 1 .
10. The organic EL device according to claim 9, wherein said electron transport layer further contains an alkali metal complex compound.
An organic EL device comprising at least a charge-generating layer and a light-emitting layer between an anode and a cathode and emitting light by electric energy, wherein the charge-generating layer contains the compound according to claim 1 .
12. The organic EL device according to claim 11, wherein said charge generating layer further contains a phenanthroline dimer.
12. The organic EL device according to claim 11, wherein said charge generation layer further contains an alkali metal and/or a rare earth metal.
14. The organic EL device according to claim 13, wherein said alkali metal is Li.
14. The organic EL device according to claim 13, wherein said rare earth metal is Yb.
2. An organic EL device comprising at least an electron injection layer and a light emitting layer between an anode and a cathode and emitting light by electrical energy, wherein the electron injection layer contains the compound according to claim 1.
A display device comprising the organic EL element according to any one of claims 9 to 16.
A lighting device comprising the organic EL device according to any one of claims 9 to 16.