JP2020123477A - Light-emitting element, display device and illumination apparatus - Google Patents

Abstract

To provide an organic thin film light-emitting element which improves light emission efficiency and a durable lifetime.SOLUTION: The present invention relates to a light-emitting element in which at least one light-emitting layer and at least one organic layer exist between a cathode and an anode and light is emitted by electric energy. The light-emitting element contains in one layer of the organic layers, an oligopyridine compound represented by a general formula (1) and a rare metal dopant (in the general formula (1), (n) is an integer of 1 or 2, (m) and an integer of 0 to 2 wherein it leads n+m≥2, L, Land Lare single-bold, substituted or unsubstituted arylene groups or substituted or unsubstituted heteroarylene groups, and A is a substituted group).SELECTED DRAWING: None

Description

The present invention relates to a light emitting element, a display device, and a lighting device.

In recent years, organic thin-film light emitting devices have been steadily put into practical use, such as being adopted in the displays of televisions and smartphones. However, the existing organic thin film light emitting device still has many technical problems. Among them, achieving both highly efficient light emission and prolonging the life of the organic thin film light emitting device is a major issue.

As a method for realizing low driving voltage and high brightness/high current density in an organic thin film light emitting device, n-type doping in a charge injection layer, a charge transport layer and a charge generation layer can be mentioned. For example, the charge injection/transport layer and the charge generation layer in the organic thin film light emitting device can be formed by depositing a specific compound together with a metal dopant such as Li (see, for example, Patent Documents 1 to 3).

International Publication No. 2015/182547 JP, 2017-224808, A JP, 2018-121046, A

Patent Document 1 describes a charge generation layer in which a fluoranthene derivative is doped with an alkali metal or an alkaline earth metal. However, since alkali metals and alkaline earth metals are unstable to water, there is a problem in handling property. Moreover, the luminous efficiency and durability of the light emitting device using these are not sufficient.

Patent Document 2 describes an organic semiconductor layer in which a phenanthroline derivative is doped with a rare earth metal. However, the element using these elements is not sufficient in light emitting efficiency, durability and driving stability in a high temperature state in the light emitting element.

Patent Document 3 describes an organic semiconductor material obtained by doping a compound having a specific aryl group with an arbitrary n-type dopant. However, the compounds described in this document do not have a sufficient ability to coordinate with a metal, and the luminous efficiency, durability and driving stability of a light emitting device have not been sufficient.

As described above, it has been difficult for the conventional technique to improve the driving voltage and the durability while increasing the luminous efficiency of the organic thin film light emitting device. Moreover, even if the driving voltage could be lowered, the light emitting efficiency and the durability of the organic thin film light emitting device were insufficient at the same time. As described above, a technique for achieving both high luminous efficiency and durable life has not been found yet.

It is an object of the present invention to solve the problems of the prior art and provide an organic thin film light emitting device having improved luminous efficiency and durable life.

A device which has at least one organic layer between an anode and a cathode and emits light by electric energy, wherein one layer of the organic layer comprises an oligopyridine compound represented by the following general formula (1) and a rare earth metal element. A light emitting device containing.

(In the general formula (1), n is an integer of 1 or 2, and m is an integer of 0 to 2. However, n+m≧2. When n is 2, m contained in each is L ¹ , L ² and L ³ are a single bond or a substituted or unsubstituted arylene group, and A is a substituted or unsubstituted monocyclic aromatic group having 6 to 40 carbon atoms. Hydrocarbon group, substituted or unsubstituted condensed aromatic hydrocarbon group having 6 to 40 carbon atoms, substituted or unsubstituted monocyclic aromatic hetero group having 1 to 40 carbon atoms, substituted or unsubstituted having 1 to 40 carbon atoms Represents a condensed aromatic hetero group or a substituted or unsubstituted aromatic amino group having 6 to 40 carbon atoms.)

According to the present invention, it is possible to provide an organic electroluminescent device having high luminous efficiency and also having a sufficient durability life.

Hereinafter, preferred embodiments of a light emitting element, a display device, and a lighting device according to the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be carried out according to the purpose and use.

(Compound represented by the general formula (1))
A light emitting device according to an embodiment of the present invention is a device that has at least one organic layer between an anode and a cathode and emits light by electric energy, and one of the organic layers has the following general formula (1 ) And the rare earth metal element.

In the general formula (1), n is an integer of 1 or 2 and m is an integer of 0-2. However, n+m≧2. When n is 2, m contained in each may be the same or different. L ¹ , L ² and L ³ are single bonds or substituted or unsubstituted arylene groups. A is a substituted or unsubstituted monocyclic aromatic hydrocarbon group having 6 to 40 carbon atoms, a substituted or unsubstituted condensed aromatic hydrocarbon group having 6 to 40 carbon atoms, a substituted or unsubstituted C 1 to 40 substituted or unsubstituted It represents a monocyclic aromatic hetero group, a substituted or unsubstituted fused aromatic hetero group having 1 to 40 carbon atoms, or a substituted or unsubstituted aromatic amino group having 6 to 40 carbon atoms.

The term “unsubstituted” in the case of “substituted or unsubstituted” means that a hydrogen atom is replaced. In the case of "substituted or unsubstituted" in the compound or the partial structure thereof described below, the same applies to the above.

The arylene group refers to a divalent or higher-valent group derived from an aryl group, and examples thereof include a phenylene group, a naphthylene group, a biphenylene group, a fluorenylene group, a phenanthrylene group, a terphenylene group, an anthracenylene group, and a pyrenylene group. The carbon number of the arylene group is not particularly limited, but is usually in the range of 6 or more and 40 or less. When the arylene group has a substituent, the carbon number of the arylene group including the substituent is preferably 6 or more and 60 or less.

The heteroarylene group is a divalent or more valent group derived from an aromatic group having one or more atoms other than carbon, such as pyridine, quinoline, pyrimidine, pyrazine, triazine, quinoxaline, quinazoline, dibenzofuran and dibenzothiophene, in the ring. The group of is shown. The heteroarylene group may or may not have a substituent. A preferred heteroarylene group is a divalent or trivalent heteroarylene group. The carbon number of the heteroarylene group is not particularly limited, but is usually in the range of 2 or more and 30 or less.

The monocyclic aromatic hydrocarbon group includes an uncondensed aromatic hydrocarbon group composed of one or more benzene rings such as a phenyl group, a biphenyl group and a terphenyl group. The monocyclic aromatic hydrocarbon group may have a substituent.

The condensed aromatic hydrocarbon group, for example, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthene ring, pentacene ring, Examples thereof include a perylene ring, a pentaphene ring, a picene ring, a pyrantrene ring, and an anthraanthrene ring. The condensed aromatic hydrocarbon group may have a substituent.

The monocyclic aromatic hetero group, for example, furan ring, thiophene ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring and the like. Can be mentioned. Further, the monocyclic aromatic hetero group may have a substituent.

The condensed aromatic hetero group includes, for example, quinoline ring, isoquinoline ring, quinoxaline ring, benzimidazole ring, indole ring, benzothiazole ring, benzoxazole ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, diazacarbazole ring. (One of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) and the like. Furthermore, the condensed aromatic hetero group may have a substituent.

The aromatic amino group is a monocyclic aromatic hydrocarbon group, a condensed aromatic hydrocarbon group, a monocyclic aromatic hetero group or a condensed aromatic hetero group substituted with an amine.

The oligopyridine compound represented by the general formula (1) has a large electron transporting property. Moreover, since it has a flexible structure with a plurality of pyridyl groups, it has a large coordination property to a metal atom. Therefore, when an oligopyridine compound represented by the general formula (1) is used as an organic layer in a light emitting device with a rare earth metal which is stable to moisture and air and is easy to handle as an n-type dopant, a stable layer should be formed. You can In particular, when the organic layer is an electron transport layer, an electron injection layer or a charge generation layer, those layers show stable and excellent performance.

A preferable example of the compound represented by the general formula (1) is that n is 2 from the viewpoint of enhancing the coordination property to the rare earth metal and forming a more stable layer.

Another preferable example of the compound represented by formula (1) is that in which m is 0. This is because when m is 0, the compound has an appropriate intermolecular interaction and coordination with a rare earth metal, and thus a more stable layer can be formed. When n is 2, it is more preferable that both of the two existing m be 0.

In formula (1), L ² is preferably a single bond. This is because, when a plurality of pyridine rings in the general formula (1) are linked by a single bond, the coordination of each pyridine ring to the rare earth metal becomes strong, and a more stable layer can be formed.

When n is 2, at least one of two existing L ² is preferably a single bond, and more preferably both are single bonds.

Further, from the viewpoint of further enhancing the coordination property, it is more preferable that the general formula (1) is an oligopyridine compound represented by the following general formula (2).

In the general formula (2), any one of X ^{1 to} X ³ is a nitrogen atom, and the others are carbon atoms. L ¹ and A are the same as those in the general formula (1). It is particularly preferable that X ³ in the general formula (2) is a nitrogen atom.

In the general formula (1) or (2), it is preferable that A has a fluoranthene structure. The fluoranthene structure has high planarity and a large overlap between molecules, and thus has a high charge transporting property. Therefore, in the general formula (1) or (2), when A has a fluoranthene structure, the charge transporting capacity can be further enhanced, and a more efficient light emitting device can be realized. More preferably, A is a fluoranthenyl group.

It is also preferable that A is an aromatic amino group. The aromatic amino group has high stability to holes. Therefore, when A is an aromatic amino group, driving stability in the light emitting device can be improved.

The compound represented by the general formula (1) is not particularly limited, but specific examples include the following. Note that the following is an example, and compounds other than the compounds specified here are similarly preferably used as long as they are represented by the general formula (1).

A known method can be used for the synthesis of the oligopyridine compound as described above. As a synthetic method, for example, a method using a coupling reaction of a primary or secondary amine derivative with a halide or a triflate using a palladium or copper catalyst, a halogenated amine derivative with an arylboronic acid derivative using palladium, and the like. Examples thereof include, but are not limited to, a coupling reaction with and the like.

The compound represented by the general formula (1) is preferably used as a light emitting device material. Here, the light emitting device material in the present invention represents a material used for any layer of the light emitting device, and as described later, it can be used as a hole injection layer, a hole transport layer, a light emitting layer and/or an electron transport layer. In addition to the materials used, the materials used for the protective film (cap layer) of the electrode are also included. By using the compound represented by the general formula (1) in the present invention in any of the layers of the light emitting device, a light emitting device having high luminous efficiency and excellent durability can be obtained.

(Rare earth metal element)
The rare earth metals in the present invention are scandium, yttrium and 15 lanthanoids. In the present invention, the rare earth metal is used as a zero-valent n-type dopant. Among the above 17 rare earth metals, Sm, Eu, and Yb are preferable, and Yb is particularly preferable.

The rare earth metal element can have a higher doping concentration when compared with alkali metal, particularly lithium which is often used as an n-type dopant. Therefore, as compared with the case where an alkali metal such as lithium is used as a dopant, it is easier to control the vapor deposition rate during vapor deposition, and the productivity of the light emitting element can be improved. Further, the rare earth metal is more stable to moisture than the alkali metal and the alkaline earth metal, and can be safely used in mass production.

Furthermore, when the rare earth metal is used in a light emitting device together with the compound represented by the general formula (1), the compound represented by the general formula (1) is strongly coordinated with the rare earth metal, so that it is difficult to diffuse in the device. Become. Therefore, it is possible to increase the driving voltage over time and improve the durable life of the light emitting element.

The doping concentration of the n-type dopant is controlled by the deposition rate ratio at the time of co-deposition. The suitable doping concentration varies depending on the material and the film thickness of the doping region, but for example, the deposition rate ratio of the general formula (1) and the n-type dopant is preferably 100:1 to 1:1 and 20:1 to 1:1. Is more preferable.

(Light emitting element)
Next, embodiments of the light emitting device of the present invention will be described in detail. The organic thin film light emitting device has an anode and a cathode, and an organic layer interposed between the anode and the cathode, and the organic layer emits light by electric energy.

In such a light emitting device, the layer structure between the anode and the cathode is 1) light emitting layer/electron transporting layer, 2) hole transporting layer/light emitting layer, 3) hole transporting, in addition to the structure comprising only the light emitting layer. Layer/light emitting layer/electron transport layer, 4) hole injection layer/hole transport layer/light emitting layer/electron transport layer, 5) hole transport layer/light emitting layer/electron transport layer/electron injection layer, 6) hole Injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer, 7) hole injection layer/hole transport layer/light emitting layer/hole blocking layer/electron transport layer/electron injection layer Can be mentioned.

Furthermore, a tandem type in which a plurality of the above laminated structures are laminated with an intermediate layer interposed therebetween may be used. The intermediate layer is generally 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 a known material structure can be used. Specific examples of the tandem type are, 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 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 such as a charge generation layer as an intermediate layer between the anode and the cathode. A laminated structure including the above can be given. As a material forming the intermediate layer, specifically, an oligopyridine derivative is preferably used.

Each of the above layers may be a single layer or a plurality of layers, and may be doped. Furthermore, each of the above layers includes an anode, one or more organic layers including a light emitting layer, a cathode, and an element structure including a layer using a capping material for improving light emission efficiency due to an optical interference effect.

The oligopyridine compound represented by the general formula (1) and the rare earth metal dopant may be used in any of the above layers in the light emitting device, but are particularly preferably used in the charge generation layer.

In the light emitting device according to the embodiment of the present invention, the anode and the cathode have a role of supplying a sufficient current for light emission of the device, and at least one of them is transparent or semitransparent in order to extract light. Is desirable. Usually, the anode formed on the substrate is a transparent electrode.

(substrate)
In order to maintain the mechanical strength of the light emitting element, it is preferable to form the light emitting element on the substrate. As the substrate, a glass substrate such as soda glass or non-alkali glass is preferably used. The thickness of the glass substrate need only be thick enough to maintain mechanical strength, so 0.5 mm or more is sufficient. As for the material of the glass, alkali-free glass is preferable because it is preferable that the amount of ions eluted from the glass is small. Further, soda lime glass coated with a barrier coat such as SiO _{2 is} also commercially available, and this can also be used. Further, if the first electrode formed on the substrate functions stably, the substrate need not be glass, and may be, for example, a plastic substrate.

(anode)
The material used for the anode is zinc oxide, tin oxide, indium oxide, indium tin oxide (ITO), zinc oxide, as long as it is a material capable of efficiently injecting holes into the organic layer and transparent or translucent for extracting light. Conductive metal oxides such as indium (IZO), metals such as gold, silver and chromium, inorganic conductive substances such as copper iodide and copper sulfide, conductive polymers such as polythiophene, polypyrrole and polyaniline are not particularly limited. It is not limited to this, but it is particularly preferable to use ITO glass or Nesa glass. 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 is not limited as long as it can supply a sufficient current for light emission of the element, but is preferably low resistance from the viewpoint of power consumption of the element. For example, an ITO substrate of 300 Ω/□ or less will function as an element electrode, but since it is now possible to supply a substrate of about 10 Ω/□, use a substrate with a low resistance of 20 Ω/□ or less. Is especially desirable. The thickness of ITO can be arbitrarily selected according to the resistance value, but it 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 is a substance that can efficiently inject electrons into the light emitting layer. Generally, metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys of these metals with low work function metals such as lithium, sodium, potassium, calcium, and magnesium, and multilayer lamination Is preferred. Among them, aluminum, silver, and magnesium are preferable as the main component in terms of electric resistance value, easiness of film formation, film stability, light emission efficiency, and the like. In particular, it is preferable to use magnesium and silver because it facilitates electron injection into the electron transport layer and the electron injection layer in the present invention and enables low voltage driving.

(Protective layer)
In order to protect the cathode, it is preferable to stack a protective layer (cap layer) on the cathode. The material constituting the protective layer is not particularly limited, but for example, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, alloys using these metals, silica, titania, silicon nitride, etc. Examples thereof include inorganic polymers, polyvinyl alcohol, polyvinyl chloride, organic polymer compounds such as hydrocarbon polymer compounds, and the like. Further, the compound represented by the general formula (1) can also be used as this protective layer. However, when the light emitting element has an element structure (top emission structure) for extracting light from the cathode side, the material used for the protective layer is selected from materials having light transmittance in the visible light region.

(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 plurality of layers stacked. The presence of the hole injecting layer between the hole transporting layer and the anode is preferable because not only driving at a lower voltage and improving the durable life but also improving the carrier balance of the device and improving the luminous efficiency.

The material used for the hole injection layer is not particularly limited, but, for example, 4,4′-bis(N-(3-methylphenyl)-N-phenylamino)biphenyl (TPD), 4,4′-bis(N -(1-Naphtyl)-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), a benzidine derivative, 4,4',4"-tris(3-methylphenyl(phenyl)amino ) A material group called a starburst arylamine such as triphenylamine (m-MTDATA), 4,4′,4″-tris(1-naphthyl(phenyl)amino)triphenylamine (1-TNATA), bis(N). -Arylcarbazole) or bis(N-alkylcarbazole) or other biscarbazole derivative, pyrazoline derivative, stilbene compound, hydrazone compound, benzofuran derivative, thiophene derivative, oxadiazole derivative, phthalocyanine derivative, porphyrin derivative or other heterocyclic compound In the polymer system, polycarbonate having a side chain of the above monomer, styrene derivative, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, polysilane and the like are used. From the viewpoint of smoothly injecting and transporting holes from the anode to the hole transport layer, a benzidine derivative and a starburst arylamine-based material group are more preferably used.

These materials may be used alone or in combination of two or more. Further, a plurality of materials may be laminated to form a hole injection layer. Further, it is more preferable that the hole injection layer is composed of the acceptor compound alone or the hole injection material as described above is doped with the acceptor compound, because the above-mentioned effects can be more remarkably obtained. .. The acceptor compound is a material which forms a charge transfer complex with a material which constitutes a hole transporting layer which is in contact when used as a single layer film and a hole injection layer which is used when doped. When such a material is used, the conductivity of the hole injection layer is improved, which contributes to further lowering of the driving voltage of the device, and the effects of improving the light emission efficiency and the durable life are obtained.

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

(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 either a single layer or a laminate of a plurality of layers.

The hole transport layer may be a single compound or a mixture of two or more kinds of materials. In this case, examples of the material used include 4,4′-bis(N-(3-methylphenyl)-N-phenylamino)biphenyl (TPD) and 4,4′-bis(N-(1-naphthyl). )-N-Phenylamino)biphenyl (NPD), 4,4′-bis(N,N-bis(4-biphenylyl)amino)biphenyl (TBDB), bis(N,N′-diphenyl-4-aminophenyl) A benzidine derivative such as -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) and other materials called starburst arylamines, bis(N-arylcarbazole) or Heterocyclic compounds such as biscarbazole derivatives such as bis(N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, and polymer systems described above. Examples thereof include polycarbonate having a monomer in the side chain, styrene derivative, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, and polysilane.

(Light emitting layer)
The light emitting layer may be a single layer or a plurality of layers, each formed of a light emitting material (host material, dopant material), which may be a mixture of a host material and a dopant material or a single host material. It may be a mixture of two kinds of host materials and one kind of dopant material, or any of them may be used. That is, in the light emitting device according to the embodiment of the present invention, in each light emitting layer, only the host material or the dopant material may emit light, or both the host material and the dopant material may emit light. From the viewpoint of efficiently utilizing electric energy and obtaining light emission of high color purity, the light emitting layer is preferably composed of a mixture of a host material and a dopant material. In addition, the host material and the dopant material may each be one kind or a combination of a plurality of kinds. The dopant material may be contained in the whole host material, partially contained, or both. The dopant material may be either laminated or dispersed. The dopant material can control the emission color. Since the concentration quenching phenomenon occurs when the amount of the dopant material is too large, it is preferably used in an amount of 30% by weight or less, and more preferably 20% by weight or less, based on the host material. The doping method can be performed by a co-evaporation method with a host material, but it may be mixed with the host material in advance and then evaporated at the same time.

Luminescent 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, and bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives. , Tetraphenylbutadiene derivative, indene derivative, coumarin derivative, oxadiazole derivative, pyrrolopyridine derivative, perinone derivative, cyclopentadiene derivative, oxadiazole derivative, thiadiazolopyridine derivative, dibenzofuran derivative, carbazole derivative, indolocarbazole derivative, In the polymer system, a polyphenylene vinylene derivative, a polyparaphenylene derivative, a polythiophene derivative and the like can be used, but are not particularly limited.

The host material contained in the light emitting material is not limited to one kind of compound, and a plurality of compounds of the present invention may be mixed and used, or one or more kinds of other host materials may be mixed and used. .. Moreover, you may laminate|stack and use. The host material is not particularly limited, but a compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, and indene, and N,N′-dinaphthyl- Aromatic amine derivatives such as N,N′-diphenyl-4,4′-diphenyl-1,1′-diamine, metal chelated oxinoid compounds including tris(8-quinolinato)aluminum(III), and distyrylbenzene Bisstyryl derivatives such as derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, India With respect to the locarbazole derivative, the triazine derivative, and the polymer system, a polyphenylene vinylene derivative, a polyparaphenylene derivative, a polyfluorene derivative, a polyvinylcarbazole derivative, a polythiophene derivative, and the like can be used, but are not particularly limited. Among them, as a host used when the light emitting layer emits triplet light (phosphorescence), metal chelated oxinoid compounds, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, triphenylene derivatives, etc. Is preferably used.

The dopant material contained in the light emitting material is not particularly limited, but a compound having an aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, fluoranthene, triphenylene, perylene, fluorene, and indene or a derivative thereof (for example, 2-(benzothiazole- 2-yl)-9,10-diphenylanthracene, 5,6,11,12-tetraphenylnaphthacene, etc.), furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9'-spirobisilafluorene, Compounds having a heteroaryl ring such as benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine and thioxanthene, derivatives thereof, distyrylbenzene derivatives, 4,4'- Aminostyryl derivatives such as bis(2-(4-diphenylaminophenyl)ethenyl)biphenyl and 4,4′-bis(N-(stilben-4-yl)-N-phenylamino)stilbene, aromatic acetylene derivatives, tetra Phenyl butadiene derivative, stilbene derivative, aldazine derivative, pyrromethene derivative, diketopyrrolo[3,4-c]pyrrole derivative, 2,3,5,6-1H,4H-tetrahydro-9-(2′-benzothiazolyl)quinolidino[9, Coumarin derivatives such as 9a,1-gh]coumarin, azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, and triazole, and metal complexes thereof and N,N′-diphenyl-N,N′-di( Aromatic amine derivatives represented by 3-methylphenyl)-4,4'-diphenyl-1,1'-diamine and the like can be mentioned. Among them, it is preferable to use a dopant containing a diamine skeleton or a dopant containing a fluoranthene skeleton, since high-efficiency light emission can be easily obtained.

In addition, as a dopant used when the light emitting layer emits triplet light (phosphorescence), iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and rhenium are used. It is preferably a metal complex compound containing at least one metal selected from the group consisting of (Re). The ligand preferably has a nitrogen-containing aromatic heterocycle such as a phenylpyridine skeleton, a phenylquinoline skeleton, or a carbene skeleton. However, the complex is not limited to these, and an appropriate complex is selected in view of the required emission color, device performance, and 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)(acetylacetonato)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)(acetylaceto Nato)iridium complex, bisbenzoquinoline (acetylacetonato)iridium complex, bis{2-(2,4-difluorophenyl)pyridyl}(acetylacetonato)iridium complex, tetraethylporphyrin platinum complex, {tris(cenoyltrifluoroacetone) ) Mono(1,10-phenanthroline)} europium complex, {tris(cenoyltrifluoroacetone)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 can be mentioned. Further, the phosphorescent dopant described in JP-A-2009-130141 is also preferably used. Although not limited to these, an iridium complex or a platinum complex is preferably used because high efficiency luminescence is easily obtained.

The triplet light emitting material used as the dopant material may include only one kind in the light emitting layer, or may be a mixture of two or more kinds. When two or more triplet light emitting materials are used, the total weight of the dopant material is preferably 30% by weight or less, and more preferably 20% by weight or less with respect to the host material.

The preferred host and dopant in the triplet light emitting system are not particularly limited, but specific examples include the following.

In the light emitting device according to the embodiment of the present invention, it is also preferable that the light emitting layer contains a triplet light emitting material.

It is also preferred that the light emitting layer contains a heat activated delayed fluorescent material. The heat-activated delayed fluorescence is described on pages 87 to 103 of "State-of-the-art Organic EL" (edited by Chitaya Adachi and Hiroshi Fujimoto, published by CMC Publishing). In that document, by making the energy levels of the excited singlet state and the excited triplet state of the fluorescent material close to each other, the reverse energy transfer from the excited triplet state to the excited singlet state, which usually has a low transition probability, is high. It is described that it occurs with high efficiency, and thermally activated delayed fluorescence (TADF) is expressed. Furthermore, FIG. 5 in the document describes the mechanism of delayed fluorescence generation. The emission of delayed fluorescence can be confirmed by transient PL (Photo Luminescence) measurement.

Heat activated delayed fluorescent materials are also commonly referred to as TADF materials. The heat-activated delayed fluorescence material may be a material that exhibits heat-activated delayed fluorescence with a single material, or may be a material that exhibits heat-activated delayed fluorescence with a plurality of materials. When the material is composed of a plurality of materials, it may be used as a mixture, or layers composed of the respective materials may be laminated and used. A known material can be used as the heat-activated delayed fluorescent material. Specific examples thereof include a benzonitrile derivative, a triazine derivative, a disulfoxide derivative, a carbazole derivative, an indolocarbazole derivative, a dihydrophenazine derivative, a thiazole derivative, and an oxadiazole derivative, but are not limited to these. Absent.

In the device 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, whereby high emission efficiency and long device life can be achieved.

The light emitting layer is preferably a plurality of layers including an intermediate layer from the viewpoint of light emitting efficiency, durability and driving stability of the light emitting element. When the light emitting layer has a plurality of layers, it preferably has a first light emitting layer and a second light emitting layer, and particularly preferably has a third light emitting layer.

When the light emitting layer has a first light emitting layer and a second light emitting layer, a layer containing an oligopyridine compound represented by the general formula (1) and a rare earth metal dopant is provided between the first light emitting layer and the second light emitting layer. Is preferably configured.

When the light emitting layer further has a third light emitting layer, a layer containing an oligopyridine compound represented by the general formula (1) and a rare earth metal dopant is provided between the first light emitting layer and the second light emitting layer, and the second light emitting layer. It is preferably formed between the layer and the third light emitting layer.

Further, since the blue light emitting layer uses a large amount of energy for light emission, the light emitting efficiency and durability are lower than those of the red or green light emitting layer. Therefore, when the blue light emitting layer has a plurality of layers, low light emitting efficiency and durability can be improved, which is more preferable.

Specifically, when the light emitting layer has a first light emitting layer and a second light emitting layer, it is preferable that both of them are blue light emitting layers. When the light emitting layer further has a third light emitting layer, it is preferable that all of the first light emitting layer, the second light emitting layer, and the third light emitting layer are blue light emitting layers.

(Electron transport layer)
In the present invention, the electron transport layer is a layer in which electrons are injected from the cathode and further transports the electrons. The electron transport layer has high electron injection efficiency, and it is desired to efficiently transport the injected electrons. Therefore, the electron transport layer is required to be a substance having a high electron affinity, a high electron mobility, excellent stability, and a substance that does not easily generate impurities serving as traps during manufacturing and use. In particular, when a film having a large film thickness is stacked, a compound having a molecular weight of 400 or more that maintains stable film quality is preferable because a compound having a low molecular weight is likely to be crystallized and the film quality is deteriorated. However, considering the transport balance of holes and electrons, if the electron transport layer mainly plays a role of efficiently preventing holes from the anode from flowing to the cathode without recombination, the electron transport layer Even if the material is not so high in efficiency, the effect of improving the light emission efficiency is the same as that of the material having a high electron transporting capacity. Therefore, the electron-transporting layer in the present invention also includes a hole-blocking layer that can effectively block the movement of holes as a synonym, and the hole-blocking layer and the electron-transporting layer may be used alone or in combination of a plurality of materials. It may be configured.

Examples of the electron transport material used in the electron transport layer include condensed polycyclic aromatic derivatives such as naphthalene and anthracene, styryl aromatic ring derivatives represented by 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 compound having a heteroaryl ring structure containing an electron-accepting nitrogen, which is composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus because driving voltage is reduced and highly efficient light emission can be obtained. Is preferably used.

The electron-accepting nitrogen as used herein refers to a nitrogen atom forming a multiple bond with an adjacent atom. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron-accepting property. Therefore, an aromatic heterocycle containing an electron-accepting nitrogen has a high electron affinity. The electron transporting material having electron-accepting nitrogen makes it easy to receive electrons from the cathode having a high electron affinity, and can be driven at a lower voltage. In addition, since the number of electrons supplied to the light emitting layer increases and the recombination probability increases, the light emission efficiency improves.

Examples of the heteroaryl ring containing an 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, Examples thereof include 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.

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. Preferred compounds include derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoquinoline derivatives, oligopyridine derivatives such as bipyridine and terpyridine, quinoxaline derivatives and naphthyridine derivatives. Among them, 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-phenanthroline-9-yl)benzene, 2,2′ A benzoquinoline derivative 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) A naphthyridine derivative such as -4-(1,8-naphthyridin-2-yl)phenylphosphine oxide is preferably used from the viewpoint of electron transporting ability.

Further, it is more preferable that these derivatives have a condensed polycyclic aromatic skeleton, because the glass transition temperature is improved, the electron mobility is increased, and the effect of lowering the voltage of the light emitting device is large. Furthermore, considering that the device durability life is improved, easiness of synthesis and availability of raw materials are taken into consideration, the condensed polycyclic aromatic skeleton is more preferably a fluoranthene skeleton, anthracene skeleton, pyrene skeleton or phenanthroline skeleton A fluoranthene skeleton or a phenanthroline skeleton is particularly preferable.

The preferable electron transport material is not particularly limited, but specific examples include the following.

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 of the other electron transporting materials may be mixed and used with the electron transporting material. Absent. Moreover, you may contain a donor compound. Here, the donor compound is a compound that facilitates electron injection from the cathode or the electron injection layer to the electron transport layer by improving the electron injection barrier, and further improves the electric conductivity of the electron transport layer.

Preferred examples of the donor compound are alkali metals, inorganic salts containing alkali metals, complexes of alkali metals and organic substances, alkaline earth metals, inorganic salts containing alkaline earth metals or alkaline earth metals and organic substances. And the like. Preferable types of alkali metals and alkaline earth metals include alkali metals such as lithium, sodium, potassium, rubidium and cesium, which have a low work function and a large effect of improving electron transport ability, and alkaline earth metals such as magnesium, calcium, cerium and barium. Examples include metals.

In addition, since it is easy to deposit in a vacuum and is easy to handle, it is preferably in a state of an inorganic salt or a complex with an organic substance rather than a simple metal. Furthermore, in terms of facilitating handling in the air and controlling the concentration of addition, it is more preferable that the complex is in the state of a complex with an organic substance. Examples of the inorganic salt include oxides such as LiO and Li ₂ O, nitrides, fluorides such as LiF, NaF and KF, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ and Rb ₂ CO ₃ , Examples thereof include carbonates such as Cs ₂ CO ₃ . Further, preferable examples of the alkali metal or the alkaline earth metal include lithium and cesium from the viewpoint that a large low-voltage driving effect can be obtained. Further, preferable examples of the organic substance in the complex with the organic substance include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, hydroxytriazole and the like. Among them, a complex of an alkali metal and an organic substance is preferable from the viewpoint that the effect of lowering the voltage of the light emitting device is greater, and further, a complex of lithium and an organic substance is more preferable from the viewpoint of ease of synthesis and thermal stability, and a comparison Particularly preferred is lithium quinolinol (Liq), which is available at a relatively low cost.

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 for forming each of the layers constituting the light-emitting device is not particularly limited, such as resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, coating method, etc., but usually resistance heating vapor deposition or electron beam vapor deposition from the viewpoint of device characteristics. preferable.

(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 injecting layer is inserted for the purpose of helping injection of electrons from the cathode to the electron transporting layer, but in the case of inserting, a compound having a heteroaryl ring structure containing an electron-accepting nitrogen may be used. Alternatively, a layer containing the above-mentioned donor material may be used.

In addition, an inorganic substance such as an insulator or a semiconductor can be used for the electron injection layer. It is preferable to use these materials because short-circuiting of the light emitting element can be prevented and the electron injection property can be improved.

As such an insulator, it is preferable to use at least one metal compound selected from the group consisting of an alkali metal chalcogenide, an alkaline earth metal chalcogenide, an alkali metal halide and an alkaline earth metal halide.

Specifically, preferable alkali metal chalcogenides include, for example, Li ₂ O, Na ₂ S and Na ₂ Se, and preferable alkaline earth metal chalcogenides include, for example, CaO, BaO, SrO, BeO, BaS and CaSe. Is mentioned. Examples of preferable alkali metal halides include LiF, NaF, KF, LiCl, KCl and NaCl. In addition, examples of preferable alkaline earth metal halides include fluorides such as CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ and BeF ₂ and halides other than fluorides.

Further, a complex of an organic substance and a metal is also suitably used. It is preferable to use a complex of an organic substance and a metal for the electron injection layer because the film thickness can be easily adjusted. Preferred examples of the organic substance in such an organometallic complex include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, hydroxytriazole and the like.

A layer containing the oligopyridine compound represented by the general formula (1) and a rare earth metal dopant is also preferable because it has a high electron injection property and exhibits excellent properties as an electron injection layer.

(Charge generation layer)
The charge generation layer in the present invention is generally composed of a double layer, and specifically, it can be used as a pn junction charge generation layer composed of an n-type charge generation layer and a p-type charge generation layer. The pn junction type charge generation layer generates a charge by applying a voltage in the light emitting device or separates the charge into holes and electrons, and these holes and electrons are separated into a hole transport layer and an electron transport layer. It is then injected into the light emitting layer. Specifically, it functions as a charge generation layer as an intermediate layer in a light emitting device in which light emitting layers are stacked. The n-type charge generation layer supplies electrons to the first light-emitting layer on the anode side, and the p-type charge generation layer supplies holes to the second light-emitting layer on the cathode side. Therefore, it is possible to improve the light emission efficiency of the light emitting element in which a plurality of light emitting layers are laminated, reduce the driving voltage, and improve the durability of the element.

The n-type charge generation layer is composed of an n-type dopant and a host, and conventional materials can be used for these. For example, an alkali metal, alkaline earth metal, or rare earth metal can be used as the n-type dopant. Moreover, a triazine derivative, a phenanthroline derivative, and an oligopyridine derivative can be used as the host. In particular, the layer containing the oligopyridine compound represented by the general formula (1) and the rare earth metal dopant is preferable because it exhibits excellent properties as the n-type charge generation layer.

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, as p-type dopants, tetrafluore-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), tetracyanoquinodimethane derivative, radialene derivative, iodine, FeCl ₃ , FeF ₃ , and SbCl ₅ or the like can be used. The p-type dopant is preferably a radialene derivative. The host is preferably an arylamine derivative.

The thickness of the organic layer cannot be limited because it depends on the resistance value of the light emitting substance, but is preferably 1 to 1000 nm. The thickness of each of the light emitting layer, the electron transporting layer and the hole transporting layer is preferably 1 nm or more and 200 nm or less, and more preferably 5 nm or more and 100 nm or less.

The light emitting element according to the embodiment of the present invention has a function of converting electric energy into light. Here, a direct current is mainly used as the electric energy, but a pulse current or an alternating current can also be used. The current value and voltage value are not particularly limited, but considering the power consumption and life of the device, they should be selected so that the maximum brightness can be obtained with the lowest possible energy.

The light emitting element according to the embodiment of the present invention is preferably used as a display device such as a display that displays in a matrix and/or segment system.

The light emitting element according to the embodiment of the present invention is also preferably used as a backlight for various devices. The backlight is mainly used for the purpose of improving the visibility of a display device such as a display that does not emit light, and is used for a liquid crystal display, a clock, an audio device, an automobile panel, a display board, a sign, and the like. In particular, the light emitting device of the present invention is preferably used for a liquid crystal display, especially a backlight for a personal computer whose thinning is being considered, and can provide a thinner and lighter backlight than a conventional one.

The light emitting element according to the embodiment of the present invention is preferably used as various lighting devices. The light-emitting device according to the embodiment of the present invention can achieve both high luminous efficiency and high color purity, and further, because it can be thin and lightweight, low power consumption and vivid emission color, It is possible to realize a lighting device that also has high design characteristics.

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

Example 1
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω/□, sputtered product) on which an ITO transparent conductive film was deposited to a thickness of 125 nm was cut into 38×46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing an element, placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5×10 ⁻⁴ Pa or less. Compound 1 and a metal element Yb as a dopant were vapor-deposited by a resistance heating method at a vapor deposition rate ratio of compound 1:Yb=9:1 to 100 nm to form a layer having a concentration ratio of 9:1. After that, aluminum was vapor-deposited to a thickness of 60 nm to form a cathode, and a 5×5 mm square device was produced. The film thickness referred to here is a crystal oscillation type film thickness monitor display value.

When this element was driven by direct current at 10 mA/cm ² , the driving voltage was 0.041V. When the voltage increase was measured at a current density of 10 mA/cm ² and 70° C. for 100 hours, the voltage increase after 100 hours was 0.002V.

Examples 2-10, Comparative Examples 1-25
A device was produced in the same manner as in Example 1 except that the compounds and metal elements used and the vapor deposition rate ratio thereof were changed as shown in Table 1. The results of each Example and Comparative Example are shown in Table 1. Compounds 2 to 18 are the compounds shown below.

Example 11
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω/□, sputtered product) on which an ITO transparent conductive film was deposited at 165 nm was cut into 38×46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing an element, placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5×10 ⁻⁴ Pa or less. By the resistance heating method, first as a hole injection layer, the HAT-CN ₆ to 5nm deposited, then a hole transport layer was 50nm deposited HT-1. Next, as a light emitting layer, a mixed layer of a host material H-1 and a dopant material D-1 was vapor-deposited with a thickness of 20 nm so that the doping concentration was 5% by weight. Next, as the electron transport layer, ET-1 and 2E-1 were vapor-deposited at a vapor deposition rate ratio of ET-1 and 2E-1=1:1 to a thickness of 35 nm. Next, as the electron injection layer, the compound 1 and the metal element Yb as the dopant were vapor-deposited with a vapor deposition rate ratio of compound 1:Yb=9:1 to a thickness of 10 nm. Then, 60 nm of aluminum was vapor-deposited to form a cathode, and a 5×5 mm square light emitting device was produced. The film thickness referred to here is a value displayed by a crystal oscillation type film thickness monitor, and is common to other examples and comparative examples.

When the light emitting device was turned on at a brightness of 1000 cd/m ² , the characteristics were a drive voltage of 4.11 V and an external quantum efficiency of 5.63%. Further, when continuously driven at a constant current of 10 mA/cm ² , the time (durability) when the brightness was reduced by 20% from the initial brightness was 1020 hours. Further, when the elapsed voltage increase at the time of constant current driving of 10 mA/cm ² was measured, the voltage increase after 100 hours was 0.001V. Note _{HAT-CN 6, HT-1} , H-1, D-1, ET-1 is a compound shown below.

Examples 12-20, Comparative Examples 26-50
A device was produced in the same manner as in Example 11 except that the compounds and metal elements used and the vapor deposition rate ratios thereof were changed as shown in Table 1. The results of each Example and Comparative Example are shown in Table 2.

Examples 1 to 10 show the results of the single charge devices containing the compound represented by the general formula (1) and Yb which is a rare earth metal element, and Comparative Examples 1 to 7 show Li which is an alkali metal element instead of Yb. The result of the element containing is shown. As can be understood from these results, it is understood that the compound represented by the general formula (1) is used together with the rare earth metal element to form a stable layer with a smaller increase in driving voltage. On the other hand, as shown in Comparative Examples 8 to 25, even if the compounds 8 to 18 were used together with the alkali metal element Li and the rare earth metal element Yb, the same effect was not obtained. This is because the compounds 8 to 18 have insufficient interaction such as coordination with an alkali metal element or a rare earth metal element, the electron transportability is low due to diffusion of the metal element in the layer, and the voltage rises during driving. Is understood to have occurred.

In addition, in Examples 11 to 20, the results of applying the organic layer used in Examples 1 to 10 to the light emitting element are shown. As compared with the results of Examples 11 to 20, the elements of Comparative Examples 26 to 32 using Li exhibited a decrease in durability and an increase in driving voltage. This indicates that the compound represented by the general formula (1) forms a stable layer only when used in combination with a rare earth metal element, similar to the results of the single charge devices in Examples 1 to 10. Also in Comparative Examples 33 to 50, when Compounds 8 to 18 were used, the durability was decreased and the driving voltage was increased.

Claims (15)

A device which has at least one organic layer between an anode and a cathode and emits light by electric energy, wherein one layer of the organic layer comprises an oligopyridine compound represented by the following general formula (1) and a rare earth metal element. A light-emitting device containing and.

(In the general formula (1), n is an integer of 1 or 2, and m is an integer of 0 to 2. However, n+m≧2. When n is 2, m contained in each is L ¹ , L ² and L ³ are a single bond or a substituted or unsubstituted arylene group, and A is a substituted or unsubstituted monocyclic aromatic group having 6 to 40 carbon atoms. Hydrocarbon group, substituted or unsubstituted condensed aromatic hydrocarbon group having 6 to 40 carbon atoms, substituted or unsubstituted monocyclic aromatic hetero group having 1 to 40 carbon atoms, substituted or unsubstituted having 1 to 40 carbon atoms Represents a condensed aromatic hetero group or a substituted or unsubstituted aromatic amino group having 6 to 40 carbon atoms.) The light emitting device according to claim 1, wherein n is 2 in the general formula (1). The light emitting device according to claim 1, wherein m is 0 in the general formula (1). The light emitting device according to claim 1, wherein L ² in the general formula (1) is a single bond. The light emitting device according to claim 1, wherein the general formula (1) is an oligopyridine compound represented by the following general formula (2).

(In the general formula (2), any one of X ^{1 to} X ³ is a nitrogen atom and the other are carbon atoms. L ¹ and A are the same as those in the general formula (1). ) The light emitting device according to claim 5, wherein in the general formula (2), X ³ is a nitrogen atom and the others are carbon atoms. The light emitting device according to claim 1, wherein A has a fluoranthene structure in the general formula (1). The light emitting device according to claim 1, wherein A in the general formula (1) is an aromatic amino group. The light emitting device according to claim 1, wherein the rare earth metal element is any one of Sm, Eu, and Yb. The organic layer has a first light emitting layer and a second light emitting layer, and a layer containing the oligopyridine compound represented by the general formula (1) and a rare earth metal element is the first light emitting layer and the second light emitting layer. The light emitting device according to claim 1, which is configured between the light emitting device and the light emitting device. The light emitting device further has a third light emitting layer, and a layer containing the oligopyridine compound represented by the general formula (1) and a rare earth metal element is provided between the first light emitting layer and the second light emitting layer, and The light emitting device according to claim 10, which is configured between the second light emitting layer and the third light emitting layer. The light emitting device according to claim 10, wherein both the first light emitting layer and the second light emitting layer are blue light emitting layers. The light emitting device according to claim 1, wherein the organic layer is a charge generation layer. A display device comprising the light emitting device according to claim 1. A lighting device comprising the light emitting element according to claim 1.