TW201308710A - Light emitting element - Google Patents

Abstract

An organic thin film light emitting element which improves light emitting efficiency, driving voltages, and endurance life is provided. The light emitting element of the disclosure is characterized in that a hole transport layer contains a compound having a triphenylene skeleton, and an electron transport layer contains a compound having a donor compound or an acceptor compound is used in a hole injection layer.

Description

Light-emitting element

The present invention relates to a light-emitting element capable of converting electrical energy into light. More particularly, the present invention relates to light-emitting elements that can be used in the fields of display elements, flat panel displays, backlights, illumination, interiors, signage, billboards, electronic cameras, and optical signal generators.

In recent years, an active research has been actively conducted on an organic thin film light-emitting element that emits light when electrons injected from a cathode and a hole injected from an anode are recombined in an organic fluorescent body sandwiched between two electrodes. The light-emitting element is characterized by high-brightness light emission at a thin and low driving voltage, and multi-color light emission by selecting a fluorescent material. Since the high-intensity luminescence of organic thin film elements has been pointed out by Kodak's C.W. Tang et al., the above research has been studied by a number of research institutions.

Then, as a result of a lot of practical research, the organic thin film light-emitting device has been put into practical use, for example, in a main display of a mobile phone or the like. However, there are still many technical problems, and the combination of low voltage driving and long life of components is a major issue.

The driving voltage of the element is largely governed by the carrier transport material which transports the so-called hole or electron carrier to the luminescent layer. There is disclosed a technique of using a material having a triphenylene skeleton as a hole transporting material (see, for example, Patent Document 1 to Patent Document 3).

In addition, as one of the techniques for reducing the voltage of components, electron injection From the viewpoint of transmission, a technique of doping a donor compound into a material used as an electron transport layer has been disclosed (for example, refer to Patent Document 4 to Patent Document 6). Further, from the viewpoint of hole injection and transport, a technique of doping an acceptor compound into a hole transport material has been disclosed (for example, Patent Document 7 and Patent Document 8).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 11-251063

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-259472

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2009-292760

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2003-347060

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2002-352961

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2004-2297

[Patent Document 7] Japanese Patent Laid-Open Publication No. 2010-100621

[Patent Document 8] International Publication No. 2010/132236

However, in the prior art, a light-emitting element which is low-voltage-driven, has high luminous efficiency, and is excellent in endurance life has not been found. For example, the previously known hole transporting material or electron transporting material is excellent in the performance as a light-emitting element in the case of being used in combination, even if it is excellent in its own hole transporting property or electron transporting property.

According to the study by the inventors of the present invention, the technique of doping the donor compound into the electron transport layer, which is known from Patent Documents 4 to 6, exhibits an effect of lowering the driving voltage, but causes The luminous efficiency is lowered and the endurance life is lowered. The inventor speculated that the reason As described below. The electron transport layer doped with an alkali metal is improved in conductivity, and when it is used for the electron transport layer, the electron injectability from the cathode is improved, and the electron transport property is also excellent. However, it is considered that due to the high performance, the amount of electrons in the light-emitting layer is excessive depending on the type of the hole transporting material to be used in combination, and as a result, the above-described problems occur.

On the other hand, according to the study by the inventors of the present invention, the technique of doping the acceptor compound into the hole transport layer as known from Patent Document 7 and Patent Document 8 exhibits an effect of lowering the driving voltage. However, depending on the doped hole transport material, a large endurance life improvement effect cannot be obtained. The inventors speculated that the reason is as follows. In the driving, the individual or doped acceptor compound diffuses in the hole transport layer, causing the hole conductivity of the hole transport layer to change slowly during driving. Therefore, it is considered that the carrier balance from the pre-drive is gradually shifted, causing a decrease in luminous efficiency, that is, deterioration.

An object of the present invention is to solve the above problems of the prior art and to provide an organic thin film light-emitting element which all improves luminous efficiency, driving voltage, and durability.

The present invention has been studied as a result of a balance between the mobility of electrons and holes in a light-emitting element, and has been found to be an optimum combination of a material contained in a hole transport layer and an electron transport layer. In addition, an optimum hole transport material for preventing diffusion of an acceptor compound doped in the hole transport layer in driving has been found.

That is, a configuration of the present invention is a light-emitting element including at least a hole transport layer and an electron transport layer between an anode and a cathode, and by electrical energy The light-emitting element is characterized in that the hole transport layer contains a compound represented by the following formula (1), and the electron transport layer contains an alkali metal, an alkali metal-containing inorganic salt, an alkali metal, and A donor compound in a group consisting of a complex of an organic compound, an alkaline earth metal, an inorganic salt containing an alkaline earth metal, or a complex of an alkaline earth metal and an organic compound.

In the formula (1), R ¹ to R ¹² may be the same or different and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, amine, aryl, heterocyclic, alkenyl, cycloalkenyl, alkynyl, A group consisting of an alkoxy group, an alkylthio group, an aryl ether group, an aryl sulfide group, a halogen, a cyano group, -P(=O)R ¹³ R ¹⁴ and a decyl group. R ¹³ and R ¹⁴ may be the same or different and each may be an aryl group or a heteroaryl group. The substituents may be further substituted, and the adjacent substituents may further form a ring with each other. Among them, n of R ¹ to R ¹² is an amine group represented by -NR ¹⁵ R ¹⁶ . R ¹⁵ and R ¹⁶ may be the same or different and are selected from the group consisting of alkyl groups, cycloalkyl groups, aryl groups and heteroaryl groups. n represents an integer from 1 to 6.

Further, another configuration of the present invention is a light-emitting element including at least a hole transport layer and a hole injection layer between an anode and a cathode, and emitting light by electrical energy, the light-emitting element being characterized by: said hole transmission Floor The compound represented by the above formula (1) is contained, and the hole injection layer is composed of an acceptor compound alone or an acceptor compound.

The light-emitting element of the present invention can not only perform low-voltage driving, but also exhibits an effect of improving luminous efficiency and durability.

<Light-emitting element of the first configuration>

The light-emitting element of the first aspect of the present invention is characterized in that a compound having a specific structure is used in each of the hole transport layer and the electron transport layer.

First, the compound represented by the formula (1) will be described in detail. The hole transport layer of the light-emitting element of the present invention contains the compound represented by the formula (1).

In the formula (1), R ¹ to R ¹² may be the same or different and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, amine, aryl, heterocyclic, alkenyl, cycloalkenyl, alkynyl, A group consisting of an alkoxy group, an alkylthio group, an aryl ether group, an aryl sulfide group, a halogen, a cyano group, -P(=O)R ¹³ R ¹⁴ and a decyl group. R ¹³ and R ¹⁴ may be the same or different and each may be an aryl group or a heteroaryl group. The substituents may be further substituted, and the adjacent substituents may further form a ring with each other. Among them, n of R ¹ to R ¹² is an amine group represented by -NR ¹⁵ R ¹⁶ . R ¹⁵ and R ¹⁶ may be the same or different and are selected from the group consisting of alkyl groups, cycloalkyl groups, aryl groups and heteroaryl groups. n represents an integer from 1 to 6.

The hydrogen in the substituents may be hydrazine. The alkyl group means, for example, a saturated aliphatic hydrocarbon group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl or t-butyl, which may have a substituent or may have no substitution. base. The substituent to be added in the case of the substitution is not particularly limited, and examples thereof include an alkyl group and an aryl group. This aspect is also common to the following description. In addition, the number of carbon atoms of the alkyl group is not particularly limited, and is usually in the range of 1 or more and 20 or less, and more preferably in the range of 1 or more and 8 or less, from the viewpoint of easiness of obtaining raw materials or cost. Further, when the carbon number of the alkyl group is large, there is a concern that the hole transport property is inhibited. Therefore, a methyl group or an ethyl group is particularly preferable.

The cycloalkyl group means, for example, a saturated alicyclic hydrocarbon group such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group or an adamantyl group, which may or may not have a substituent. The carbon number of the alkyl moiety is not particularly limited, and is usually in the range of 3 or more and 20 or less. Further, when the carbon number is large, there is a concern that the hole transport property is inhibited, and therefore it is more preferably a cyclopropyl group, a cyclopentyl group or a cyclohexyl group.

The amine group may have a substituent or may have no substituent, and examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group and the like, and the substituents may be further substituted.

The aryl group means, for example, phenyl, naphthyl, biphenyl, phenanthryl, fluorenyl, An aromatic hydrocarbon group such as anthracenyl, pyrenyl or terphenyl. The aryl group may further have a substituent or may have no substituent. The substituent to be added in the case of substitution is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, a heteroaryl group, an alkoxy group, and an amine group. The carbon number of the aryl group is not particularly limited, but is usually in the range of 6 to 40.

The heterocyclic group means, for example, a cyclic aliphatic group having an atom other than carbon in a ring such as pyranyl, piperidinyl or cyclic amido, and a furyl group ( Furanyl), thiophenyl, pyridyl, quinolinyl, pyrazinyl, naphthyridyl, benzofuranyl, benzothiophenyl a cyclic aromatic having one or more atoms other than carbon in one or more rings, such as indolyl, dibenzofuranyl, dibenzothiophenyl, or carazolyl A (heteroaryl) group which may be unsubstituted or substituted. Among the heterocyclic groups, a heteroaryl group is preferred. The substituent to be added in the case of substitution is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, and an amine group. The carbon number of the heterocyclic group is not particularly limited, but is usually in the range of 2 to 30.

The alkenyl group means, for example, an unsaturated aliphatic hydrocarbon group containing a double bond such as a vinyl group, an allyl group or a butadienyl group, and may have a substituent or may have no substituent. The carbon number of the alkenyl group is not particularly limited, but is usually in the range of 2 to 20.

The cycloalkenyl group means, for example, an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group or a cyclohexenyl group, which may have a substitution. The base may or may not have a substituent.

The alkynyl group is, for example, an unsaturated aliphatic hydrocarbon group containing a triple bond such as ethynyl, which may have a substituent or may have no substituent. The carbon number of the alkynyl group is not particularly limited, but is usually in the range of 2 to 20.

The alkoxy group is, for example, a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond such as a methoxy group, an ethoxy group or a propoxy group, and the aliphatic hydrocarbon group may have a substituent or may have no substituent. The carbon number of the alkoxy group is not particularly limited, and is usually in the range of 1 or more and 20 or less. Further, when the carbon number of the alkoxy group is large, there is a concern that the hole transport property is inhibited, and therefore, a methoxy group or an ethoxy group is more preferable.

The alkylthio group means a group in which an oxygen atom of an ether bond of an alkoxy group is substituted with a sulfur atom. The alkylthio group may have a substituent or may have no substituent. The carbon number of the alkylthio group is not particularly limited, but is usually in the range of 1 or more and 20 or less.

The aryl ether group may, for example, be a functional group such as a phenoxy group which has an aromatic hydrocarbon group bonded via an ether bond, and the aromatic hydrocarbon group may have a substituent or may have no substituent. The carbon number of the aryl ether group is not particularly limited, and is usually in the range of 6 or more and 40 or less.

The arylthioether group means a group in which an oxygen atom of an ether bond of an aryl ether group is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may have a substituent or may have no substituent. The carbon number of the aryl ether group is not particularly limited, and is usually in the range of 6 or more and 40 or less.

The halogen means fluorine, chlorine, bromine or iodine.

In the substituent -P(=O)R ¹³ R ¹⁴ , R ¹³ and R ¹⁴ are an aryl group or a heteroaryl group, and the substituent -P(=O)R ¹³ R ¹⁴ has an aryl group or a heteroaryl group having the above The same meaning.

The decyl group is, for example, a functional group having a bond with a ruthenium atom such as a trimethylsulfanyl group, and may have a substituent or may have no substituent. The carbon number of the decyl group is not particularly limited, but is usually in the range of 3 to 20. In addition, the number of turns is usually 1 to 6.

The term "adjacent substituents" form a ring to each other means that any two adjacent substituents (for example, R ¹ and R ^{2 of the} formula (1)) are bonded to each other to form a conjugated or non-conjugated condensed ring. The constituent elements of the condensed ring may contain nitrogen, oxygen, sulfur, phosphorus, or ruthenium atoms in addition to carbon, and may be condensed with other rings.

Preferred examples of R ¹ to R ¹² are hydrogen, an alkyl group, an amine group, an alkoxy group, an aryl group, in view of vapor deposition stability (thermal stability) of the material, synthesis cost, and ease of raw material acquisition. Or a heteroaryl group. More preferably, it is hydrogen, an amine group, an aryl group or a heteroaryl group. In the case where a preferred example of R ¹ to R ¹² is an aryl group or a heteroaryl group, an aryl group having a carbon number of 6 to 18 or preferably is considered in consideration of evaporating stability (thermal stability) of the material. Heteroaryl, specifically: phenyl, naphthyl, biphenyl, anthracenyl, fluorenyl, phenanthryl, anthracenyl, dibenzofuranyl, dibenzothiophenyl, oxazolyl. These groups may have more substituents.

In the formula (1), n of R ¹ to R ¹² is an amine group represented by -NR ¹⁵ R ¹⁶ , and R ¹⁵ and R ^{16 are} preferably an alkyl group in consideration of the synthesis cost and the ease of obtaining the raw material. , aryl or heteroaryl. Among them, an aryl group or a heteroaryl group is preferred in view of vapor deposition stability (thermal stability) or stability of an amorphous film (having a high glass transition temperature) or good hole transport characteristics. Specifically, an aryl group or a heteroaryl group having 6 to 20 carbon atoms is preferred, and examples thereof include a phenyl group, a naphthyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a fluorenyl group, a phenanthryl group, and a fluorenyl group. As a preferred specific example, a phenylene group, a dibenzofuranyl group, a dibenzothiophenyl group, an oxazolyl group and the like are exemplified. These groups may have more substituents. Among these groups, a good amorphous film stability (high glass transition temperature) is obtained, and the device can be made longer in life, and the energy gap (the highest occupied molecular orbital - the lowest unoccupied portion) The difference in energy of the noble occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) is narrowed and there is a concern that the exciton energy of the light-emitting layer is deactivated, so that it is more preferably a phenyl group, a naphthyl group or a biphenyl group. , triphenylene, fluorenyl, phenanthryl, bis-phenylene.

In the formula (1), the number n of the substituent -NR ¹⁵ R ¹⁶ represents an integer of 1 to 6, and in consideration of vapor deposition stability (thermal stability), n is preferably 1 to 3, and further suitable The free potential is more preferably 2 or 3 from the viewpoint that the hole is more easily injected. In the case of n=1, it is preferable that R ¹ is -NR ¹⁵ R ^{16 in} consideration of easiness of synthesis. In the case of n=2, it is preferable that R ¹ and R ⁶ , R ² and R ⁵ , or R ³ and R ¹² are -NR ¹⁵ R ^{16 in} consideration of ease of synthesis; More preferably, R ¹ and R ⁶ are -NR ¹⁵ R ¹⁶ from the viewpoint of free potential. Further, in the case of n = 3, it is preferable that R ¹ , R ⁵ and R ⁹ or R ¹ , R ⁶ and R ⁹ are -NR ¹⁵ R ^{16 in} consideration of ease of synthesis; More preferably, R ¹ , R ⁶ and R ⁹ are -NR ¹⁵ R ¹⁶ from the viewpoint of the free potential. In the case of n=4, R ¹ , R ² , R ⁵ and R ⁶ , or R ¹ , R ⁶ , R ⁸ and R ¹¹ , or R ² , R are preferred in view of ease of synthesis. ⁵ , R ⁸ and R ¹¹ are -NR ¹⁵ R ¹⁶ ; Further, from the viewpoint of having a suitable free potential, it is more preferred that R ¹ , R ⁶ , R ⁸ and R ¹¹ are -NR ¹⁵ R ¹⁶ .

The compound represented by the formula (1) as described above is not particularly limited, and specific examples thereof include the following compounds.

The compound represented by the formula (1) can be synthesized by a combination of known methods. The synthesis example of the diamine group type of n=2 is shown below.

Further, as a synthesis method of a monoamine group type of n = 1, for example, a commercially available bromotriphenylene can be easily coupled with a desired diarylamine by using a palladium catalyst. synthesis. Further, the synthesis method is not limited to the methods.

The electron transport layer in the light-emitting device of the first aspect of the present invention contains a donor compound. The electron transport layer containing the donor compound has an increased carrier density and an improved electron conductivity in the electron transport layer as compared with the electron transport layer containing no such donor compound. Therefore, it is considered that when combined with the previous hole transporting material, electrons are excessive in the light-emitting layer, and as a result, the light-emitting efficiency is lowered and the durability life is lowered. However, when the electron transport layer containing the donor compound is combined with the hole transport layer containing the compound represented by the general formula (1), it is found that not only the low voltage is driven but also the hair is obtained. Improved light efficiency and improved durability. The reason is considered to be that the hole transporting material represented by the general formula (1) has large hole mobility and good hole injection characteristics as compared with, for example, the previously known arylamine-based hole transporting material. When combined with an electron transport layer containing a donor compound, electron excess in the light-emitting layer is eliminated, and electrons can be prevented from being injected into the hole transport layer.

The donor compound in the present invention refers to a compound which facilitates injection of electrons from a cathode or an electron injection layer into an electron transport layer by improving the electron injection barrier, thereby improving conductivity of the electron transport layer. .

Preferable examples of the donor compound in the present invention include an alkali metal, an alkali metal-containing inorganic salt, an alkali metal-organic complex, an alkaline earth metal, an alkaline earth metal-containing inorganic salt or an alkaline earth metal and an organic substance. Compounds, etc. Preferred examples of the alkali metal and the alkaline earth metal include alkali metals such as lithium, sodium, potassium, rubidium, and cesium having a low work function and high electron transporting ability, or alkaline earth metals such as magnesium, calcium, barium, and strontium.

Further, since the donor compound contained in the electron transport layer is easily vapor-deposited in a vacuum and excellent in handleability, it is preferably a state of an inorganic salt or a complex with an organic compound than a metal monomer. Further, in terms of facilitating the operation in the atmosphere and facilitating the control of the concentration, it is more preferable to be in a state of being in 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 , Rb ₂ CO ₃ , and Cs _{2 .} Carbonate such as CO ₃ or the like. Further, from the viewpoint of obtaining a large low-voltage driving effect, examples of the alkali metal or alkaline earth metal include lithium and ruthenium. Further, preferred examples of the organic substance in the case where the donor compound is an alkali metal or a complex of an alkaline earth metal and an organic substance include quinoline alcohol, benzoquinolinol, pyridylphenol, flavonol, and hydroxyimidazole. And pyridine, hydroxybenzoxazole, hydroxytriazole and the like. In view of the fact that the effect of lowering the voltage of the light-emitting element is greater, it is preferably a complex of an alkali metal and an organic substance, and further preferably lithium and from the viewpoint of easiness of synthesis and thermal stability. A complex of an organic compound is particularly preferred as lithium quinolate which can be obtained at a relatively low price. Further, the electron transport layer may contain two or more kinds of donor compounds.

A suitable doping concentration varies depending on the film thickness of the material or the doped region, but for example, in the case where the donor compound is an alkali metal or alkaline earth metal inorganic material, it is preferably an electron transporting material and a donor compound. The vapor deposition rate is co-evaporated so as to be in the range of 10,000:1 to 2:1 to form an electron transport layer. The evaporation rate ratio is preferably 100:1 to 5:1, and more preferably 100:1 to 10:1. Further, when the donor compound is a complex of a metal and an organic compound, it is preferred that the ratio of the vapor deposition rate of the electron transporting material to the donor compound is in the range of 100:1 to 1:100. Evaporation to form an electron transport layer. The evaporation rate ratio is preferably from 10:1 to 1:10, more preferably from 7:3 to 3:7.

Next, an electron transporting material used in combination with a donor compound will be described. The electron transporting material to be used in combination with the donor compound is not particularly limited, and examples thereof include a compound having a skeleton in which a plurality of benzene rings are bonded, such as biphenyl, terphenyl, and triphenylbenzene, and a derivative thereof, and fluorene (fluorene) ), fluoranthene, benzofluoranthene, naphthalene (naphthalene), anthracene, phenanthrene, benzene, pyrene, etc., compounds having a condensed polycyclic aromatic skeleton and derivatives thereof, 4,4'-bis(diphenylvinyl) a styrene-based aromatic ring derivative represented by biphenyl, a perylene derivative, a perinone derivative, a coumarin derivative, and a naphthalimide derivative. Anthracene derivative such as anthraquinone or diphenoquinone, phosphorous oxide derivative, carbazole derivative and indole derivative, tris(8-hydroxyl) Alkaline metal such as quinoline (a) (tris(8-quinolinolato)aluminum (III)), quinoline complex other than alkaline earth metal, hydroxyzole complex such as hydroxyphenyl oxazole complex, azo A azomethine complex, a tropolone metal complex, and a flavonol metal complex. Since the driving voltage can be lowered, the electron transporting material preferably uses a compound having a heteroaryl ring structure containing an element selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, helium, and phosphorus, and containing electrons. Receptive nitrogen.

The electron-accepting nitrogen is a nitrogen atom which forms a multiple bond with an adjacent atom. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property and is excellent in electron transporting ability, and the driving voltage of the light emitting element can be lowered by the electron transporting layer. Therefore, a heteroaryl ring containing an electron-accepting nitrogen has high electron affinity. Examples of the heteroaryl ring containing an electron-accepting nitrogen include a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazine ring, and a quinoline ring. (quinoline ring), quinoxaline ring, acridine ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, brown A porine ring, an imidazole ring, an oxazole ring, an oxadiazole ring, a triazole ring, a thiazole ring, a thiadiazole ring , a benzooxazole ring, a benzothiazole ring, a benzimidazole ring, a phenanthroimidazole ring, and the like.

As the compound having such a heteroaryl ring structure, for example, the following compounds are preferred: a benzimidazole derivative, a benzoxazole derivative, a benzothiazole derivative, an oxadiazole derivative, and a thiadiazole. An azole derivative, a triazole derivative, a pyridine derivative, a pyrimidine derivative, a pyrazine derivative, a triazine derivative, a phenanthroline derivative, a quinoxaline derivative, a quinoline derivative, a benzoquinoline derivative, An oligopyridine derivative such as bipyridine or terpyridine, a quinoxaline derivative, a naphthyridine derivative, a phenanthroline derivative or the like. Among these derivatives, a benzimidazole derivative, a pyridine derivative, a bipyridine derivative, a triazine derivative, a quinoline derivative, a quinoxaline derivative, or a brown is more preferable if electrochemical stability is also considered. A porphyrin derivative, an oligopyridine derivative. Further, when the derivatives have a condensed polycyclic aromatic skeleton, not only the glass transition temperature is increased but also the electron mobility is increased, and the effect of lowering the voltage of the light-emitting element is larger, which is more preferable. Further, in consideration of improvement in durability of the element, easiness of synthesis, and easy acquisition of raw materials, the condensed polycyclic aromatic skeleton is particularly preferably an anthracene skeleton, a phenanthrene skeleton or an anthracene skeleton. Electronic transmission The transport material may be used singly or in combination of two or more kinds of the above-mentioned electron transport materials or one or more of other electron transport materials may be used in the above-mentioned electron transport material.

The electron transporting material used in combination with the donor compound is preferably a material containing electron accepting nitrogen as described above, and other materials containing no electron accepting nitrogen are added by adding a donor compound. It is also suitable to improve conductivity or electron injection transportability.

The electron transporting material used in combination with the above-described donor compound is not particularly limited, and specific examples thereof are as follows.

Further, the configuration of other layers of the light-emitting element will be described below.

<Light-emitting element of the second configuration>

Then, the light-emitting element of the second configuration of the present invention has the following features: A compound having a specific structure is used in the hole transport layer, and an acceptor compound is used in the hole injection layer.

The compound used in the hole transport layer is a compound represented by the above formula (1), and the detailed description thereof is the same as that of the light-emitting device of the first configuration. From the viewpoint of preventing the diffusion of the acceptor compound, a compound having a high glass transition temperature in an amorphous film state or a strong interaction with an acceptor compound is preferred, and R ¹⁵ of the formula (1) is preferred. At least one of R ¹⁶ is a polyphenyl group or a condensed aromatic hydrocarbon group. Here, the polyphenyl group means a substituent in which a plurality of benzene rings are bonded such as a biphenyl group or a biphenyl group. Preferred polyphenyl groups are a biphenyl group, a biphenyl group, and a biphenyl group. More preferably, it is a biphenyl group or a triphenyl group. Further, preferred examples of the condensed aromatic hydrocarbon group include an anthracenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a naphthalenyl group, a phenanthrenyl group, and a bis-phenylene group. Triphenylenyl), fluorenyl, benzoanthracenyl, sulfhydryl, chrysenyl, dibenzochrysenyl. Particularly preferred among them are anthracenyl, naphthyl, phenanthryl and phenylene.

Further, the hole injection layer in the light-emitting element of the second aspect of the present invention contains an acceptor compound. More specifically, the hole injection layer is composed of an acceptor compound alone, or the acceptor compound is doped with another hole injecting material or a compound represented by the formula (1). In the case of using a hole injection layer having an acceptor compound, although it is effective for low-voltage driving of the element, there is a case where an effect of improving a large endurance life cannot be obtained depending on the combined hole transport material. The reason is considered to be that the single or doped acceptor compound is also expanded in the hole transport layer during driving. The hole conductivity of the dispersion, hole injection layer or hole transport layer. However, when the compound represented by the formula (1) is used for the hole transport layer and the acceptor compound is present in the hole injection layer, it is found that the effect of obtaining low voltage driving and improving durability life is obtained. It is considered to be due to the following reasons. That is, it is considered that the compound represented by the general formula (1) has a higher glass transition temperature than the previous hole transport material, and has a large π electron plane at the center of the triazine ring, and thus with the acceptor compound The interaction is large and prevents the diffusion of the acceptor compound in the drive. Therefore, it is difficult to change the hole conductivity of the hole injection layer or the hole transport layer in the driving, and it is difficult to cause a decrease in luminous efficiency accompanying the carrier balance change.

The term "receptor compound" refers to a material which, when used as a single layer film, forms a charge transfer complex with a hole transport layer that is in contact with it, and is used for doping, and constitutes electricity. The material of the hole injection layer forms a charge transfer complex. When such a material is used, the conductivity of the hole injection layer is improved, and the driving voltage of the element is further lowered, and the luminous efficiency is improved and the durability life is improved.

Examples of the acceptor compound include metal chlorides such as iron (III) chloride, aluminum chloride, gallium chloride, indium chloride, and cesium chloride, such as molybdenum oxide, vanadium oxide, tungsten oxide, and oxidation. a metal oxide such as ruthenium, such as tris(4-bromophenyl) hexachloroantimonate A charge transfer complex such as tris(4-bromophenyl)aluminum hexachloroantimonate (TBPAH). Further, an organic compound having a nitro group, a cyano group, a halogen or a trifluoromethyl group in the molecule, an anthraquinone compound, an acid anhydride compound, a fullerene or the like is also suitably used. Specific examples of such compounds include hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane (TCNQ), Tetrafluorotetracyanoquinodimethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaaza Benzene (2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, HAT-CN6), p-fluoranil, p-fluoranil P-chloranil, p-bromanil, p-benzoquinone, 2,6-dichlorobenzoquinone, 2,5- 2,5-dichlorobenzoquinone, tetramethylbenzoquinone, 1,2,4,5-tetracyanobenzene, o-dicyanobenzene (o-dicyanobenzene), p-dicyanobenzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzene 2(2,3-dichloro-5,6-dicyanobenzoquinone), p-dinitrobenzene, m-dinitrobe Nzene), o-dinitrobenzene, p-cyanonitrobenzene, m-cyanonitrobenzene, o-cyanonitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1-nitronaphthalene, 2-nitronaphthalene ), 1,3-dinitronaphthalene, 1,5-dinitronaphthalene, 9-cyanoanthracene, 9-nitroguanidine (9-nitroanthracene), 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole, 2,4,7 -2,4,7-trinitro-9-fluorenone, 2,3,5,6-tetracyanopyridine, 2,3,5,6-tetracyanopyridine Maleic anhydride, phthalic anhydride, C60, and C70.

Among these compounds, a metal oxide or a cyano group-containing compound is easy to handle, and vapor deposition is also easy, so that the above effects are easily obtained, which is preferable. Examples of preferred metal oxides include molybdenum oxide, vanadium oxide, or ruthenium oxide. Among the cyano group-containing compounds, the following compounds are more preferred because they become strong electron acceptors: (a) a compound having at least one electron-accepting nitrogen and having a cyano group in addition to a nitrogen atom of a cyano group in the molecule; b) a compound having both a halogen and a cyano group in the molecule; (c) a compound having both a carbonyl group and a cyano group in the molecule; or (d) an electron accepting nitrogen other than a nitrogen atom having a cyano group, a halogen, and a cyano group All of the compounds. Specific examples of such a compound include the compounds described below.

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 or may be laminated by multiple layers. And constitute. Further, from the viewpoint that the hole injection barrier in the hole transport layer can be alleviated, the hole injecting material used in combination in the case where the acceptor compound is doped is preferably a compound represented by the formula (1). More preferably, it is the same compound as the hole transport layer.

In the case where the hole injection layer is doped with an acceptor compound, other materials used in the hole injection layer are directly represented by the formula (1). Other than the material, there is no particular limitation, for example, 4,4'-bis(N-(3-methylphenyl)-N-phenylamino)biphenyl (4,4'-bis (N-(3) -methylphenyl)-N-phenylamino)biphenyl,TPD), 4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (4,4'-bis(N-(1) -naphthyl)-N-phenylamino)biphenyl,NPD), 4,4'-bis(N,N-bis(4-biphenyl)amino)biphenyl (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 (bis(N,N'-diphenyl-4-aminophenyl)-N,N-diphenyl-4,4'-diamino-1,1'-biphenyl, TPD232) and other benzidine derivatives, 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, bis(N-arylcarbazole) or bis(N-alkylcarbazole) Biscarbazole derivatives, pyrazoline derivatives, stilbene (stilben) e) a compound, a hydrazone compound, a benzofuran derivative, a thiophene derivative, an oxadiazole derivative, a phthalocyanine derivative, a porphyrin a heterocyclic compound such as a derivative, and a polycarbonate or styrene derivative having the above monomer in a side chain, polythiophene, polyaniline, poly Antimony, polyvinylcarbazole, polydecane, and the like. Among them, in view of having a shallow HOMO energy level of the compound represented by the general formula (1) and smoothly injecting a hole from the anode into the hole transport layer, it is more preferable to use a benzidine derivative, A starburst arylamine based material group.

Next, an embodiment of the light-emitting element of the present invention will be described in detail by way of examples. In addition, unless otherwise indicated, the following description is common to the above-mentioned 1st structure and 2nd structure. The light-emitting element of the present invention includes an anode, a cathode, and at least a hole transport layer and an electron transport layer, or a hole transport layer and a hole injection layer between the anode and the cathode.

In the first configuration, the layer configuration between the anode and the cathode in the light-emitting element includes, in addition to the configuration including the hole transport layer/light-emitting layer/electron transport layer, a hole injection layer/hole transport layer/light emission. Layer/electron transport layer, hole transport layer/light emitting layer/electron transport layer/electron injection layer, hole injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer. Further, each of the above layers may be a single layer or a plurality of layers. Further, in the second configuration, in addition to the configuration including the hole injection layer/hole transport layer/light emitting layer, a hole injection layer/hole transport layer/light emitting layer/electron transport layer and a hole injection layer/ The layered structure of the hole transport layer/light emitting layer/electron transport layer/electron injection layer. Further, each of the above layers may be a single layer or a plurality of layers.

The compound represented by the formula (1) is contained in the hole transport layer in the light-emitting element. The hole transport layer is a layer that transports holes injected from the anode into the light-emitting layer. The hole transport layer may be one layer or may be composed of a plurality of layers, which may be any case. The compound represented by the formula (1) has high electricity Since the sub-barrier property is such that, in the case of including a plurality of layers, the hole transport layer containing the compound represented by the formula (1) is preferably in direct contact with the light-emitting layer from the viewpoint of preventing electron intrusion.

The hole transport layer may be composed only of the compound represented by the general formula (1), and other materials may be mixed within a range not impairing the effects of the present invention. In this case, other materials used may, for example, be 4,4'-bis(N-(3-methylphenyl)-N-phenylamino)biphenyl (TPD), 4,4'- Bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPD), 4,4'-bis(N,N-bis(4-biphenyl)amino)biphenyl (TBDB) ), bis(N,N'-diphenyl-4-aminophenyl)-N,N-diphenyl-4,4'-diamino-1,1'-biphenyl (TPD232) Aniline derivative, 4,4',4"-tris(3-methylphenyl(phenyl)amino)triphenylamine (m-MTDATA), 4,4',4"-tris(1-naphthalene) a group of materials known as starburst arylamines, bis(N-arylcarbazole) or bis(N-alkylcarbazole), such as (phenyl)amino)triphenylamine (1-TNATA) a biscarbazole derivative, a pyrazoline derivative, a stilbene compound, an anthraquinone compound, a benzofuran derivative, a thiophene derivative, an oxadiazole derivative, a phthalocyanine derivative, a porphyrin derivative, etc. Examples of the cyclic compound and the polymer include a polycarbonate or a styrene derivative having a monomer in the side chain, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, and polydecane.

Next, the electron transport layer of the present invention will be described. The electron transport layer is a layer that transports electrons injected from the cathode into the light emitting layer. In the light-emitting element of the first aspect of the invention, the electron-transporting layer contains the donor compound, but in the light-emitting device of the second configuration, it is preferable that the electron transport contains the donor compound. The electron transport layer may be a single layer or a plurality of layers. In the case of multi-layer lamination and the use of a donor compound, only It is desirable to have a donor compound in one layer. Further, in the case where the donor compound is an inorganic material of an alkali metal, an alkaline earth metal, or an oxide, a nitride, a fluoride or a carbonate thereof, if the layer containing the compound is in direct contact with the light-emitting layer, it exists The light-emitting layer is subjected to a matting action to lower the light-emitting efficiency. Therefore, it is preferred that the layer containing the donor compound is not in direct contact with the light-emitting layer. However, when the donor compound is a complex with an organic substance, since the light-emitting layer is hardly subjected to the matting action, the layer containing the donor compound may be in direct contact with the light-emitting layer. Further, in the case where the electron transport layer is formed of a plurality of layers, the undoped electron transport material may be the same as or different from the doped electron transport material. Further, the electron transport layer containing the donor compound of the present invention can be used as a charge generating layer in a series structure type element in which a plurality of light emitting elements are connected.

The hole injection layer is a layer interposed between the anode and the hole transport layer. In the light-emitting device of the second aspect of the present invention, the hole injection layer is formed of an acceptor compound alone, or the acceptor compound is doped into another hole injecting material, and is also used in the light-emitting element of the first structure. Similarly, it is preferred that the hole injection layer is composed of an acceptor compound alone or that the acceptor compound is doped into other hole injection materials. The hole injection layer may be one layer or a plurality of layers, and may be any case. When a hole injection layer is provided between the hole transport layer containing the compound represented by the general formula (1) and the anode, not only a lower voltage drive but also an endurance life is improved, and the carrier balance of the element is improved, and the luminous efficiency is improved. It is also improved, so it is better. Further, the hole injection layer of the present invention which is composed of an acceptor compound alone or contains an acceptor compound can be used as a series structure in which a plurality of light-emitting elements are connected. A charge generating layer in a type element.

The anode is not particularly limited as long as it can efficiently inject a hole into the organic layer, and a material having a relatively large work function is preferably used. Examples of the material of the anode include conductive metal oxides such as tin oxide, indium oxide, zinc indium oxide, and indium tin oxide (ITO), or metals such as gold, silver, and chromium, and inorganic conductive materials such as copper iodide and copper sulfide. Conductive polymers such as polythiophene, polypyrrole, and polyaniline. The electrode materials may be used singly or in combination of a plurality of materials.

The electric resistance of the anode is sufficient as long as it can supply a sufficient current for light emission of the light-emitting element, and it is preferable that the electric resistance of the light-emitting element is low. For example, if the electric resistance is 300 Ω/□ or less, it can function as an electrode. However, an ITO substrate of about 10 Ω/□ can be supplied at present. Therefore, it is particularly preferable to use a low-resistance product of 100 Ω/□ or less. The thickness of the anode can be arbitrarily selected according to the resistance value, but it is usually used in the range of 100 nm to 300 nm.

Further, in order to maintain the mechanical strength of the light-emitting element, it is preferred to form an anode on the substrate. A glass substrate such as soda glass or alkali free glass is suitably used as the substrate. The thickness of the glass substrate is sufficient as long as it has a sufficient thickness to maintain the mechanical strength. Therefore, it is sufficient if it is 0.5 mm or more. As for the material of the glass, it is preferable that the amount of eluted ions from the glass is small. Therefore, alkali-free glass is preferable, but soda lime glass which is subjected to barrier coating such as SiO _{2 is} also commercially available, and therefore This soda lime glass can be used. Further, when the anode functions stably, the substrate does not have to be glass, and for example, an anode can be formed on the plastic substrate. The method for forming the anode is not particularly limited, and for example, an electron beam method, a sputtering method, a chemical reaction method, or the like can be used.

The material used in the cathode is not particularly limited as long as it can efficiently inject electrons into the organic layer, and examples thereof include platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, and chromium. Lithium, sodium, potassium, barium, calcium and magnesium, and alloys thereof. In order to improve the electron injection efficiency and improve the element characteristics, lithium, sodium, potassium, barium, calcium, magnesium or an alloy containing the low work function metals is effective. However, these low-work function metals are often unstable in the atmosphere, and therefore, it is possible to obtain a stable amount of lithium or magnesium doped with a small amount (shown as 1 nm or less in a vacuum-deposited film thickness) in the organic layer. A method of a highly electrode is preferred. Further, an inorganic salt such as lithium fluoride can also be used. Further, as a preferable example, in order to protect the electrode, a metal such as platinum, gold, silver, copper, iron, tin, aluminum, or indium, or an alloy of the metal, yttrium oxide, titanium oxide, and nitriding may be laminated. An inorganic polymer such as hydrazine, an organic polymer compound such as polyvinyl alcohol, polyvinyl chloride or a hydrocarbon-based polymer compound. The method of forming the cathode is not particularly limited, and for example, resistance heating, electron beam, sputtering, ion plating, coating, or the like can be used.

The luminescent layer may be a single layer or a plurality of layers, and is formed of a luminescent material (host material, dopant material), which may be a mixture of the host material and the dopant material, or may be a separate host material, which may be In either case. That is, in the light-emitting element of the present invention, only the host material or the dopant material may emit light in each of the light-emitting layers, or the host material and the dopant material may emit light at the same time. From the viewpoint of efficiently utilizing electrical energy to obtain luminescence of high color purity, it is preferred that the luminescent layer comprises a host material and a dopant material. mixture. In addition, the host material and the dopant material may be one type or a combination of a plurality of materials, and may be any of them. The dopant material may be included in the entirety of the host material, or may be included in a portion of the host material, either in any case. The dopant material may be laminated or dispersed, and may be either case. The dopant material controls the luminescent color. When the amount of the dopant material is too large, a concentration extinction phenomenon occurs. Therefore, the amount of the dopant material is preferably 20% by mass or less, and particularly preferably 10% by mass or less based on the host material. The doping method may be formed by a co-evaporation method with a host material, or may be simultaneously vapor-deposited after being premixed with the host material.

Specifically, as the luminescent material, a condensed ring derivative such as ruthenium or osmium which is known as an illuminant, a metal chelate oxinoid compound typified by tris(8-hydroxyquinoline)aluminum, or the like, a bisstyryl derivative such as a bisstyrylhydrazine derivative or a distyrylbenzene derivative, a tetraphenylbutadiene derivative, an indene derivative, a coumarin derivative, or an oxadiazole derivative , pyrrodopyridine derivative, benzalkonone derivative, cyclopentadiene derivative, oxadiazole derivative, thiadiazolopyridine derivative, dibenzofuran derivative, carbazole derivative And indolocarbazole derivatives, polyphenylenevinylene derivatives, polyparaphenylene derivatives, polythiophene derivatives, etc., but not particularly limited.

The host material contained in the luminescent material is not particularly limited, and may be used: naphthalene, anthracene, phenanthrene, ruthenium, chrysene, naphthacene, benzene, fluoranthene, and fluoranthene. ), 茀, A compound having a condensed aryl ring or a derivative thereof, such as N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine a metal amine chelate compound, a stilbene benzene derivative, etc. represented by tris(8-quinolinolato)aluminum (III) a bisstyryl derivative, a tetraphenylbutadiene derivative, an anthracene derivative, a coumarin derivative, an oxadiazole derivative, a pyrrolopyridinium derivative, a piconone derivative, a cyclopentadiene derivative , pyrrolopyrrole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, polyphenylene can be used in the polymer system An ethylene derivative, a polyparaphenylene derivative, a polyfluorene derivative, a polyvinylcarbazole derivative, a polythiophene derivative, or the like; however, it is not particularly limited. Further, the dopant material is not particularly limited, and a compound having a condensed aryl ring or a derivative thereof such as naphthalene, anthracene, phenanthrene, anthracene, fluorene, hydrazine, fluorene, fluorene, fluorene, fluorene or the like can be used. (eg 2-(benzothiazol-2-yl)-9,10-diphenylfluorene or 5,6,11,12-tetraphenyl fused tetraphenyl, etc.), furan, pyrrole, thiophene, pyrene, 9 - hydrazine, 9,9'-spirobisilafluorene, benzothiophene, benzofuran, anthracene, dibenzothiophene, dibenzofuran, imidazopyridine ( Imidazopyridine), phenanthroline, pyridine, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, etc., or a derivative thereof, a borane derivative, diphenyl Vinylbenzene derivative, 4,4'-bis(2-(4-diphenylaminophenyl)vinyl)biphenyl, 4,4'-bis(N-(stilbene-4-yl) Aminostyryl derivatives such as -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)quinolizino[9,9a,1-gh]coumarin (2,3,5,6-1H,4H-tetrahydro-9-(2' -benzothiazolyl)quinolizino[9,9a,1-gh]coumarin) and other coumarin derivatives, imidazole, thiazole, thiadiazole, oxazole, oxazole, oxadiazole, triazole and other azole derivatives and their metal And an aromatic amine represented by N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine Derivatives, etc.

Further, a phosphorescent material may be included in the light-emitting layer. The term "phosphorescent material" refers to a material that also exhibits phosphorescence at room temperature. As the dopant, it is necessary to obtain phosphorescence at substantially room temperature, but it is not particularly limited, and examples thereof include an organometallic complex compound containing arsenic (Ir) and ruthenium (Ru). At least one metal selected from the group consisting of rhodium (Rh), palladium (Pd), platinum (Pt), osmium (Os), and ruthenium (Re). Among them, an organic metal complex having ruthenium or platinum is more preferable from the viewpoint of having a high phosphorescence luminescence yield at room temperature. The main body of the phosphorescent material is suitably used: an anthracene derivative, a carbazole derivative, an indolocarbazole derivative, a nitrogen-containing aromatic compound derivative having a pyridine, a pyrimidine or a triazine skeleton, a polyarylbenzene derivative, a chalcogenide-containing compound such as a spirocyclic anthracene derivative, a trixene derivative or a triphenylene derivative, a dibenzofuran derivative or a dibenzothiophene derivative; An organic metal complex such as a quinoline hydrazine complex or the like; as long as it is a triplet energy larger than the substantially used dopant, and electrons and holes are The compounds which are smoothly injected and transported in the respective transport layers are not limited to these compounds. Further, two or more kinds of triplet light-emitting dopants may be contained, and two or more types of host materials may be contained. Further, it may contain one or more kinds of triplet light-emitting dopants and one or more types of fluorescent light-emitting dopants.

The preferred phosphorescent dopant is not particularly limited, and specific examples thereof are as follows.

Further, the main body of the preferred phosphorescent emitting layer is not particularly limited, and specific examples thereof are as follows.

The compound represented by the formula (1) has a high triplet energy level in addition to good hole injection transport characteristics and high electron blocking properties. Therefore, in the case where the phosphorescent emitting layer is combined with the hole transporting layer containing the compound represented by the general formula (1), the phosphorescent emitting layer is transported from the phosphorescent emitting layer to the hole. The triplet energy transfer of the layer is suppressed, and thermal deactivation of the phosphorescent energy in the hole transport layer can be prevented. Therefore, it is preferable to prevent a decrease in luminous efficiency and to obtain a low-voltage-driven, long-life light-emitting element.

In the present invention, an electron injecting layer may be provided between the cathode and the electron transporting layer. Usually, the electron injecting layer is inserted for the purpose of injecting electrons from the cathode into the electron transporting layer, and in the case of insertion, the above compound having a heteroaryl ring structure containing electron-accepting nitrogen may be used as it is, or may be used. The above layer containing the donor compound. Further, an inorganic material of an insulator or a semiconductor may be used in the electron injecting layer. By using these materials, short-circuiting of the light-emitting element can be effectively prevented, and electron injectability can be improved, which is preferable. The insulator as described above preferably uses 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. When the electron injecting layer contains the alkali metal chalcogenide or the like, it is more preferable in terms of further improving the electron injectability. Specific examples of preferred alkali metal chalcogenides include Li ₂ O, Na ₂ S, and Na ₂ Se. Preferred alkaline earth metal chalcogenides include, for example, CaO, BaO, SrO, BeO, BaS, and CaSe. Further, preferred examples of the alkali metal halide include LiF, NaF, KF, LiCl, KCl, and NaCl. Further, preferred examples of the alkaline earth metal halide include fluorides such as CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ and BeF ₂ or halides other than fluorides. Further, a complex of an organic substance and a metal is also suitably used. When an inorganic material of an insulator or a semiconductor is used for the electron injecting layer, if the film thickness is too thick, there is a problem that the light emitting element is insulated or the driving voltage is increased. In other words, although the film thickness range of the electron injecting layer is narrowed, the yield of the light-emitting element is lowered, but when the complex of the organic substance and the metal is used in the electron injecting layer, the film thickness is easily adjusted. good. Preferable examples of the organic substance in the complex of the organic substance and the metal include quinoline alcohol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzoxazole, hydroxytriazole, and the like. . Among them, a complex of an alkali metal and an organic compound is preferred, and a complex of lithium and an organic compound is more preferred, and lithium quinolate is particularly preferred.

The light-emitting element of the present invention has a function of converting electrical energy into light. Here, the electrical energy mainly uses a direct current, and a pulse current or an alternating current can also be used. The current value and the voltage value are not particularly limited, but in consideration of the power consumption or the life of the element, it is possible to select the maximum brightness by using as low an energy as possible.

The light-emitting element of the present invention is suitably used, for example, as a display that is displayed in a matrix and/or a segment.

In the matrix method, pixels for display are arranged in a two-dimensional shape such as a grid or a mosaic, and characters or images are displayed in a set of pixels. The shape or size of the pixels is determined by the use. For example, in the case of a personal computer, a monitor, a television, and a character display, a quadrilateral pixel having a side of 300 μm or less is usually used, and in the case of a large display such as a display panel, the use side is a mm level. Picture. In the case of monochrome display, pixels of the same color may be arranged, and in the case of color display, pixels of red, green, and blue are arranged to be displayed. In this case, there are usually a delta type and a stripe type. Moreover, the driving method of the matrix may be line sequential driving Any of a method or an active matrix. Although the structure of the line sequential driving is simple, in the case of considering the operational characteristics, there is a case where the active matrix is excellent, and therefore it is also necessary to use it separately depending on the use.

The segment method in the present invention refers to a method in which a pattern is formed so as to display predetermined information, and an area determined by the arrangement of the patterns is illuminated. For example, a time or temperature display in a digital timepiece or a thermometer, an operation state display of an audiovisual machine or an electromagnetic conditioner, and a panel display of a car can be cited. Moreover, the above matrix display and segment display can also coexist in the same panel.

The light-emitting element of the present invention is also preferably used as a backlight for various machines and the like. The backlight is mainly used for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a timepiece, an audiovisual device, an automobile panel, a display panel, a logo, and the like. Particularly in a liquid crystal display device in which a light-emitting element of the present invention is being studied in a thin-filmed personal computer use backlight, it is possible to provide a thin and lightweight backlight from a prior backlight.

[Example]

Hereinafter, the invention will be described by way of examples, but the invention is not limited by the examples. Further, the numbers of the compounds in the following examples refer to the numbers of the compounds described above. In addition, the first electron transport layer in Tables 1 to 5 refers to an electron transport layer that is in contact with the light-emitting layer, and the second electron transport layer means that it is not in contact with the light-emitting layer but is laminated on the first electron transport layer. The electron transport layer on the layer. However, when the first electron transport layer is "none", the electron transport layer is composed only of the second electron transport layer. And the second electron transport layer is in contact with the light emitting layer.

<Examples 1 to 21: Light-emitting elements containing a compound represented by the formula (1) in a hole transport layer and containing a donor compound in an electron transport layer> (Example 1)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. A 60 nm compound HT-1 was vapor-deposited as a hole transport layer by a resistance heating method. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, compound E-1 was used as the electron transporting material, and Liq was used as the donor compound, and the thickness of the compound E-1 and Liq was 1:1 so as to be laminated to a thickness of 20 nm. Electronic transport layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 5.4 V and an external quantum efficiency of 4.1%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 160 hours. Further, the compound HT-1, the compound H-1, the compound D-1, the compound E-1, and Liq are the compounds shown below.

(Example 2 to Example 7)

Using the materials described in Table 1 as the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, a light-emitting device was produced and evaluated in the same manner as in Example 1. The results of each example show In Table 1. Further, the compound HT-2, the compound HT-3, the compound HT-4, the compound HT-5, the compound HT-6, and the compound HT-7 are the compounds shown below.

(Example 8)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. A 60 nm compound HT-1 was vapor-deposited as a hole transport layer by a resistance heating method. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, 5 nm of the compound E-1 was deposited as the first electron transport layer, and further, the compound E-1 was used for the electron transport material, and ruthenium was used as the donor compound, and the vapor deposition rate of the compound E-1 and ruthenium was used. A thickness of 15 nm is laminated to a thickness of 15 nm as a second electron transport layer.

Then, magnesium and silver were vapor-deposited 1000 nm so that the mass ratio became 1:1, and a 5 mm × 5 mm square element was produced. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were blue light emission at a driving voltage of 5.2 V and an external quantum efficiency of 4.2%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 164 hours.

(Example 9 to Example 21)

Using the materials described in Table 1 as a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, a first electron transport layer, and a second electron transport layer, a light-emitting device was produced in the same manner as in Example 8 and carried out. Evaluation. The results of the respective examples are shown in Table 1. Further, the compound E-2 is a compound shown below.

<Example 22 to Example 77: The compound represented by the formula (1) is contained in the hole transport layer, and the luminescence of the acceptor compound is contained in the hole injection layer. element> (Example 22)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. Using the resistance heating method, a 10 nm acceptor compound HAT-CN6 was first evaporated as a hole injection layer, and then a 50 nm compound HT-1 was vapor-deposited as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, a thickness of the compound E-1 to 20 nm was laminated in the electron transporting material to serve as the second electron transporting layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 5.2 V and an external quantum efficiency of 4.1%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction of 20% was 162 hours. Further, the compound HAT-CN6 is a compound shown below.

(Example 23 to Example 28)

Using the materials described in Table 2 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 22. . The results of the respective examples are shown in Table 2.

(Example 29)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was 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, compound HT-1 is used in the hole injection material, and compound F4-TCNQ is used in the acceptor compound, and 30 nm is evaporated in such a manner that the doping concentration of the acceptor compound becomes 10% by mass. As a hole injection layer. Then, 30 nm of compound HT-1 was evaporated as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, a thickness of the compound E-1 to 20 nm was laminated in the electron transporting material to serve as the second electron transporting layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 5.2 V and an external quantum efficiency of 4.2%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction of 20% was 159 hours. Further, the compound F4-TCNQ is a compound shown below.

(Example 30 to Example 35)

Using the materials described in Table 2 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 29. . The results of the respective examples are shown in Table 2.

(Example 36)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. Using the resistance heating method, first, molybdenum oxide (MoO ₃ ) 1 nm was deposited as a hole injection layer, and then 59 nm of compound HT-1 was vapor-deposited as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, a thickness of the compound E-1 to 20 nm was laminated in the electron transporting material to serve as the second electron transporting layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 5.2 V and an external quantum efficiency of 4.2%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction of 20% was 157 hours.

(Example 37 ~ Example 42)

Using the materials described in Table 2 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 36. . The results of the respective examples are shown in Table 2.

(Example 43 to Example 49)

Using the materials described in Table 2 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 22. . The results of the respective examples are shown in Table 2.

(Example 50 ~ Example 56)

Using the materials described in Table 2 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 29. . The results of the respective examples are shown in Table 2.

(Example 57 to Example 63)

Using the materials described in Table 2 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 36. . The results of the respective examples are shown in Table 2.

(Example 64)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. In the resistance heating method, first, compound HT-1 is used in the hole injecting material, and compound PD-1 is used in the acceptor compound, and 30 nm is deposited in such a manner that the doping concentration of the accepting compound is 3% by mass. As a hole injection layer. Then, 30 nm of compound HT-1 was evaporated as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, a thickness of the compound E-1 to 20 nm was laminated in the electron transporting material to serve as the second electron transporting layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a drive voltage of 5.1 V and an external quantum efficiency of 4.3%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction of 20% was 172 hours. Further, the compound PD-1 is a compound shown below.

(Example 65 ~ Example 77)

Using the materials described in Table 3 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 64. . The results of the respective examples are shown in Table 3.

<Comparative Example 1 to Comparative Example 14: The compound represented by the formula (1) was contained in the hole transport layer, but the electron transport layer did not contain the donor compound and did not have the hole injection layer containing the acceptor compound. Light-emitting components> (Comparative Example 1)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. A 60 nm compound HT-1 was vapor-deposited as a hole transport layer by a resistance heating method. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, a thickness of the compound E-1 to 20 nm was laminated in the electron transporting material to serve as the second electron transporting layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 6.6 V and an external quantum efficiency of 3.1%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 135 hours.

(Comparative Example 2 to Comparative Example 14)

Using the materials described in Table 3 as the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, a light-emitting device was produced and evaluated in the same manner as in Comparative Example 1. The results of the respective comparative examples are shown in Table 4.

<Comparative Example 15 to Comparative Example 23: Light-emitting device containing a donor compound in the electron transport layer but not containing the compound represented by the formula (1) in the hole transport layer> (Comparative Example 15 to Comparative Example 17)

Using the materials described in Table 4 as the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, a light-emitting device was produced and evaluated in the same manner as in Example 1. The knot of each comparative example The results are shown in Table 4. Further, the compound HT-8, the compound HT-9, and the compound HT-10 are the compounds shown below.

(Comparative Example 18 to Comparative Example 23)

Using the materials described in Table 4 as the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer, a light-emitting device was produced in the same manner as in Example 8 and was carried out. Evaluation. The results of the respective comparative examples are shown in Table 4.

According to Tables 1 and 4, by comparison of Examples 1 to 7 and Comparative Examples 1 to 7, and Examples 15 to 21 and Comparative Examples 8 to 14, it is known that the general formula is used in the hole transport layer. (1) In the case of the compound shown, the electron transport layer contains a donor compound, and exhibits an effect of low voltage driving, improved luminous efficiency, and improved durability life. Further, by comparison of Examples 1 to 7 and Comparative Example 15 to Comparative Example 17, Example 8 to Example 14, and Comparative Example 18 to Comparative Example 20, Example 15 to Example 21, and Comparative Example 21 to Comparative Example 23, it is understood that: Containing a conformational compound in the electron transport layer In the case of using the compound represented by the formula (1) in the hole transport layer, the effect of low voltage driving, improvement in luminous efficiency, and improvement in durability life is exhibited.

<Comparative Example 24 to Comparative Example 47: Light-emitting device containing an acceptor compound in the hole injection layer but not containing the compound represented by the general formula (1) in the hole transport layer> (Comparative Example 24 to Comparative Example 26)

Using the materials described in Table 5 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 22. . The results of the respective examples are shown in Table 5.

(Comparative Example 27 to Comparative Example 29)

Using the materials described in Table 5 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 29. . The results of the respective examples are shown in Table 5.

(Comparative Example 30 to Comparative Example 32)

Using the materials described in Table 5 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 36. . The results of the respective examples are shown in Table 5.

(Comparative Example 33 to Comparative Example 35)

The materials described in Table 5 were used as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport. For the layers, light-emitting elements were fabricated in the same manner as in Example 22 and evaluated. The results of the respective examples are shown in Table 5.

(Comparative Example 36 to Comparative Example 38)

Using the materials described in Table 5 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 29. . The results of the respective examples are shown in Table 5.

(Comparative Example 39 to Comparative Example 41)

Using the materials described in Table 5 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 36. . The results of the respective examples are shown in Table 5.

(Comparative Example 42 to Comparative Example 47)

Using the materials described in Table 5 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 64. . The results of the respective examples are shown in Table 5.

According to Tables 2, 3 and 5, Examples 22 to 28 and Comparative Examples 24 to 26, Examples 29 to 35, and Comparative Examples 27 to 29, Examples 36 to 42 and Comparative Examples 30 to Comparative Example 32, Example 43 to Example 49 and Comparative Example 33 to Comparative Example 35, Example 50 to Example 56, and Comparative Example 36 to Comparative Example 38, Example 57 to Example 63, and Comparative Example 39 to Comparative Example 41, Example 64 to Example 70, in comparison with Comparative Example 42 to Comparative Example 44, Example 71 to Example 77, and Comparative Example 45 to Comparative Example 47, it is understood that when the hole injection layer is composed of an acceptor compound alone or contains an acceptor compound, By using the compound represented by the general formula (1) in the hole transport layer, the effect of low voltage driving, improved luminous efficiency, and improved durability life is exhibited.

<Examples 78 to 138: a light-emitting element containing a compound represented by the formula (1) in a hole transport layer, a donor compound in an electron transport layer, and an acceptor compound in a hole injection layer. (Example 78)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. Using the resistance heating method, a 10 nm acceptor compound HAT-CN6 was first evaporated as a hole injection layer, and then a 50 nm compound HT-1 was vapor-deposited as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, compound E-1 was used as the electron transporting material, and Liq was used as the donor compound, and the thickness of the compound E-1 and Liq was 1:1 so as to be laminated to a thickness of 20 nm. Electronic transport layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 4.1 V and an external quantum efficiency of 5.5%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction of 20% was 305 hours.

(Example 79 to Example 82)

Using the materials described in Table 6 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 78. . The results of the respective examples are shown in Table 6.

(Example 83)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was 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, compound HT-1 is used in the hole injection material, and compound F4-TCNQ is used in the acceptor compound, and 30 nm is evaporated in such a manner that the doping concentration of the acceptor compound becomes 10% by mass. As a hole injection layer. Then, 30 nm of compound HT-1 was evaporated as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, compound E-1 was used as the electron transporting material, and Liq was used as the donor compound, and the thickness of the compound E-1 and Liq was 1:1 so as to be laminated to a thickness of 20 nm. Electronic transport layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 4.1 V and an external quantum efficiency of 5.3%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 310 hours.

(Example 84 to Example 87)

Using the materials described in Table 6 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 83. . The results of the respective examples are shown in Table 6.

(Example 88)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. Using the resistance heating method, first, a 10 nm compound HAT-CN6 was vapor-deposited as a hole injection layer, and then a 50 nm compound HT-1 was vapor-deposited as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, 5 nm of the compound E-1 was deposited as the first electron transport layer, and further, the compound E-1 was used for the electron transport material, and ruthenium was used as the donor compound, and the vapor deposition rate of the compound E-1 and ruthenium was used. A thickness of 15 nm is laminated to a thickness of 15 nm as a second electron transport layer.

Then, magnesium and silver were vapor-deposited 1000 nm so that the mass ratio became 1:1, and a 5 mm × 5 mm square element was produced. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 4.0 V and an external quantum efficiency of 5.4%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 313 hours.

(Example 89 ~ Example 92)

The material described in Table 6 was used in the same manner as in Example 88, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 93)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was 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, compound HT-1 is used in the hole injection material, and compound F4-TCNQ is used in the acceptor compound, and 30 nm is evaporated in such a manner that the doping concentration of the acceptor compound becomes 10% by mass. As a hole injection layer. Then, 30 nm of compound HT-1 was evaporated as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, 5 nm of the compound E-1 was deposited as the first electron transport layer, and further, the compound E-1 was used for the electron transport material, and ruthenium was used as the donor compound, and the vapor deposition rate of the compound E-1 and ruthenium was used. A thickness of 15 nm is laminated to a thickness of 15 nm as a second electron transport layer.

Then, magnesium and silver were vapor-deposited at 1000 nm in a mass ratio of 1:1 to form a cathode, and a 5 mm × 5 mm square element was produced. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were obtained as blue light having a driving voltage of 4.0 V and an external quantum efficiency of 5.5%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 301 hours.

(Example 94 to Example 97)

The material described in Table 6 was used in the same manner as in Example 93, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 98)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. Using the resistance heating method, first, molybdenum oxide (MoO ₃ ) 1 nm was deposited as a hole injection layer, and then 59 nm of compound HT-1 was vapor-deposited as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, compound E-1 was used as the electron transporting material, and Liq was used as the donor compound, and the thickness of the compound E-1 and Liq was 1:1 so as to be laminated to a thickness of 20 nm. Electronic transport layer.

Then, magnesium and silver were vapor-deposited 1000 nm so that the mass ratio became 1:1, and a 5 mm × 5 mm square element was produced. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 4.2 V and an external quantum efficiency of 5.4%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 294 hours.

(Example 99 ~ Example 102)

Using the materials described in Table 6 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 98. . The results of the respective examples are shown in Table 6.

(Example 103)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. Using the resistance heating method, first, molybdenum oxide (MoO ₃ ) 1 nm was deposited as a hole injection layer, and then 59 nm of compound HT-1 was vapor-deposited as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, 5 nm of the compound E-1 was deposited as the first electron transport layer, and further, the compound E-1 was used for the electron transport material, and ruthenium was used as the donor compound, and the vapor deposition rate of the compound E-1 and ruthenium was used. A thickness of 15 nm is laminated to a thickness of 15 nm as a second electron transport layer.

Then, magnesium and silver were vapor-deposited 1000 nm so that the mass ratio became 1:1, and a 5 mm × 5 mm square element was produced. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 4.0 V and an external quantum efficiency of 5.4%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 301 hours.

(Example 104 to Example 107)

The material described in Table 6 was used in the same manner as in Example 103, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 108 ~ Example 112)

The material described in Table 6 was used in the same manner as in Example 88, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 113 to Example 117)

The material described in Table 6 was used in the same manner as in Example 93, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 118 ~ Example 122)

The material described in Table 6 was used in the same manner as in Example 103, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 123)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was 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, the compound HT-3 is used in the hole injecting material, and the compound PD-1 is used in the acceptor compound, and 30 nm is deposited in such a manner that the doping concentration of the accepting compound is 3% by mass. As a hole injection layer. Then, 30 nm of compound HT-3 was evaporated as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, compound E-1 was used as the electron transporting material, and Liq was used as the donor compound, and the thickness of the compound E-1 and Liq was 1:1 so as to be laminated to a thickness of 20 nm. Electronic transport layer.

Then, 0.5 nm of Liq was vapor-deposited as an electron injecting layer, and then magnesium and silver were vapor-deposited at a ratio of 1:1 to a cathode to prepare a 5 mm × 5 mm square element. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were a driving voltage of 4.0 V and an external quantum efficiency of 5.3%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 364 hours.

(Example 124, Example 125)

The material described in Table 6 was used in the same manner as in Example 123, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 126)

A glass substrate (manufactured by Geomatec, 11 Ω/□, sputtered product) having an ITO transparent conductive film of 165 nm was cut into 38 mm × 46 mm and etched. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes under "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to UV-ozone treatment for 1 hour before the device was fabricated, and was placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. In the resistance heating method, first, the compound HT-3 is used in the hole injecting material, and the compound PD-1 is used in the acceptor compound, and the doping concentration of the accepting compound is 3% by mass. As a hole injection layer. Then, 30 nm of compound HT-3 was evaporated as a hole transport layer. Then, the compound H-1 was used in the host material, and the compound D-1 was used in the dopant material, and the thickness of the dopant material was 5% by mass to a thickness of 40 nm as a light-emitting layer. Then, 5 nm of the compound E-1 was deposited as the first electron transport layer, and further, the compound E-1 was used for the electron transport material, and ruthenium was used as the donor compound, and the vapor deposition rate of the compound E-1 and ruthenium was used. A thickness of 15 nm is laminated to a thickness of 15 nm as a second electron transport layer.

Then, magnesium and silver were vapor-deposited 1000 nm so that the mass ratio became 1:1, and a 5 mm × 5 mm square element was produced. The film thickness referred to herein means the display value of the quartz oscillation type film thickness monitor. The characteristics of the light-emitting element at 1000 cd/m ² were obtained as blue light having a driving voltage of 3.9 V and an external quantum efficiency of 5.4%. The initial luminance was set to 1000 cd/m ² to measure the endurance life of the device, and as a result, the time from the initial luminance reduction by 20% was 372 hours.

(Example 127, Example 128)

The material described in Table 6 was used in the same manner as in Example 126, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 6.

(Example 129 ~ Example 138)

Using the materials described in Table 7 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 78. . The results of the respective examples are shown in Table 7. Further, the compound HT-11, the compound HT-12, the compound E-3, and the compound E-4 are the compounds shown below.

<Comparative Example 48 to Comparative Example 84: The donor compound was contained in the electron transport layer, and the acceptor compound was contained in the hole injection layer, but the compound represented by the formula (1) was not contained in the hole transport layer. Light-emitting components> (Comparative Example 48 to Comparative Example 50)

Using the materials described in Table 8 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 78. . The results of the respective comparative examples are shown in Table 8.

(Comparative Example 51 to Comparative Example 53)

Using the materials described in Table 8 as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, and the second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 83. . The results of the respective comparative examples are shown in Table 8.

(Comparative Example 54 to Comparative Example 56)

The material described in Table 8 was used in the same manner as in Example 88, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective comparative examples are shown in Table 8.

(Comparative Example 57 to Comparative Example 59)

The material described in Table 8 was used in the same manner as in Example 93, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective comparative examples are shown in Table 8.

(Comparative Example 60 to Comparative Example 62)

Using the materials described in Table 8 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 98. . The results of the respective comparative examples are shown in Table 8.

(Comparative Example 63 to Comparative Example 65)

The material described in Table 8 was used in the same manner as in Example 103, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective comparative examples are shown in Table 8.

(Comparative Example 66 to Comparative Example 68)

The material described in Table 8 was used in the same manner as in Example 88, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective comparative examples are shown in Table 8.

(Comparative Example 69 to Comparative Example 71)

The material described in Table 8 was used in the same manner as in Example 93, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective comparative examples are shown in Table 8.

(Comparative Example 72 to Comparative Example 74)

The material described in Table 8 was used in the same manner as in Example 103, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective comparative examples are shown in Table 8.

(Comparative Example 75 to Comparative Example 77)

The material described in Table 8 was used in the same manner as in Example 123, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 8.

(Comparative Example 78 to Comparative Example 80)

The material described in Table 8 was used in the same manner as in Example 126, using the material as the hole injection layer, the hole transport layer, the light-emitting layer host material, the light-emitting layer dopant material, the first electron transport layer, and the second electron transport layer. Light-emitting elements were evaluated. The results of the respective examples are shown in Table 8.

(Comparative Example 81 to Comparative Example 90)

Using the materials described in Table 8 as a hole injection layer, a hole transport layer, a light-emitting layer host material, a light-emitting layer dopant material, and a second electron transport layer, light-emitting elements were fabricated and evaluated in the same manner as in Example 78. . The results of the respective comparative examples are shown in Table 8. Further, the compound HT-13, the compound HT-14, and the compound HT-15 are the compounds shown below.

According to Table 6, Table 7, and Table 8, by Examples 78 to 82 and Comparative Example 48 to Comparative Example 50, Example 83 to Example 87, and Comparative Example 51 to Comparative Example 53, Example 88 to Example 92, and Comparative Example 54~ Comparative Example 56, Example 93 to Example 97 and Comparative Example 57 to Comparative Example 59, Example 98 to Example 102 and Comparative Example 60 to Comparative Example 62, Example 103 to Example 107, and Comparative Example 63 to Comparative Example 65, Example 108 to Example 112 and Comparative Example 66 to Comparative Example 68, Example 113 to Example 117 and Comparative Example 69 to Comparative Example 71, Example 118 to Example 122, and Comparative Example 72 to Comparative Example 74, Example 123 to Example 125, and Comparative Example 75 to Comparative Example 77, Example 126 to Example 128 and Comparative Example 78 to Comparative Example 80, Example 129 to Example 133 and Comparative Example 81 to Comparative Example 85, Example 134 to Example 138, and Comparative Example 86 to Comparative Example 90, it is known that: The hole injection layer is composed of an acceptor compound alone or contains an acceptor compound, and when the electron transport layer contains a donor compound, it is expressed by using the compound represented by the general formula (1) in the hole transport layer. Low voltage drive, improved luminous efficiency, and greatly improved durability.

[Industrial availability]

The light-emitting element of the present invention is useful in the field of driving at a low voltage, requiring high luminous efficiency and long-lasting life, and can be used for display elements, flat panel displays, backlights, illumination, interiors, signs, billboards, electronic cameras, and optical signal generators. Wait.

Claims (6)

A light-emitting element comprising at least a hole transport layer and an electron transport layer between an anode and a cathode, and emitting light by electrical energy, wherein the light-emitting element is characterized in that the hole transport layer contains the following general formula (1) a compound represented by the above, wherein the electron transport layer contains a compound selected from the group consisting of an alkali metal, an alkali metal-containing inorganic salt, an alkali metal and an organic compound, an alkaline earth metal, an alkaline earth metal-containing inorganic salt, and an alkaline earth metal and an organic substance. a donor compound in a group of objects, (In the formula (1), R ¹ to R ¹² may be the same or different and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, amine, aryl, heterocyclic, alkenyl, cycloalkenyl, alkynyl. , alkoxy, alkylthio, aryl ether, aryl sulfide, halogen, cyano, -P(=O)R ¹³ R ¹⁴ and a decyl group; R ¹³ and R ¹⁴ The aryl group or the heteroaryl group may be the same or different, and the above substituent may be further substituted, and the adjacent substituents may further form a ring with each other; wherein n of R ¹ to R ¹² is -NR ¹⁵ R ¹⁶ The amine group represented; R ¹⁵ and R ¹⁶ may be the same or different and selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group and a heteroaryl group; n represents an integer of 1 to 6). A light-emitting element comprising at least a hole transport layer and a hole injection layer between an anode and a cathode, and emitting light by electrical energy, wherein the light-emitting element is characterized in that the hole transport layer contains the following formula (1) a compound represented by the above, and the above-mentioned hole injection layer is composed of an acceptor compound alone or contains an acceptor compound. (In the formula (1), R ¹ to R ¹² may be the same or different and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, amine, aryl, heterocyclic, alkenyl, cycloalkenyl, alkynyl. , alkoxy, alkylthio, aryl ether, aryl sulfide, halogen, cyano, -P(=O)R ¹³ R ¹⁴ and a decyl group; R ¹³ and R ¹⁴ The aryl group or the heteroaryl group may be the same or different, and the above substituent may be further substituted, and the adjacent substituents may further form a ring with each other; wherein n of R ¹ to R ¹² is -NR ¹⁵ R ¹⁶ The amine group represented; R ¹⁵ and R ¹⁶ may be the same or different and selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group and a heteroaryl group; n represents an integer of 1 to 6). The light-emitting element of claim 2, wherein the above The acceptor compound is composed of a compound which is a metal oxide or a compound containing a cyano group, or an acceptor compound. The light-emitting element according to claim 2, wherein an electron transport layer is further present between the anode and the cathode, and the electron transport layer contains an inorganic salt selected from the group consisting of an alkali metal and an alkali metal. A donor compound in a group consisting of a complex of an alkali metal and an organic compound, an alkaline earth metal, an inorganic salt containing an alkaline earth metal, and a complex of an alkaline earth metal and an organic substance. The light-emitting element according to claim 1, wherein the electron transport layer comprises a compound having a heteroaryl ring structure, and the heteroaryl ring structure comprises a component selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, ruthenium and phosphorus. More than one element in a group and contains electron-accepting nitrogen. The light-emitting element according to claim 4, wherein the electron transport layer comprises a compound having a heteroaryl ring structure, and the heteroaryl ring structure comprises a compound selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, ruthenium and phosphorus. More than one element in a group and contains electron-accepting nitrogen.