WO2014057873A1

WO2014057873A1 - Phosphine oxide derivative and light-emitting element provided with same

Info

Publication number: WO2014057873A1
Application number: PCT/JP2013/077045
Authority: WO
Inventors: 上岡耕司; 田中大作; 新井猛; 市橋泰宜
Original assignee: 東レ株式会社
Priority date: 2012-10-10
Filing date: 2013-10-04
Publication date: 2014-04-17
Also published as: TW201414743A; JPWO2014057873A1

Abstract

The present invention addresses the problem of providing a phosphine oxide derivative compound of exceptional electron affinity, the phosphine oxide derivative compound having a specific fluoranthene backbone and a phosphine oxide structure; and of providing a light-emitting element such as an organic thin-film light-emitting element of greater light-emitting efficiency, drive voltage, and durability. The light-emitting element contains the aforementioned compound.

Description

Phosphine oxide derivative and light emitting device having the same

The present invention relates to a phosphine oxide compound having excellent electron affinity that can be used for a light-emitting element. The present invention can be used in fields such as display elements, flat panel displays, backlights, lighting, interiors, signs, signboards, electrophotographic machines, and optical signal generators.

In recent years, research on organic thin-film light emitting devices that emit light when electrons injected from a cathode and holes injected from an anode are recombined in an organic phosphor sandwiched between both electrodes has been actively conducted. This light emitting element is characterized by thin light emission with high luminance under a low driving voltage and multicolor light emission by selecting a fluorescent material.

This research was conducted by Kodak's C.I. W. Since Tang et al. Showed that organic thin film devices emit light with high brightness, many practical studies have been made, and organic thin film light emitting devices have been steadily put into practical use, such as being used in mobile phone main displays. Is progressing. However, there are still many technical issues. Above all, it is one of the major issues to achieve both high efficiency and long life of the device.

Organic thin-film light-emitting elements must satisfy improved luminous efficiency, lower drive voltage, and improved durable life. Although techniques using a phosphine oxide derivative to improve the luminous efficiency are disclosed in Patent Documents 1 to 3, the durability life is insufficient. Moreover, although the technique which uses a fluoranthene derivative as a blue light-emitting material is disclosed by patent document 4, it was not satisfied at the point of coexistence of a drive voltage and a durable life.

Japanese Patent Laid-Open No. 2002-63989 JP 2006-73581 A Japanese Patent Application Laid-Open No. 2008-244012 International Publication No. 2007/100010

As described above, in the conventional technology, there is a problem that if the light emission efficiency of the element is improved or the drive voltage is lowered, the durability life is reduced, and both high light emission efficiency, low drive voltage, and durability life are compatible. Technology has not yet been found.

An object of the present invention is to solve the problems of the conventional technology and to provide an organic thin film light emitting device excellent in luminous efficiency, driving voltage and durability life.

The present invention is a phosphine oxide derivative represented by the following general formula (1).

(In the formula, R ¹ and R ² may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group. , Aryl ether group, aryl thioether group, aryl group, heteroaryl group, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, and a condensed ring formed between adjacent substituents L ¹ is a single bond, an arylene group, or a heteroarylene group, Ar ¹ is a condensed polycyclic aromatic group represented by the following general formula (2), and n ¹ is 1 or more. (When n ¹ is 2 or more, L ¹ , R ¹ and R ² may be the same or different.)

(Wherein R ³ to R ¹² may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group. , Aryl ether group, aryl thioether group, aryl group, heteroaryl group, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group and silyl group, provided that R ³ to R ¹² are selected. Of which at least one pair of adjacent substituents forms a condensed ring, provided that it is linked to L ¹ at at least one of R ³ to R ^12. )

According to the present invention, a phosphine oxide compound having excellent electron affinity can be provided. Furthermore, by using it as a material for each layer of the light emitting element, it is possible to provide an organic thin film light emitting element that simultaneously satisfies the required characteristics of luminous efficiency, driving voltage, and durability life.

The phosphine oxide derivative represented by the general formula (1) will be described in detail.

In the formula, R ¹ and R ² may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, An aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a cyano group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group, and an adjacent substituent. Choose from the inside. L ¹ is a single bond, an arylene group, or a heteroarylene group. Ar ¹ is a condensed polycyclic aromatic group represented by the following general formula (2). n ¹ is an integer of 1 or more. When n ¹ is 2 or more, L ¹ , R ¹ and R ² may be the same or different.

In the formula, R ³ to R ¹² may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, It is selected from the group consisting of aryl ether groups, aryl thioether groups, aryl groups, heteroaryl groups, cyano groups, carbonyl groups, carboxyl groups, oxycarbonyl groups, carbamoyl groups, amino groups, and silyl groups. However, at least one pair of adjacent substituents among R ³ to R ¹² forms a condensed ring. In addition, it is connected to L ¹ at at least one position among R ³ to R ¹² .

[R ¹ and R ² ]
R ¹ and R ² are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group , A heteroaryl group, a cyano group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group and a condensed ring formed between adjacent substituents (hereinafter, in the description of R ¹ and R ² And may be abbreviated as “substituent etc.”). Hereinafter, a substituent etc. are demonstrated.

In the above substituents, etc., hydrogen may be deuterium. It should be noted that deuterium may be used for hydrogen other than all R ¹ and R ² in the present invention.

In the above substituents and the like, halogen represents an atom selected from fluorine, chlorine, bromine and iodine.

In the above substituents and the like, the alkyl group is, for example, a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group. This may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an aryl group, heteroaryl group, etc. can be mentioned. The number of carbon atoms of the alkyl group is not particularly limited, but is preferably 1 or more and 20 or less, more preferably 1 or more and 8 or less, from the viewpoint of availability and cost. The carbon number of the alkyl group does not include the carbon number of the substituent.

In the above substituents and the like, the cycloalkyl group means, for example, a saturated alicyclic hydrocarbon group such as a cyclopropyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, etc., which may have a substituent. You don't have to. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms in the alkyl group portion in the cycloalkyl group is not particularly limited, but is preferably in the range of 3 or more and 20 or less. In addition, the carbon number of the alkyl group part in a cycloalkyl group shall show the carbon number of the alkyl group contained as a cycloalkyl group and a substituent.

In the above substituents and the like, the heterocyclic group refers to, for example, an aliphatic ring having atoms other than carbon, such as a pyran ring, a piperidine ring, and a cyclic amide, in the ring, which may have a substituent. It may not have. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the heterocyclic group is not particularly limited, but is preferably in the range of 2 or more and 20 or less. The carbon number of the heterocyclic group includes the carbon number of an additional substituent when the heterocyclic group has a substituent.

In the above substituents and the like, the alkenyl group refers to, for example, an unsaturated aliphatic hydrocarbon group containing a double bond such as a vinyl group, an allyl group, or a butadienyl group, which may have a substituent. You don't have to. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the alkenyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less. The carbon number of the alkenyl group includes the carbon number of an additional substituent when the alkenyl group has a substituent.

In the above substituents and the like, the cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group, a cyclohexenyl group, and the like. It may or may not have. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned.

In the above substituents and the like, the alkynyl group means, for example, an unsaturated aliphatic hydrocarbon group containing a triple bond such as an ethynyl group, which may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the alkynyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less. In addition, the carbon number of an alkynyl group shall include the carbon number of an additional substituent, when an alkynyl group has a substituent.

In the above substituents, etc., the alkoxy group refers to a functional group to which an aliphatic hydrocarbon group is bonded through an ether bond such as a methoxy group, an ethoxy group, or a propoxy group, and the aliphatic hydrocarbon group is substituted. It may or may not have a group. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the alkoxy group is not particularly limited, but is preferably in the range of 1 or more and 20 or less. The carbon number of the alkoxy group includes the carbon number of an additional substituent when the alkoxy group has a substituent.

In the above substituents and the like, the alkylthio group is a group in which an oxygen atom of an ether bond of an alkoxy group is substituted with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the alkylthio group is not particularly limited, but is preferably in the range of 1 or more and 20 or less. In addition, the carbon number of the alkylthio group includes the carbon number of an additional substituent when the alkylthio group has a substituent.

In the above substituents and the like, the aryl ether group refers to a functional group to which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and the aromatic hydrocarbon group has a substituent. May not be included. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the aryl ether group is not particularly limited, but is preferably in the range of 6 or more and 40 or less. The carbon number of the aryl ether group includes the carbon number of an additional substituent when the aryl ether group has a substituent.

In the above substituents and the like, the aryl thioether group is a group in which the oxygen atom of the ether bond of the aryl ether group is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the aryl thioether group is not particularly limited, but is preferably in the range of 6 or more and 40 or less. The carbon number of the aryl thioether group includes the carbon number of an additional substituent when the aryl thioether group has a substituent.

In the above substituents and the like, the aryl group represents an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, a pyrenyl group, or a fluoranthenyl group. The aryl group may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the aryl group is not particularly limited, but is preferably in the range of 6 to 40. The carbon number of the aryl group includes the carbon number of an additional substituent when the aryl group has a substituent.

In the above substituents, etc., the heteroaryl group is a furanyl group, thiophenyl group, pyridyl group, quinolinyl group, isoquinolinyl group, pyrazinyl group, pyrimidyl group, naphthyridyl group, benzofuranyl group, benzothiophenyl group, indolyl group, dibenzofuran group. A cyclic aromatic group having one or more atoms other than carbon in the ring, such as an nyl group, a dibenzothiophenyl group, and a carbazolyl group, which may be unsubstituted or substituted. There is no restriction | limiting in particular in the additional substituent in the case of having a substituent, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. The number of carbon atoms of the heteroaryl group is not particularly limited, but is preferably in the range of 2 to 30. The carbon number of the heteroaryl group includes the carbon number of an additional substituent when the heteroaryl group has a substituent.

In the above substituents and the like, the carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group and silyl group may or may not have a substituent. Here, examples of the additional substituent in the case of having a substituent include an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like, and these substituents may further have a substituent. Furthermore, the substituent in the case of having a substituent is as described above.

In the above-mentioned substituents and the like, the condensed ring formed between adjacent substituents is, for example, R ¹ and R ² , or R ¹ or R ² and L ¹ . A conjugated or non-conjugated fused ring is formed between them. When L ¹ is a single bond, a condensed ring may be formed between R ¹ and Ar ¹ or R ² and Ar ¹ . These fused rings may contain nitrogen, oxygen, sulfur atoms in the ring structure, or may be condensed with another ring. The meaning of the single bond when L ¹ is a single bond will be described later.

In addition, when R ¹ and R ² are an aryl group or a heteroaryl group, the electrochemical stability described later is increased, and the durability of the light-emitting element is improved, which is preferable.

[L ¹ ]
L ¹ is a single bond, an arylene group, or a heteroarylene group.

A single bond means that L ¹ does not exist as a bonding group, and Ar ¹ and phosphorus are directly bonded in the general formula (1).

An arylene group refers to a divalent or trivalent group derived from an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, or a biphenyl group, which may or may not have a substituent. . When L ^{1 in the} general formula (1) is an arylene group, the number of nuclear carbon atoms is preferably in the range of 6 to 30. Specific examples of the arylene group include 1,4-phenylene group, 1,3-phenylene group, 1,2-phenylene group, 4,4′-biphenylene group, 4,3′-biphenylene group, 3,3 Examples include '-biphenylene group, 1,4-naphthylene group, 1,5-naphthylene group, 2,5-naphthylene group, 2,6-naphthylene group, 2,7-naphthylene group and the like. More preferred are a 1,4-phenylene group and a 1,3-phenylene group.

A heteroarylene group is an aromatic group having one or more atoms other than carbon, such as a pyridyl group, a quinolinyl group, a pyrimidinyl group, a pyrazinyl group, a naphthyridyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and a carbazolyl group. A divalent or trivalent group derived from a group is shown, which may or may not have a substituent. The number of carbon atoms of the heteroarylene group is not particularly limited, but a range of 2 to 30 nuclear carbon atoms is preferable.

In addition, when L ¹ is an arylene group or a heteroarylene group, the fluorescence quantum yield of the phosphine oxide derivative represented by the general formula (1) is improved, and the efficiency of the light-emitting element is preferably improved.

[R ³ to R ¹² ]
R ³ to R ¹² may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group , An arylthioether group, an aryl group, a heteroaryl group, a cyano group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, and a silyl group (hereinafter referred to as “substituents for R ³ to R ¹² etc.”) May be abbreviated as). However, at least one pair of adjacent substituents among R ³ to R ¹² forms a condensed ring. In addition, it is connected to L ¹ at at least one position among R ³ to R ¹² .

As the substituents and the like listed in the substituents of R ³ to R ¹² , the same as the corresponding ones of the substituents of R ¹ and R ² can be applied.

The adjacent substituents of R ³ to R ¹² are specifically R ³ and R ⁴ , R ⁴ and R ⁵ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , R ⁷ and R ⁸ , R ⁸ and It refers to any combination of R ⁹ , R ⁹ and R ¹⁰ , R ¹⁰ and R ¹¹ , R ¹¹ and R ¹² , R ¹² and R ³ .

Of these adjacent substituents, at least one set of adjacent substituents forms a condensed ring. The size of the condensed ring formed at this time is not particularly limited, but a 5-membered ring or a 6-membered ring is preferable from the viewpoint of the stability of the molecular structure. The condensed ring formed may be an aliphatic ring or an aromatic ring. The condensed ring formed by the adjacent substituent may further have a substituent, or may be further condensed. Examples of the substituent in such a case include the substituents of R ¹ and R ² .

In addition, if the condensed polycyclic aromatic group represented by the general formula (2) contains an electron-donating nitrogen, the electron affinity may be lowered. Therefore, the condensed polycyclic aromatic represented by the general formula (2) It is preferred that the group does not contain electron donating nitrogen in the ring. Therefore, the formed condensed ring may contain a heteroatom other than carbon, but it is preferable that no electron-donating nitrogen is contained in the ring. The electron donating nitrogen represents a nitrogen atom in which all the bonds between adjacent atoms are single bonds. In particular, it is preferable that the ring is composed of only carbon and hydrogen because the electrochemical stability is increased and the durability of the device is improved. In addition, when the ring formed contains electron-accepting nitrogen, reduction by electrons is performed smoothly, and the electron affinity is increased. This is preferable because drive voltage and light emission efficiency are improved. The electron-accepting nitrogen represents a nitrogen atom that forms a multiple bond with an adjacent atom.

[Ar ¹ ]
Ar ¹ satisfying the above is not particularly limited, but examples include the following.

R ³ is to be connected to the ^{L 1} at least one position of the ~ ^{R ^12,} means that the carbon atom to which R 3 ^{~ R 12} is attached and ^{L 1} is directly connected. In addition, when a ring is formed by an adjacent substituent among R ³ to R ¹² , it includes connection to L ¹ at any position of the ring (R ¹³ to R ²⁴ , R ²⁵ described later). The same applies to .about.R ³⁸ ).

[Phosphine oxide group]
The phosphine oxide derivative represented by the general formula (1) has a phosphine oxide group. Since the phosphine oxide group has a three-dimensional pyramid bulky steric structure, the phosphine oxide group has a large steric hindrance and has an effect of suppressing intermolecular interaction. This effect increases the amorphous nature of the material and the glass transition temperature. Therefore, when a thin film of the phosphine oxide derivative of the present invention is formed and used for a light emitting device, the stability of the thin film is improved and the durability of the light emitting device is improved. The service life is improved compared to the conventional one. Moreover, since concentration quenching can be reduced by suppressing the interaction between molecules, having a phosphine oxide group also contributes to an improvement in luminous efficiency when used in a light emitting element. Furthermore, since the phosphine oxide group is a strong electron-attracting group, the compound of the general formula (1) is a material having excellent electron affinity, and its driving voltage can be lowered when used in a light-emitting element.

[N ¹ ]
In the phosphine oxide derivative of the present invention, n ¹ is an integer of 1 or more. When n ¹ is 2 or more, L ¹ , R ¹ and R ² may be the same or different.

Note that if the molecular weight of the phosphine oxide derivative is too large, the sublimation property is lowered, and the probability of thermal decomposition during vacuum deposition when forming a thin film increases. Accordingly, n ¹ is preferably 1 or 2, and particularly preferably n ¹ = 1.

[Phosphine oxide derivatives]
The phosphine oxide derivative represented by the general formula (1) has a structure Ar ^{1 in} which at least one of the group consisting of an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring, an aliphatic group and an aromatic heterocyclic ring is condensed to fluoranthene. Have. This skeleton has a 5-membered 5-membered ring structure. The 5π-electron five-membered ring structure becomes a 6π-electron system when one electron enters (reduced), and aromatic stabilization occurs (Hückel rule). For this reason, the 5-membered ring structure of the 5π electron system exhibits high electron affinity.

For this reason, a drive voltage can be lowered | hung by using the light emitting element material containing the phosphine oxide derivative represented by General formula (1) for a light emitting element. Further, Ar ¹ has a π-conjugated plane wider than that of fluoranthene because an aliphatic or aromatic hydrocarbon ring or an aliphatic or aromatic heterocyclic ring is condensed to the fluoranthene skeleton. Since the molecules overlap each other well due to this planarity, Ar ¹ has a high charge transporting property and can reduce the driving voltage of the light emitting element.

In addition, since the skeleton represented by Ar ¹ can smoothly and repeatedly perform reduction by electrons and oxidation by holes, it contributes to improvement in durability of the light-emitting element. The fluoranthene skeleton has an emission spectrum peak in the ultraviolet region, but when the π-conjugate plane is expanded by condensing a ring with fluoranthene, the emission spectrum peak shifts to the visible light region and exhibits strong blue to green fluorescence. Therefore, the phosphine oxide derivative represented by the general formula (1) having Ar ¹ can be particularly suitably used as a blue to green fluorescent material.

As described above, since the phosphine oxide derivative represented by the general formula (1) of the present invention has a phosphine oxide group and Ar ¹ in the molecule, strong fluorescence emission, high electron affinity, thin film stability, It also has features such as electrochemical stability. Due to these characteristics, when a light-emitting element material containing the phosphine oxide derivative represented by the general formula (1) of the present invention is used in any layer constituting the light-emitting element, high light emission efficiency, low driving voltage, and durability are achieved. An organic thin film light emitting device having excellent properties can be obtained.

[Preferred embodiment of Ar ¹ ]
When Ar ¹ is represented by the following general formula (3) or (4), it is preferable because charge transport properties are further improved. Further, since the π-electron conjugated system of Ar ¹ spreads moderately and exhibits strong blue to green fluorescent light emission, it is preferable when used as a fluorescent light-emitting material because the light emission efficiency is improved.

When Ar ¹ is the following general formula (3)

In the formula, R ¹³ to R ²⁴ may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, A group consisting of an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a cyano group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, and a silyl group (hereinafter referred to as “substitution of R ¹³ to R ²⁴ ” Group ”or the like. However, it is connected to L ¹ at at least one position among R ¹³ to R ²⁴ .

In the general formula (3), as the substituents listed in the substituents of R ¹³ to R ²⁴ and the like, the same ones as the corresponding ones of the substituents of R ¹ and R ² can be applied. Among these, R ¹⁹ and R ²⁴ are preferably a substituted or unsubstituted aryl group. When R ¹⁹ and R ²⁴ are substituted or unsubstituted aryl groups, it is possible to moderately reduce the overlap of π conjugate planes between molecules. Moreover, heat resistance improves by being an aryl group. As a result, without impairing the high charge transport property of the skeleton represented by the general formula (3), the sublimation property is improved, the deposition stability is improved, the crystallinity is lowered, and the thin film stability is improved by the high glass transition temperature. It becomes possible. Further, when used as a light emitting material, it also contributes to suppression of concentration quenching due to interaction between molecules. Further, R ¹⁹ and R ²⁴ are more preferably a substituted or unsubstituted phenyl group. When R ¹⁹ and R ²⁴ are substituted or unsubstituted phenyl groups, it is possible to reduce the overlap of π conjugate planes between molecules to a more appropriate range. Moreover, since it becomes a moderate molecular weight, sublimation property and vapor deposition stability further improve.

Ar ¹ represented by the general formula (3) is preferably linked to L ¹ at any position of R ¹⁵ , R ¹⁶ , R ¹⁹ , R ²¹ , R ²² , R ²⁴ , particularly R ¹⁵ or R ^16. It is preferable to connect at the position. In the skeleton represented by the general formula (3), conjugation easily spreads at the positions of R ¹⁵ and R ¹⁶ , and conjugation efficiently spreads by connecting to L ³ . Thereby, the phosphine oxide derivative represented by the general formula (1) becomes more electrochemically stable, and the light emission efficiency is further improved.

When Ar ¹ is the following general formula (4)

In the formula, R ²⁵ to R ³⁸ may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, A group consisting of aryl ether group, aryl thioether group, aryl group, heteroaryl group, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group and silyl group (hereinafter referred to as “substitution of R ²⁵ to R ³⁸ ” Group ”or the like. However, at least one of R ²⁵ to R ³⁸ is linked to L ¹ .

In the general formula (4), as the substituents and the like listed in the substituents of R ²⁵ to R ³⁸ , the same as the corresponding ones of the substituents of R ¹ and R ² can be applied. Among these, R ²⁵ is preferably a substituted or unsubstituted aryl group. When R ²⁵ is a substituted or unsubstituted aryl group, it is possible to moderately reduce the overlap of π conjugate planes between molecules. Moreover, heat resistance improves by being an aryl group. As a result, without impairing the high charge transport property of the skeleton represented by the general formula (4), the sublimation property is improved, the deposition stability is improved, the crystallinity is lowered, and the thin film stability is improved by a high glass transition temperature. It becomes possible. Further, when used as a light emitting material, it also contributes to suppression of concentration quenching due to interaction between molecules. Furthermore, R ²⁵ in the general formula (4) is more preferably a substituted or unsubstituted phenyl group. When R ²⁵ is a substituted or unsubstituted phenyl group, it is possible to reduce the overlap of π conjugate planes between molecules to a more appropriate range. Moreover, since it becomes a moderate molecular weight, sublimation property and vapor deposition stability further improve.

Ar ¹ represented by the general formula (4) is preferably linked to L ¹ at any of the positions of R ²⁵ , R ²⁷ , R ³⁵ or R ³⁶ . In particular, it is preferable to link at the position of R ²⁷ or R ^{35 because} the intermolecular interaction suppression effect is high and contributes to the improvement of the light emission efficiency.

The phosphine oxide derivative represented by the general formula (1) is not particularly limited, but specific examples include the following.

[Synthesis of phosphine oxide derivatives]
A known method can be used for the synthesis of the phosphine oxide derivative represented by the general formula (1). Examples of the method for introducing a phosphine oxide group into Ar ¹ include a method in which an alkyl lithium reagent is added to substituted or unsubstituted halogen Ar ¹ at a low temperature and chlorophosphine oxide is further added dropwise. It is not limited. In addition, when introducing phosphine oxide into Ar ¹ via an arylene group or heteroarylene group, a substituted or unsubstituted aryl halide under a palladium catalyst or a nickel catalyst and an aryl boronic acid substituted with phosphine oxide or hetero A coupling reaction with an aryl boronic acid can be used. Moreover, it can replace with said various boronic acid and can also use boronic acid ester.

[Uses of phosphine oxide derivatives]
The phosphine oxide derivative represented by the general formula (1) is used as a light emitting element material. Here, the light emitting element is a light emitting element in which an organic layer exists between an anode and a cathode and emits light by electric energy, and the light emitting element material refers to a material used in any of the organic layers. As described later, the organic layer of such a light-emitting element includes a hole transport layer, a light-emitting layer, an electron transport layer, a hole injection layer, and an electron injection layer, and also includes a cathode protective film layer. By using the light-emitting element material containing the phosphine oxide derivative represented by the general formula (1) for any layer that is at least part of the organic layer of the light-emitting element, high luminous efficiency can be obtained and low A light emitting element excellent in driving voltage and durability can be obtained.

Since the light-emitting element material containing the phosphine oxide derivative represented by the general formula (1) has high electron affinity and fluorescence quantum yield, it is preferably used for the light-emitting layer or the electron transport layer. In particular, when the phosphine oxide derivative represented by the general formula (1) is used as a dopant material of the light emitting layer, excessive electron is trapped in the light emitting layer due to the strength of the electron affinity, and the hole transport layer is prevented from deteriorating. It is preferable because the durability of the element is improved.

Further, when the phosphine oxide derivative represented by the general formula (1) is used as the dopant material of the light emitting layer, any one of the compounds represented by the general formulas (5) to (8) is used as the material for the electron transport layer. More electrons can be injected into the light emitting layer, which is preferable because driving voltage and light emission efficiency of the light emitting element are improved. In general, when the electron injecting property to the light emitting layer is increased by the material of the electron transporting layer, the influence of the electron attack on the hole transporting layer is increased and the durability of the device is lowered, but the general formula (1 In combination with a phosphine oxide derivative represented by (2) as a dopant material of the light emitting layer, a light emitting element satisfying all of drive voltage, light emission efficiency, and durability life can be obtained.

[Material of electron transport layer]
The compounds represented by the general formulas (5) to (8) will be described in detail.

R ³⁹ to R ⁴⁸ may be the same or different and each represents hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, A group consisting of arylthioether group, aryl group, heteroaryl group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group and —P (═O) R ⁴⁹ R ⁵⁰ (hereinafter referred to as “R ^39- R ⁴⁸ substituents etc. ”may also be abbreviated. However, it is connected to L ² at at least one position among R ³⁹ to R ⁴⁸ . L ² is a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, and Ar ² is an aromatic heterocyclic group containing an electron-accepting nitrogen. n ² is an integer of 1 or more. When n ² is 2 or more, L ² and Ar ² may be the same or different.

As the substituents and the like listed in the substituents of R ³⁹ to R ⁴⁸ , the same as the corresponding ones of the substituents of R ¹ and R ² can be applied. In addition, R ⁴⁹ and R ⁵⁰ can independently apply the substituents listed as the substituents of R ¹ and R ² or the like.

Ar ² is an aromatic heterocyclic group containing electron-accepting nitrogen. Aromatic heterocyclic groups containing electron-accepting nitrogen are pyridyl group, quinolinyl group, isoquinolinyl group, quinoxalinyl group, pyrazinyl group, pyrimidyl group, pyridazinyl group, phenanthrolinyl group, imidazopyridyl group, triazyl group, acridyl group , A benzoimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, and the like, as a non-carbon atom, a cyclic aromatic group having at least one electron-accepting nitrogen atom in the ring. May be unsubstituted or may have a substituent. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property. Therefore, an aromatic heterocycle containing electron-accepting nitrogen has a high electron affinity. Although carbon number of the aromatic heterocyclic group containing electron-accepting nitrogen is not specifically limited, Usually, it is the range of 2-30. The connecting position of the aromatic heterocyclic group containing an electron-accepting nitrogen may be any part. For example, in the case of a pyridyl group, it may be any of 2-pyridyl group, 3-pyridyl group and 4-pyridyl group.

The pyrene compound represented by the general formula (5) has an aromatic heterocycle containing a pyrene skeleton and electron-accepting nitrogen in the molecule. As a result, it is possible to achieve both high electron transportability and electrochemical stability of the pyrene skeleton and high electron acceptability of the aromatic heterocycle containing electron accepting nitrogen, and high electron injecting and transporting ability is exhibited. Ar ² is preferably a pyridyl group, a quinolinyl group, a quinoxalinyl group, a pyrimidyl group, a phenanthrolinyl group, a benzo [d] imidazolyl group, an imidazo [1,2-a] pyridyl group, or the like. More specifically, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-quinolinyl group, 3-quinolinyl group, 6-quinolinyl group, 1-isoquinolinyl group, 3-isoquinolinyl group, 2-quinoxanyl group, 5-pyrimidyl group, 2-phenanthrolinyl group, 1-benzo [d] imidazolyl group, 2-benzo [d] imidazolyl group, 2-imidazol [1,2-a] pyridyl group, 3-imidazolo [1, 2-a] pyridyl group and the like, more preferably 2-pyridyl group, 3-pyridyl group, 4-pyridyl group and the like.

L ² is a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, and these definitions are the same as L ¹ . L ² is preferably an arylene group. Since aromatic heterocycles containing electron-accepting nitrogen are vulnerable to oxidation, bonding via an arylene group is more electrochemically stable than bonding directly to a pyrene skeleton. This creates a synergistic effect with the high electron transport property of the pyrene skeleton, and expresses higher electron injecting and transporting ability.

N ² is an integer of 1 or more, but if the molecular weight of the material is too large, the sublimation property is lowered and the probability of thermal decomposition during vacuum deposition increases. Therefore, n ² is preferably 4 or less, more preferably n ² = 1 or 2.

Further, (a) R ³⁹ is used for linking with L ² and R ⁴⁴ is an aryl group or a heteroaryl group, or (b) R ³⁹ is used for linking with L ² , and R ⁴¹ is An aryl group or a heteroaryl group, and R ⁴⁴ , R ⁴⁵ , and R ⁴⁶ are all hydrogen atoms, or (c) R ³⁹ is used for linking with L ² , and R ⁴¹ is an aryl group or When it is a heteroaryl group and R ⁴⁵ is an alkyl group, an aryl group or a heteroaryl group, the interaction between the pyrene skeletons is moderately suppressed due to the steric hindrance of the substituent on the pyrene skeleton, and the glass transition temperature is high. Become. This effect improves the stability of the thin film state and improves the durability of the light emitting element.

The compound represented by the general formula (5) is not particularly limited, but specifically, compounds described in Chemical Formulas 3 to 14 of International Publication No. 2010/113743, Japanese Patent Laid-Open No. 2011-204844 And the compounds described in Chemical Formulas 9 to 24. Moreover, the following compounds can also be mentioned.

R ⁵¹ to R ⁵⁸ may be the same as or different from each other, and may be hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, An arylthioether group, an aryl group, a carbonyl group, a carboxyl group, a carbamoyl group, an amino group, a silyl group, and a group consisting of —P (═O) R ⁵⁹ R ⁶⁰ (hereinafter referred to as “substituents of R ⁵¹ to R ⁵⁸ , etc.”) (It may be abbreviated). R ⁵⁹ and R ⁶⁰ are an aryl group or a heteroaryl group. R ⁵⁹ and R ⁶⁰ may be condensed to form a ring. However, at least one of R ⁵¹ to R ⁵⁸ itself has a three-dimensional structure, or has a three-dimensional structure by steric repulsion with a phenanthroline skeleton or an adjacent substituent.

R ⁶¹ to R ⁶⁸ may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, An arylthioether group, an aryl group, a carbonyl group, a carboxyl group, a carbamoyl group, an amino group, a silyl group, and a group consisting of —P (═O) R ⁶⁹ R ⁷⁰ (hereinafter referred to as “substituents of R ⁶¹ to R ⁶⁸ , etc.”) (It may be abbreviated). R ⁶⁹ and R ⁷⁰ are an aryl group or a heteroaryl group. R ⁶⁹ and R ⁷⁰ may be condensed to form a ring. However, n ³ phenanthroline skeletons are each linked to X at at least one of R ⁶¹ to R ⁶⁸ . n ³ represents an integer of 2 or more. X is a connecting unit that connects a single bond or a plurality of phenanthroline skeletons.

As the substituents and the like listed in the substituents of R ⁵¹ to R ⁵⁸ , the same as the corresponding ones of the substituents of R ¹ and R ² can be applied. R ⁵⁹ and R ⁶⁰ are each independently the same as the corresponding ones of the substituents of R ¹ and R ² . Similarly, as the substituents and the like listed in the substituents of R ⁶¹ to R ⁶⁸ , the same ones as the corresponding ones of the substituents of R ¹ and R ² can be applied. R ⁶⁹ and R ⁷⁰ are each independently the same as the corresponding ones of the substituents of R ¹ and R ² and the like.

R ⁵¹ to R ⁵⁸ having a three-dimensional structure per se means a structure in which atoms constituting a group are not in the same plane and have an effect of preventing overlapping of molecules by steric repulsion. . Examples of the substituent having a particularly remarkable steric repulsion effect include isopropyl group, t-butyl group, cyclohexyl group, adamantyl group, norbornyl group, 9,9′-dimethylfluorenyl group, 9,9′-diphenylfluorene. Nyl group, spirofluorenyl group, etc. are mentioned. These groups may be unsubstituted or may have a substituent.

In addition, substituents that give a three-dimensional structure by steric repulsion with the phenanthroline skeleton or adjacent substituents are substituents such as phenyl, naphthyl, phenanthryl, anthryl, pyrenyl, and fluoranthenyl groups. Even if it is a planar structure itself, the steric repulsion between the substituent and the phenanthroline skeleton, or the substituent and the adjacent substituent indicates that the substituent plane is different from the phenanthroline skeleton plane. Specific examples of the substituent that causes steric repulsion with the phenanthroline skeleton include a 1-naphthyl group, 9-phenanthryl group, 9-anthryl group, 1-pyrenyl group, and 3-fluoranthenyl group.

In addition, even if the substituent itself has a poor steric repulsion effect with the phenanthroline skeleton, such as a phenyl group or a 2-naphthyl group, the same steric repulsion may be obtained if the substituent further has a substituent at the ortho position. An effect is obtained. Specific examples of such substituents include 2-methylphenyl group, 2,6-dimethylphenyl group, mesityl group, 2-t-butylphenyl group, 2-biphenyl group, 2- (1-methyl) naphthyl group, Examples include 2- (1-t-butyl) naphthyl group and 2- (1-phenyl) naphthyl group. Even when there is no substituent at the ortho position, a steric repulsion effect with the adjacent substituent can be obtained when the adjacent position on the phenanthroline skeleton has a substituent such as a phenyl group.

A compound containing a phenanthroline skeleton has low planarity and can be crystallized because the substituent itself has a three-dimensional steric structure, or a steric repulsion with the phenanthroline skeleton or a neighboring substituent brings about a three-dimensional steric structure. It is difficult to occur and a good amorphous thin film state can be maintained.

In addition, by linking a plurality of phenanthroline skeletons, a compound containing the phenanthroline skeleton has a high molecular weight and a glass transition temperature rises, so that crystallization hardly occurs and a good amorphous thin film state can be maintained.

Among the compounds having the phenanthroline skeletons of the general formulas (6) and (7) in the present invention, it is more preferable to introduce substituents at the 2, 4, 7, and 9 positions of the phenanthroline skeleton. For these substituents, the same substituents as those described in the section <Compounds represented by formulas (6) and (7)> can be applied.

N ^{3 in the} general formula (7) is an integer of 2 or more. However, if the molecular weight of the material is too large, the sublimation property is lowered and the probability of thermal decomposition during vacuum deposition increases. For this reason, n ^{3 in the} general formula (7) is more preferably 2.

In the general formula (7), X is a connecting unit that connects a single bond or a plurality of phenanthroline skeletons. Such X is not particularly limited, but from the viewpoint of thermal stability and chemical stability, an arylene group or a heteroarylene group is preferable, and at least selected from a benzene ring, a substituent having a terphenyl skeleton, and a naphthalene ring. One type is preferable.

When X is a benzene ring, X is preferably a 1,4-phenylene group or a 1,3-phenylene group for ease of synthesis. In this case, at least one of R ⁶¹ to R ⁶⁸ is from the viewpoint of heat resistance. To an aryl group. As the aryl group, an unsubstituted or substituted phenyl group, p-tolyl group, m-tolyl group, 3,5-dimethylphenyl group, 4-t-butylphenyl group, etc. from the viewpoint of ease of synthesis and sublimation An unsubstituted or substituted naphthyl group such as a substituted phenyl group, 1-naphthyl group, 2-naphthyl group, and 1- (2-methyl) naphthyl group is more preferable. In addition, when X in the general formula (7) is a naphthalene ring, X is a 1,6-naphthylene group, 1,7-naphthylene group, 2,6-naphthylene group, 2,7-naphthylene group because of ease of synthesis. Groups are more preferred. Further, when X in the general formula (7) is a substituent having a terphenyl skeleton, it is preferably a substituent having the following structure.

Further, from the viewpoint of sublimability, it is more preferable that the structure has the following structure in which at least one benzene ring is linked at the ortho position.

The compound represented by the general formula (6) or (7) is not particularly limited, but specifically, the compounds described in Chemical formulas 6 to 9 of JP-A No. 2001-267080, Examples include compounds described in Chemical Formulas 3 to 7 and Chemical Formulas 13 to 14 of Japanese Patent No. 281390.

In the formula, Ar ³ represents an aryl group or a heteroaryl group, and L ³ represents a single bond, an arylene group, or a heteroarylene group. Z is represented by the following general formula (9). n ⁴ is 1 or 2. When n ⁴ is 2, two Zs may be the same or different.

In the formula, each of ring A and ring B represents a benzene ring, a condensed aromatic hydrocarbon ring, a monocyclic aromatic heterocyclic ring, or a condensed aromatic heterocyclic ring. However, ring A and / or ring B contains at least one electron-accepting nitrogen. The substituent in the case where ring A and ring B have a substituent, and R ⁷¹ are each an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, Selected from the group consisting of a group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, and —P (═O) R ⁷² R ⁷³ . R ⁷¹ may be hydrogen. R ⁷² and R ⁷³ are an aryl group or a heteroaryl group. R ⁷² and R ⁷³ may be condensed to form a ring. However, it is connected to L ³ at any position among R ⁷¹ , ring A and ring B. When n ⁴ is 2, the positions at which two Z are linked to L ³ may be the same or different.

In the general formula (8), Ar ³ represents an aryl group or a heteroaryl group. The definitions of the aryl group and heteroaryl group are the same as those listed as the substituents for R ¹ and R ² and the like.

In the general formula (8), L ³ represents a single bond, an arylene group or a heteroarylene group. A single bond means that L ³ does not exist as a bonding group, and Ar ³ and Z are directly bonded. The definitions of the arylene group and the heteroarylene group are the same as those in L ¹ described above.

In the general formula (8), n ⁴ is 1 or 2. Since the compound represented by the general formula (8) has one or two groups represented by Z, the crystallinity is lowered or the glass transition temperature is increased, so that the stability of the film is improved. improves. When n ⁴ is 2, two Zs may be the same or different. In Z represented by the general formula (9), ring A and ring B each represent a benzene ring, a condensed aromatic hydrocarbon ring, a monocyclic aromatic heterocyclic ring, or a condensed aromatic heterocyclic ring. However, ring A and / or ring B contains at least one electron-accepting nitrogen. The electron-accepting nitrogen represents a nitrogen atom forming a multiple bond with an adjacent atom as described. Since such a nitrogen atom has a high electronegativity, a multiple bond formed between adjacent atoms has an electron-accepting property. Therefore, Z having electron-accepting nitrogen has a high electron affinity. For this reason, when the compound of General formula (8) is used for an electron carrying layer, the favorable electron injection property from an electrode is shown, and the drive voltage of a light emitting element can be made low. As a result, the light emission efficiency of the light emitting element can be improved.

The substituent in the case where ring A and ring B have a substituent, and R ⁷¹ are each an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, Group, aryl ether group, aryl thioether group, aryl group, heteroaryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group and —P (═O) R ⁷² R ⁷³ (hereinafter referred to as “Z Or the like. R ⁷¹ may be hydrogen. As the substituents and the like listed in the substituent for Z and the like, the same ones as those corresponding to the substituents for R ¹ and R ² can be applied. R ⁷² and R ⁷³ are each independently the same as the corresponding ones of the substituents of R ¹ and R ² .

Connecting to L ³ at any position of R ⁷¹ , ring A and ring B means the following. ^First, the coupling with ^{L 3} at the position of ^{R 71} ^refers to the nitrogen atom and ^{L 3} ^{which R 71} is linked directly binds. In addition, when linked to L ³ at any position of ring A and ring B, for example, when ring A is a benzene ring, L ³ is directly bonded to any of the carbon atoms constituting the benzene ring. Say.

Z has electron donating nitrogen. In Z, the nitrogen atom to which R ⁷¹ is bonded corresponds to this. Electron-donating nitrogen has high stability against holes and can be smoothly and repeatedly oxidized by holes. Therefore, when the compound of the general formula (8) is used for the electron transport layer, deterioration of the electron transport layer due to holes leaking from the light emitting layer can be prevented, and the lifetime of the light emitting element is extended as compared with the conventional one. be able to.

In the general formula (8), Ar ³ is preferably a group containing a fluoranthene skeleton or a group containing a benzofluoranthene skeleton. Since the fluoranthene skeleton or benzofluoranthene skeleton has a 5π-electron five-membered ring structure as described above, it has a strong electron affinity and exhibits good electron injection from the electrode when used in an electron transport layer. The driving voltage of the light emitting element can be lowered. As a result, the light emission efficiency of the light emitting element can be improved. In addition, it contributes to extending the life of the light emitting element.

Further, the fluoranthene skeleton and the benzofluoranthene skeleton have high planarity and have high charge transport properties because the molecules overlap each other well. For this reason, when the compound represented by the general formula (8) is used in the electron transport layer, electrons generated from the cathode can be efficiently transported, so that the driving voltage of the device can be lowered. As a result, the light emission efficiency of the light emitting element can be improved. In addition, it contributes to extending the life of the light emitting element.

In addition, the fluoranthene skeleton and the benzofluoranthene skeleton are highly stable against electric charges, and can be smoothly and repeatedly reduced by electrons and oxidized by holes. Therefore, when the compound represented by the general formula (8) is used for the electron transport layer, the lifetime can be improved.

<Preferred embodiment of the compound represented by the general formula (8)>
When Ar ³ is a group containing a fluoranthene skeleton, the compound represented by the general formula (8) is preferably a compound represented by the following general formula (10). The compound represented by the general formula (10) is a compound in which the 3-position of the fluoranthene skeleton is substituted with a substituent containing Z. In the fluoranthene derivative, when the 3-position is substituted with an aromatic substituent, the electronic state of the fluoranthene skeleton is greatly changed, and conjugation is efficiently expanded, so that the charge transport property is improved. As a result, the light emitting element can be driven at a low voltage, and the light emission efficiency can be improved. Furthermore, since the conjugation spreads, the stability against charges is also improved.

In the formula, each of R ⁷⁴ to R ⁸² may be the same or different, and is hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group. , An arylthioether group, an aryl group, a heteroaryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, and a carbamoyl group (hereinafter, sometimes abbreviated as “substituents for R ⁷⁴ to R ⁸² ”, etc.) More selected. R ⁷⁴ to R ⁸² may form a ring with adjacent substituents. L ³ , Z and n ⁴ are the same as those in the general formula (8).

As the substituents and the like listed in the substituents R ⁷⁴ to R ⁸² in the general formula (10), the same ones as the corresponding ones among the substituents R ¹ and R ² can be applied. Among these, it is preferably selected from the group consisting of hydrogen, alkyl group, cycloalkyl group, aryl group, heteroaryl group and halogen. When R ⁷⁴ to R ⁸² are hydrogen, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or a halogen, the glass transition temperature is increased and the thin film stability is improved. In addition, since the substituent is difficult to decompose even at high temperatures, the heat resistance is improved. Furthermore, when it is an aryl group or a heteroaryl group, conjugation spreads, so that it becomes more electrochemically stable and charge transportability is improved.

When Ar ³ is a group containing a benzofluoranthene skeleton, Ar ³ is preferably a group represented by the following general formula (11). When benzofluoranthene is represented by the general formula (11), the conjugated system spreads moderately. Thereby, it becomes electrochemically stable and further the charge transport property is improved.

In the formula, each of R ⁸³ to R ⁹⁴ may be the same or different and is hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group. , An arylthioether group, an aryl group, a heteroaryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, and a carbamoyl group (hereinafter sometimes abbreviated as “substituents for R ⁸³ to R ⁹⁴ , etc.”) More selected. R ⁸³ to R ⁹⁴ may form a ring with adjacent substituents. However, it is connected to L ³ at any one of R ⁸³ to R ⁹⁴ .

As the substituents and the like listed in the substituents R ⁸³ to R ⁹⁴ in the general formula (11), the same ones as the corresponding ones among the substituents R ¹ and R ² can be applied. Among these, it is preferably selected from the group consisting of hydrogen, alkyl group, cycloalkyl group, aryl group, heteroaryl group and halogen. When R ⁸³ to R ⁹⁴ are hydrogen, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or a halogen, the glass transition temperature is increased and the thin film stability is improved. When the thin film stability is improved, the deterioration of the film is suppressed even if the light emitting element is driven for a long time, so that the durability is improved. In addition, since the substituent is difficult to decompose even at high temperatures, the heat resistance is improved. When the heat resistance is improved, the decomposition of the material can be suppressed at the time of device fabrication, so that the durability is improved. Furthermore, when it is an aryl group or a heteroaryl group, conjugation spreads, so that it becomes more electrochemically stable and charge transportability is improved.

In the general formula (11), R ⁸⁷ and R ⁹² are preferably a substituted or unsubstituted aryl group. When R ⁸⁷ and R ⁹² are substituted or unsubstituted aryl groups, it is possible to moderately avoid overlapping of π conjugate planes between molecules. Moreover, heat resistance improves by being an aryl group. As a result, it is possible to improve sublimation, improve deposition stability, decrease crystallinity, and improve thin film stability due to a high glass transition temperature without impairing the high charge transport property of the benzofluoranthene compound.

R ⁸⁷ and R ⁹² in general formula (11) are more preferably a substituted or unsubstituted phenyl group. When R ⁸⁷ and R ⁹² are substituted or unsubstituted phenyl groups, it is possible to appropriately avoid overlapping of π-conjugated planes between molecules. Moreover, since it becomes a moderate molecular weight, sublimation property and vapor deposition stability further improve.

The compound represented by the general formula (8) is preferably a compound represented by the following general formula (12). In benzofluoranthene, conjugation easily spreads at the positions of R ⁸³ and R ^{84 in} the general formula (11), and conjugation efficiently spreads when R ⁸³ is linked to L ³ . Thereby, the compound represented by the general formula (12) becomes more electrochemically stable, and the charge transport property is further improved.

In the formula, each of R ⁹⁵ to R ¹⁰⁵ may be the same or different and is hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group. , An arylthioether group, an aryl group, a heteroaryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, and a carbamoyl group (hereinafter, abbreviated as “substituents for R ⁹⁵ to R ¹⁰⁵ , etc.”) More selected. R ⁹⁵ to R ¹⁰⁵ may form a ring with adjacent substituents. L ³ , Z and n ⁴ are the same as those in the general formula (8).

As the substituents and the like listed in the substituents of R ⁹⁵ to R ¹⁰⁵ in the general formula (12), the same as the corresponding ones of the substituents of R ¹ and R ² can be applied. Among these, it is preferably selected from the group consisting of hydrogen, alkyl group, cycloalkyl group, aryl group, heteroaryl group and halogen. When R ⁹⁵ to R ¹⁰⁵ are hydrogen, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or a halogen, the glass transition temperature is increased and the thin film stability is improved. In addition, since the substituent is difficult to decompose even at high temperatures, the heat resistance is improved. Furthermore, when it is an aryl group or a heteroaryl group, conjugation spreads, so that it becomes more electrochemically stable and charge transportability is improved.

In the compound represented by the general formula (8), n ⁴ is preferably 1. When n ⁴ is 1, sublimation property and deposition stability are improved.

Z is preferably a group represented by any one of the following general formulas (13) to (17). When Z is a group represented by any one of the following general formulas (13) to (17), high electron mobility and high electron acceptability are exhibited, and the driving voltage of the light emitting element can be lowered. As a result, the light emission efficiency of the light emitting element can be improved.

In the formula, ring B represents a substituted or unsubstituted benzene ring, a substituted or unsubstituted condensed aromatic hydrocarbon ring, a substituted or unsubstituted monocyclic aromatic heterocyclic ring, or a substituted or unsubstituted condensed aromatic heterocyclic ring. To express. However, in the case of general formula (13), ring B is a substituted or unsubstituted monocyclic aromatic heterocyclic ring or a substituted or unsubstituted condensed aromatic heterocyclic ring, and ring B is at least one electron accepting ring. Contains nitrogen. The substituents in the case where ring B has a substituent, R ⁷¹ and R ¹⁰⁶ to R ¹²¹ (the substituents of Z described above, etc.) are the same as those in the general formula (8). However, in the case of general formula (13), in any position of R ⁷¹ , R ¹⁰⁶ to R ¹⁰⁹ and ring B, in the case of general formula (14), of R ⁷¹ , R ¹¹⁰ to R ¹¹² and ring B In any position, in the case of general formula (15), R ⁷¹ , R ¹¹³ to R ¹¹⁵ , and in any position of ring B, in the case of general formula (16), R ⁷¹ , R ¹¹⁶ to R ¹¹⁸ , In the general formula (17) at any position in the ring B, R ⁷¹ , R ¹¹⁹ to R ¹²¹ and at any position in the ring B are connected to L ³ .

Ring B preferably has a structure represented by any of the following general formulas (18) to (21). When the ring B has a structure represented by any one of the following general formulas (18) to (21), high carrier mobility and high electron acceptability are expressed. As a result, the light emitting element can be driven at a low voltage, and the light emission efficiency can be improved. In addition, the sublimation property, deposition stability, crystallinity deterioration, and film stability due to high glass transition temperature are improved.

In the formula, B ¹ to B ²² represent a substituted or unsubstituted carbon atom or a nitrogen atom. However, when Z is a group represented by the general formula (13), at least one of B ^k (k = 1 to 22) contained in the ring B is electron-accepting nitrogen. The substituents when B ¹ to B ²² have a substituent are the same as those in the general formula (8).

Ring B is not particularly limited, but is preferably General Formulas (19) to (21). When ring B is represented by the general formulas (19) to (21), conjugation is further expanded, and high carrier mobility and high electron acceptability are expressed. As a result, the light emitting element can be driven at a low voltage, and the light emission efficiency can be improved.

The compound represented by the general formula (8) is not particularly limited, but specific examples include the following compounds.

[Light emitting element]
Next, embodiments of the light emitting device of the present invention will be described in detail. The light-emitting element of the present invention has an anode and a cathode, and an organic layer interposed between the anode and the cathode. The organic layer has at least a light-emitting layer and an electron transport layer, and the light-emitting layer is formed by electric energy. Emits light.

The organic layer is composed of only the light emitting layer / electron transport layer, 1) hole transport layer / light emitting layer / electron transport layer and 2) hole transport layer / light emitting layer / electron transport layer / electron injection layer, 3) Laminate structure such as hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer can be mentioned. Each of the layers may be a single layer or a plurality of layers.

The light emitting device material containing the phosphine oxide derivative represented by the general formula (1) may be used for any layer in the above device configuration, but has a high electron injection / transport capability, a fluorescence quantum yield, and a thin film stability. Therefore, it is preferably used for a light emitting layer or an electron transport layer of a light emitting element. In particular, since it has an excellent fluorescence quantum yield, it is preferably used as a dopant material for the light emitting layer.

[Anode and cathode]
In the light emitting device of the present invention, the anode and the cathode have a role of supplying a sufficient current for light emission of the device, and at least one of them is preferably transparent or translucent in order to extract light. Usually, the anode formed on the substrate is a transparent electrode.

If the material used for the anode is a material that can efficiently inject holes into the organic layer and is transparent or translucent to extract light, tin oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO) ), Etc., metals such as gold, silver and chromium, inorganic conductive materials such as copper iodide and copper sulfide, conductive polymers such as polythiophene, polypyrrole and polyaniline, etc. However, it is particularly preferable to use ITO glass or Nesa glass. These electrode materials may be used alone, or a plurality of materials may be laminated or mixed. The resistance of the transparent electrode is not limited as long as it can supply a sufficient current for light emission of the element, but it is preferably low resistance from the viewpoint of power consumption of the element. For example, an ITO substrate of 300Ω / □ or less functions as a device electrode, but since a substrate of about 10Ω / □ is now available, use a low resistance substrate of 20Ω / □ or less. Is particularly preferred. The thickness of ITO can be arbitrarily selected according to the resistance value, but is usually used in a range of 100 to 300 nm.

In order to maintain the mechanical strength of the light emitting element, the light emitting element is preferably formed over a substrate. As the substrate, a glass substrate such as soda glass or non-alkali glass is preferably used. As the thickness of the glass substrate, it is sufficient that the thickness is sufficient to maintain the mechanical strength. As for the glass material, alkali-free glass is preferred because it is better that there are fewer ions eluted from the glass. Alternatively, soda lime glass provided with a barrier coat such as SiO ₂ is also commercially available and can be used. Furthermore, if the first electrode functions stably, the substrate need not be glass, and for example, an anode may be formed on a plastic substrate. The ITO film forming method is not particularly limited, such as an electron beam method, a sputtering method, and a chemical reaction method.

The material used for the cathode is not particularly limited as long as it can efficiently inject electrons into the light emitting layer. Generally, metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys and multilayer stacks of these metals with low work function metals such as lithium, sodium, potassium, calcium, and magnesium Is preferred. Among these, aluminum, silver, and magnesium are preferable as the main component from the viewpoints of electrical resistance, ease of film formation, film stability, luminous efficiency, and the like. In particular, magnesium and silver are preferable because electron injection into the electron transport layer and the electron injection layer in the present invention is facilitated and driving at a low voltage is possible.

Furthermore, for cathode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, inorganic materials such as silica, titania and silicon nitride, polyvinyl alcohol, polyvinyl chloride As a preferred example, an organic polymer compound such as a hydrocarbon polymer compound is laminated on the cathode as a protective film layer. Moreover, the phosphine oxide derivative represented by General formula (1) can also be utilized as this protective film layer. However, in the case of an element structure (top emission structure) that extracts light from the cathode side, the protective film layer is selected from materials that are light transmissive in the visible light region. The production method of these electrodes is not particularly limited, such as resistance heating, electron beam, sputtering, ion plating and coating.

[Hole transport layer]
The hole transport layer is formed by a method of laminating or mixing one or more hole transport materials or a method using a mixture of a hole transport material and a polymer binder. In addition, the hole transport material needs to efficiently transport holes from the anode between electrodes to which an electric field is applied, has high hole injection efficiency, and can efficiently transport injected holes. preferable. For this purpose, it is required that the material has an appropriate ionization potential, has a high hole mobility, is excellent in stability, and does not easily generate trapping impurities during manufacture and use. A substance satisfying such conditions is not particularly limited. For example, 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-biphenylyl) amino) biphenyl (TBDB), bis (N, N Benzidine derivatives such as '-diphenyl-4-aminophenyl) -N, N-diphenyl-4,4'-diamino-1,1'-biphenyl (TPD232), 4,4', 4 "-tris (3-methylphenyl) (Phenyl) amino) triphenylamine (m-MTDATA), 4,4 ′, 4 ″ -tris (1-naphthyl (phenyl) amino) triphenylamine (1-TNATA), etc. A group of materials called triarylamine, a material having a carbazole skeleton, especially a carbazole multimer, specifically a derivative of a carbazole dimer such as bis (N-arylcarbazole) or bis (N-alkylcarbazole), a carbazole trimer Derivatives, carbazole tetramer derivatives, triphenylene compounds, pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives and thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives and other heterocyclic compounds, fullerene derivatives, In the polymer system, polycarbonate having a monomer in the side chain, styrene derivative, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, polysilane, and the like are preferable. Furthermore, inorganic materials such as p-type Si and p-type SiC can also be used.

The phosphine oxide derivative represented by the general formula (1) can also be used as a hole transporting material because of its high hole mobility and excellent electrochemical stability. The phosphine oxide derivative represented by the general formula (1) may be used as a hole injection material. However, since it has high hole mobility, it is preferably used as a hole transport material.

In addition, since the phosphine oxide derivative represented by the general formula (1) has excellent electron injecting and transporting properties, when a light emitting device material containing the phosphine oxide derivative is used for a light emitting layer or an electron transporting layer, electrons are recombined in the light emitting layer. There is a concern that a part of the hole transport layer may leak. Therefore, it is preferable to use a compound having an excellent electron blocking property for the hole transport layer. Among these, a compound containing a carbazole skeleton is preferable because it has excellent electron blocking properties and can contribute to the improvement in efficiency of the light-emitting element. Further, the compound containing a carbazole skeleton preferably contains a carbazole dimer, a carbazole trimer, or a carbazole tetramer skeleton. This is because they have both a good electron blocking property and a hole injection / transport property. In addition, it is preferable to use a compound containing a triphenylene skeleton, which is excellent in having high hole mobility, in the hole transport layer because the effects of improving the carrier balance and improving the light emission efficiency and durability are obtained. More preferably, the compound containing a triphenylene skeleton has two or more diarylamino groups. The compound containing a carbazole skeleton or the compound containing a triphenylene skeleton may be used alone as a hole transport layer, or may be used as a mixture with each other. Further, other materials may be mixed within a range not impairing the effects of the present invention. In the case where the hole transport layer is composed of a plurality of layers, any one layer may contain a compound containing a carbazole skeleton or a compound containing a triphenylene skeleton.

[Hole injection layer]
A hole injection layer may be provided between the anode and the hole transport layer. By providing the hole injection layer, the light emitting element has a low driving voltage and the durability life is improved. For the hole injection layer, a material having a smaller ionization potential than that of the material normally used for the hole transport layer is preferably used. Specifically, a benzidine derivative such as TPD232 and a starburst arylamine material group can be used, and a phthalocyanine derivative can also be used. It is also preferred that the hole injection layer is composed of an acceptor compound alone or that the acceptor compound is doped with another hole transport material. Examples of acceptor compounds include metal chlorides such as iron (III) chloride, aluminum chloride, gallium chloride, indium chloride, antimony chloride, metal oxides such as molybdenum oxide, vanadium oxide, tungsten oxide, ruthenium oxide, A charge transfer complex such as tris (4-bromophenyl) aminium hexachloroantimonate (TBPAH). In addition, organic compounds having a nitro group, cyano group, halogen or trifluoromethyl group in the molecule, quinone compounds, acid anhydride compounds, fullerenes, and the like are also preferably used. Specific examples of these compounds include hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane (TCNQ), tetrafluorotetracyanoquinodimethane (F4-TCNQ), 2, 3, 6, 7 , 10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN6), p-fluoranyl, p-chloranil, p-bromanyl, p-benzoquinone, 2,6-dichlorobenzoquinone 2,5-dichlorobenzoquinone, tetramethylbenzoquinone, 1,2,4,5-tetracyanobenzene, o-dicyanobenzene, p-dicyanobenzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5 , 6-Dicyanobenzoquinone, p-dinitrobenzene, m-dini Lobenzene, o-dinitrobenzene, p-cyanonitrobenzene, m-cyanonitrobenzene, o-cyanonitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1-nitronaphthalene, 2-nitronaphthalene, 1,3-dinitro Naphthalene, 1,5-dinitronaphthalene, 9-cyanoanthracene, 9-nitroanthracene, 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole, 2,4,7-trinitro-9-fluorenone, 2 , 3,5,6-tetracyanopyridine, maleic anhydride, phthalic anhydride, C60, and C70.

Among these, metal oxides and cyano group-containing compounds are preferable because they are easy to handle and can be easily deposited, so that the above-described effects can be easily obtained. Examples of preferred metal oxides include molybdenum oxide, vanadium oxide, or ruthenium oxide. Among the cyano group-containing compounds, (a) a compound having in the molecule at least one electron-accepting nitrogen other than the nitrogen atom of the cyano group, and (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) at least one electron other than the nitrogen atom of the cyano group, having both a halogen and a cyano group in the molecule. A compound having an accepting nitrogen is more preferable because it becomes a strong electron acceptor. Specific examples of such a compound include the following compounds.

In any case where the hole injection layer is composed of an acceptor compound alone or when the hole injection layer is doped with an acceptor compound, the hole injection layer may be a single layer, A plurality of layers may be laminated. Moreover, the hole injection material used in combination when the acceptor compound is doped is the same compound as the compound used for the hole transport layer from the viewpoint that the hole injection barrier to the hole transport layer can be relaxed. Is more preferable.

[Light emitting layer]
The light emitting layer may be either a single layer or a plurality of layers, each formed by a light emitting material (host material, dopant material), which may be a mixture of a host material and a dopant material or a host material alone, Either is acceptable. That is, in the light emitting element of the present invention, only the host material or the dopant material may emit light in each light emitting layer, or both the host material and the dopant material may emit light. From the viewpoint of efficiently using electric energy and obtaining light emission with high color purity, the light emitting layer is preferably composed of a mixture of a host material and a dopant material. Further, the host material and the dopant material may be either one kind or a plurality of combinations, respectively. The dopant material may be included in the entire host material or may be partially included. The dopant material may be laminated or dispersed. The emission color can be controlled by the dopant material. If the amount of the dopant material is too large, a concentration quenching phenomenon occurs, so that it is preferably used at 20% by weight or less, more preferably 10% by weight or less with respect to the host material. The doping method can be formed by a co-evaporation method with a host material, but may be simultaneously deposited after being previously mixed with the host material.

Specifically, the light-emitting material includes fused ring derivatives such as anthracene and pyrene, which have been conventionally known as light emitters, metal chelated oxinoid compounds such as tris (8-quinolinolato) aluminum, bisstyrylanthracene derivatives and diesters. Bisstyryl derivatives such as styrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole In derivatives, indolocarbazole derivatives, and polymer systems, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polythiophene derivatives, etc. can be used, but are not particularly limited. Not shall.

The phosphine oxide derivative represented by the general formula (1) can also be used as a light-emitting material because of its high fluorescence quantum yield and excellent electrochemical stability. The phosphine oxide derivative represented by the general formula (1) may be used as a host material. However, since it has a strong electron affinity, it traps excess electrons injected into the light emitting layer when used as a dopant material. This is particularly preferable because the hole transport layer can be prevented from being deteriorated by the attack of electrons.

The host material contained in the light-emitting material is not particularly limited. In addition to the phosphine oxide derivative represented by the general formula (1), naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene Compounds having a condensed aryl ring such as, derivatives thereof, aromatic amine derivatives such as N, N′-dinaphthyl-N, N′-diphenyl-4,4′-diphenyl-1,1′-diamine, tris (8- Quinolinato) metal chelated oxinoid compounds such as aluminum (III), bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives , Cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, in polymer systems, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinyl carbazole derivatives, Although a polythiophene derivative etc. can be used, it is not specifically limited.

Although it does not specifically limit in the dopant material contained in a luminescent material, In addition to the phosphine oxide derivative represented by General formula (1), naphthalene, anthracene, phenanthrene, pyrene, chrysene, triphenylene, perylene, fluoranthene, fluorene, indene, etc. Compounds having a fused aryl ring or derivatives thereof (for example, 2- (benzothiazol-2-yl) -9,10-diphenylanthracene and 5,6,11,12-tetraphenylnaphthacene), furan, pyrrole, thiophene , Silole, 9-silafluorene, 9,9'-spirobisilafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyridine, pyrazine, naphthyridine, quinoxa , Pyrrolopyridine, thioxanthene and other heteroaryl ring compounds and derivatives thereof, borane derivatives, distyrylbenzene derivatives, 4,4′-bis (2- (4-diphenylaminophenyl) ethenyl) biphenyl, 4,4 Aminostyryl derivatives such as' -bis (N- (stilben-4-yl) -N-phenylamino) stilbene, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, stilbene derivatives, aldazine derivatives, pyromethene derivatives, diketopyrrolo [3,4] -C] pyrrole derivatives, 2,3,5,6-1H, 4H-tetrahydro-9- (2'-benzothiazolyl) quinolidino [9,9a, 1-gh] coumarin derivatives, such as imidazole, thiazole, thiadiazole, Carbazole, oxazole, oxa Azole derivatives such as azole and triazole and metal complexes thereof, and fragrances represented by N, N′-diphenyl-N, N′-di (3-methylphenyl) -4,4′-diphenyl-1,1′-diamine Group amine derivatives and the like can be used.

Further, a phosphorescent material may be included in the light emitting layer. A phosphorescent material is a material that exhibits phosphorescence even at room temperature. When a phosphorescent material is used as a dopant, it is basically necessary to obtain phosphorescence even at room temperature, but there is no particular limitation, and iridium (Ir), ruthenium (Ru), rhodium (Rh), palladium It is preferably an organometallic complex compound containing at least one metal selected from the group consisting of (Pd), platinum (Pt), osmium (Os), and rhenium (Re). Among these, from the viewpoint of having a high phosphorescence emission yield even at room temperature, an organometallic complex having iridium or platinum is more preferable. Hosts used in combination with a phosphorescent dopant include indole derivatives, carbazole derivatives, indolocarbazole derivatives, pyridine, pyrimidine, nitrogen-containing aromatic compound derivatives having a triazine skeleton, polyarylbenzene derivatives, spirofluorene derivatives, Aromatic hydrocarbon compound derivatives such as truxene derivatives and triphenylene derivatives, compounds containing chalcogen elements such as dibenzofuran derivatives and dibenzothiophene derivatives, and organometallic complexes such as beryllium quinolinol complexes are preferably used. It is not limited to these as long as the energy is high and electrons and holes are smoothly injected and transported from the respective transport layers. Two or more triplet light-emitting dopants may be contained, or two or more host materials may be contained. Further, one or more triplet light emitting dopants and one or more fluorescent light emitting dopants may be contained.

Preferred phosphorescent host or dopant is not particularly limited, but specific examples include the following.

[Electron transport layer]
In the present invention, the electron transport layer is a layer in which electrons are injected from the cathode and further transports electrons. The electron transport layer has high electron injection efficiency, and it is desired to efficiently transport injected electrons. Therefore, the electron transport layer is preferably made of a material having a high electron affinity, a high electron mobility, excellent stability, and impurities that are traps are less likely to be generated during manufacture and use. However, considering the transport balance between holes and electrons, if the electron transport layer mainly plays a role of effectively preventing the holes from the anode from recombining and flowing to the cathode side, the electron transport Even if it is made of a material that does not have a high capability, the effect of improving the luminous efficiency is equivalent to that of a material that has a high electron transport capability. Therefore, the electron transport layer in the present invention includes a hole blocking layer that can efficiently block the movement of holes as the same meaning.

Examples of the electron transport material used for the electron transport layer include condensed polycyclic aromatic derivatives such as naphthalene and anthracene, styryl aromatic ring derivatives represented by 4,4′-bis (diphenylethenyl) biphenyl, anthraquinone and diphenoquinone Quinoline derivatives, phosphorus oxide derivatives, quinolinol complexes such as tris (8-quinolinolato) aluminum (III), benzoquinolinol complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes, and flavonol metal complexes. A compound having a heteroaryl ring structure composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus and containing electron-accepting nitrogen, because driving voltage is reduced and high-efficiency light emission is obtained. Is preferably used.

An aromatic heterocycle containing electron-accepting nitrogen has high electron affinity. An electron transport material having electron-accepting nitrogen makes it easier to receive electrons from a cathode having a high electron affinity, and can be driven at a lower voltage. In addition, since the number of electrons supplied to the light emitting layer increases and the recombination probability increases, the light emission efficiency is improved.

Examples of the heteroaryl ring containing an electron-accepting nitrogen include, for example, a pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, Examples thereof include an oxadiazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, and a phenanthrimidazole ring.

Examples of these compounds having a heteroaryl ring structure include benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoins. Preferred compounds include quinoline derivatives, oligopyridine derivatives such as bipyridine and terpyridine, quinoxaline derivatives and naphthyridine derivatives. Among them, imidazole derivatives such as tris (N-phenylbenzimidazol-2-yl) benzene, oxadiazole derivatives such as 1,3-bis [(4-tert-butylphenyl) 1,3,4-oxadiazolyl] phenylene, Triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole, phenanthroline derivatives such as bathocuproine and 1,3-bis (1,10-phenanthroline-9-yl) benzene, 2,2 ′ A benzoquinoline derivative such as bis (benzo [h] quinolin-2-yl) -9,9′-spirobifluorene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1, Bipyridine derivatives such as 1-dimethyl-3,4-diphenylsilole, 1,3-bis (4 ′-(2,2 ′: 6′2 ″ -ta Terpyridine derivatives such as pyridinyl)) benzene, naphthyridine derivatives such as bis (1-naphthyl) -4- (1,8-naphthyridin-2-yl) phenylphosphine oxide are preferably used from the viewpoint of electron transporting capability. In addition, it is more preferable that these derivatives have a condensed polycyclic aromatic skeleton because the glass transition temperature is improved, the electron mobility is increased, and the effect of lowering the voltage of the light-emitting element is increased. Further, considering that the durability life of the device is improved, the synthesis is easy, and the availability of raw materials is easy, the condensed polycyclic aromatic skeleton is particularly preferably an anthracene skeleton, a pyrene skeleton or a phenanthroline skeleton. The electron transport material may be used alone, but two or more of the electron transport materials may be mixed and used, or one or more of the other electron transport materials may be mixed with the electron transport material.

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

Other than these, International Publication No. 2004-63159, International Publication No. 2003-60956, Appl. Phys. Lett. 74, 865, Org. Electron. 4, 113 (2003), International Publication No. 2010-113743, An electron transport material disclosed in International Publication No. 2010-1817 and the like can also be used.

In addition, the phosphine oxide derivative represented by the general formula (1) also has a high electron injecting and transporting ability, so that it can be suitably used as an electron transporting material for an electron transporting layer. When the phosphine oxide derivative represented by the general formula (1) is used, the phosphine oxide derivative represented by the general formula (1) of the present invention may be mixed. One or more other electron transport materials may be used in combination with the phosphine oxide derivative represented by the general formula (1) of the present invention as long as the effects of the present invention are not impaired.

The electron transport material that can be mixed is not particularly limited, but is a compound having a condensed aryl ring such as naphthalene, anthracene, or pyrene or a derivative thereof, or a styryl aromatic ring typified by 4,4′-bis (diphenylethenyl) biphenyl. Derivatives, perylene derivatives, perinone derivatives, coumarin derivatives, naphthalimide derivatives, quinone derivatives such as anthraquinone and diphenoquinone, carbazole derivatives and indole derivatives, quinolinol complexes such as tris (8-quinolinolato) aluminum (III), and hydroxyphenyloxazole complexes Examples include hydroxyazole complexes, azomethine complexes, tropolone metal complexes, and flavonol metal complexes.

As described above, when the phosphine oxide derivative represented by the general formula (1) is used as the dopant material of the light emitting layer, any one of the compounds represented by the general formulas (5) to (8) is used as the electron transport material. When used, it is particularly preferable because more electrons can be injected into the light emitting layer and the driving voltage and light emission efficiency of the light emitting element are improved.

The electron transport material may be used alone, but two or more of the electron transport materials may be mixed and used, or one or more of the other electron transport materials may be mixed and used in the electron transport material. Further, a donor material may be contained. Here, the donor material is a material that facilitates electron injection from the cathode or the electron injection layer to the electron transport layer by improving the electron injection barrier and further improves the electrical conductivity of the electron transport layer.

Preferred examples of the donor material in the present invention include an alkali metal, an inorganic salt containing an alkali metal, a complex of an alkali metal and an organic material, an alkaline earth metal, an inorganic salt containing an alkaline earth metal, or an alkaline earth metal And a complex of organic substance. Preferable types of alkali metals and alkaline earth metals include alkali metals such as lithium, sodium and cesium, which have a low work function and a large effect of improving the electron transport ability, and alkaline earth metals such as magnesium and calcium.

Examples of inorganic salts include oxides such as LiO, Li ₂ O, Ba (OH) ₂ , nitrides, fluorides such as LiF, NaF, KF, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Carbonates such as Rb ₂ CO ₃ and Cs ₂ CO ₃ . In addition, preferable examples of the alkali metal or alkaline earth metal include lithium, cesium, calcium, barium, and the like, but lithium is particularly preferable because it is inexpensive and easy to synthesize. Preferred examples of the organic substance in the complex with the organic substance include quinolinol, benzoquinolinol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, hydroxytriazole and the like. Among these, a complex of an alkali metal and an organic substance is preferable, a complex of lithium and an organic substance is more preferable, and lithium quinolinol is particularly preferable. Two or more of these donor materials may be mixed and used.

The preferred doping concentration varies depending on the material and the film thickness of the doping region. For example, when the donor material is an inorganic material such as an alkali metal or alkaline earth metal, the deposition rate ratio between the electron transport material and the donor material is 10,000: It is preferable to use an electron transport layer by co-evaporation so as to be in the range of 1 to 2: 1. The deposition rate ratio is more preferably 100: 1 to 5: 1, and further preferably 100: 1 to 10: 1. When the donor material is a complex of a metal and an organic material, the electron transport layer and the donor material are co-deposited so that the deposition rate ratio of the electron transport material and the donor material is in the range of 100: 1 to 1: 100. Is preferred. The deposition rate ratio is more preferably 10: 1 to 1:10, and more preferably 7: 3 to 3: 7.

In addition, an electron transport layer in which a donor material is doped to the phosphine oxide derivative represented by the general formula (1) as described above is used as a charge generation layer in a tandem structure type element connecting a plurality of light emitting elements. May be.

The method for improving the electron transport ability by doping a donor material into the electron transport layer is particularly effective when the thin film layer is thick. It is particularly preferably used when the total film thickness of the electron transport layer and the light emitting layer is 50 nm or more. For example, there is a method of using the interference effect to improve the light emission efficiency, but this improves the light extraction efficiency by matching the phase of the light directly emitted from the light emitting layer and the light reflected by the cathode. Is. This optimum condition varies depending on the light emission wavelength, but the total film thickness of the electron transport layer and the light-emitting layer is 50 nm or more, and in the case of long-wavelength light emission such as red, the film thickness may be nearly 100 nm. .

The thickness of the electron transport layer to be doped may be a part or all of the electron transport layer. In the case of partial doping, it is desirable to provide a doping region at least at the electron transport layer / cathode interface, and the effect of lowering the voltage can be obtained only by doping in the vicinity of the cathode interface. On the other hand, when the donor material is in direct contact with the light emitting layer, the light emission efficiency may be lowered. In that case, it is preferable to provide a non-doped region at the light emitting layer / electron transport layer interface.

[Electron injection layer]
In the present invention, an electron injection layer may be provided between the cathode and the electron transport layer. In general, the electron injection layer is inserted for the purpose of assisting injection of electrons from the cathode to the electron transport layer, but in the case of insertion, a compound having a heteroaryl ring structure containing electron-accepting nitrogen may be used. Alternatively, a layer containing the above donor material may be used. Since the phosphine oxide derivative represented by the general formula (1) has a high electron affinity, it is also preferably used as an electron injection layer. In this case, it is preferable that the above-mentioned donor material is included. As the donor material to be mixed, the above-mentioned alkali metal, inorganic salt containing alkali metal, complex of alkali metal and organic substance, alkaline earth metal, inorganic salt containing alkaline earth metal or alkaline earth metal and Organic complex is preferable, and alkali metal or alkaline earth metal is particularly preferable. Preferable examples of the alkali metal or alkaline earth metal include lithium, cesium, calcium, barium, etc. Among them, lithium is particularly preferable. An insulator or a semiconductor inorganic substance can also be used for the electron injection layer. Use of these materials is preferable because a short circuit of the light emitting element can be effectively prevented and the electron injection property can be improved. As such an insulator, it is preferable to use at least one metal compound selected from the group consisting of alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides and alkaline earth metal halides. If the electron injection layer is composed of these alkali metal chalcogenides or the like, it is more preferable because the electron injection property can be further improved. Specifically, preferred alkali metal chalcogenides include, for example, Li ₂ O, Na ₂ S, and Na ₂ Se, and preferred alkaline earth metal chalcogenides include, for example, CaO, BaO, SrO, BeO, BaS, and CaSe. Is mentioned. Further, preferable alkali metal halides include, for example, LiF, NaF, KF, LiCl, KCl, and NaCl. Examples of preferable alkaline earth metal halides include fluorides such as CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ and BeF ₂ , and halides other than fluorides. Furthermore, a complex of an organic substance and a metal is also preferably used. In the case where a complex of an organic substance and a metal is used for the electron injection layer, the film thickness can be easily adjusted. Examples of such organometallic complexes include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, hydroxytriazole, and the like as preferred examples of the organic substance in a complex with an organic substance. Among these, a complex of an alkali metal and an organic substance is preferable, a complex of lithium and an organic substance is more preferable, and lithium quinolinol is particularly preferable.

[Method for forming each layer]
The method of forming each layer constituting the light emitting element is not particularly limited, such as resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, coating method, etc., but resistance heating vapor deposition or electron beam vapor deposition is usually used in terms of element characteristics. preferable.

The thickness of the organic layer is not limited because it depends on the resistance value of the luminescent material, but is preferably 1 to 1000 nm. The film thicknesses of the light emitting layer, the electron transport layer, and the hole transport layer are each preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

The light emitting element of the present invention has a function of converting electrical energy into light. Here, a direct current is mainly used as the electric energy, but a pulse current or an alternating current can also be used. The current value and voltage value are not particularly limited, but should be selected so that the maximum luminance can be obtained with as low energy as possible in consideration of the power consumption and lifetime of the device.

[display]
The light emitting device of the present invention is suitably used as a display for displaying in a matrix and / or segment system, for example.

In the matrix method, pixels for display are arranged two-dimensionally such as a lattice shape or a mosaic shape, and characters and images are displayed by a set of pixels. The shape and size of the pixel are determined by the application. For example, a square pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, monitor, TV, and a pixel with a side of mm order for a large display such as a display panel. become. In monochrome display, pixels of the same color may be arranged. However, in color display, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. The matrix driving method may be either a line sequential driving method or an active matrix. Although the structure of the line sequential drive is simple, the active matrix may be superior in consideration of the operation characteristics.

The segment system in the present invention is a system in which a pattern is formed so as to display predetermined information and a region determined by the arrangement of the pattern is caused to emit light. For example, the time and temperature display in a digital clock or a thermometer, the operation state display of an audio device or an electromagnetic cooker, the panel display of an automobile, and the like can be mentioned. The matrix display and the segment display may coexist in the same panel.

The light-emitting element of the present invention is also preferably used as a backlight for various devices. The backlight is used mainly 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 clock, an audio device, an automobile panel, a display panel, a sign, and the like. In particular, the light-emitting element of the present invention is preferably used for a backlight for a liquid crystal display device, particularly a personal computer for which a reduction in thickness is being considered, and a backlight that is thinner and lighter than conventional ones can be provided.

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

(Synthesis Example 1)
Synthesis of compound [1]

Acenaphthylene (14.0 g), diphenylisobenzofuran (25.0 g) and o-xylene (200 ml) were mixed and heated to reflux for 2 hours under a nitrogen stream. After cooling to room temperature, the solvent was distilled off and 300 mL of ether was added. The precipitate was filtered and vacuum-dried to obtain 27.7 g of intermediate [A] (yield 71%).

Next, 27.7 g of the intermediate [A] and 200 mL of acetic acid were mixed, 20 mL of 48% aqueous hydrogen bromide was added, and the mixture was heated to reflux for 3 hours. After cooling the reaction mixture to room temperature, the precipitate was filtered and washed with water and methanol. The obtained solid was vacuum-dried to obtain 25.8 g of intermediate [B] (yield 96%).

Next, 25.8 g of the intermediate [B], 11.3 g of N-bromosuccinimide, and 318 mL of chloroform were mixed and heated to reflux for 1 hour. An additional 3.4 g of N-bromosuccinimide was added, and the mixture was further heated to reflux for 2 hours. After cooling to room temperature, the chloroform solution was washed with water and an aqueous sodium thiosulfate solution. The organic layer was dried over magnesium sulfate, added with 3 g of activated carbon, filtered, and the solvent was distilled off. The obtained solid was recrystallized with 800 mL of butyl acetate, filtered, and vacuum-dried to obtain 26.9 g of intermediate [C] (yield 87%).

Next, 2.00 g of intermediate [C] and 40 ml of dehydrated THF were mixed, purged with nitrogen, and then cooled to −78 ° C. Subsequently, 2.8 ml of 1.6M n-butyllithium / hexane solution was added dropwise, and the mixture was stirred at -78 ° C. for 1 hour. Next, 1.08 g of diphenylphosphinic chloride dissolved in 1 ml of dehydrated THF was added dropwise and stirred at room temperature for 3 hours. Then, water and toluene were added and liquid-separated and the organic layer was dried with magnesium sulfate. After the solvent was distilled off, purification was performed by silica gel column chromatography (toluene / ethyl acetate = 3: 1), and the eluate was concentrated. Methanol was added to the obtained yellow foam-like solid and heated under reflux for 1 hour, and the crystallized solid was collected by filtration. The obtained solid was vacuum-dried to obtain 1.28 g (yield 51%) of a yellow solid. The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the yellow crystals obtained above were the compound [1].
¹ H-NMR (CDCl ₃ (δ = ppm)) δ 8.18 (d, 1H), 7.80-7.56 (m, 24H), 7.38 (t, 1H), 7.19 (dd , 1H), 6.50 (t, 2H).

Compound [1] was used as a light emitting device material after sublimation purification at about 290 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.12% before sublimation purification and 99.57% after sublimation purification.

(Synthesis Example 2)
Synthesis of compound [2]

Diphenylphosphine oxide 5.65 g, 4-bromoiodobenzene 4.04 g, triethylamine 2.02 g, and toluene 40 mL were mixed and purged with nitrogen. To this mixed solution was added 578 mg of tetrakis (triphenylphosphine) palladium, and the mixture was heated to reflux for 3 hours. After cooling to room temperature, 40 ml of toluene and 40 ml of water were added for liquid separation, and the organic layer was dried over magnesium sulfate. After the solvent was distilled off, purification was performed by silica gel column chromatography (heptane / ethyl acetate / methanol = 1: 2: 1), and the eluate was concentrated. The obtained oily liquid was crystallized by adding ethyl acetate, and further heptane was added and filtered. The obtained solid was vacuum-dried to obtain 6.06 g (yield 85%) of an intermediate [D] as a tan solid.

Next, 6.18 g of intermediate [C], 4.87 g of bispinacolatodiboron, 3.46 g of potassium acetate, and 64 mL of DMF were mixed and purged with nitrogen. To this mixed solution were added 74 mg of bis (dibenzylideneacetone) palladium (0) and 142 mg of bis (diphenylphosphino) ferrocene, and the mixture was heated to reflux for 3 hours. After cooling to room temperature, 64 ml of toluene and 64 ml of water were added for liquid separation, and the organic layer was dried over magnesium sulfate. After the solvent was distilled off, purification was performed by silica gel column chromatography (toluene / heptane = 1: 1), and the eluate was concentrated. After adding methanol to the obtained solid and filtering, the obtained solid was vacuum-dried to obtain 4.69 g (yield 69%) of an intermediate [E] as a tan solid.

Next, 1.61 g of intermediate [D], 2.00 g of intermediate [E], 19 ml of 1,2-dimethoxyethane, and 3.8 ml of 2.0 M aqueous sodium carbonate solution were mixed and purged with nitrogen. To this mixed solution was added 26 mg of bis (triphenylphosphine) palladium dichloride, and the mixture was heated to reflux for 3 hours. After cooling to room temperature, 20 ml of toluene and 20 ml of water were added for liquid separation, and the organic layer was dried over magnesium sulfate. After the solvent was distilled off, purification was performed by silica gel column chromatography (toluene / ethyl acetate = 1: 1), and the eluate was concentrated. To the obtained tan oil, 40 ml of THF and 1.0 g of QuadrasilMP (registered trademark) were added and heated under reflux for 1 hour. The solution was cooled to room temperature, filtered through celite, and the solvent was distilled off. Methanol was added to the resulting tan oil and heated to reflux for 1 hour, and the crystallized solid was collected by filtration. The obtained solid was vacuum-dried to obtain 1.80 g (yield 70%) of a yellow solid. The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the yellow crystals obtained above were the compound [2].
Compound [2]: ¹ H-NMR (CDCl ₃ (δ = ppm)) δ 7.81-7.43 (m, 32H), 6.62 (dd, 1H).

Compound [2] was used as a light emitting device material after sublimation purification at about 320 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.39% before sublimation purification and 99.72% after sublimation purification.

(Synthesis Example 3)
Synthesis of compound [3]

Acenaphthenequinone 18.2 g, 1,3-diphenyl-2-propanone 21.0 g, and ethanol 400 ml were mixed and purged with nitrogen. After heating to 60 ° C., 40 ml of 5M aqueous sodium hydroxide solution was added dropwise. After completion of dropping, the mixture was heated to 80 ° C. and refluxed for 2 hours, then cooled to room temperature, and the precipitated black solid was collected by filtration. After washing with water and ethanol, drying under reduced pressure was performed to obtain 31.2 g of a black solid intermediate [F] (yield 88%).

Next, 11.9 g of the intermediate [F], 10.0 g of 2-amino-3-bromo-5-chlorobenzoic acid, and 166 ml of o-xylene were mixed, heated to 80 ° C., and then 4.68 g of isoamyl nitrite. Was dripped. Thereafter, the temperature was raised to 100 ° C. and stirred for 5 hours. After cooling to room temperature, the solid was separated by Celite filtration. After evaporating the solvent of the filtrate, purification was performed by silica gel column chromatography (toluene / heptane = 1: 2), and the eluate was concentrated. The obtained solid was vacuum-dried to obtain 6.13 g of a yellow solid intermediate [G] (yield 36%).

Next, 6.13 g of the intermediate [G], 9.01 g of 1,8-diazabicyclo [5.4.0] undec-7-ene and 59 ml of DMF were mixed and purged with nitrogen. To this mixed solution were added 340 mg of bis (dibenzylideneacetone) palladium and 343 mg of tricyclohexylphosphine tetrafluoroborate, and the mixture was heated to reflux for 2 hours. After cooling to room temperature, 100 ml of methanol was added and the precipitated solid was collected by filtration and washed with water and methanol. The obtained solid was heated and dissolved in 150 ml of toluene, and then purified by silica gel column chromatography (developed only with toluene), and the eluate was concentrated. The obtained yellow solid was dissolved in 100 ml of THF by heating, 1.0 g of QuadrasilMP (registered trademark) was added thereto, the mixture was heated to reflux for 1 hour, filtered through celite, and then the solvent was distilled off. Drying under reduced pressure yielded 4.47 g of yellow solid intermediate [H] (yield 86%).

Next, 2.00 g of the intermediate [H], 1.39 g of bispinacolatodiboron, 1.35 g of potassium acetate and 23 mL of 1,4-dioxane were mixed and purged with nitrogen. To this mixed solution were added 26 mg of bis (dibenzylideneacetone) palladium (0) and 44 mg of 2-dicyclohexylphosphino-2 ', 4', 6'-triisopropylbiphenyl, and the mixture was heated to reflux. After 3 hours, after cooling to room temperature, 50 ml of water was added and the precipitated solid was collected by filtration and washed with water and methanol. The obtained solid was vacuum-dried to obtain 2.38 g of a yellow solid intermediate [I] (yield 99%).

Intermediate [I] 2.38 g, intermediate [D] 1.79 g, 1,2-dimethoxyethane 23 ml, 2.0 M sodium carbonate aqueous solution 4.6 ml were mixed and purged with nitrogen. To this mixed solution, 32 mg of bis (triphenylphosphine) palladium dichloride was added and heated to reflux for 3 hours. After cooling to room temperature, 20 ml of toluene and 20 ml of water were added for liquid separation, and the organic layer was dried over magnesium sulfate. After the solvent was distilled off, purification was performed by silica gel column chromatography (toluene / ethyl acetate = 2: 1), and the eluate was concentrated. To the obtained yellow foam-like solid, 50 ml of methanol was added and heated under reflux for 1 hour. Thereafter, the crystallized solid was collected by filtration and vacuum-dried to obtain 1.99 g (yield 64%) of a yellow solid. The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the yellow crystals obtained above were the compound [3].
Compound [3]: ¹ H-NMR (CDCl ₃ (δ = ppm)) δ 8.75 (d, 1H), 8.67 (d, 1H), 8.20 (s, 1H), 8.08 ( d, 1H), 7.96 (d, 1H), 7.81-7.46 (m, 24H), 7.38 (t, 1H), 6.73 (d, 1H).

Compound [3] was used as a light emitting device material after sublimation purification at about 350 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.40% before sublimation purification and 99.92% after sublimation purification.

(Example 1)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was vapor-deposited as a hole injection layer by 5 nm and the compound (HT-1) as a hole-transport layer by 70 nm by a resistance heating method. Next, the compound (H-1) as a host material and the compound [1] of the present invention as a dopant material were deposited in a thickness of 30 nm on the light emitting layer so that the doping concentration was 3% by weight. Next, the compound (1E-1) was deposited as an electron transport layer to a thickness of 25 nm and laminated.

Next, after depositing compound (2E-1) by 1 nm, a co-evaporated film of magnesium and silver was deposited by 100 nm with a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s). As a cathode, a 5 × 5 mm square element was produced. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. When this light-emitting element was DC-driven at 10 mA / cm ² , a blue light-emitting element excellent in durability with an external quantum efficiency of 4.3%, a driving voltage of 5.0 V, and a luminance half-life time of 8400 hours was obtained.

Note that (HI-1), (HT-1), (H-1), (1E-1), and (2E-1) are the compounds shown below.

(Examples 2 to 7)
A light emitting device was produced in the same manner as in Example 1 except that the materials listed in Table 1 were used as the dopant material. The results of each example are shown in Table 1. In Table 1, the compounds [1] to [3] are the compounds obtained by the above (Synthesis Example 1) to (Synthesis Example 3), and the compounds [4] to [7] are the compounds shown below. It is.

(Comparative Examples 1 to 3)
A light emitting device was produced in the same manner as in Example 1 except that the materials listed in Table 1 were used as the dopant material. The results are shown in Table 1. In Table 1, (D-1) to (D-3) are the compounds shown below.

(Example 8)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was vapor-deposited as a hole injection layer by 5 nm and the compound (HT-1) as a hole-transport layer by 70 nm by a resistance heating method. Next, the compound (H-1) as a host material and the compound [2] as a dopant material were vapor-deposited on the light emitting layer to a thickness of 30 nm so as to have a doping concentration of 3% by weight. Next, the compound (1E-2) was deposited as an electron transport layer to a thickness of 25 nm and laminated.

Next, after depositing the compound (2E-1) as an electron injection layer to a thickness of 1 nm, a co-deposition film of magnesium and silver has a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s). Then, a 5 × 5 mm square element was produced by depositing 100 nm as a cathode. When this light-emitting element was DC-driven at 10 mA / cm ² , a blue light-emitting element excellent in durability with an external quantum efficiency of 5.4%, a driving voltage of 4.0 V, and a luminance half time of 8000 hours was obtained.

(1E-2) is a compound shown below.

(Examples 9 to 20)
A light emitting device was produced in the same manner as in Example 8 except that the materials described in Table 2 were used as the electron transport layer. The results of each example are shown in Table 2. (1E-3) to (1E-8) are the compounds shown below.

(Comparative Examples 4 to 6)
A light emitting device was produced in the same manner as in Example 8 except that the materials described in Table 2 were used as the dopant material and the electron transport layer. The results are shown in Table 2.

(Example 21)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was vapor-deposited as a hole injection layer by 5 nm and the compound (HT-1) as a hole-transport layer by 70 nm by a resistance heating method. Next, the compound (H-1) as a host material and the compound [2] as a dopant material were vapor-deposited on the light emitting layer to a thickness of 30 nm so as to have a doping concentration of 3% by weight. Next, the compound (1E-2) and the donor material (2E-1) are used for the electron transport layer so that the deposition rate ratio of the compounds (1E-2) and (2E-1) is 1: 1. Then, the electron transport layer was deposited to a thickness of 25 nm and laminated.

Next, after depositing the compound (2E-1) as an electron injection layer to a thickness of 1 nm, a co-deposition film of magnesium and silver has a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s). Then, a 5 × 5 mm square element was produced by depositing 100 nm as a cathode. When this light-emitting element was DC-driven at 10 mA / cm ² , a blue light-emitting element excellent in durability with an external quantum efficiency of 5.9%, a driving voltage of 3.8 V, and a luminance half time of 8800 hours was obtained.

(Examples 22 to 30)
A light emitting device was produced in the same manner as in Example 21 except that the materials described in Table 3 were used as the electron transport layer. The results of each example are shown in Table 3.

(Comparative Examples 7 to 9)
A light emitting device was fabricated in the same manner as in Example 21 except that the materials described in Table 3 were used as the dopant material and the electron transport layer. The results are shown in Table 3.

(Example 31)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was deposited as a hole injection layer by 5 nm and the compound (HT-1) as a first hole transport layer by 60 nm by a resistance heating method. Further, 10 nm of a compound (HT-2) was deposited as a second hole transport layer. Next, the compound (H-1) as a host material and the compound [2] as a dopant material were vapor-deposited on the light emitting layer to a thickness of 30 nm so as to have a doping concentration of 3% by weight. Next, the compound (1E-1) was deposited as an electron transport layer to a thickness of 25 nm and laminated.

Next, after depositing the compound (2E-1) as an electron injection layer to a thickness of 1 nm, a co-deposition film of magnesium and silver has a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s). Then, a 5 × 5 mm square element was produced by depositing 100 nm as a cathode. When this light-emitting element was DC-driven at 10 mA / cm ² , a blue light-emitting element excellent in durability with an external quantum efficiency of 4.9%, a driving voltage of 4.5 V, and a luminance half time of 8100 hours was obtained. (HT-2) is a compound shown below.

(Examples 32 to 36)
A light emitting device was produced in the same manner as in Example 31 except that the materials described in Table 4 were used as the second hole transport layer and the electron transport layer. The results of each example are shown in Table 4. The results of Examples 2 and 12 are also shown again for reference. (HT-3) and (HT-4) are the compounds shown below.

(Comparative Examples 10 to 15)
A light emitting device was fabricated in the same manner as in Example 31 except that the materials described in Table 4 were used as the dopant material and the electron transport layer. The results are shown in Table 4.

(Example 37)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was vapor-deposited as a hole injection layer by 5 nm and the compound (HT-1) as a hole-transport layer by 70 nm by a resistance heating method. Next, the compound (H-1) as a host material and the compound (D-3) as a dopant material were vapor-deposited on the light emitting layer to a thickness of 30 nm with a doping concentration of 3% by weight. Next, the compound [1] of the present invention was deposited as an electron transport layer to a thickness of 25 nm and laminated.

Next, after depositing the compound (2E-1) as an electron injection layer to a thickness of 1 nm, a co-deposition film of magnesium and silver has a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s). Then, a 5 × 5 mm square element was produced by depositing 100 nm as a cathode. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. When this light emitting device was DC-driven at 10 mA / cm ² , a blue light emitting device excellent in durability with an external quantum efficiency of 4.3%, a driving voltage of 4.5 V, and a luminance half time of 5200 hours was obtained.

(Examples 38 to 45)
A light emitting device was produced in the same manner as in Example 37 except that the materials described in Table 5 were used as the electron transport layer. The results of each example are shown in Table 5. Compound [8] and Compound [9] are the compounds shown below.

(Example 46)
The compound [1] and the donor material (2E-1) are used for the electron transport layer, and the electron transport layer is 25 nm so that the deposition rate ratio of the compounds [1] and (2E-1) is 1: 1. A light emitting device was fabricated in the same manner as in Example 37 except that the thickness was evaporated and laminated. The results are shown in Table 5.

(Examples 47 to 54)
A light emitting device was produced in the same manner as in Example 46 except that the materials described in Table 5 were used as the electron transport layer. The results of each example are shown in Table 5.

(Comparative Examples 16 to 17)
A light emitting device was produced in the same manner as in Example 37 except that the materials described in Table 5 were used as the electron transport layer. The results are shown in Table 5.

(Comparative Examples 18-19)
A light emitting device was produced in the same manner as in Example 46 except that the materials described in Table 5 were used as the electron transport layer. The results are shown in Table 5.

(Example 55)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was vapor-deposited as a hole injection layer by 5 nm and the compound (HT-1) as a hole-transport layer by 70 nm by a resistance heating method. Next, the compound (H-1) as a host material and the compound (D-3) as a dopant material were vapor-deposited on the light emitting layer to a thickness of 30 nm with a doping concentration of 3% by weight. Next, the compound (1E-1) was deposited as an electron transport layer to a thickness of 15 nm. Furthermore, the compound [1] of the present invention and lithium as a donor material are used, and the electron injection layer is made 10 nm so that the deposition rate ratio of the compound [1] and lithium is compound [1]: lithium = 99: 1. Vapor deposited to a thickness of

Next, a co-deposited film of magnesium and silver is deposited at a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s) to 100 nm to form a cathode, thereby producing a 5 × 5 mm square device. did. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. When this light emitting device was DC-driven at 10 mA / cm ² , a blue light emitting device having an external quantum efficiency of 4.9%, a driving voltage of 4.2 V, and a luminance half time of 5500 hours was obtained.

(Examples 56 to 63)
A light emitting device was produced in the same manner as in Example 55 except that the materials described in Table 6 were used as the electron injection layer. The results of each example are shown in Table 6.

(Comparative Examples 20 to 21)
A light emitting device was produced in the same manner as in Example 55 except that the materials described in Table 6 were used as the electron injection layer. The results are shown in Table 6.

(Example 64)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was vapor-deposited as a hole injection layer by 5 nm and the compound (HT-1) as a hole-transport layer by 70 nm by a resistance heating method. This hole transport layer is shown in Table 6 as the first hole transport layer. Next, the compound (H-2) as a host material and the compound (D-4) as a dopant material were deposited on the light emitting layer in a thickness of 30 nm so that the doping concentration was 10 wt%. Next, Compound [2] was deposited as an electron transport layer to a thickness of 25 nm and laminated.

Next, after depositing the compound (2E-1) as an electron injection layer to a thickness of 1 nm, a co-deposition film of magnesium and silver has a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s). Then, a 5 × 5 mm square element was produced by depositing 100 nm as a cathode. The characteristics of this green light emitting device at 4000 cd / m ² were an external quantum efficiency of 11.1% and a driving voltage of 4.8V. When the initial luminance was set to 4000 cd / m ² and driven at a constant current, the luminance half time was 7100 hours. (H-2) and (D-4) are the compounds shown below.

(Example 65)
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which ITO transparent conductive film was deposited at 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, the compound (HI-1) was deposited as a hole injection layer by 5 nm and the compound (HT-1) as a first hole transport layer by 60 nm by a resistance heating method. Further, 10 nm of a compound (HT-2) was deposited as a second hole transport layer. Next, the compound (H-2) as a host material and the compound (D-4) as a dopant material were deposited on the light emitting layer in a thickness of 30 nm so that the doping concentration was 10 wt%. Next, Compound [2] was deposited as an electron transport layer to a thickness of 25 nm and laminated.

Next, after depositing compound (2E-1) by 1 nm, a co-evaporated film of magnesium and silver was deposited by 100 nm with a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s). As a cathode, a 5 × 5 mm square element was produced. The characteristics of this green light emitting device at 4000 cd / m ² were an external quantum efficiency of 14.0% and a driving voltage of 4.5V. When the initial luminance was set to 4000 cd / m ² and driven at a constant current, the luminance half time was 7500 hours.

(Examples 66 to 75)
A light emitting device was fabricated in the same manner as in Example 65 except that the materials described in Table 7 were used as the second hole transport layer and the electron transport layer. The results of each example are shown in Table 7.

(Comparative Examples 22 to 25)
A light emitting device was fabricated in the same manner as in Example 65 except that the materials described in Table 7 were used as the second hole transport layer and the electron transport layer. The results are shown in Table 7.

Claims

A phosphine oxide derivative represented by the following general formula (1).

(In the formula, R 1 and R 2 may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group. , Aryl ether group, aryl thioether group, aryl group, heteroaryl group, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, and a condensed ring formed between adjacent substituents L 1 is a single bond, an arylene group, or a heteroarylene group, Ar 1 is a condensed polycyclic aromatic group represented by the following general formula (2), and n 1 is 1 or more. When n 1 is 2 or more, L 1 , R 1 and R 2 may be the same or different.

(Wherein R 3 to R 12 may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group. , Aryl ether group, aryl thioether group, aryl group, heteroaryl group, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group and silyl group, provided that R 3 to R 12 are selected. Of which at least one pair of adjacent substituents forms a condensed ring, provided that it is linked to L 1 at at least one of R 3 to R 12. )
The phosphine oxide derivative according to claim 1, wherein the condensed polycyclic aromatic group represented by the general formula (2) does not contain electron-donating nitrogen in the ring.
The phosphine oxide derivative according to claim 1 or 2, wherein L 1 is an arylene group or a heteroarylene group.
The phosphine oxide derivative according to any one of claims 1 to 3, wherein R 1 and R 2 are an aryl group or a heteroaryl group.
The phosphine oxide derivative according to any one of claims 1 to 4, wherein Ar 1 is represented by the following general formula (3) or (4).

(Wherein R 13 to R 24 may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group. , Aryl ether group, aryl thioether group, aryl group, heteroaryl group, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group and silyl group, provided that R 13 to R 24 are selected. among and ligated with L 1 at least one position.)

(Wherein R 25 to R 38 may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group. , Aryl ether group, aryl thioether group, aryl group, heteroaryl group, cyano group, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group and silyl group, provided that R 25 to R 38 are selected. among and ligated with L 1 at least one position.)
A light emitting device material containing the phosphine oxide derivative according to any one of claims 1 to 5.
The light emitting device according to claim 6, wherein an organic layer having at least a light emitting layer and an electron transport layer exists between the anode and the cathode, and emits light by electric energy, wherein at least one of the organic layers is a light emitting device. A light-emitting element using a material.
An organic layer including a light emitting layer exists between an anode and a cathode, and is a light emitting element that emits light by electric energy, wherein the light emitting element uses the light emitting element material according to claim 6.
An organic layer including a light emitting layer having a host material and a dopant material between an anode and a cathode, wherein the light emitting element emits light by electric energy, and the dopant material is a phosphine according to any one of claims 1 to 5. A light-emitting element containing an oxide derivative.
An organic layer including an electron transport layer is present between an anode and a cathode, and is a light emitting element that emits light by electric energy, wherein the light emitting element material according to claim 6 is used for the electron transport layer.
An organic layer including an electron transport layer exists between an anode and a cathode, and emits light by electric energy, wherein an electron injection layer exists between the electron transport layer and the cathode, and the electron injection layer includes The light emitting element using the light emitting element material of Claim 6.
An organic layer including an electron transport layer is present between an anode and a cathode, and is a light emitting device that emits light by electric energy, wherein an electron injection layer is present between the electron transport layer and the cathode, and the electron transport layer and A light emitting device wherein the electron injection layer contains the light emitting device material according to claim 6 and a donor material.
The donor material is composed of an alkali metal, an inorganic salt containing an alkali metal, a complex of an alkali metal and an organic substance, an alkaline earth metal, an inorganic salt containing an alkaline earth metal, and a complex of an alkaline earth metal and an organic substance. The light emitting device according to claim 12, wherein the light emitting device is at least one compound selected from the above.
An organic layer including a light-emitting layer having a host material and a dopant material and an electron transport layer is present between the anode and the cathode, and is a light-emitting element that emits light by electric energy, wherein the dopant material of the light-emitting layer is claimed. A light emitting device comprising the phosphine oxide derivative according to any one of 1 to 5, and an electron transport layer comprising a compound represented by any one of the following general formulas (5) to (8).

(R 39 to R 48 may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group. , An arylthioether group, an aryl group, a heteroaryl group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group, and —P (═O) R 49 R 50, provided that R L 2 is linked to L 2 at at least one position among 39 to R 48. L 2 is a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, and Ar 2 is an electron-accepting nitrogen. the .n 2 is an aromatic heterocyclic group containing an integer of 1 or more .n 2 is 2 or more field , L 2 and Ar 2 may be the same or different.)

(R 51 to R 58 may be the same or different from each other, and may be hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group. , An arylthioether group, an aryl group, a carbonyl group, a carboxyl group, a carbamoyl group, an amino group, a silyl group, and —P (═O) R 59 R 60. R 59 and R 60 are an aryl group or hetero R 59 and R 60 may be condensed to form a ring, provided that at least one of R 51 to R 58 itself has a three-dimensional structure or phenanthroline. It has a three-dimensional structure by steric repulsion with the skeleton or with adjacent substituents. )

(R 61 to R 68 may be the same or different and are each hydrogen, halogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group. , An arylthioether group, an aryl group, a carbonyl group, a carboxyl group, a carbamoyl group, an amino group, a silyl group, and —P (═O) R 69 R 70, where R 69 and R 70 are an aryl group or hetero R 69 and R 70 may be condensed to form a ring, provided that n 3 phenanthroline skeletons are linked to X at at least one of R 61 to R 68. .n 3 is an integer of 2 or more .X is to connect the single bond or phenanthroline skeleton A consolidated unit.)

(In the formula, Ar 3 represents an aryl group or a heteroaryl group, and Z is represented by the following general formula (9). L 3 represents a single bond, an arylene group or a heteroarylene group. N 4 represents 1 or 2 When n 4 is 2, the two Zs may be the same or different.)

(In the formula, each of ring A and ring B represents a benzene ring, a condensed aromatic hydrocarbon ring, a monocyclic aromatic heterocyclic ring, or a condensed aromatic heterocyclic ring, provided that ring A and / or ring B is at least One electron-accepting nitrogen, the substituent in the case where ring A and ring B have a substituent, and R 71 are each an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, Cycloalkenyl, alkynyl, alkoxy, alkylthio, arylether, arylthioether, aryl, heteroaryl, halogen, carbonyl, carboxyl, oxycarbonyl, carbamoyl and -P (= O) R 72 R 73 is selected from the group consisting of R 73. R 71 may be hydrogen R 72 and R 73 may be an aryl group or a heteroa R 72 and R 73 may be condensed to form a ring, but linked to L 3 at any position of R 71 , ring A and ring B. n 4 is In the case of 2, the positions at which two Z are linked to L 3 may be the same or different.
The light emitting device according to claim 14, wherein the general formula (5) satisfies any of the following conditions (a) to (c).
(A) R 39 is used for linking with L 2 , and R 44 is an aryl group or a heteroaryl group.
(B) R 39 is used for linking with L 2 , R 41 is an aryl group or heteroaryl group, and R 44 , R 45 , and R 46 are all hydrogen atoms.
(C) R 39 is used for linking with L 2 , R 41 is an aryl group or a heteroaryl group, and R 45 is an alkyl group, an aryl group or a heteroaryl group.
The light-emitting element according to claim 14, wherein the electron transport layer contains a compound represented by the general formula (7), and Ar 3 is a group containing a fluoranthene skeleton or a group containing a benzofluoranthene skeleton.
The light emitting device according to claim 7, further comprising a hole transport layer between the anode and the cathode, wherein the hole transport layer contains a material having a carbazole skeleton.
The light-emitting element according to claim 17, wherein the material having a carbazole skeleton is a carbazole multimer.