JP2007258692A - Organic electroluminescent device and chemical compounds used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device having high efficiency and excellent durability by having a specific chemical compound contained in one or more organic compound layers, each of which has a light-emitting layer between a pair of electrodes. <P>SOLUTION: The organic electroluminescent device has one or more organic compound layers, each of which has a light-emitting layer between a pair of electrodes, wherein at least one of the organic compound layers contains a chemical compound represented by the formula (Z). In the formula, R<SP>31</SP>and R<SP>32</SP>each represent a hydrogen atom or a substituent; R3A represents a substituent other than an aromatic hetero ring bonding through a nitrogen atom, or a hydrogen atom; X<SP>31</SP>to X<SP>38</SP>each represent a substituted or unsubstituted carbon atom or a nitrogen atom; and Y<SP>31</SP>to Y<SP>33</SP>each represent a nitrogen atom or C-R<SP>3B</SP>(R<SP>3B</SP>represents a substituent other than an aromatic hetero ring bonding through a nitrogen atom, or a hydrogen atom). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device capable of emitting light by converting electric energy into light, and more particularly to an organic electroluminescent device and a novel compound used therefor.

  An organic electroluminescence (EL) element has attracted attention as a promising display element because it can emit light with high luminance at a low voltage. An important characteristic value of the organic electroluminescence device is external quantum efficiency. The external quantum efficiency is calculated by “external quantum efficiency φ = number of photons emitted from the device / number of electrons injected into the device”, and it can be said that the larger this value, the more advantageous the device in terms of power consumption.

  The external quantum efficiency of the organic electroluminescence device is determined by “external quantum efficiency φ = internal quantum efficiency × light extraction efficiency”. In an organic EL device using fluorescence emission from an organic compound, the limit value of the internal quantum efficiency is 25%, and the light extraction efficiency is approximately 20%. Therefore, the limit value of the external quantum efficiency is approximately 5%. Has been.

An element (triplet light emitting element) using a triplet light emitting material (phosphorescent light emitting material) has been reported as a method for improving the external quantum efficiency of the element by improving the internal quantum efficiency of the organic electroluminescent element (patent) Reference 1). This device can improve the external quantum efficiency as compared with a conventional device using fluorescent light emission (singlet light emitting device), and the external quantum of the device using Ir (ppy) ₃ which is a green phosphorescent material. It is described that the maximum value of efficiency reaches 8% (the external quantum efficiency at 100 cd / m ² is 7.5%). On the other hand, in order to apply an element using a triplet light emitting material to a full color display or a white light emitting element, an element capable of highly efficient light emission in other colors, particularly in a blue region, is desired.

  Recently, a device using a light emitting material having a maximum emission wavelength of 500 nm or less and a host material having a lowest triplet energy level larger than that of the light emitting material has been reported (Patent Document 2). Although this device can improve the external quantum efficiency as compared with a device using a conventional host material, improvement in durability is desired.

In addition, an organic electroluminescent device using a compound in which a plurality of imidazole skeletons are connected by a linking group has been proposed (Patent Document 3). However, the lowest triplet energy level is low, and a material for a triplet light emitting device (particularly, When used as a light-emitting layer and a material constituting a layer adjacent to the light-emitting layer, there is a problem that the light emission efficiency of the device is lowered.
International Publication No. 00/070655 Pamphlet JP 2002-1000047 A JP 2005-89544 A

  An object of the present invention is to provide a light-emitting element having high efficiency and good durability and a novel compound used for the element.

  A preferred configuration for achieving the above object is as follows.

[1] It has at least one organic compound layer including a light emitting layer between a pair of electrodes, and at least one of the organic compound layers contains a compound represented by the following general formula (Z) Organic electroluminescent device.
General formula (Z)

R ³¹ and R ³² represent a hydrogen atom or a substituent, R ^3A represents a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom, X ^{31 to} X ³⁸ are substituted or unsubstituted carbon atoms, Alternatively, it represents a nitrogen atom, and Y ^{31 to} Y ³³ represent a nitrogen atom or C—R ^3B (R ^3B represents a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom).
[2] The organic electroluminescent element as described in [1] above, wherein the compound represented by the general formula (Z) is a compound represented by the following general formula (Z-2).
General formula (Z-2)

R ³¹ and R ³² represent a hydrogen atom or a substituent, R ^{33 to} R ³⁵ and R ^3A represent a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom, and X ^{31 to} X ³⁸ represent a substituent or An unsubstituted carbon atom or a nitrogen atom is represented.
[3] The organic electroluminescent element as described in [2] above, wherein the compound represented by the general formula (Z-2) is a compound represented by the following general formula (Z-3).
General formula (Z-3)

R ³¹ and R ³² represent a hydrogen atom or a substituent, and R ^{33 to} R ³⁵ and R ^3A represent a substituent or a hydrogen atom other than an aromatic heterocycle connected by a nitrogen atom.
[4] The organic electroluminescent element as described in any one of [1] to [3], wherein the light emitting layer contains a compound that emits light from a triplet excited state.
[5] The organic electroluminescent element as described in any one of [1] to [4], wherein the compound represented by the general formula (Z) is contained in the light emitting layer.
[6] The organic electroluminescence according to any one of [1] to [5], wherein the compound represented by the general formula (Z) is contained in an organic compound layer adjacent to the light emitting layer. element.
[7] The organic electroluminescence according to any one of [1] to [6], wherein the compound represented by the general formula (Z) has a minimum triplet energy level of 65 kcal / mol or more. element.
[8] A compound represented by the general formula (Z).
[9] A compound represented by the general formula (Z-2).
[10] A compound represented by the general formula (Z-3).

  ADVANTAGE OF THE INVENTION According to this invention, the light emitting element which can perform highly efficient and highly durable light emission can be provided.

  The organic electroluminescent element of the present invention has at least one organic compound layer (hereinafter also referred to as “organic layer”) including a light emitting layer between a pair of electrodes (hereinafter, “element of the present invention”). , "Light-emitting element" or "EL element"), wherein at least one layer of the organic compound layer contains a compound represented by the general formula (Z). With this configuration, it is possible to provide a light-emitting element with excellent light emission efficiency and durability.

As described above, the organic electroluminescent device of the present invention has at least one organic compound layer including a light emitting layer, and as an organic compound layer other than the light emitting layer, a hole injection layer, a hole transport layer, an electron block layer In addition, an exciton block layer, a hole block layer, an electron transport layer, an electron injection layer, a protective layer, and the like may be appropriately disposed, and each may have the function of another layer. Each layer may be composed of a plurality of layers.
The compound represented by the general formula (Z) is preferably contained in one or both of the light emitting layer and the organic compound layer adjacent to the light emitting layer, and more preferably contained in the light emitting layer.
The amount of the compound represented by the formula (Z) in each layer is preferably 1 to 100% by mass, more preferably 10 to 90% by mass, and further preferably 10 to 70% by mass with respect to the light emitting layer. Especially preferably, it is 15-50 mass%.
Regarding layers other than a light emitting layer, Preferably it is 1-100 mass%, More preferably, it is 10-100 mass%, More preferably, it is 30-100 mass%, Most preferably, it is 50-100 mass%. .

Hereinafter, the compound represented by Formula (Z) to be added to the organic compound layer of the organic electroluminescence device of the present invention will be described in detail.
General formula (Z)

R ³¹ and R ³² represent a hydrogen atom or a substituent. The following substituent group A is mentioned as a substituent.

Substituent group A:
An alkyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n- Decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), perfluoroalkyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms). , Trifluoromethyl, pentafluoroethyl, etc.), alkenyl groups (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms such as vinyl, Allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having a carbon number) To 30, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as propargyl and 3-pentynyl), aryl groups (preferably 6 to 30 carbon atoms, more preferably It has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl, anthranyl, etc., an amino group (preferably having 0 to 30 carbon atoms, more preferably carbon. The number is from 0 to 20, particularly preferably from 0 to 10, and examples thereof include amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, dipyridylamino, dithienylamino, and phenylpyridylamino. ), An alkoxy group (preferably having 1 to 30 carbon atoms, more preferably carbon 1 to 20, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc.), an aryloxy group (preferably 6 to 30 carbon atoms, more preferably It has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy, 1-naphthyloxy, 2-naphthyloxy and the like, and a heterocyclic oxy group (preferably having 1 to 30 carbon atoms, More preferably, it is C1-C20, Most preferably, it is C1-C12, for example, pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy etc.), an acyl group (preferably C1-C30, more preferably). C1-20, particularly preferably C1-12, such as acetyl, benzoyl, formyl, piva Examples include Roile. ), An alkoxycarbonyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), aryloxycarbonyl A group (preferably having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonyl), an acyloxy group (preferably having 2 to 2 carbon atoms). 30, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetoxy and benzoyloxy), acylamino groups (preferably 2 to 30 carbon atoms, more preferably carbon atoms). 2 to 20, particularly preferably 2 to 10 carbon atoms, such as acetylamino, benzoylamino An alkoxycarbonylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino). An aryloxycarbonylamino group (preferably having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino), a sulfonylamino group (Preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino, benzenesulfonylamino, etc.), sulfamoyl group (preferably carbon Number 0 to 30, more preferably 0 to 20 carbon atoms, particularly preferably 0 carbon atoms 12, for example, sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), carbamoyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably Has 1 to 12 carbon atoms, and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably C1-C12, for example, methylthio, ethylthio, etc.), arylthio groups (preferably C6-C30, more preferably C6-C20, particularly preferably C6-C12, For example, phenylthio and the like), a heterocyclic thio group (preferably Has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms. For example, pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio Etc. ), A sulfonyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl and tosyl), a sulfinyl group (preferably carbon). 1 to 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl and benzenesulfinyl), ureido groups (preferably 1 to 30 carbon atoms, and more). Preferably it is C1-C20, Most preferably, it is C1-C12, for example, a ureido, methylureido, phenylureido etc. are mentioned), phosphoric acid amide groups (preferably C1-C30, More preferably It has 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms. Examples thereof include diethyl phosphoric acid amide and phenyl phosphoric acid amide. Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group Group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom. Imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl group, azepinyl group, silolyl group, etc.), silyl group (preferably having 3 to 40 carbon atoms, More preferably, it has 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms. For example, trimethylsilyl, triphenylsilyl, etc.), silyloxy groups (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, for example, trimethylsilyloxy, And triphenylsilyloxy).

Among these substituents, alkyl groups, perfluoroalkyl groups, aryl groups, heterocyclic groups, alkenyl groups, alkoxy groups, aryloxy groups, alkylamino groups, arylamino groups, heterocyclic amino groups, silicon-containing heterocyclic groups, Silyl group, hydroxy group, mercapto group and halogen atom are preferable, alkyl group, perfluoroalkyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, arylamino group and silyl group are more preferable, alkyl group and perfluoroalkyl. A group, an aryl group, a heterocyclic group, and a silyl group are more preferable.
R ³¹ and R ³² may be the same or different.

R ^3A represents a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom. As the substituent, the substituent represented by the substituent group A excluding the aromatic heterocycle connected by a nitrogen atom can be applied, and an alkyl group, an aryl group, a heterocyclic group, an alkenyl group, an alkoxy group, an aryloxy group , Alkylamino group, arylamino group, heterocyclic amino group, silicon-containing heterocyclic group, silyl group, hydroxy group, mercapto group, halogen atom, cyano group are preferable, alkyl group, perfluoroalkyl group, aryl group, heterocyclic group An alkoxy group, an aryloxy group, an arylamino group, a silyl group, and a cyano group are more preferable, and an alkyl group, a perfluoroalkyl group, an aryl group, a heterocyclic group, a silyl group, and a cyano group are more preferable.

X ^{31 to} X ^{38 each} represents a substituted or unsubstituted carbon atom or a nitrogen atom. Although it does not specifically limit as a substituent on carbon, The said substituent group A is applicable.

When X ^{31 to} X ³⁸ are carbon atoms, examples of the substituent on the carbon include alkyl groups, aryl groups, heterocyclic groups, alkenyl groups, alkoxy groups, aryloxy groups, alkylamino groups, arylamino groups, and heterocyclic amino groups. Group, silicon-containing heterocyclic group, silyl group, hydroxy group, mercapto group and halogen atom are preferable, alkyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, arylamino group and silyl group are more preferable, alkyl group A group, an aryl group, a heterocyclic group, and a silyl group are more preferable.

Y ^{31 to} Y ³³ represent a nitrogen atom or C—R ^3B . R ^3B has the same meaning as R ^3A , and the preferred range is also the same.

  The compound represented by the general formula (Z) is more preferably a compound represented by the general formula (Z-2). Next, the compound represented by general formula (Z-2) is demonstrated.

In the general formula (Z-2), R ³¹ , R ³² , R ^3A and X ^{31 to} X ³⁸ have the same meanings as those in the general formula (Z), and preferred ranges are also the same. R ³³ to R ³⁵ represents a substituent, or a hydrogen atom other than an aromatic hetero ring connected by a nitrogen atom. The preferred range of the group represented by R ^{33 to} R ³⁵ is the same as R ^3A .

  The compound represented by the general formula (Z-2) is more preferably a compound represented by the general formula (Z-3). Next, the compound represented by general formula (Z-3) is demonstrated.

In the general formula (Z-3), R ³¹ , R ³² , R ^3A and R ^{33 to} R ³⁵ have the same meanings as those in the general formula (Z-2), and preferred ranges thereof are also the same.

  The compounds represented by the general formula (Z), the general formula (Z-2) and the general formula (Z-3) may be contained in any organic layer, but the organic compound layer adjacent to the light emitting layer or light emitting It is preferably contained in the layer and more preferably contained in the light emitting layer. Moreover, even if it is contained in one organic layer, it may be contained in several organic layers.

The T ₁ level (lowest triplet excited state energy level) of the compound represented by the general formula (Z) is preferably 45 kcal / mol (188.3 kJ / mol) or more, and 55 kcal / mol. (251.0 kJ / mol) or more is more preferable, 60 kcal / mol (272.0 kJ / mol) or more is further preferable, and 65 kcal / mol (294.7 kJ / mol) or more is particularly preferable. The upper limit is preferably 85 kcal / mol (355.6 kJ / mol) or less.
In particular, when the light emitting layer contains a compound that emits light from a triplet excited state, the T ₁ level in the film state of the compound represented by the general formula (Z) is preferably in the above range.

The T ₁ level can be obtained from the wavelength of the short wavelength end of the spectrum by measuring the phosphorescence spectrum of the compound in the film state.

  Next, although the compound example of this invention is shown, this invention is not limited to this.

The compound of the present invention can be synthesized, for example, according to the method described in “Heterocycles, Vol. 55, No. 5, 2001, 905-924”.
The compound represented by the formula (Z) can be synthesized using various known methods. For example, aryl halides, aryl triflates, heteroaryl halides, heteroaryl triflates, imidazole derivatives, catalysts (Pd, Cu, etc.), bases (carbonates, alkoxides, amine derivatives, etc.), solvents (hydrocarbon solvents, halogen series) In the presence or absence of a solvent, an ether solvent, an alcohol solvent, water, etc.). Moreover, after reacting an amine derivative and an aryl halide, aryl triflate, heteroaryl halide, heteroaryl triflate, an imidazole cyclization reaction can be carried out for synthesis.

  The synthesis method of the compound of the present invention will be described below.

<Synthesis Example 1>
Synthesis of exemplary compound (3)

[Synthesis of Compound 3a]
21.4 g (0.3 mol) of 2-nitroaniline, 39.8 g (0.33 mol) of pivalic acid chloride and 250 mL of toluene were placed in a 1 L round bottom flask and stirred under a nitrogen atmosphere. After heating under reflux for 1 hour, the reaction solution was cooled to room temperature. After extraction by adding 300 mL of ethyl acetate and 300 mL of distilled water, the organic layer was further washed with 300 mL of distilled water, and the organic layer was dried over magnesium sulfate. Magnesium sulfate was filtered off and concentrated under reduced pressure to obtain 66.8 g (0.3 mol) of compound 3a. Yield 100%

[Synthesis of Compound 3b]
66.8 g (0.3 mol) of compound 3a and 250 mL of ethanol were placed in a 1 L round bottom flask and stirred under a nitrogen atmosphere. Thereto was added 10 g of Pd—C having a water content of 55% and refluxed. Further, 47.3 g (0.75 mol) of ammonium formate was slowly added. After heating to reflux for 1 hour, the reaction mixture was filtered through celite. The filtrate was concentrated twice and cooled with ice water to obtain 34.6 g (0.18 mol) of compound 3b as flesh-colored crystals. Yield 60%

[Synthesis of Compound 3c]
Compound 3b 6.34 g (33 mmol), 1,3-dibromobenzene 3.54 g (15 mmol), palladium acetate 0.34 g (1.5 mmol), 2- (di-t-butylphosphino) biphenyl 34 g (4.5 mmol), 13.9 g (60 mmol) of rubidium carbonate and 100 mL of toluene were placed in a 500 mL round bottom flask and stirred under a nitrogen atmosphere. After heating to reflux for 4 hours, the reaction solution was filtered. The filtrate was concentrated and purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate = 5/2) to obtain 4.4 g (9.6 mmol) of compound 3c. Yield 64%

[Synthesis of Exemplified Compound (3)]
Compound 3c (4.4 g, 9.6 mmol) and xylene (50 mL) were placed in a 300 mL round bottom flask and stirred. Acetic acid 10mL and 35% hydrochloric acid 5mL were added there, and it heated and refluxed for 2 hours. After cooling to room temperature, 200 mL of chloroform and 300 mL of distilled water were added and stirred at room temperature. Further, sodium bicarbonate was added to make the mixture basic. The organic layer was dried over magnesium sulfate and concentrated. The obtained solid was heated to reflux in 100 mL of methanol to obtain 1.2 g (2.8 mmol) of Exemplary Compound (3) as a white powder. Yield 30%.
It was confirmed by NMR measurement and MS measurement that it was the target compound.

<Synthesis Example 2>
Synthesis of exemplified compound (31)

[Synthesis of Compound 31a]
Compound 3b 8.1 g (42.16 mmol), 3,5-dibromobenzonitrile 5 g (19.16 mmol), rubidium carbonate 17.7 g (76.65 mmol), 2-dicyclohexylphosphino 2 ', 4', 6'- 183 mg (0.38 mmol) of triisopropylbiphenyl and 100 mL of xylene were added to a 300 mL three-necked round bottom flask and stirred under a nitrogen stream. The temperature of the solution was raised to 50 ° C., and 43 mg (0.19 mmol) of palladium acetate was added. The solution was heated to 115 ° C. and stirred with heating for 1 hour. The solution was cooled to 100 ° C. and filtered while hot to remove insolubles. The filtrate was evaporated under reduced pressure to remove the solvent, and then recrystallized from ethyl acetate to obtain 6.22 g of compound 31a as white crystals (yield 67%).

[Synthesis of Exemplary Compound (31)]
Compound 31a 6.22 g (12.86 mmol), p-toluenesulfonic acid monohydrate 1.22 g (6.43 mmol), 4-t-butyl-o-xylene 50 mL were added to a 300 mL three-necked round bottom flask, and a nitrogen stream Stir below. The solution was heated to 190 ° C. and stirred with heating for 5 hours. A gray precipitate formed upon cooling to room temperature. The obtained precipitate was separated and purified with a silica gel column (hexane: ethyl acetate = 1: 1) to obtain 2.61 g of Exemplified Compound (31) as white crystals (yield 45%).
It was confirmed by NMR measurement and MS measurement that it was the target compound.

<Synthesis Example 3>
Synthesis of Exemplified Compound (33)

[Synthesis of Compound 33a]
Compound 3b 20 g (0.104 mol), 2,6-dichlorobenzonitrile 8.52 g (49.5 mmol), rubidium carbonate 47.4 g (0.198 mol), 2- (di-t-butylphosphino) biphenyl 21 g (7.43 mmol), 557 mg of palladium acetate (2.48 mmol), and 318 mL of toluene were added to a 1000 mL three-necked round bottom flask and stirred under a nitrogen stream. The mixture was heated to 80 ° C. and stirred with heating for 5 hours. The solution was cooled to room temperature and insolubles were removed by filtration. The filtrate was extracted with ethyl acetate, washed successively with water and saturated brine, and the organic phase was dried over magnesium sulfate. The solvent was distilled off under reduced pressure to obtain 21 g of compound 33a as white crystals (yield 88%).

[Synthesis of Exemplified Compound (33)]
20 g (41.4 mmol) of Compound 33a, 15.8 g (82.8 mmol) of paratoluenesulfonic acid monohydrate and 100 mL of benzonitrile were added to a 300 mL three-necked round bottom flask and stirred under a nitrogen stream. The solution was heated to 180 ° C. and stirred for 16 hours. The reaction mixture was cooled to room temperature, extracted with ethyl acetate, washed successively with water and saturated brine, and the organic phase was dried over magnesium sulfate. The solvent was distilled off under reduced pressure and recrystallized from an ethyl acetate-hexane solution to obtain 1.3 g of Exemplified Compound (33) as white crystals (yield 7%).
It was confirmed by NMR measurement and MS measurement that it was the target compound.

  Next, the organic electroluminescent element of the present invention will be described. The organic electroluminescent element of the present invention is not particularly limited, such as a system, a driving method, and a usage form. An organic EL (electroluminescence) element can be mentioned as a typical organic electroluminescent element.

The external quantum efficiency of the light emitting device of the present invention is preferably 5% or more, more preferably 10% or more, and further preferably 13% or more. The maximum value of the external quantum efficiency when numeric external quantum efficiency of the device is driven at 20 ° C., or around 100~300cd / m ² when the device is driven at 20 ° C. (preferably 200~300cd / m ²⁾ The value of external quantum efficiency at can be used.

  The internal quantum efficiency of the light emitting device of the present invention is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. The internal quantum efficiency of the device is calculated by “internal quantum efficiency = external quantum efficiency / light extraction efficiency”. In a normal organic EL element, the light extraction efficiency is about 20%. However, the shape of the substrate, the shape of the electrode, the thickness of the organic layer, the thickness of the inorganic layer, the refractive index of the organic layer, the refractive index of the inorganic layer, etc. By devising it, it is possible to increase the light extraction efficiency to 20% or more.

The glass transition point of the host material contained in the light emitting layer of the present invention, the material contained in the electron transport layer, and the hole transport material is preferably 90 ° C. or higher and 400 ° C. or lower, and 100 ° C. or higher and 380 ° C. or lower. Is more preferably 120 ° C. or higher and 370 ° C. or lower, and particularly preferably 140 ° C. or higher and 360 ° C. or lower.
Here, Tg can be confirmed by thermal measurement such as differential scanning calorimetry (DSC) and differential thermal analysis (DTA), X-ray diffraction (XRD), and polarization microscope observation.

The light emitting material used in the present invention will be described. A light-emitting material is a compound that has a function of substantially emitting light in a light-emitting layer, and the light emission may be fluorescent, phosphorescent, or both. A compound that emits phosphorescence is preferred.
The organic electroluminescent element of the present invention is more preferably an element in which the light emitting layer does not contain a fluorescent light emitting compound and the phosphorescent light emitting compound substantially emits light.

  The concentration of the light-emitting material in the light-emitting layer is not particularly limited, but is preferably equal to or less than that of the main component host material, more preferably 0.1% by mass or more and 50% by mass or less. More preferably, the content is 2% by mass or more and 30% by mass or less, particularly preferably 0.3% by mass or more and 20% by mass or less, and most preferably 0.5% by mass or more and 10% by mass or less.

  The phosphorescent compound is not particularly limited, but is preferably a transition metal complex, more preferably an iridium complex, a platinum complex, a rhenium complex, a ruthenium complex, a palladium complex, a rhodium complex, or a rare earth complex, and more preferably an iridium complex or a platinum complex. . Further, ortho-metalated iridium complexes having a difluorophenylpyridine ligand described in Japanese Patent Application Nos. 2001-239281 and 2001-248165 of JP-A Nos. 2002-235076 and 2002-170684 are preferable.

  Also, US Pat. No. 6,303,238, US Patent Application Publication No. 6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234 A2, WO01 / 41512 A1, WO02 / 02714 A2, WO02 / 15645 A1, JP Japanese Patent Application No. 2001-247859, Japanese Patent Application No. 2000-33561, Japanese Patent Application Laid-Open No. 2002-117978, Japanese Patent Application No. 2001-248165, Japanese Patent Application Laid-Open No. 2002-2335076, Japanese Patent Application No. 2001-239281, Japanese Patent Application Laid-Open No. 2002-170684. Gazette, EP 12111257, JP 2002-26495, JP 2002-234894, JP 2001-247859, JP 2001-298470, JP 2002-173684, JP 2002-1 Phosphorescent compounds described in patent documents such as JP-A-73674, JP-A-2002-203678, and JP-A-2002-203679 can also be suitably used.

  The phosphorescence lifetime (room temperature) of the phosphorescent compound used in the present invention is not particularly limited, but is preferably 1 ms or less, more preferably 100 μs or less, and even more preferably 10 μs or less.

The T ₁ level (lowest triplet excited state energy level) of the phosphorescent compound is 45 kcal / mol or more (188.3 kJ / mol or more), 90 kcal / mol or less (377.1 kJ / mol or less). Preferably, 55 kcal / mol or more (251.0 kJ / mol or more), 85 kcal / mol or less (356.15 kJ / mol or less), more preferably 60 kcal / mol or more (272.0 kJ / mol or more), 85 kcal / mol or less. (355.6 kJ / mol or less) is more preferable, and 65 kcal / mol or more (272.35 kJ / mol or more), 80 kcal / mol or less (335.2 kJ / mol or less) is particularly preferable.

The layer adjacent to the light-emitting layer (hole transport layer, electron transport layer, charge block layer, exciton block layer, etc.) has a T ₁ level (lowest triplet excited state energy level) of 45 kcal / mol or more (188.3). kJ / mol or more), 85 kcal / mol or less (355.6 kJ / mol or less) is preferable, 55 kcal / mol or more (251.0 kJ / mol or more), 85 kcal / mol or less (355.6 kJ / mol or less) is more preferable, More preferably, they are 60 kcal / mol or more (272.0 kJ / mol or more), 85 kcal / mol or less (355.6 kJ / mol or less).

  The light-emitting element of the present invention can improve the light extraction efficiency by various known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.

  The light-emitting element of the present invention may be a so-called top emission method (described in Japanese Patent Application Laid-Open Nos. 2003-208109, 2003-248441, 2003-257651, 2003-282261, etc.) in which light emission is extracted from the anode side.

  The substrate used in the light-emitting device of the present invention is not particularly limited, but inorganic materials such as zirconia-stabilized yttrium and glass, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polycarbonate, and polyethersulfone. , Polyarylate, allyl diglycol carbonate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), polytetrafluoroethylene, polytetrafluoroethylene-polyethylene copolymer, etc. .

  The organic electroluminescent device of the present invention may contain a blue fluorescent light emitting compound, or a blue light emitting device containing a blue fluorescent compound and the light emitting device of the present invention are used simultaneously to produce a multicolor light emitting device or a full color light emitting device. A device may be manufactured.

  The light emitting layer of the organic electroluminescent element of the present invention may have a laminated structure. The number of stacked layers is preferably 2 or more and 50 or less, more preferably 4 or more and 30 or less, and still more preferably 6 or more and 20 or less.

  The thickness of each layer constituting the stacked structure is not particularly limited, but is preferably 0.2 nm or more and 20 nm or less, more preferably 0.4 nm or more and 15 nm or less, further preferably 0.5 nm or more and 10 nm or less, and more preferably 1 nm or more and 5 nm or less. Is particularly preferred.

The light emitting layer of the organic electroluminescent element of the present invention may have a plurality of domain structures. The light emitting layer may have another domain structure. For example, the light emitting layer, and a region of approximately 1 nm ³ of a mixture of a host material A and a light emitting material B, may be configured in the region of about 1 nm ³ of a mixture of a host material C and a light-emitting material D. The diameter of each domain is preferably from 0.2 nm to 10 nm, more preferably from 0.3 nm to 5 nm, still more preferably from 0.5 nm to 3 nm, and particularly preferably from 0.7 nm to 2 nm.

  The method for forming the organic layer of the light-emitting element containing the compound of the present invention is not particularly limited, but resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method (spray coating method, dip coating method, Impregnation method, roll coat method, gravure coat method, reverse coat method, roll brush method, air knife coat method, curtain coat method, spin coat method, flow coat method, bar coat method, micro gravure coat method, air doctor coat, blade Coating methods, squeeze coating methods, transfer roll coating methods, kiss coating methods, cast coating methods, extrusion coating methods, wire bar coating methods, screen coating methods, etc.), inkjet methods, printing methods, transfer methods, etc. are used, Resistance heating vapor deposition and coating in terms of characteristics and manufacturing Packaging method, a transfer method is preferable.

The light-emitting device of the present invention is a device in which a light-emitting layer or a plurality of organic compound films including a light-emitting layer is formed between a pair of anode and cathode electrodes. In addition to the light-emitting layer, a hole injection layer, a hole transport layer, and an electron injection It may have a layer, an electron transport layer, a protective layer, etc., and each of these layers may have other functions. Various materials can be used for forming each layer.

  The anode supplies holes to a hole injection layer, a hole transport layer, a light emitting layer, and the like, and a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Is a material having a work function of 4 eV or more. Specific examples include conductive metal oxides such as tin oxide, zinc oxide, indium oxide and indium tin oxide (ITO), metals such as gold, silver, chromium and nickel, and these metals and conductive metal oxides. Inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO, preferably conductive metals It is an oxide, and ITO is particularly preferable from the viewpoint of productivity, high conductivity, transparency, and the like. Although the film thickness of the anode can be appropriately selected depending on the material, it is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, still more preferably 100 nm to 500 nm.

As the anode, a layer formed on a soda-lime glass, non-alkali glass, a transparent resin substrate or the like is usually used. When glass is used, it is preferable to use non-alkali glass as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. The thickness of the substrate is not particularly limited as long as it is sufficient to maintain the mechanical strength, but when glass is used, a thickness of 0.2 mm or more, preferably 0.7 mm or more is usually used.
Various methods are used for producing the anode depending on the material. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (such as a sol-gel method), an application of an indium tin oxide dispersion, etc. A film is formed by the method.
The anode can be subjected to cleaning or other treatments to lower the drive voltage of the element or increase the light emission efficiency. For example, in the case of ITO, UV-ozone treatment, plasma treatment, etc. are effective.

The cathode supplies electrons to the electron injection layer, the electron transport layer, the light emitting layer, etc., and the adhesion, ionization potential, stability, etc., between the negative electrode and the adjacent layer such as the electron injection layer, electron transport layer, light emitting layer, etc. Selected in consideration of As a material for the cathode, a metal, an alloy, a metal halide, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Specific examples include an alkali metal (for example, Li, Na, K, etc.) and its fluoride. Or oxides, alkaline earth metals (eg Mg, Ca, etc.) and fluorides or oxides thereof, gold, silver, lead, aluminum, sodium-potassium alloys or their mixed metals, lithium-aluminum alloys or their mixtures Examples thereof include metals, magnesium-silver alloys or mixed metals thereof, rare earth metals such as indium and ytterbium, preferably materials having a work function of 4 eV or less, more preferably aluminum, lithium-aluminum alloys or mixed metals thereof. , Magnesium-silver alloys or mixed metals thereof. The cathode can take not only a single layer structure of the compound and the mixture but also a laminated structure including the compound and the mixture. For example, a laminated structure of aluminum / lithium fluoride and aluminum / lithium oxide is preferable.
The film thickness of the cathode can be appropriately selected depending on the material, but is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, still more preferably 100 nm to 1 μm.
For production of the cathode, methods such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a coating method, and a transfer method are used, and a metal can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited.
The sheet resistance of the anode and the cathode is preferably low, and is preferably several hundred Ω / □ or less.

The material of the light emitting layer is a function that can inject holes from the anode or hole injection layer, hole transport layer and cathode or electron injection layer, electron transport layer when an electric field is applied, Any compound can be used as long as it can form a layer having a function of transferring injected charges and a function of emitting light by providing a recombination field of holes and electrons. Oxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, perylene, perinone, oxadiazole, aldazine, pyralidine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, Thiadiazolopyridine, cyclopentadi , Styrylamine, aromatic dimethylidin compounds, various metal complexes represented by 8-quinolinol metal complexes and rare earth complexes, polymer compounds such as polythiophene, polyphenylene, polyphenylene vinylene, organic silanes, iridium trisphenylpyridine complexes, and platinum Examples include transition metal complexes represented by porphyrin complexes and derivatives thereof. Although the film thickness of a light emitting layer is not specifically limited, Usually, the thing of the range of 1 nm-5 micrometers is preferable, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm.
The method for forming the light emitting layer is not particularly limited, and methods such as resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method, ink jet method, printing method, LB method, and transfer method are used. Of these, resistance heating vapor deposition and coating are preferred.

  There may be one or a plurality of light emitting layers, and each layer may emit light with a different emission color, for example, white light. White light may be emitted from a single light emitting layer.

The material of the hole injection layer and the hole transport layer may be any one having a function of injecting holes from the anode, a function of transporting holes, or a function of blocking electrons injected from the cathode. Good. Specific examples thereof include the compound of the present invention, carbazole, triazole, oxazole, oxadiazole, imidazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, Stilbene, silazane, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, polythiophenes, etc. Examples thereof include conductive polymer oligomers, organic silanes, carbon films, and derivatives thereof. The film thicknesses of the hole injection layer and the hole transport layer are not particularly limited, but are usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and still more preferably 10 nm to 500 nm. . The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.
As a method for forming the hole injection layer and the hole transport layer, a vacuum deposition method, an LB method, a method in which the hole injection / transport material is dissolved or dispersed in a solvent, a coating method, an ink jet method, a printing method, or a transfer method is used. It is done. In the case of the coating method, it can be dissolved or dispersed together with the resin component. Examples of the resin component include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, and poly (N -Vinyl carbazole), hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicone resin, and the like.

The material for the electron injection layer and the electron transport layer may be any material having any one of a function of injecting electrons from the cathode, a function of transporting electrons, and a function of blocking holes injected from the anode. Specific examples thereof include triazole, oxazole, oxadiazole, imidazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, and distyrylpyrazine in addition to the compounds of the present invention. , Aromatic metal tetracarboxylic anhydrides such as naphthalene and perylene, phthalocyanines, metal complexes of 8-quinolinol, metal phthalocyanines, various metal complexes represented by metal complexes having benzoxazole and benzothiazole as ligands, organic silanes, And derivatives thereof. Although the film thickness of an electron injection layer and an electron carrying layer is not specifically limited, The thing of the range of 1 nm-5 micrometers is preferable normally, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm. The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.
As a method for forming the electron injection layer and the electron transport layer, a vacuum vapor deposition method, an LB method, a method in which the electron injection transport material is dissolved or dispersed in a solvent, a coating method, an ink jet method, a printing method, a transfer method, and the like are used. In the case of the coating method, it can be dissolved or dispersed together with the resin component. As the resin component, for example, those exemplified in the case of the hole injection transport layer can be applied.

As a material for the protective layer, any material may be used as long as it has a function of preventing substances that promote device deterioration such as moisture and oxygen from entering the device. Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ , and CaF ₂ , SiN _x , SiO _x N _y Such as nitride, polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene And a copolymer obtained by copolymerizing a monomer mixture containing at least one comonomer, a fluorine-containing copolymer having a cyclic structure in the copolymer main chain, a water-absorbing substance having a water absorption of 1% or more, a water absorption of 0 .1% or less of moisture-proof substances and the like.
There is no particular limitation on the method for forming the protective layer. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation ions) Plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, and transfer method can be applied.

  The use of the light emitting device of the present invention is not particularly limited, but is suitable for the fields of display device, display, backlight, electrophotography, illumination light source, recording light source, exposure light source, reading light source, sign, signboard, interior, optical communication, etc. Can be used.

  Specific examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

[Example 1: Element 1 of the present invention]
The cleaned ITO substrate was put into a vapor deposition apparatus, and α-NPD was vapor-deposited by 40 nm. On top of this, FIrpic (phosphorescent compound), compound (3), and mCP were deposited at a ratio (mass ratio) of 6:20:74 to 30 nm, and then Balq was deposited at 6 nm, on which Alq was deposited. Was deposited by 20 nm. On top of this, magnesium and silver were co-evaporated at a ratio of 10: 1 (molar ratio) to 100 nm to produce an EL device. In addition, the lowest triplet energy in the film | membrane state of a compound (3) is 71.5 kcal / mol.
When a source constant unit 2400 type manufactured by Toyo Technica was used to emit light by applying a DC constant voltage to the EL element, light emission having a maximum emission wavelength in the vicinity of 485 nm was obtained.
When the driving durability of the element 1 of the present invention was measured at an initial luminance of 300 cd / m ² , the luminance half-life was about 10 times that of the element of Comparative Example 1.

[Example 2: Element 2 of the present invention]
A light emitting device was produced in the same manner as in Example 1 except that the compound (4) was used instead of the compound (3) in the production of the light emitting device of Example 1. When the device was made to emit light in the same manner as in Example 1, light emission having a maximum emission wavelength in the vicinity of 485 nm was obtained. In addition, the lowest triplet energy in the film | membrane state of a compound (4) is 71 kcal / mol.
When the driving durability of the element 2 of the present invention is measured at an initial luminance of 300 cd / m ² , the luminance half-life is about 10 times that of the element of Example 4 (element 1 of the comparative example).

[Example 3: Element 3 of the present invention]
A light emitting device was produced in the same manner as in Example 1 except that BAlq: compound (3) = 80: 20 (mass ratio) was used instead of BAlq in the production of the light emitting device of Example 1. When the device was made to emit light in the same manner as in Example 1, light emission having a maximum emission wavelength in the vicinity of 485 nm was obtained. The external quantum efficiency of the device is about 1.5 times that of the device of Example 1.

[Example 4: Element 1 of Comparative Example]
A light emitting device was produced in the same manner as in Example 1 except that Compound A was used instead of Compound (3) in the production of the light emitting device of Example 1. When the device was made to emit light in the same manner as in Example 1, light emission having a maximum emission wavelength in the vicinity of 485 nm was obtained.

[Example 5: Preparation of comparative element B-1]
A glass substrate having an ITO film of 0.5 mm thickness and 2.5 cm square (manufactured by Geomatek Co., Ltd., surface resistance 10 Ω / □) is placed in a cleaning container, ultrasonically cleaned in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. Went. The following organic compound layers were sequentially deposited on the transparent anode (ITO film) by vacuum deposition.

(First layer): Film thickness 120 nm
HIL-A
(Second layer): Film thickness 10 nm
α-NPD
(Third layer): Film thickness 30 nm
CBP = 90% by mass,
Firpic = 10% by mass
(Fourth layer): Film thickness 40 nm
BAlq

Finally, 0.5 nm of lithium fluoride and 100 nm of metallic aluminum were vapor-deposited in this order to form a cathode.
This is put in a glove box substituted with argon gas without being exposed to the atmosphere, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.). Comparative element B-1 was obtained.

[Examples 6 and 7: Preparation of elements J-1 and J-2 of the present invention]
Organic electroluminescent elements J-1 and J-2 of the present invention were prepared in the same manner as Comparative element B-1, except that CBP was replaced with exemplary compound (3) and exemplary compound (31), respectively.

{Evaluation of organic electroluminescent elements J-1 and J-2}
When a constant voltage was applied to the comparative element B-1 and the elements J-1 and J-2 of the present invention in increments of 1 V from 1 V to 20 V, light emission derived from the Ferpic was observed. The maximum values of the external quantum efficiencies are 3.2%, 7.4%, and 8.0%, respectively, and the elements J-1 and J-2 of the present invention are more than twice as large as the comparative element B-1. It was a high value. In addition, the lowest triplet energy in the film | membrane state of a compound (31) was 69 kcal / mol.

[Example 8: Preparation of comparison element B-2]
A glass substrate having an ITO film of 0.5 mm thickness and 2.5 cm square (manufactured by Geomatek Co., Ltd., surface resistance 10 Ω / □) is placed in a cleaning container, ultrasonically cleaned in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. Went. The following organic compound layers were sequentially deposited on the transparent anode (ITO film) by vacuum deposition.

(First layer): Film thickness 120 nm
HIL-A
(Second layer): Film thickness 10 nm
NPD
(Third layer): Film thickness 30 nm
mCP = 90% by mass,
EML-A = 10% by mass
(Fourth layer): Film thickness 10 nm
BAlq
(Fifth layer): Film thickness 30 nm
Alq

Finally, 0.5 nm of lithium fluoride and 100 nm of metallic aluminum were vapor-deposited in this order to form a cathode.
This is put in a glove box substituted with argon gas without being exposed to the atmosphere, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.). And the organic electroluminescent element of comparative example B-2 was obtained.

[Example 9: Preparation of device J-3 of the present invention]
Organic electroluminescent element J-3 of the present invention was prepared in the same manner as Comparative element B-2 except that BAlq was replaced with exemplary compound (31).

{Evaluation of organic electroluminescent element J-3}
When a constant voltage was applied to the comparative element B-2 and the element J-3 of the present invention in increments of 1 V from 1 V to 20 V, light emission derived from EML-A was observed. The maximum values of the external quantum efficiency were 4.4% and 11.5%, respectively, and the device J-3 of the present invention was 2.5 times or more higher than the comparative device B-2.

Claims (10)

An organic electroluminescence comprising at least one organic compound layer including a light emitting layer between a pair of electrodes, wherein at least one of the organic compound layers contains a compound represented by the following general formula (Z) element.
General formula (Z)

(R ³¹ and R ³² represent a hydrogen atom or a substituent, R ^3A represents a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom, and X ^{31 to} X ³⁸ are substituted or unsubstituted carbon atoms. Or Y ^{31 to} Y ^{33 each} represents a nitrogen atom or C—R ^3B (R ^3B represents a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom). The organic electroluminescent element according to claim 1, wherein the compound represented by the general formula (Z) is a compound represented by the following general formula (Z-2).
General formula (Z-2)

(R ³¹ and R ³² represent a hydrogen atom or a substituent, R ^{33 to} R ³⁵ and R ^3A represent a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom, and X ^{31 to} X ³⁸ represent a substituent. Or an unsubstituted carbon atom or a nitrogen atom.) The organic electroluminescent device according to claim 2, wherein the compound represented by the general formula (Z-2) is a compound represented by the following general formula (Z-3).
General formula (Z-3)

(R ³¹ and R ³² represent a hydrogen atom or a substituent, and R ^{33 to} R ³⁵ and R ^3A represent a substituent or a hydrogen atom other than an aromatic heterocycle connected by a nitrogen atom.)   The organic electroluminescent element according to claim 1, wherein the light emitting layer contains a compound that emits light from a triplet excited state.   The organic electroluminescent element according to claim 1, wherein the compound represented by the general formula (Z) is contained in the light emitting layer.   The organic electroluminescent element according to claim 1, wherein the compound represented by the general formula (Z) is contained in an organic compound layer adjacent to the light emitting layer.   The organic electroluminescent element according to any one of claims 1 to 6, wherein the compound represented by the general formula (Z) has a minimum triplet energy level of 65 kcal / mol or more. The compound represented by the following general formula (Z).
General formula (Z)

(R ^31, R ³² represents a hydrogen atom or a substituent, R ^3A represents a substituent or a hydrogen atom other than an aromatic hetero ring connected by a nitrogen atom, X ³¹ to X ³⁸ is a substituted or unsubstituted carbon atom Or Y ^{31 to} Y ^{33 each} represents a nitrogen atom or C—R ^3B (R ^3B represents a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom). The compound represented by the following general formula (Z-2).
General formula (Z-2)

(R ³¹ and R ³² represent a hydrogen atom or a substituent, R ^{33 to} R ³⁵ and R ^3A represent a substituent other than an aromatic heterocycle connected by a nitrogen atom or a hydrogen atom, and X ^{31 to} X ³⁸ represent a substituent. Or an unsubstituted carbon atom or a nitrogen atom.) The compound represented by the following general formula (Z-3).
General formula (Z-3)

(R ^31, R ³² represents a hydrogen atom or a substituent, R ³³ to R ³⁵ and R ^3A represents a substituent or a hydrogen atom other than an aromatic hetero ring connected through a nitrogen atom.)