JP2014110357A - Organic el material containing cyclic compound having carbazolyl group and organic el element including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL material and an organic EL element, achieving improved luminous efficiency and prolonged life.SOLUTION: An organic EL material is represented by the following formula (1). [Y-Yindependently represent an alkylene group, a cycloalkylene group, an arylene group, or a heteroarylene group, Z-Zindependently represent an alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group, a, b and c represent an integer of one or more, respectively, and satisfy a relationship of a+b+c≤9, and Y is single bonded with Z or with other Y to form a carbazolyl group, Y and Z being bonded to at least the same one nitrogen atom among the three nitrogen atoms in the formula (1).]

Description

  The present invention relates to an organic EL material containing a cyclic compound having a carbazolyl group and an organic EL element using the same.

  In recent years, organic electroluminescence display (organic EL display) has been actively developed as an image display device. Unlike a liquid crystal display device or the like, an organic EL display device recombines holes and electrons injected from an anode and a cathode in a light emitting layer, thereby causing a light emitting material containing an organic compound in the light emitting layer to emit light for display. This is a so-called self-luminous display device to be realized.

  Examples of the light emitting element (hereinafter referred to as an organic EL element) include an anode, a hole transport layer disposed on the anode, a light emitting layer disposed on the hole transport layer, and an electron transport layer disposed on the light emitting layer. An organic EL element composed of a cathode disposed on an electron transport layer is also known. Holes are injected from the anode, and the injected holes move through the hole transport layer and are injected into the light emitting layer. On the other hand, electrons are injected from the cathode, and the injected electrons move through the electron transport layer and are injected into the light emitting layer. Excitons are generated in the light emitting layer by recombination of holes and electrons injected into the light emitting layer. The organic EL element emits light using light generated by radiation deactivation of the exciton. The organic EL element is not limited to the configuration described above, and various modifications can be made.

  In applying an organic EL element to a display device, there is a demand for higher efficiency and longer life of the organic EL element, and in order to realize higher efficiency and longer life of the organic EL element, Stabilization, stabilization, and durability are being studied.

  Various compounds such as anthracene derivatives and aromatic amine compounds are known as hole transport materials used for the hole transport layer of organic EL devices. As organic EL materials advantageous for extending the lifetime of organic EL elements, cyclic amine compounds have been proposed in Patent Documents 1 to 4. Patent Document 5 proposes a cyclic compound containing a carbazolyl group as a hole transport material. However, it is difficult to say that organic EL elements using these materials also have sufficient light emission efficiency. At present, organic EL elements that can be driven with higher efficiency and lower voltage and have a longer light emission lifetime are available. It is desired. In order to extend the lifetime of organic EL elements, organic materials with high heat resistance are required. Generally, this can be realized by introducing many rigid groups such as naphthyl groups and phenanthryl groups into the molecule. However, since the molecular weight of the molecule also increases at the same time, there is a problem in that the molecule is decomposed during vapor deposition in the layer forming process of the organic EL element.

JP 2002-173488 A JP 2007-214364 A Korean Published Patent No. 10-2008-0071664 Chinese Patent Application No. 101088992 Korean Published Patent No. 10-2012-0088644

  In view of the above-described problems, an object of the present invention is to provide an organic EL material that further improves the light emission efficiency and achieves a long lifetime, and an organic EL element using the same.

The organic EL material according to an embodiment of the present invention is:
Following formula (1)

[In Formula (1), Y _{1 to} Y ₃ are each independently an alkylene group having 1 to 5 carbon atoms, a cycloalkylene group having 3 to 6 ring carbon atoms, or a substituted or unsubstituted ring carbon number 6 Is an arylene group having 1 to 18 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 18 ring carbon atoms, and Z _{1 to} Z ₃ are each independently an alkyl group having 1 to 5 carbon atoms and a ring carbon atom number. A cycloalkyl group having 3 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 18 ring carbon atoms, and a, b and c are , Each of which is an integer of 1 or more and satisfies a + b + c ≦ 9, and Y and Z bonded to at least one identical nitrogen atom among the three nitrogen atoms in the formula (1), or Y is a single bond The carbazolyl group Form. ]
It is represented by

  According to this organic EL material, the light emission efficiency of the organic EL element can be improved, and the lifetime of the organic EL element can be extended.

  The organic EL material represented by the formula (1) may be used as a hole transport material of the organic EL element.

  By using the organic EL material represented by the formula (1) as a hole transport material of the organic EL element, the light emission efficiency of the organic EL element can be improved and the life of the organic EL element can be extended.

  The organic EL material represented by the formula (1) may be used as a host material for the light emitting layer of the organic EL element.

  By using the organic EL material represented by the formula (1) as a host material of the light emitting layer of the organic EL element, the light emission efficiency of the organic EL element can be improved and the life of the organic EL element can be extended. .

An organic EL device according to an embodiment of the present invention is:
Following formula (1)
[In Formula (1), Y _{1 to} Y ₃ are each independently an alkylene group having 1 to 5 carbon atoms, a cycloalkylene group having 3 to 6 ring carbon atoms, or a substituted or unsubstituted ring carbon number 6 Is an arylene group having 1 to 18 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 18 ring carbon atoms, and Z _{1 to} Z ₃ are each independently an alkyl group having 1 to 5 carbon atoms and a ring carbon atom number. A cycloalkyl group having 3 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 18 ring carbon atoms, and a, b and c are , Each of which is an integer of 1 or more and satisfies a + b + c ≦ 9, and Y and Z bonded to at least one identical nitrogen atom among the three nitrogen atoms in the formula (1), or Y is a single bond The carbazolyl group Form. ]
The organic EL material represented by is included.

  According to this light emitting element, the luminous efficiency can be improved and the life can be extended.

  ADVANTAGE OF THE INVENTION According to this invention, the organic EL material which improves the luminous efficiency of an organic EL element and implement | achieves lifetime improvement, and an organic EL element using the same can be provided.

It is the schematic which shows the structure of an organic EL element.

  As a result of examining the above-mentioned problems, the present inventor has conceived that a cyclic compound having a carbazolyl group is used as the organic EL material, and has confirmed that an improvement in the light emission efficiency of the organic EL element and a longer life can be achieved. Hereinafter, the cyclic compound having a carbazolyl group conceived by the present inventor will be described.

The cyclic compound having a carbazolyl group of the present invention used as an organic EL material is a compound represented by the following structural formula (1).

In the above structural formula (1), Y _{1 to} Y ₃ each independently represent an alkylene group having 1 to 5 carbon atoms, a cycloalkylene group having 3 to 6 ring carbon atoms, or a substituted or unsubstituted ring-forming carbon. It is an arylene group of 6 to 18 or a substituted or unsubstituted heteroarylene group having 5 to 18 ring carbon atoms. In Structural Formula (1), Z _{1 to} Z ₃ are each independently an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 3 to 6 ring carbon atoms, or a substituted or unsubstituted ring forming carbon atom. It is an aryl group having 6 to 18 or a substituted or unsubstituted heteroaryl group having 5 to 18 ring carbon atoms. In the structural formula (1), a, b, and c are integers that are each 1 or more and satisfy a + b + c ≦ 9.

  The cyclic compound of the present invention represented by the structural formula (1) is formed by Y and Z bonded to at least one identical nitrogen atom among the three nitrogen atoms forming a ring, or a single bond between Y. It has a carbazolyl group. That is, in Structural Formula (1), at least one Y bonded to at least one identical nitrogen atom among the three nitrogen atoms forming a ring is a substituted or unsubstituted phenylene group, and Z is a substituted or unsubstituted group. It is a phenyl group, and Y and Z form a single bond to form a carbazolyl group. Alternatively, in Structural Formula (1), two Ys bonded to at least one identical nitrogen atom among the three nitrogen atoms forming a ring are substituted or unsubstituted phenylene groups, and these Ys are single-bonded. To form a carbazolyl group.

  As specific examples of the cyclic compound having a carbazolyl group of the present invention, compounds 1 to 53 are shown below. The cyclic compound having a carbazolyl group of the present invention is not limited to the following compounds.

  The cyclic compound having a carbazolyl group of the present invention has a low molecular weight and a rigid carbazolyl group introduced into the molecule, and the molecule has a cyclic structure. it can. Therefore, when the cyclic compound having a carbazolyl group of the present invention is used as an organic EL material, it is easy to vapor-deposit when producing an organic EL element and has high heat resistance, so that decomposition of the material itself can be suppressed. In addition, since the heat resistance is high, deterioration of the material during driving of the organic EL element is suppressed, which contributes to extending the life of the organic EL element. In addition, the cyclic compound having a carbazolyl group of the present invention has a large band gap, and thus contributes to the improvement of the light emission efficiency of the organic EL device.

  Further, in the cyclic compound having a carbazolyl group of the present invention, since the carbazolyl group has a high hole transport ability and has a high T1 (excited triplet state) level, the cyclic compound having a carbazolyl group of the present invention is organic EL. By using it as a hole transport material of the device or a host material of the light emitting layer, the light emission efficiency of the organic EL device can be improved. In particular, since the cyclic compound having a carbazolyl group of the present invention has a high T1 level, it can be used as a phosphorescent host material or a hole transport material adjacent to the phosphorescent light emitting layer in a red to blue light emitting region. The use of the cyclic compound having a carbazolyl group of the present invention is not limited to the phosphorescent host material or the hole transporting material close to the phosphorescent light emitting layer, but is used as the fluorescent host material or the hole transporting material close to the fluorescent light emitting layer. You can also. Any of the compounds 1 to 53 mentioned as specific examples of the cyclic compound having a carbazolyl group of the present invention can be used as a hole transport material of an organic EL device or a host material of a light emitting layer. 2, Compound 4, Compound 15, Compound 18, and Compound 45 are preferred as materials for the organic EL device.

  With respect to the cyclic compound having a carbazolyl group of the present invention, a synthesis method of the above-mentioned compound 1, compound 2, compound 4, compound 15 and compound 45 will be described below. However, the synthesis method described below is an example, and the present invention is not limited to this.

Synthesis of compound 1

(Synthesis of Intermediate 1-1)
2-iodo-9H-carbazole (5.0 g, 17.1 mmol), 2-bromo-9H-carbazole (4.2 g, 17.1 mmol), and sodium-t-butoxide (2.5 g, 26.3 mmol) were added to the reaction vessel purged with nitrogen. In addition, xylene (100 mL) was added as a solvent, then P (t-Bu) ₃ (0.23 g, 1.16 mmol) and Pd ₂ (dba) ₃ (0.15 g, 0.17 mmol) were added, and the inside of the container was purged with nitrogen. Thereafter, the mixed solution was stirred at 100 ° C. for 6 hours. After cooling, the reaction solution was diluted with toluene (100 mL), and the diluted reaction solution was filtered through celite and washed with saturated brine. The obtained organic layer was dried over anhydrous magnesium sulfate, and after filtration, the filtrate was concentrated by a rotary evaporator. The obtained crude product was purified by silica gel column chromatography (developing solvent toluene: hexane = 1: 1), and the obtained solid was recrystallized with toluene / ethanol. As a result, 3.0 g of intermediate 1-1 was collected. Obtained at a rate of 42%.

(Synthesis of Compound 1)
In the same manner as the synthesis of Intermediate 1-1 except that 2-iodo-9H-carbazole in the synthesis of Intermediate 1-1 described above was changed to Intermediate 1-1, 0.71 g of Compound 1 was obtained. Obtained at a rate of 20%.

Synthesis of compound 2

  Intermediate 1-1 was prepared in the same manner as the synthesis method for Intermediate 1-1 described above, and 2-bromo-9H-carbazole in the synthesis of Compound 1 described above was changed to 3-bromo-N-phenylaniline. Except for the above, compound 2 was obtained in the same manner as in the synthesis of compound 1 to obtain 1.1 g of compound 2 in a yield of 22%.

Synthesis of compound 4

(Synthesis of Intermediate 4-1)
Intermediate 4 was prepared in the same manner as in the synthesis of Intermediate 1-1 except that 2-bromo-9H-carbazole in the synthesis of Intermediate 1-1 was changed to 3-bromo-N-phenylaniline. -1 was obtained in 4.2 g, yield 59%.

(Synthesis of Compound 4)
Except that 3-bromo-N-phenylaniline in the synthesis of Intermediate 4-1 was changed to Intermediate 4-1 in the same manner as in the synthesis of Intermediate 4-1, 1.26 g of Compound 4 was obtained. Obtained at a rate of 25%.

Synthesis of Compound 15

(Synthesis of Intermediate 15-1)
1,3-diiodobenzene (5.0 g, 15.2 mmol), 3-bromo-9H-carbazole (11.2 g, 45.5 mmol), sodium-t-butoxide (2.9 g, 30.3 mmol) are added to the reaction vessel purged with nitrogen, xylene (500 mL) was added as a solvent, then P (t-Bu) ₃ (0.18 g, 0.90 mmol) and Pd ₂ (dba) ₃ (0.42 g, 0.46 mmol) were added, and the inside of the container was purged with nitrogen. The mixed solution was stirred at 100 ° C. for 6 hours. After cooling, the reaction solution was diluted with toluene (100 mL), and the diluted reaction solution was filtered through celite and washed with saturated brine. The obtained organic layer was dried over anhydrous magnesium sulfate, and after filtration, the filtrate was concentrated by a rotary evaporator. The obtained crude product was purified by silica gel column chromatography (developing solvent toluene: hexane = 1: 1), and the obtained solid was recrystallized with toluene / ethanol to obtain 5.6 g of intermediate 15-1. Obtained at a rate of 65%.

(Synthesis of Intermediate 15-2)
1-bromo-3-iodobenzene (5.0 g, 17.6 mmol), 2-bromo-9H-carbazole (4.3 g, 17.6 mmol), sodium-t-butoxide (3.4 g, 35.3 mmol) are placed in a nitrogen-substituted reaction vessel. In addition, xylene (50 mL) was added as a solvent, then P (t-Bu) ₃ (0.21 g, 1.05 mmol) and Pd ₂ (dba) ₃ (0.49 g, 0.54 mmol) were added, and the inside of the container was replaced with nitrogen. Thereafter, the mixed solution was stirred at 100 ° C. for 5 hours. After cooling, the reaction solution was diluted with toluene (100 mL), and the diluted reaction solution was filtered through celite and washed with saturated brine. The obtained organic layer was dried over anhydrous magnesium sulfate, and after filtration, the filtrate was concentrated by a rotary evaporator. The obtained crude product was purified by silica gel column chromatography (developing solvent toluene: hexane = 1: 2), and the obtained solid was recrystallized with toluene / ethanol. As a result, 3.2 g of intermediate 15-2 was collected. Obtained at a rate of 45%.

(Synthesis of Intermediate 15-3)
Under a nitrogen atmosphere, intermediate 15-2 (3.2 g, 7.95 mmol) was dissolved in anhydrous THF at −78 ° C. in a reaction vessel, and an n-butyllithium-n-hexane solution (1.6 M, 5.5 ml, 8.75 mmol) was dissolved. After dropping, the mixed solution was stirred for 1 hour. Trimethoxyborane (B (OMe) ₃ ) (1.07 ml, 10.3 mmol) was added thereto and stirred for 2 hours, and the temperature in the reaction system was raised to room temperature. 1N Hydrochloric acid (100 ml) was added to the reaction mixture and stirred for 3 hours. The organic layer was separated and the solvent was distilled off. Hexane was added to the resulting crude product, and the precipitated product was collected by filtration to obtain 2.1 g of intermediate 15-3 in a yield of 81%.

(Synthesis of Compound 15)
In a reaction vessel purged with nitrogen, intermediate 15-1 (3.0 g, 5.30 mmol), intermediate 15-3 (2.1 g, 6.36 mmol), 2M aqueous potassium carbonate solution (10 ml), Pd (PPh ₃ ) ₄ (0.61 g, 0.53 mmol) was added, and the mixture was stirred for 8 hours while heating under reflux in 40 ml of THF. After completion of the reaction, the reaction solution was cooled to room temperature, the organic layer was separated, purified by silica gel chromatography (developing solvent toluene: hexane = 2: 1), and the resulting solid was recrystallized from toluene / ethanol. Compound 15 (0.82 g, 24% yield) was obtained.

Synthesis of Compound 18

(Synthesis of Intermediate 18-1)
In the synthesis of Intermediate 15-2 described above, except that 1-bromo-3-iodobenzene was changed to 4-bromo-9-phenyl-9H-carbazole and 2-bromo-9H-carbazole was changed to carbazole, Intermediate 18-1 was obtained in the same manner as in the synthesis of compound 15-2, yielding 5.2 g of intermediate 18-1 in a yield of 82%.

(Synthesis of Intermediate 18-2)
Intermediate 18-1 (5.2 g, 12.7 mmol) and N-bromosuccinimide (4.8 g, 26.7 mmol) dissolved in chloroform (100 ml) were added to the reaction vessel, and the mixture was stirred at room temperature for 3 hours. Thereafter, distilled water was added to the reaction solution to terminate the reaction, and the organic layer was extracted. The obtained organic layer was dried over anhydrous magnesium sulfate, and after filtration, the filtrate was concentrated on a rotary evaporator. When the obtained crude product was recrystallized with toluene / ethanol, 5.2 g of intermediate 18-2 was obtained with a yield of 72%.

(Synthesis of Compound 18)
1.6 g of Compound 18 was obtained in a yield of 27% by the same method as the synthesis of Compound 15 except that Intermediate 15-1 in the synthesis of Compound 15 was changed to Intermediate 18-2. .

Synthesis of Compound 45

(Synthesis of Intermediate 45-1)
In the synthesis of the intermediate 15-2 described above, 1-bromo-3-iodobenzene is converted to 3-bromo-4'-iodo-1,1'-biphenyl, and 2-bromo-9H-carbazole is converted to 3-bromo-9H-carbazole. The intermediate 45-1 was obtained in the same manner as the synthesis of the intermediate 15-2 described above except that the intermediate 45-1 was obtained in a yield of 51%.

(Synthesis of Intermediate 45-2)
The intermediate 45-2 is converted to 1.9 by the same method as the synthesis of the intermediate 15-3 described above except that the intermediate 15-2 in the synthesis of the intermediate 15-3 is changed to the intermediate 45-1. g, yield 43%.

(Synthesis of Compound 45)
Intermediate 45-2 (1.9 g, 4.46 mmol), 2M aqueous potassium carbonate solution (10 ml) and Pd (PPh ₃ ) ₄ (1.54 g, 1.34 mmol) were added to a nitrogen-substituted reaction vessel, and heated under reflux in 30 ml of THF. The mixture was stirred for 8 hours. After completion of the reaction, the reaction solution was cooled to room temperature, the organic layer was separated, purified by silica gel chromatography (developing solvent toluene: hexane = 5: 1), and the obtained solid was recrystallized from toluene / ethanol. Compound 45 (0.17 g, 12% yield) was obtained.

Example Current efficiency and half-life of an organic EL device using the cyclic compound having a carbazolyl group of the present invention as a material for a hole transport layer were measured. The above-mentioned compound 1 was used as the hole transport material used for the hole transport layer of the organic EL device. Further, as a comparative compound, Comparative Compound 1 represented by the following structural formula was used as a material for the hole transport layer of the organic EL device.

The structure of the organic EL element used for the measurement is shown in FIG. An organic EL device 100 shown in FIG. 1 is disposed on a glass substrate 102, a glass substrate 102, an anode 104 made of ITO, a hole injection layer 106 containing 2-TNATA, and the hole injection layer 106 disposed on the anode 104. A hole transport layer 108 that is disposed on the injection layer 106 and includes any one of the above-described compound 1 and comparative compound 1, and is disposed on the hole transport layer 108 and has a 3% concentration of TBP in a host material that includes ADN. A doped light emitting layer 110, an electron transport layer 112 disposed on the light emitting layer 110 and including Alq ₃ , an electron injection layer 114 disposed on the electron transport layer 112 and including LiF, and the electron injection layer 114 A cathode 116 made of Al is disposed on the top. The thickness of the anode 104 is 150 nm, the thickness of the hole injection layer 106 is 60 nm, the thickness of the hole transport layer 108 is 30 nm, the thickness of the light emitting layer 110 is 25 nm, the thickness of the electron transport layer 112 is 25 nm, and the electrons The thickness of the injection layer 114 was 1 nm, and the thickness of the cathode 116 was 100 nm.

A current was supplied from the power source to the organic EL element 100 through the anode 104 and the cathode 116, and the current efficiency of the organic EL element 100 when the compound 1 or the comparative compound 1 was used as the material of the hole transport layer 108 was measured. The results are shown in the table below. The current efficiency was measured at 10 mA / cm ² and the half-life was measured at 1000 cd / m ² at room temperature and 85 ° C.

  As shown in the table, the organic EL device using Compound 1 which is a cyclic compound having a carbazolyl group of the present invention as a hole transport material has a lower voltage than the organic EL device using Comparative Compound 1 as a hole transport material. The emission efficiency could be improved while being able to be driven. In addition, the organic EL device using Compound 1 as a hole transport material has a longer life than the organic EL device using Comparative Compound 1 as a hole transport material, and particularly when driven at a high temperature of 85 ° C. The lifetime of the device could be extended significantly.

  Therefore, when the cyclic compound having a carbazolyl group of the present invention is used as the material for the hole transport layer of the organic EL device, it is possible to improve the light emission efficiency and extend the life of the organic EL device.

  In the above embodiment, the example in which the cyclic compound having a carbazolyl group of the present invention is used as the organic EL material of the passive organic EL element has been described, but the present invention is not limited to this. The cyclic compound having a carbazolyl group can also be used as an organic EL material of an active organic EL element, and can improve the light emission efficiency of the active organic EL element and achieve a long lifetime.

  In the above examples, the cyclic compound having a carbazolyl group of the present invention was used as a hole transport material. However, the use of the cyclic compound having a carbazolyl group of the present invention is not limited to this, and the host of the light emitting layer is used. Even when used as a material, it is possible to improve the luminous efficiency of the organic EL element and achieve a long life.

  The organic EL element using the cyclic compound having a carbazolyl group of the present invention as an organic EL material can be used for an organic EL display device, a lighting device, and the like.

DESCRIPTION OF SYMBOLS 100 Organic EL element 102 Glass substrate 104 Anode 106 Hole injection layer 108 Hole transport layer 110 Light emitting layer 112 Electron transport layer 114 Electron injection layer 116 Cathode

Claims (6)

An organic EL material represented by the following formula (1).


[In Formula (1), Y _{1 to} Y ₃ are each independently an alkylene group having 1 to 5 carbon atoms, a cycloalkylene group having 3 to 6 ring carbon atoms, or a substituted or unsubstituted ring carbon number 6 Is an arylene group having 1 to 18 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 18 ring carbon atoms, and Z _{1 to} Z ₃ are each independently an alkyl group having 1 to 5 carbon atoms and a ring carbon atom number. A cycloalkyl group having 3 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 18 ring carbon atoms, and a, b and c are , Each of which is an integer of 1 or more and satisfies a + b + c ≦ 9, and Y and Z bonded to at least one identical nitrogen atom among the three nitrogen atoms in the formula (1), or Y is a single bond The carbazolyl group Form. ]   The organic EL material according to claim 1, wherein the organic EL material represented by the formula (1) is used as a hole transport material of an organic EL element.   The organic EL material according to claim 1, wherein the organic EL material represented by the formula (1) is used as a host material of a light emitting layer of an organic EL element. Following formula (1)


[In Formula (1), Y _{1 to} Y ₃ are each independently an alkylene group having 1 to 5 carbon atoms, a cycloalkylene group having 3 to 6 ring carbon atoms, or a substituted or unsubstituted ring carbon number 6 Is an arylene group having 1 to 18 carbon atoms, or a substituted or unsubstituted heteroarylene group having 5 to 18 ring carbon atoms, and Z _{1 to} Z ₃ are each independently an alkyl group having 1 to 5 carbon atoms and a ring carbon atom number. A cycloalkyl group having 3 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 18 ring carbon atoms, and a, b and c are , Each of which is an integer of 1 or more and satisfies a + b + c ≦ 9, and Y and Z bonded to at least one identical nitrogen atom among the three nitrogen atoms in the formula (1), or Y is a single bond The carbazolyl group Form. ]
An organic EL element including an organic EL material represented by   The organic EL element according to claim 4, wherein the organic EL material is used as a material for a hole transport layer.   The organic EL element according to claim 4, wherein the organic EL material is used as a host material of a light emitting layer.