JP2017145198A - Triazine-substituted indolocarbazole derivative, alcohol insoluble coating film for forming organic electronic device made of the same, and organic electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new compound capable of forming a laminated structure insoluble to an alcohol solvent and also functionally separated by a coating method, concretely, a new compound as a phosphorescence holst material combining the excitation energy in a high triplet state of a luminescent layer capable of lamination without dissolving a hole transport layer as the lower layer and an electron transport layer as the upper layer and charge injection-transport, and an organic electronic device using the new compound.SOLUTION: Provided is a triazine-substituted indrocarbazole derivative represented by formula (1).SELECTED DRAWING: None

Description

  The present invention relates to a novel triazine-substituted indolocarbazole derivative that can be suitably used for a coating type organic electronic device, and an organic electronic device using the same.

  An organic electronic device such as an organic electroluminescence element (hereinafter referred to as “organic EL element”) requires a highly functionally separated laminated structure and doping. In general, materials for organic EL devices include low molecular weight organic substances and high molecular weight organic substances. Among these, for low molecular weight organic substances, it is common to use a vacuum vapor deposition method to form a thin film to form a laminated structure, and an organic layer having an independent function by using the vapor deposition method. A laminated structure can be easily formed, and a high-performance organic EL element can be produced. At present, low molecular weight organic substances that exhibit excellent performance in organic EL elements have been synthesized and reached a practical level. However, in the vapor deposition method, since the film is formed in a vacuum, it is difficult to increase the area, and the utilization efficiency of the material is not sufficient.

  On the other hand, coating methods such as a casting method, a spin coating method, an ink jet method, a dipping method, a spray method, and a printing method are used for the production method of the high molecular weight organic material. These films can be formed under atmospheric pressure, and the area can be easily increased as compared with the vapor deposition method. Moreover, since the utilization efficiency of material is also high, it is advantageous in terms of cost. However, when the laminated structure is formed, the organic material in the lower layer is dissolved in the solvent, so that the lamination is difficult. In addition, high molecular weight organic substances are more difficult to purify than low molecular weight organic substances, and the influence of impurities tends to appear. In addition, since the coating method is used, it is difficult to form a stack, and therefore, functional separation is also difficult, and the performance of the organic EL element tends to be lower than that of a low molecular organic material formed by a vapor deposition method. Therefore, there is a demand for a method for producing an organic EL element by a coating method that can form a film at atmospheric pressure using a low molecular weight organic material that is superior in performance to a high molecular weight organic material, and can easily increase the area. Has been.

By the way, Patent Document 1 discloses, for example, the following indolocarbazole compound as a low-molecular phosphorescent host material, and an organic EL element using the compound exhibits high efficiency and high driving stability. It is disclosed.

Patent Document 2 discloses, for example, the following indolocarbazole compound, and it is disclosed that an organic EL device using the compound is excellent in light emission characteristics, driving life and durability.

  Furthermore, in Patent Document 2, as an indolocarbazole compound, by having an N-substituted carbazolyl group on the nitrogen of the indolocarbazole skeleton, hole and electron injecting and transporting characteristics are exhibited and high durability is provided. Furthermore, by changing the type or number of aromatic rings on the other nitrogen, the transfer rate of holes and electrons can be adjusted, and the ionization potential (Ip), electron affinity (Ea) and triplet It is disclosed that the excitation energy (T1) of the state can be controlled. Further, by connecting an aromatic ring in an indolocarbazole compound, it can be expected that a material with high mobility can be provided from the electronic stability of the molecule via a conjugated system. It is disclosed that there is a possibility that an organic EL element with greatly improved performance can be realized by adjusting the carrier balance.

  However, in both Patent Documents 1 and 2, these compounds are laminated by a vacuum vapor deposition method, and there is a problem in using a vapor deposition method such that it is difficult to increase the area or the utilization efficiency of the material is not sufficient. Still there.

On the other hand, Patent Document 3 discloses the following phenylcarbazole group-substituted diphenyl ketone compound as a host material of a light emitting layer capable of laminating an electron transport layer on the light emitting layer by a coating method.

  However, the phenylcarbazole group-substituted diphenyl ketone compound has a problem that its driving life is shorter than that of a conventional organic EL device.

  Therefore, it is possible to solve the problems of using a vapor deposition method such that it is difficult to increase the area, or the utilization efficiency of the material is not sufficient, and high triplet state excitation energy (T1) and charge injection / transport properties are achieved. It was necessary to develop a low molecular weight material.

International Publication No. 2008/056746 International Publication No. 2013/088973 JP 2014-156420 A

  An object of the present invention is to provide a novel triazine-substituted indolocarbazole derivative suitable as a material for a coating type organic electronic device.

The present invention solves the above-described problems in the prior art, and includes the following items.
The triazine-substituted indolocarbazole derivative of the present invention is represented by any of the following structural formulas (1) to (4).

The alcohol-insoluble coating film for forming an organic electronic device of the present invention is characterized by comprising the above triazine-substituted indolocarbazole derivative.
The organic electronic device of the present invention is obtained using the triazine-substituted indolocarbazole derivative or the alcohol-insoluble coating film.
The method for producing an organic electronic device of the present invention includes a step of forming a layer by coating film formation on the layer on which the triazine-substituted indolocarbazole derivative is coated.

  The triazine-substituted indolocarbazole derivative of the present invention is suitable as a material for a coating type organic EL element because it exhibits solvent resistance against an alcohol solvent usually used for stacking organic electronic devices.

  The organic electronic device using the triazine-substituted indolocarbazole derivative exhibits a low driving voltage equivalent to that of an organic electronic device using the existing triazine-substituted indolocarbazole derivative and high luminous efficiency.

  According to the present invention, since the triazine-substituted indolocarbazole derivative exhibits solvent resistance to alcohol solvents, the triazine-substituted indolocarbazole derivative, which is the light-emitting layer host material, can be dissolved without dissolving the underlying hole transport layer. It is possible to stack the layers without dissolving the electron transport layer on the light emitting layer. Therefore, when the triazine-substituted indolocarbazole derivative of the present invention is used, it is possible to form a laminated structure in an organic EL element by a coating method. According to such a manufacturing method, it is possible to work in the atmosphere, and it is expected that the organic electronic device can be enlarged and mass-produced inexpensively and easily.

FIG. 1 (a) shows the UV-vis absorption spectrum of the compound (1) in the residual film property test for methanol, and FIG. 1 (b) shows the UV-vis absorption spectrum of the compound (2) in the residual film property test for methanol. 1 (c) shows the UV-vis absorption spectrum in the residual film property test of compound (3) for methanol, and FIG. 1 (d) shows the UV-vis absorption in the residual film property test of compound (4) for methanol. It is a figure showing a spectrum. FIG. 2 is a diagram showing a UV-vis absorption spectrum in a residual film property test of methanol of the existing compound A-2. FIG. 3 is a schematic cross-sectional view showing the layer structure of the coating type organic EL element. FIG. 4A is a diagram showing an EL spectrum when a current of 5 mA / cm ² is passed through the coating type organic EL element. FIG. 4B is a diagram illustrating a relationship between current density and voltage characteristics of the coating type organic EL element. FIG. 4C is a diagram illustrating a relationship between luminance and voltage characteristics of the coating type organic EL element. FIG. 4D is a diagram illustrating a relationship between current efficiency and current density of the coating type organic EL element. FIG. 4E is a diagram illustrating the relationship between the power efficiency and the current density of the coating type organic EL element. FIG. 4F is a diagram illustrating the relationship between the external quantum efficiency and the current density of the coating type organic EL element. FIG. 5 is a schematic cross-sectional view showing a layer structure of a vapor deposition type organic EL element. FIG. 6A is a diagram showing an EL spectrum when a current of 5 mA / cm ² is passed through the vapor deposition type organic EL element. FIG. 6B is a diagram illustrating a relationship between current density and voltage characteristics of the vapor deposition type organic EL element. FIG. 6C is a diagram illustrating a relationship between luminance and voltage characteristics of the vapor deposition type organic EL element. FIG. 6D is a diagram illustrating a relationship between current efficiency and current density of the vapor deposition type organic EL element. FIG.6 (e) is a figure showing the relationship of the power efficiency-current density of a vapor deposition type organic EL element. FIG. 6F is a diagram illustrating the relationship between the external quantum efficiency and the current density of the vapor deposition type organic EL element. FIG. 6G is a diagram showing a relationship between relative luminance and time when a current of 4.25 mA / cm ² is passed through the vapor deposition type organic EL element. FIG. 7 is a diagram showing a typical configuration of an organic EL element. FIG. 8 is a diagram showing a ¹ H-NMR spectrum of compound (1). FIG. 9 is a diagram showing a ¹ H-NMR spectrum of compound (2). FIG. 10 is a diagram showing a ¹ H-NMR spectrum of compound (3). FIG. 11 is a diagram showing a ¹ H-NMR spectrum of compound (4).

Hereinafter, the present invention will be described in detail.
[Triazine substituted indolocarbazole derivatives]
The triazine-substituted indolocarbazole derivative of the present invention is represented by any of the following structural formulas (1) to (4). Hereinafter, the triazine-substituted indolocarbazole derivatives represented by the structural formulas (1) to (4) are referred to as compounds (1) to (4), respectively.

The compounds (1) to (4) have a common skeleton represented by the following structural formula.

  The common skeleton is a skeleton including an indolocarbazole skeleton and a triazine skeleton. Such a skeleton has a high charge transporting property. The triazine-substituted indolocarbazole derivative has a conjugated structure containing one or more carbazolyl groups in addition to such a common skeleton, thereby exhibiting favorable hole and electron transport properties. And the organic electronic device using the said triazine substituted indolocarbazole derivative has high durability.

  The molecular weight of the triazine-substituted indolocarbazole derivative is 970.15 for the compounds (1) and (2), 894.05 for the compound (3), and 1059.25 for the compound (4). The triazine-substituted indolocarbazole derivative is insoluble or hardly soluble in an alcohol solvent. On the other hand, for example, the molecular weight of the existing compound A-2 is as low as 563.66, and is soluble in an alcohol solvent as shown in the residual film rate test of Examples described later. That is, in the present invention, the number of aromatic rings can be increased to increase the molecular rigidity, and the molecular weight of the triazine-substituted indolocarbazole derivative can be increased to about 1000, thereby making it insoluble in alcohol solvent. It is said.

  A triazine-substituted indolocarbazole derivative having a conjugated structure as described above has a sufficiently high triplet state excitation energy (T1) and hole and electron transport properties, and is excellent as a host material in a light emitting layer. .

  The triazine-substituted indolocarbazole derivative can be produced by various known methods. Compounds (1) to (4) can be synthesized by, for example, the methods as shown in the examples, but are not limited to these methods, and can be synthesized by combining various known methods.

[Organic electronic devices]
The organic electronic device of the present invention comprises the above triazine-substituted indolocarbazole derivative.
Here, FIG. 7 shows a typical layer structure of an organic EL element which is one form of the organic electronic device.
The organic EL element typically has, for example, an ITO film formed on the substrate 1 as the anode 2, and a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, and an electron transport layer formed thereon. 6, the electron injection layer 7 and the cathode 8 are laminated in this order.
In the present invention, an excellent organic electronic device can be obtained by including the triazine-substituted indolocarbazole derivative in at least one layer of an organic EL element in which the anode 2, the above-described layer, and the cathode 8 are laminated on the substrate 1. give. Specifically, the light-emitting layer 5, the hole transport layer 4 or the electron transport layer 6 preferably contains the triazine-substituted indolocarbazole derivative. As the host material of the light-emitting layer 5, the triazine is used together with a phosphorescent dopant. It is more preferable to contain a substituted indolocarbazole derivative.

  The substrate 1 is transparent and smooth and has a total light transmittance of at least 70%. Specifically, the substrate 1 is a flexible transparent substrate such as a glass substrate having a thickness of several μm or a special transparent substrate. Plastic or the like is used.

Thin films such as the anode 2, the hole injection layer 3, the hole transport layer 4, the light emitting layer 5, the electron transport layer 6, the electron injection layer 7, and the cathode 8 formed on the substrate are formed by a vacuum evaporation method or a coating method. Laminated. When using a vacuum vapor deposition method, the deposited material is usually heated in an atmosphere reduced to 10 ⁻³ Pa or lower. The thickness of each layer varies depending on the type of layer and the material used, but usually the anode 2 and the cathode 8 are about 100 nm, and the other layers including the light emitting layer 5 are less than 50 nm. The electron injection layer 7 or the like may be formed with a thickness of 1 nm or less, for example.

As the anode 2, for example, a material having a large work function and a total light transmittance of 80% or more, such as ITO, is used. The film thickness of the anode 2 is usually 10 to 200 nm.
The hole injection layer 3 is made of poly (ethylenedioxythiophene): polystyrene sulfonic acid (PEDOT / PSS), phosphomolybdic acid, polyaniline, and other charge transport materials for transmitting light emitted from the anode 2. Used.

In the light emitting layer 5, it is preferable to use a dopant together with the triazine-substituted indolocarbazole derivative of the present invention as a host material, as in the case of other light emitting layers used in organic EL elements. Examples of the dopant include tris (2-phenylpyridinato) iridium (III) (Ir (ppy) ₃ ), bis (3,5-difluoro-2- (2-pyridylphenyl- (2-carboxypyridyl) iridium). (III) (Firpic) and bis (2-methyldibenzo [f, h] quinoxaline (acetylacetone) (III) (Ir (MDQ) ₂ (acac)), etc. Among the components constituting the light emitting layer 5, the host The addition rate of the dopant with respect to the material (that is, the triazine-substituted indolocarbazole derivative) is usually 0.1 to 70 wt%, preferably 1 to 20 wt%.

  In order to efficiently transport holes from the anode 2 to the light emitting layer, a hole transport layer 4 is provided between the anode 2 and the light emitting layer 5. Examples of the hole transport material forming the hole transport layer 4 include poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4- sec-butylphenyl)) diphenylamine)]] (TFB), 1,1-bis [(di-4-tolylamino) phenyl] cyclohexane (TAPC), N, N′-diphenyl-N, N′-di (m-tolyl) ) Benzidine (TPD), N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (α-NPD), (4,4 ′, 4 ″ tri-9-carbazolyltriphenylamine ( TCTA)) and (4,4 ′, 4 ″ tris [phenyl (m-tolyl) amino] triphenylamine)) and the like.

  Further, a hole injection layer 3 as a buffer is provided between the anode 2 and the hole transport layer 4. Examples of the hole injection material for forming the hole injection layer 3 include KLHIP: PPBi, 1,4,5,8,9,12-hexaazatriphenylenehexacarbonitrile in addition to the above-described PEDOT / PSS and polyaniline. (HATCN) and copper phthalocyanine (CuPc).

An electron transport layer 6 is provided between the cathode 8 and the light-emitting layer 5 in order to efficiently transport electrons from the cathode to the light-emitting layer. Examples of the electron transport material forming the electron transport layer 6 include biphenyloxyaluminum bisquinolate (BAlq ₂ ), tris (8-quinolinolato) aluminum (Alq ₃ ), B3PymPm, and 2- (4-biphenylyl) -5. (Pt-butylphenyl) -1,3,4-oxadiazole (tBu-PBD), 1,3-bis [5- (4-tert-butylphenyl) -2- [1,3,4] Oxadiazolyl] benzene (OXD-7), 3- (biphenyl-4-yl) -5- (4-t-butylphenyl) -4-phenyl-4H-1,2,4-triazole (TAZ), bathocuproine (BCP And 1,3,5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi).

  In addition, since a metal such as Al or Ag is often used for the cathode, an electron injection layer 7 is provided between the electron transport layer 6 and the light emitting layer 5. Examples of the electron injection material forming the electron injection layer 7 include hybrid nanoparticles composed of polyethyleneimine ethoxylate (PEIE) and zinc oxide (ZnO) nanoparticles, lithium fluoride (LiF), and 8-hydroxyquinolinolato Examples include lithium (Liq) and lithium 2- (2 ′, 2 ″ -bipyridin-6′-yl) phenolate (Libpp).

  By selecting a material suitable for the electron transporting property as the electron injecting material, the electron can be moved faster, or by selecting a material having a good electron injecting property, the electron injecting efficiency can be increased.

  In addition to the above layers, layers such as a hole blocking layer, an electron blocking layer, and an exciton blocking layer are further formed as necessary. At this time, the triazine-substituted indolocarbazole derivative may be contained in the hole blocking layer or the electron blocking layer.

  Either the vapor deposition method or the coating method can be used as the film formation method for each of the above layers. As described above, the triazine-substituted indolocarbazole derivative of the present invention is usually used for laminating organic solvents, particularly organic electronic devices. The coating method is more preferable because it is insoluble or hardly soluble in the alcohol solvent used, and can be particularly advantageous in film formation that is advantageous in terms of increasing the area of the device and in terms of material utilization efficiency.

  As described above, the organic electronic device of the present invention is excellent as a host material in the light-emitting layer, and by using a triazine-substituted indolocarbazole derivative that is insoluble or hardly soluble in an alcohol solvent, Shows equal or better performance.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not restrict | limited by the following Example.

[Identification of compound]
The equipment and measurement conditions used for the identification of the composites are as follows.
(1) Mass spectrometry (MS) apparatus JMS-K9 [desktop GCQMS] manufactured by JEOL Ltd. and Zspray manufactured by Waters (SQ detector 2)
(2) ¹ H Nuclear Magnetic Resonance (NMR) Device JNM-EX (400 MHz) JNM-EX270FT-NMR type

[Residual film rate and optical property evaluation]
The equipment and measurement conditions used for the remaining film rate and optical property evaluation are as follows.
Ultraviolet-visible (UV-vis) spectrophotometer UV-3150 manufactured by Shimadzu Corporation
Measurement conditions: medium scan speed, measurement range 200 to 800 nm, sampling pitch 0.5 nm, slit width 0.5 nm

[Optical characteristics evaluation]
The equipment and measurement conditions used for the optical property evaluation are as follows.
(1) Photoelectron Yield Spectroscopy (PYS) Device Ionization Potential Measurement Device manufactured by Sumitomo Heavy Industries, Ltd. Ionization potential (Ip) was measured in vacuum using an ionization potential measurement device.
(2) Luminescence quantum yield (PLQY) measurement device Absolute PL quantum yield measurement device manufactured by Hamamatsu Photonics Co., Ltd.

[Element performance evaluation]
The equipment used for the evaluation of the organic EL element is as follows.
EL (electroluminescence) measuring device HOMAmatsu Photonics Co., Ltd. PHOTONIC MULTI-CHANNEL ANALYZER PMA-1

[Example 1] Synthesis of Compound (1) [Synthesis of Compound c]
In a three-necked flask equipped with a stir bar, 3,6-dibromo-9-phenylcarbazole (compound a) 2.50 g (6.23 mmol), 9-phenylcarbazole-3-boronic acid (compound b) 1.79 g (6. 23 mmol), 41.6 ml of a 2M potassium carbonate (K ₂ CO ₃ ) aqueous solution (potassium carbonate 83.2 mmol), and 125 ml of tetrahydrofuran (THF) were added, and nitrogen bubbling was performed for 1 hour. Thereto was added 350 mg (0.31 mmol) of tetrakis (triphenylphosphine) palladium (Pd (PPh ₃ ) ₄ ), and the mixture was heated and stirred overnight.
The reaction solution was returned to room temperature and the solvent was distilled off. Dichloromethane was added to the residue and redissolved, followed by washing with saturated brine. Anhydrous magnesium sulfate was added to the organic layer, dried and filtered. After the filtrate was concentrated, silica gel column chromatography (dichloromethane: hexane = 1: 4) was performed to obtain 1.32 g (0.24 mmol) of the target compound c in a yield of 38%.

[Synthesis of Compound d]
Compound c 500 mg (0.89 mmol), 11,12-dihydroindolo [2,3-a] carbazole (compound 1) 226 mg (0.89 mmol), potassium carbonate 730 mg (5.30 mmol) in a pressure tube equipped with a stir bar. ), 600 mg (3.17 mg) of copper iodide (CuI) and 9 ml of quinoline were added, the mixture was sealed after vacuuming, and stirred at a bath temperature of 190 ° C. for 72 hours. The reaction solution was returned to room temperature, dissolved in dichloromethane, and washed with saturated brine. Anhydrous magnesium sulfate was added to the organic layer, dried and filtered. After the filtrate was concentrated, silica gel column chromatography (dichloromethane: hexane = 3: 7) was performed to obtain 311 mg (0.42 mmol) of compound d in a yield of 47%.

[Synthesis of Compound (1)]
To a three-necked flask equipped with a stirrer was added 18 mg (0.75 mmol) of sodium hydride, 111 mg (0.15 mmol) of compound d, and 3.0 ml of N, N-dimethylformamide (DMF), and then at room temperature for 1 hour under nitrogen atmosphere Stirring was performed. Then, 201 mg (0.75 mmol) of 2-chloro-4,6-diphenyl-1,3,5-triazine (Compound 2) was dissolved in 2.0 ml of N, N-dimethylformamide and added dropwise. After dropping, the mixture was stirred overnight by heating under reflux. Then, extraction and washing were performed with toluene and saturated saline. It dried with magnesium sulfate and filtered the desiccant. The filtrate was concentrated and then subjected to silica gel column chromatography (dichloromethane: hexane = 3: 7) to obtain compound (1) in a yield of 91 mg (0.094 mmol) and a yield of 64%.
The target product was identified by MS and ¹ H-NMR.
EIMS: m / z = 969.36 [M ⁺ ]
The results of ¹ H-NMR measurement are shown in FIG.

[Example 2] Synthesis of Compound (2) [Synthesis of Compound g]
In a three-necked flask equipped with a stir bar, 984 mg (4.00 mmol) of 3-bromocarbazole (compound e), 1.26 g (4.40 mmol) of 9-phenylcarbazole-3-boronic acid (compound f), 2M tripotassium phosphate 20 ml of (K ₃ PO ₄ ) aqueous solution (tripotassium phosphate 40.0 mmol), 40 ml of xylene and 20 ml of ethanol were added and nitrogen bubbling was performed for 1 hour. Thereto, 256 mg (0.28 mmol) of tris (dibenzylideneacetone) dipalladium (0) (Pd ₂ (dba) ₃ ), 230 mg of 2-dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl (SPhos) (0 .56 mmol) was added and the mixture was heated and stirred overnight. After removing the solvent, extraction and washing were performed with toluene and saturated brine. Then, it dried with magnesium sulfate and filtered the desiccant. The filtrate was concentrated and purified by silica gel column chromatography (dichloromethane: hexane = 1: 1). 937 mg (2.30 mmol) of the target product g was obtained with a yield of 57%.

[Synthesis of Compound i]
In a test tube flask equipped with a stir bar, compound 594 mg (0.69 mmol), 4-bromoiodobenzene (compound h) 195 mg (0.69 mmol), tripotassium phosphate 292 mg (1.38 mmol), copper iodide (I ) 3.8 mg (0.02 mmol) was added and a nitrogen flow was performed for 30 minutes. A 17.5 ml solution of degassed 1,4-dioxane of 4.56 mg (0.04 mmol) of trans-1,2-cyclohexanediamine was separately prepared, 3.5 ml of which was added to the system, and heated and stirred overnight. The reaction solution was returned to room temperature and the solvent was distilled off. Toluene was added to the residue and redissolved, followed by washing with saturated brine. Anhydrous magnesium sulfate was added to the organic layer, dried and filtered. The filtrate was concentrated and purified twice by silica gel column chromatography (dichloromethane: hexane = 3: 7). Compound i was obtained in a yield of 114 mg (0.20 mmol) and a yield of 29%.

[Synthesis of Compound j]
To a 25 mL three-necked flask equipped with a stir bar, 662 mg (1.17 mmol) of compound i, 300 mg (1.17 mmol) of indolocarbazole (compound 1), 972 mg (7.04 mmol) of potassium carbonate and 25 ml of dehydrated xylene were added, and nitrogen bubbling was performed for 1 hour. Went. Thereto were added palladium acetate (II) 10.2 mg (0.045 mmol) and tri-tert-butylphosphine 39 μl (0.234 mmol), and the mixture was stirred with heating at a bath temperature of 135 ° C. overnight. The reaction solution was returned to room temperature and the solvent was distilled off. Toluene was added and redissolved there, followed by washing with saturated saline. Anhydrous magnesium sulfate was added to the organic layer, dried, filtered, and the filtrate was concentrated. Purification was performed by silica gel column chromatography (dichloromethane: hexane = 3: 7). 766 mgg (1.04 mmol) of the target product j was obtained with a yield of 89%.

[Synthesis of Compound (2)]
After adding 24 mg (0.54 mmol) of sodium hydride (NaH) and 333 mg (0.45 mmol) of compound j to a three-necked flask equipped with a stir bar, the system was degassed, and then the atmosphere was changed to a nitrogen atmosphere. Thereto was added 10 ml of N, N-dimethylformamide, and the mixture was stirred at room temperature for 1 hour in a nitrogen atmosphere. Thereafter, 603 mg (2.25 mmol) of 2-chloro-4,6-diphenyl-1,3,5-triazine (Compound 2) was dissolved in 6.0 ml of N, N-dimethylformamide and added dropwise. After dropping, the mixture was stirred overnight by heating under reflux. The reaction solution was returned to room temperature and the solvent was distilled off. Toluene was added and redissolved there, followed by washing with saturated saline. Anhydrous magnesium sulfate was added to the organic layer, dried, filtered, and the filtrate was concentrated. The product was purified by silica gel column chromatography (ethyl acetate: hexane = 1: 19) to remove impurities. Next, purification was performed by alumina thin layer chromatography (TLC) (toluene: hexane = 1: 1 → 1: 0) to obtain 360 mg (0.37 mmol) of compound (2) in a yield of 68%.
The target product was identified by MS and ¹ H-NMR.
EIMS: m / z = 969.36 [M ⁺ ]
The results of ¹ H-NMR measurement are shown in FIG.

[Example 3] Synthesis of Compound (3) [Synthesis of Compound k]
In a 50 mL three-necked flask equipped with a stir bar, 3,6-dibromo-9-phenylcarbazole (Compound a) 2.00 g (4.99 mmol), carbazole 2.50 g (15.0 mmol), tripotassium phosphate 2.33 g ( 10.98 mmol), 190 mg (0.100 mmol) of copper (I) iodide, 114 mg (0.100 mmol) of trans-1,2-cyclohexanediamine and 50 ml of dehydrated 1,4-dioxane, and the mixture was stirred under reflux overnight under a nitrogen atmosphere. went. After completion of the reaction, Celite filtration was performed to remove insoluble parts. The filtrate was concentrated and purified by silica gel column chromatography (hexane: dichloromethane = 3: 1 → 7: 3) to obtain 1.04 g (2.13 mmol) of compound k in 43% yield.

[Synthesis of Compound l]
To a three-necked flask equipped with a stirrer was added 244 mg (1.72 mmol) of compound k, 411 mg (1.72 mmol) of indolocarbazole (compound 1), 1.43 g (10.35 mmol) of potassium carbonate, and 35 ml of dehydrated xylene for 1 hour. Bubbling was performed. Thereto, 15 mg (0.067 mmol) of palladium (II) acetate and 60 μl of tri-tert-butylphosphine were added, the bath temperature was maintained at 135 ° C., and the mixture was heated and stirred overnight. After completion of the reaction, the insoluble part was removed, and the filtrate was concentrated. The residue was purified by silica gel column chromatography (hexane: dichloromethane = 7: 3) to obtain the target compound 1 in a yield of 817 mg (1.23 mmol) and a yield of 72%.

[Synthesis of Compound (3)]
440 mg (0.66 mmol) of Compound 1 and 44 mg (1.01 mmol) of sodium hydride were added to a three-necked flask equipped with a stir bar and deaerated. To the degassed three-necked flask, 3 ml of dehydrated N, N-dimethylformamide was added and stirred for 1 hour under a nitrogen atmosphere. Separately, 1.77 g (6.6 mmol) of 2-chloro-4,6-diphenyl-1,3,5-triazine (compound 2) was degassed and then heated by adding 9 ml of degassed dehydrated N, N-dimethylformamide. This was dissolved and added to the previous reaction solution, and the bath temperature was maintained at 70 ° C., and the mixture was heated and stirred overnight. After returning the reaction mixture to room temperature, water was added to terminate the reaction. After extraction with dichloromethane, it was dried over anhydrous magnesium sulfate, filtered and the solvent was distilled off. The obtained residue was subjected to silica gel column chromatography (hexane: dichloromethane = 3: 1) to obtain Compound (3) in a yield of 255.7 mg (0.286 mmol) and a yield of 43% (45% recovery of raw material).
The target product was identified by MS and ¹ H-NMR.
EIMS: m / z = 893.33 [M ⁺ ]
The result of ¹ H-NMR measurement is shown in FIG.

[Example 4] Synthesis of Compound (4) [Synthesis of Compound n]
In a 100 mL three-necked flask equipped with a stir bar, 1.61 g (9.63 mmol) of carbazole, 1.00 g (2.41 mmol) of 9-benzyl-3,6-dibromocarbazole, 5.32 g (38.5 mmol) of potassium carbonate, dehydration 50 ml of xylene was added and nitrogen bubbling was performed for 1 hour. Thereto were added 27 mg (0.12 mmol) of palladium (II) acetate and 113 μl (0.48 mmol) of tri-tert-butylphosphine, and the mixture was heated and stirred overnight at a bath temperature of 135 ° C. After completion of the reaction, the insoluble part was removed by Celite filtration, and the filtrate was concentrated. The residue was purified by silica gel column chromatography (hexane: dichloromethane = 7: 3) and silica gel column chromatography (hexane: dichloromethane = 2: 1), yielding 913 mg (1.55 mmol) of compound n, yield 64% I got it.

[Synthesis of Compound o]
To a 200 mL Erlenmeyer flask equipped with a stirrer, 799.2 mg (1.36 mmol) of Compound n and 42.4 ml of dimethyl sulfoxide were added, and stirred at room temperature in the atmosphere. 13.6 ml (13.6 mmol) of potassium tert-butoxide (1M THF solution) was added thereto and further stirred. After 1 hour, 59.2 ml of ion-exchanged water was added to the reaction solution to terminate the reaction. The reaction mixture was suction filtered and dried under reduced pressure to quantitatively obtain 623 mg of a white solid crude product.

[Synthesis of Compound p]
In a 25 mL three-necked flask equipped with a stir bar, compound 623 mg (1.25 mmol), 4-bromoiodobenzene (compound h) 530 mg (1.87 mmol), tripotassium phosphate 530 mg (2.50 mmol), copper iodide ( I) 7.3 mg (0.0383 mmol) was added and deaerated. Separately, 6.9 mg (0.060 mmol) of trans-1,2-cyclohexanediamine was dissolved in 25 ml of dehydrated 1,4-dioxane, 6.3 ml was added, and the mixture was heated and stirred overnight at a bath temperature of 115 ° C. After completion of the reaction, Celite filtration was performed to remove insoluble parts. The filtrate was concentrated and purified by silica gel column chromatography (hexane: dichloromethane = 3: 1 → 1: 1) to obtain the target compound p in a yield of 596 mg (0.914 mmol), a yield of 73%. (Raw material recovery 41.8 mg (0.0840 mmol, 6.7%)).

[Synthesis of Compound r]
To a 50 mL three-necked flask equipped with a stirrer was added 1.09 g (1.67 mmol) of compound p, 428 mg (1.67 mmol) of indolocarbazole (compound 1), 1.38 g (9.98 mmol) of potassium carbonate, and 33 ml of dehydrated xylene. Nitrogen bubbling was performed for hours. Thereto were added 14.6 mg (0.065 mmol) of palladium (II) acetate and 59 μl (0.25 mmol) of tri-tert-butylphosphine, and the mixture was stirred with heating at a bath temperature of 135 ° C. overnight. After completion of the reaction, the insoluble part was filtered off and the filtrate was concentrated. The residue was reprecipitated with silica gel column chromatography (hexane: dichloromethane = 2: 1) and methanol to obtain 1.30 g (1.57 mmol) of the target compound r in 94% yield.

[Synthesis of Compound (4)]
To a 100 mL three-necked flask equipped with a stir bar, 1.29 g (1.56 mmol) of compound r and 103 mg (2.36 mmol) of sodium hydride were added for deaeration. Degassed dehydrated N, N-dimethylformamide (31.4 ml) was added, and the mixture was stirred under a nitrogen atmosphere for 1 hour. Separately, 20.9 ml of dehydrated N, N-dimethylformamide in 2.10 g (7.84 mmol) of 2-chloro-4,6-diphenyl-1,3,5-triazine (compound 2) was added, and the bath temperature was increased. The mixture was heated and stirred at 70 ° C. overnight. After returning the reaction mixture to room temperature, water was added to terminate the reaction. The reaction mixture was extracted with ethyl acetate, dried over anhydrous magnesium sulfate, filtered and evaporated to remove the solvent, then alumina column chromatography (toluene → toluene: ethyl acetate = 1000: 1) and silica gel column chromatography (hexane: dichloromethane = 3: 1 → 3: 2) was performed twice, and further reprecipitation was performed with methanol to obtain 1.27 g (1.20 mmol) of compound (4) in a yield of 77%.
The target product was identified by MS and ¹ H-NMR.
EIMS: m / z = 1058.38 [M ⁺ ]
The results of ¹ H-NMR measurement are shown in FIG.

[Comparative Examples 1 and 2]
Existing compounds A-1 and A-2 having the structural formula shown below were used.

[Solubility test]
About the compound (1)-(4) obtained in Examples 1-4, the solubility test in a powder state was done. 1 mg of each sample was weighed into a sample tube, and the solvent shown in Table 1 was added. After adding the solvent, ultrasonic waves and heating were performed.
The results are shown in Table 1.

  From Table 1, compounds (1) to (4) were dissolved in THF, p-xylene, butyl acetate and 2-ethoxyethanol, but not in methanol. That is, it was found that the compounds (1) to (4) exhibited solvent resistance with respect to an alcohol solvent usually used for forming a layer of the organic EL element. From this, it was suggested that the compounds (1) to (4) are useful as host materials for the coating type organic EL.

[Residual film rate test]
Since it turned out that compound (1)-(4) has solvent resistance with respect to an alcohol solvent, about compound (1)-(4) and compound A-2, the solvent resistance at the time of making it into a thin film is shown. Examined.
Each sample was dissolved in THF on a quartz substrate to form a film, and then a UV-vis absorption spectrum was measured, followed by rinsing with methanol. The residual film ratio was calculated from the change in the UV-vis absorption spectrum before and after rinsing. Methanol is a solvent often used for coating the upper layer of the organic EL element.
The results are shown in FIGS.

As shown in FIGS. 1A to 1D, the samples formed from the compounds (1) to (4) almost matched the peak waveform of the UV-vis absorption spectrum before and after rinsing. Specifically, compounds (1), (2) and (4) do not change the absorbance of the thin film even after rinsing with methanol, and maintain a residual film rate of 100%. It was insoluble and showed a residual film rate of 96.8%. From this, it was found that the samples formed from the compounds (1) to (4) have solvent resistance against the alcohol solvent.
On the other hand, as shown in FIG. 2, almost no spectrum could be observed after rinsing compound A-2. That is, it turned out that compound A-2 will melt | dissolve by a rinse process.

(Optical characteristic evaluation)
Optical characteristics of the samples prepared by forming the compounds (1) to (4) were evaluated. The band gap (Eg) is from the absorption edge of the UV-vis absorption spectrum, the ionization potential (Ip) is from an ionization potential measuring device (PYS; photoelectron yield spectroscopy), and the electron affinity (Ea) is from the band gap (Eg) and the ionization potential. Calculated from (Ip).
Furthermore, a thin film was prepared by using compounds (1) to (4) as host materials and Ir (ppy) ₃ as a dopant as a green phosphorescent material at a concentration of 8 wt%, and measuring the emission quantum yield (PLQY). went.
In addition, about the glass transition temperature (Tg) of compound (1)-(4), although it measured by differential scanning calorimetry (DSC), it was not obtained.
The results are shown in Table 2.

  From Table 2, all of the compounds (1) to (4) have Ip of 5.6 to 5.7 (eV), and these ionization potentials enable efficient charge injection from the hole transport layer. it is conceivable that.

[Production and evaluation of coating type organic EL elements]
A coating type organic EL element having the element structure shown below was produced. The layer structure is shown in FIG. In FIG. 3, the numbers in parentheses represent thickness (nm), and ZnONPs mean ZnO nanoparticles.
ITO / PEDOT: PSS (30) / TFB (20) / light emitting layer (EML) (70) / ZnO (10) / PEIE (20) / Al (100)
An aqueous dispersion of PEDOT: PSS, which is a hole injection material, was formed on an ITO substrate at 6500 rpm for 30 seconds in the air, and then baked at 200 ° C. for 10 minutes. Next, a p-xylene solution of TFB, which is a hole transport material, was formed into a film at 5000 rpm for 30 seconds on a PEDOT: PSS layer in a glove box, and baked at 200 ° C. for 1 hour. On the TFB layer, a THF solution of a light emitting layer (EML) forming material was formed at 2500 rpm (compound A-1 was 3000 rpm) for 30 seconds, and then baked at 130 ° C. for 10 minutes. Further, a methanol dispersion of ZnO nanoparticles as an electron injection material was formed on the light emitting layer at 2000 rpm for 30 seconds and then baked at 100 ° C. for 10 minutes. Further, PEIE methanol as an electron injection material was formed on the ZnO layer. The solution was deposited at 2000 rpm for 30 seconds and then baked at 100 ° C. for 10 minutes. On the PEIE layer, Al was formed by vacuum deposition while changing the deposition rate from 1000 Å / sec to 2500 Å / sec. A spin coater was used for all coating films.
Here, the light emitting layer (EML) forming materials are the following four types. Both are materials doped with Ir (ppy) _{3 at} a concentration of 8 wt%.
Light emitting layer (EML) forming material Compound A-1: 8 wt% Ir (ppy) ₃
Compound (1): 8 wt% Ir (ppy) ₃
Compound (2): 8 wt% Ir (ppy) ₃
Compound (3): 8 wt% Ir (ppy) ₃
Compound (4): 8 wt% Ir (ppy) ₃
The structural formulas of PEDOT: PSS, TFB, PEIE, and Ir (ppy) ₃ are shown below.

The EL spectrum of each element was measured. The results are shown in FIG.
As a result, a coating type organic EL device in which a film other than the electrodes was formed by coating was successfully produced. Moreover, from FIG. 4, compound (1)-(4) showed the efficiency equivalent to compound A-1, and succeeded in the voltage reduction significantly. The reason why the voltage is lowered is that, since the compounds (1) to (4) are bipolar, charges are efficiently injected.

[Production and evaluation of vapor deposition type organic EL elements]
Next, the vapor deposition type organic EL element which consists of an element structure shown below was produced. The layer structure is shown in FIG. The number in parentheses represents the thickness (nm).
ITO / PMA (10) / TFB (20) / EML (30) / BAlq ₂ (10) / Alq ₃ (40) / Liq (1) / Al (100)
On the ITO substrate, phosphomolybdic acid (PMA) dissolved in acetonitrile as a hole injection material was formed into a film at 4000 rpm for 30 seconds and then baked at 150 ° C. for 10 minutes. On the PMA layer, TFB dissolved in p-xylene was formed as a hole transport material at 5000 rpm for 30 seconds, and the surface was wiped off, followed by baking at 200 ° C. for 1 hour. A THF solution of a light emitting layer (EML) forming material was formed on the TFB layer at 4000 rpm for 30 seconds, wiped off the surface, and then baked at 130 ° C. for 10 minutes. BAlq ₂ and Alq ₃ that are electron transport materials, Liq that is an electron injection material, and cathode Al were all formed on the light emitting layer (EML) by vacuum deposition. A spin coater was used for all coating films.
Here, the light emitting layer (EML) forming materials are the following four types. Both are materials doped with Ir (ppy) _{3 at} a concentration of 8 wt%.
Light emitting layer (EML) forming material Compound A-1: 8 wt% Ir (ppy) ₃
Compound A-2: 8 wt% Ir (ppy) ₃
Compound (1): 8 wt% Ir (ppy) ₃
Compound (2): 8 wt% Ir (ppy) ₃
Compound (3): 8 wt% Ir (ppy) ₃
Compound (4): 8 wt% Ir (ppy) ₃
The structural formulas of Alq ₃ , BAlq ₂ , and Liq are shown below.

The EL spectrum of each element was measured. The results are shown in FIG.
As a result, although the voltage of compound A-1 was slightly increased, the same behavior was obtained for each compound.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode

Claims (4)

A triazine-substituted indolocarbazole derivative represented by any of the following structural formulas (1) to (4).

  An alcohol-insoluble coating film for forming an organic electronic device comprising the triazine-substituted indolocarbazole derivative according to claim 1.   An organic electronic device using the triazine-substituted indolocarbazole derivative according to claim 1 or the alcohol-insoluble coating film according to claim 2.   The manufacturing method of an organic electronic device including the process of forming a layer by the coating film-forming on the layer which apply | coated and formed the triazine substituted indolocarbazole derivative of Claim 1.

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