JP5325402B2 - Novel bicarbazole derivative, host material and organic electroluminescence device using the same - Google Patents

Description

  The present invention relates to a novel bicarbazole derivative, a host material using the same, and an organic electroluminescence device.

Research and development for practical application of organic EL elements (organic electroluminescence elements) is being promoted mainly by domestic and foreign electric manufacturers and material manufacturers. Reducing power consumption and prolonging the life of the elements are indispensable issues for walking alongside displays that are already known to the public such as liquid crystal display elements and light emitting diodes.
Thus, in order to solve this problem, an organic EL element using a phosphorescent material has recently been studied (Non-Patent Document 1).
Unlike conventional fluorescent materials, phosphorescent materials have a very high quantum efficiency because they can use triplet excited states, and there is almost no energy deactivation, and the internal emission quantum yield reaches almost 100%. .
However, since this phosphorescent material tends to cause concentration quenching, it is necessary to use it together with a host material in the same manner as a fluorescent material.
In order to obtain high-efficiency light emission, it is necessary to optimize transport materials and host materials. However, unlike phosphor materials, phosphorescent materials cannot obtain satisfactory effects unless triplet energy is completely confined. Especially for blue materials, the energy level is very high. Therefore, 4,4'-di (N-carbazolyl) -1,1'-biphenyl (CBP) that has been used so far cannot confine sufficient energy. Until now, there was almost no wide-gap host material capable of confining the blue phosphorescent energy satisfactorily, which was one factor hindering the development of blue phosphorescent materials.
Therefore, the present inventors have developed the compound of claim 1 in consideration of the possibility that a compound having a twisted structure in the chemical structural formula becomes a compound that meets the above-mentioned purpose. The chemical abstract was searched, but no literature on the compound was found.

Appl. Phys. Lett. , 75 (1) 4 (1999)

  An object of the present invention is to provide a novel bicarbazole derivative, a host material using the same, and an organic electroluminescence device, which are necessary for enabling the device to be driven at a low voltage and providing a highly efficient device.

（式中、Ｑは

であり、Ｒ^１〜４およびＲ ^１９ は水素および炭素数１〜６の直鎖または分岐のアルキル基よりなる群から選ばれた基であり、Ｒ^２０は炭素数１〜６の直鎖または分岐のアルキル基であり、Ｒ^５〜１２は水素、炭素数１〜６の直鎖または分岐のアルキル基、炭素数１〜６の直鎖または分岐のアルコキシ基および炭素数１〜６の直鎖または分岐のアルキルアミノ基よりなる群からそれぞれ独立して選ばれた基である。）
本発明の第２は、請求項１記載のビカルバゾール誘導体よりなるホスト材料に関する。
本発明の第３は、請求項１記載のビカルバゾール誘導体を用いた有機エレクトロルミネッセンス素子に関する。 The first of the present invention relates to a bicarbazole derivative represented by the following general formula (1).

(Where Q is

In ^{and, R 1 to 4} and R ¹⁹ are hydrogen and straight-chain or branched alkyl group selected from the group consisting of groups having 1 to 6 carbon ^{atoms, R 20} is a straight-chain or branched having 1 to 6 carbon atoms R ^5-12 is hydrogen, a linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkoxy group having 1 to 6 carbon atoms, and a linear chain having 1 to 6 carbon atoms or Each group is independently selected from the group consisting of branched alkylamino groups. )
The second of the present invention relates to a host material comprising the bicarbazole derivative according to claim 1.
3rd of this invention is related with the organic electroluminescent element using the bicarbazole derivative of Claim 1.

Examples of the linear or branched alkyl group having 1 to 6 carbon atoms in the present invention include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, and n-pentyl. , Iso-pentyl, 2,2-dimethylpropyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethyl Examples include butyl.
Examples of the linear or branched alkoxy group having 1 to 6 carbon atoms in the present invention include methoxy, ethoxy, n-propyloxy, iso-propyloxy, n-butyloxy, iso-butyloxy, sec-butyloxy, tert-butyloxy, n -Pentyloxy, iso-pentyloxy, 2,2-dimethylpropyloxy, n-hexyloxy, 2-methylpentyloxy, 3-methylpentyloxy, 4-methylpentyloxy, 2,2-dimethylbutyloxy, 2, Examples thereof include 3-dimethylbutyloxy and 3,3-dimethylbutyloxy.
Examples of the linear or branched alkylamino group having 1 to 6 carbon atoms in the present invention include methylamino, ethylamino, n-propylamino, iso-propylamino, n-butylamino, iso-butylamino, sec-butylamino. , Tert-butylamino, n-pentylamino, iso-pentylamino, 2,2-dimethylpropylamino, n-hexylamino, 2-methylpentylamino, 3-methylpentylamino, 4-methylpentylamino, 2,2 -Dimethylbutylamino, 2,3-dimethylbutylamino, 3,3-dimethylbutylamino and the like can be mentioned.

（式中、Ｑは

であり、Ｒ^１〜４およびＲ ^１９ は水素および炭素数１〜６の直鎖または分岐のアルキル基よりなる群から選ばれた基であり、Ｒ ^２０ は炭素数１〜６の直鎖または分岐のアルキル基であり、Ｒ^５〜１２は水素、炭素数１〜６の直鎖または分岐のアルキル基、炭素数１〜６の直鎖または分岐のアルコキシ基および炭素数１〜６の直鎖または分岐のアルキルアミノ基よりなる群からそれぞれ独立して選ばれた基である。） The compound of the present invention can be produced by the following reaction.

(Where Q is

In ^{and, R 1 to 4} and R ¹⁹ are hydrogen and straight-chain or branched alkyl group selected from the group consisting of groups having 1 to 6 carbon atoms, ^{R 20} is a straight-chain or branched having 1 to 6 carbon atoms of an alkyl group, R ^{5 to 12} is hydrogen, straight-chain or branched alkyl group having 1 to 6 carbon atoms, straight-chain C1-6 straight or branched alkoxy group and a carbon 1 to 6 carbon atoms or Each group is independently selected from the group consisting of branched alkylamino groups. )

Specific examples of the compound of the present invention are illustrated below. In addition, of course, the methyl group of the following exemplary compound can be replaced with the group illustrated in the above [0006].
The substitution position of the phenyl group in the example where Q is pyrimidine is (4, 6).
Furthermore, the bonding position of the carbazole group is the meta position with respect to the pyrimidine ring bonded to the phenyl group.

The bicarbazole derivative of the present invention has a wide band gap and a large energy confinement effect. Therefore, it can be used as a host material.
When the bicarbazole derivative of the present invention is used for organic electroluminescence, it can be used in combination with a suitable light emitting material.

  Next, the organic electroluminescence element (organic EL element) of the present invention will be described. The organic EL device of the present invention is a device in which a single-layer or multi-layer organic compound is laminated between an anode and a cathode. The light-emitting layer contains a light-emitting material, and in addition, holes injected from the anode or electrons injected from the cathode. Is preferably contained in the bicarbazole derivative of the present invention. As a host material of the light emitting layer, the bicarbazole derivative of the present invention is contained together with a known host material. Examples of the constitution of the organic EL device using the host material of the present invention include, for example, ITO (anode) / hole transport layer / light emitting layer / electron transport layer / cathode, ITO / hole transport layer / light emitting layer / electron transport layer / electron. Injection layer / cathode, ITO / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode, ITO / hole transport layer / light emitting layer / hole block layer / electron transport layer / electron injection layer / cathode, ITO / hole Examples thereof include those laminated in a multilayer structure such as injection layer / hole transport layer / light emitting layer / hole block layer / electron transport layer / electron injection layer / cathode. Moreover, you may have a sealing layer on a cathode as needed.

Each of the hole transport layer, the electron transport layer, and the light emitting layer may have a single layer structure or a multilayer structure. In addition, the hole transport layer and the electron transport layer can be provided separately with a layer responsible for the injection function (hole injection layer and electron injection layer) and a layer responsible for the transport function (hole transport layer and electron transport layer).
The organic EL element of the present invention is not limited to the above configuration example, and can have various configurations.

Hereinafter, the constituent elements of the organic EL element of the present invention will be described by taking as an example an element structure composed of an anode / hole transport layer / light emitting layer / electron transport layer / cathode. The organic EL element of the present invention is preferably supported on a substrate.
There is no restriction | limiting in particular about the raw material of a board | substrate, What is necessary is just what is conventionally used for the conventional organic EL element, For example, what consists of glass, quartz glass, a transparent plastic etc. can be used.

Examples of the anode of the organic EL device of the present invention include conductive transparent materials such as ITO (indium-tin oxide), tin oxide (SnO ₂ ), and zinc oxide (ZnO), and conductive polymer materials such as polypyrrole and polythiophene. It is done. For the anode, these electrode materials can be formed by a method such as vapor deposition, sputtering, or coating. The sheet electrical resistance of the anode is preferably several hundred Ω / cm ² or less. The thickness of the anode depends on the material, but is generally about 5 to 1,000 nm, preferably 10 to 500 nm.

As the cathode, an electrode material is preferably a simple metal having a low work function, an alloy of metals having a low work function, or a conductive substance and a mixture thereof. Specific examples of such electrode materials include lithium, lithium-indium alloy, sodium, sodium-potassium alloy, magnesium, magnesium-silver alloy, magnesium-indium alloy, aluminum, aluminum-lithium alloy, and aluminum-magnesium alloy. Can be mentioned. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet electrical resistance of the cathode is preferably several hundred Ω / cm ² or less. The thickness of the cathode depends on the material, but is generally about 5 to 1,000 nm, preferably 10 to 500 nm.
In order to efficiently extract light emitted from the organic EL device of the present invention, at least one of the anode and the cathode is preferably transparent or translucent.

The hole transport layer (hole transport layer) of the organic electroluminescence device of the present invention is made of a hole transport compound and has a function of transmitting holes injected from the anode to the light emitting layer. A hole transport material having a hole mobility of at least 10 ⁻⁶ cm ² / V · sec when a hole transport compound is disposed between two electrodes to which an electric field is applied and holes are injected from an anode Is preferred. The hole transport material used for the hole transport layer of the organic electroluminescence device of the present invention is not particularly limited as long as it has the above-mentioned preferable performance. Any one of materials conventionally used as a hole charge injection material in a photoconductive material or a known material used for a hole transport layer of an organic electroluminescence element can be selected and used. .

  Examples of the hole transport material include phthalocyanine derivatives such as copper phthalocyanine, N, N, N ′, N′-tetraphenyl-1,4-phenylenediamine, and N, N′-di (m-tolyl) -N. , N′-diphenyl-4,4-diaminophenyl (TPD), N, N′-di (1-naphthyl) -N, N′-diphenyl-4,4-diaminophenyl (α-NPD), etc. Examples thereof include an amine derivative, a polyphenylenediamine derivative, a polythiophene derivative, and a polymer mixture composed of PEDOT-PSS (polyethylenedioxathiophene-polystyrenesulfonic acid) represented by the following water-soluble formula. The hole transport layer may be composed of one or more of these other hole transport compounds, and a hole transport layer composed of a compound different from the hole transport material is laminated. Things can be used.

正孔輸送材料としては、下記化学式に示すＴＰＤ、ＤＴＡＳｉ、α−ＮＰＤなどを挙げることができる。 Examples of the hole injection material include PEDOT-PSS (polymer mixture) and DNTPD represented by the following chemical formula.

Examples of the hole transport material include TPD, DTASi, α-NPD, and the like represented by the following chemical formula.

The electron transport layer of the organic EL device of the present invention is made of an electron transfer compound and has a function of transmitting electrons injected from the cathode to the light emitting layer. When an electron transfer compound is disposed between two electrodes to which an electric field is applied and electrons are injected from the cathode, an electron transfer material having an electron mobility of at least 10 ⁻⁶ cm ² / V · sec or more is preferable. The electron transfer material used for the electron transport layer used in the organic EL device of the present invention is not particularly limited as long as it has the above-mentioned preferable performance. Any one of materials conventionally used as electron charge injection materials in photoconductive materials and known materials used for electron transport layers of organic EL elements can be selected and used.

Examples of the electron transfer material include quinoline complexes such as tris (8-hydroxyquinolinolato) aluminum complex (Alq ₃ ), 1-N-phenyl-2- (p-biphenylyl) -5- (p- triazine derivatives such as tert-butylphenyl) -1,3,5-triazine (TAZ), phenanthroline derivatives such as 1,4-di (1,10-phenanthroline-2-yl) benzene (DPB), fluoride Examples include alkali metal halides such as lithium. The electron transport layer may be composed of one or more of these other electron transport compounds, or may be a stack of electron transport layers composed of a compound different from the above electron transport material.

Examples of the electron transport material include Alq ₃ , TAZ, and DPB represented by the following chemical formula.

Examples of the electron injection material include lithium fluoride and 8-hydroxyquinolinolatolithium complex (Liq) represented by the following chemical formula. It is also possible to use a complex (LiPB) or a phenoxypyridine lithium complex (LiPP) described in Japanese Patent Application No. 2007-29695.

About the light emitting layer of the organic EL element of this invention, there is no restriction | limiting in particular about the conventionally well-known material, Arbitrary things can be selected and used.
Examples of the light-emitting material include perylene derivatives, naphthacene derivatives, quinacridone derivatives, coumarin derivatives (eg, coumarin 1, coumarin 540, coumarin 545), pyran derivatives (eg, DCM-1, DCM-2, DCJTB, etc.), organometallic complexes, eg, tris. Fluorescent materials such as (8-hydroxyquinolinolato) aluminum complex (Alq ₃ ) and tris (4-methyl-8-hydroxyquinolinolato) aluminum complex (Almq ₃ ) and [2- (4,6-difluorophenyl) Pyridyl-N, C2 ′] iridium (III) picolylate (FIrpic), tris {1- [4- (trifluoromethyl) phenyl] -1H-pyrazolate-N, C2 ′} iridium (III) (Irtfmpppz ₃ ), bis [2- (4 ′, 6′-difluorophenyl) pyridina -N, C2 '] iridium (III) tetrakis (1-pyrazolyl) borate (FIr6), tris (2-phenylpyridinato) iridium (III) (Irppy ₃₎ and the like phosphorescent material such as.

  The light emitting layer is preferably formed from a host material and a guest material (dopant). [Appl. Phys. Lett. 65 3610 (1989)]. In particular, when a phosphorescent material is used for the light emitting layer, it is necessary to use a host material. As the host material used at this time, it is desirable to use the bicarbazole derivative of the present invention. '-Di (N-carbazolyl) -1,1'-biphenyl (CBP), 1,4-di (N-carbazolyl) benzene-2,2'-di [4 "-(N-carbazolyl) phenyl] -1 , 1'-biphenyl (4CzPBP) may be used in combination.

The guest material is preferably 0.01 to 40% by weight, more preferably 0.1 to 20% by weight with respect to the host material. Examples of the guest material include conventionally known Firpic, Irppy ₃ , and Fir 6 shown below.

In the organic electroluminescence device of the present invention, an electron injection layer composed of a conductor may be further provided between the cathode and the organic layer for the purpose of further improving the electron injection property. As the conductor used here, it is preferable to use at least one metal compound selected from alkali metal halides, alkaline earth metal halides, and alkali metal organic complexes. Examples of the alkali metal halide include lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, and lithium chloride. Examples of the alkaline earth metal halide include magnesium fluoride, calcium fluoride, barium fluoride, and strontium fluoride. Examples of the alkali metal organic complex include 8-hydroxyquinolinolatolithium and 8-hydroxyquinolinolatocesium.
Moreover, when using this invention compound as an electron injection layer, it can also use together with said electron injection material.

Moreover, as an electron injection material used for the said electron injection layer, the compound concerning Japanese Patent Application No. 2006-292032 of this applicant, for example, the following compound group can also be illustrated.

  The method for forming the hole transport layer and the light emitting layer is not particularly limited. For example, a dry film forming method (for example, a vacuum vapor deposition method, an ionization vapor deposition method) or a wet film forming method [a solvent coating method (for example, a spin coating method, a casting method, an ink jet method, etc.)] can be used. The novel bicarbazole derivative of the present invention is preferably a dry film forming method (for example, a vacuum deposition method, an ionization deposition method, etc.). The film formation of the electron transport layer is limited to a dry film formation method (for example, a vacuum vapor deposition method, an ionization vapor deposition method, etc.) because the lower layer may be eluted when the wet film formation method is used. For the production of the element, the above film forming method may be used in combination.

When forming each layer such as a hole transport layer, a light emitting layer, and an electron transport layer by a vacuum deposition method, the vacuum deposition conditions are not particularly limited. Usually, under a vacuum of about 10 ⁻⁵ Torr or less, a boat temperature (deposition source temperature) of about 50 to 500 ° C., a substrate temperature of about −50 to 300 ° C., and 0.01 to 50 nm / sec. Vapor deposition is preferred. When forming each layer of a positive hole transport layer, a light emitting layer, and an electron carrying layer using a some compound, it is preferable to co-evaporate the boat which put the compound, respectively controlling temperature.

  When forming the hole transport layer and the light emitting layer by a solvent coating method, the components constituting each layer are dissolved or dispersed in a solvent to obtain a coating solution. Solvents include hydrocarbon solvents (eg, heptane, toluene, xylene, cyclohexane, etc.), ketone solvents (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), halogen solvents (eg, dichloromethane, chloroform, chlorobenzene, dichlorobenzene, etc.) Ester solvents (eg, ethyl acetate, butyl acetate, etc.), alcohol solvents (eg, methanol, ethanol, butanol, methyl cellosolve, ethyl cellosolve, etc.) ether solvents (eg, dibutyl ether, tetrahydrofuran, 1,4-dioxane, 1, 2-dimethoxyethane etc.), aprotic solvents (eg N, N'-dimethylacetamide, dimethyl sulfoxide etc.), water and the like. The solvent may be used alone, or a plurality of solvents may be used in combination.

The thickness of each layer such as the hole transport layer, the light emitting layer, and the electron transport layer is not particularly limited, but is usually 5 to 5,000 nm.
The organic electroluminescence device of the present invention can be protected by providing a protective layer (sealing layer) for the purpose of blocking contact with oxygen, moisture, etc., or by enclosing the device in an inert material. Examples of the inert substance include paraffin, silicon oil, and fluorocarbon. Examples of the material used for the protective layer include fluororesin, epoxy resin, silicone resin, polyester, polycarbonate, and photocurable resin.

  The organic electroluminescence device of the present invention can be used as a normal DC drive device. When a DC voltage is applied, light emission is usually observed when about 1.5 to 20 V is applied with the positive polarity of the anode and the negative polarity of the cathode. The organic electroluminescence device of the present invention can also be used as an AC drive device. When an AC voltage is applied, light is emitted when the anode is in a positive state and the cathode is in a negative state. The organic electroluminescence device of the present invention includes, for example, a flat light emitter such as an electrophotographic photosensitive member and a flat panel display, a copying machine, a printer, a backlight of a liquid crystal display, a light source such as an instrument, various light emitting devices, various display devices, and various signs. It can be used for various sensors and various accessories.

In FIGS. 11-14, the preferable example of the organic electroluminescent element of this invention is shown.
FIG. 11 is a cross-sectional view showing an example of the organic electroluminescence element of the present invention. FIG. 11 shows a structure in which an anode 2, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. This is a separation of the functions of carrier transport and light emission, and the degree of freedom in material selection increases, so that the efficiency of light emission and the degree of freedom in light emission color increase. The bicarbazole derivative of the present invention is contained in the light emitting layer 3.

  FIG. 12 is a cross-sectional view showing another example of the organic electroluminescence element of the present invention. FIG. 12 shows a structure in which an anode 2, a hole injection layer 7, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. In this case, the provision of the hole injection layer 7 improves the adhesion between the anode 2 and the hole transport layer 5, improves the injection of holes from the anode, and is effective in lowering the voltage of the light emitting element. The bicarbazole derivative of the present invention is contained in the light emitting layer 3.

  FIG. 13 is a cross-sectional view showing another example of the organic electroluminescence element of the present invention. FIG. 13 shows a configuration in which an anode 2, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6, an electron injection layer 8 and a cathode 4 are sequentially provided on a substrate 1. In this case, injection of electrons from the cathode 4 is improved, which is effective for lowering the voltage of the light emitting element. The bicarbazole derivative of the present invention is contained in the light emitting layer 3.

  FIG. 14 is a cross-sectional view showing another example of the organic electroluminescence element of the present invention. FIG. 14 shows a configuration in which an anode 2, a hole injection layer 7, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6, an electron injection layer 8 and a cathode 4 are sequentially provided on a substrate 1. In this case, the injection of holes from the anode 2 is improved and the injection of electrons from the cathode 4 is improved, which is the most effective for driving at a low voltage. The bicarbazole derivative of the present invention is contained in the light emitting layer 3.

  15 to 21 are sectional views of the device in which the hole blocking layer 9 is inserted. The hole blocking layer has an effect of preventing holes injected from the anode or excitons generated by recombination in the light emitting layer 3 from escaping to the cathode 4, thereby improving the light emission efficiency of the organic electroluminescence device. effective. The hole blocking layer 9 can be inserted between the light emitting layer 3 and the cathode 4, between the light emitting layer 3 and the electron transport layer 6, or between the light emitting layer 3 and the electron injection layer 8. More preferred is between the light emitting layer 3 and the electron transport layer 6. The bicarbazole derivative of the present invention is contained in the light emitting layer 3.

15 to 21, each of the hole transport layer 5, the hole injection layer 7, the electron transport layer 6, the electron injection layer 8, the light emitting layer 3, and the hole blocking layer 9 may have a single layer structure or a multilayer structure. It may be a structure.
FIGS. 11-21 are the fundamental element structure to the last, and the structure of the organic electroluminescent element using the compound of this invention is not limited to this.

  The bicarbazole derivative of the present invention has a wide band gap and a large energy confinement effect compared to conventional host materials such as CBP. In addition, the mobility is large and the carrier balance with holes and electrons in the device is excellent. Further, since it has a large band gap, it is suitable as a host material for blue light-emitting materials that require large energy, particularly blue phosphorescent materials. Therefore, the novel bicarbazole derivative of the present invention is extremely important industrially.

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

四つ口フラスコに１−ブロモ−３−ヨードベンゼン（１５．０ｇ，５３．０ｍｍｏｌ）、カルバゾール（８．７０ｇ，５２．０ｍｍｏｌ）、銅粉（１０．１ｇ，１５９．０ｍｍｏｌ）、炭酸カリウム（２２．０ｇ，１５９．０ｍｍｏｌ）とジメチルホルムアミド（ＤＭＦ）（１２０ｍＬ）を入れて、窒素気流下激しく撹拌しながら１３０℃まで加熱し、２４時間反応させた。反応終了後、反応溶液を酢酸エチルで希釈し、セライトでろ過した。濾過液を水に注ぎ、酢酸エチルで抽出し、飽和食塩水で洗浄した。無水硫酸マグネシウムで脱水し、溶媒をエバポレーターで除去した。
精製はカラムクロマトグラフィー法で行い（展開溶媒比：ｎ−ヘキサン／トルエン＝６／１）、無色の粘体の目的生成物を得た。収率：１３．７ｇ，８１．８％。 Reference example 1
Synthesis of 3,5-bis (3-9H-carbazol-9-yl-phenyl) pyridine (35DCzPPy) (1) Synthesis of 9- (3-bromophenyl) -9H-carbazole (mCzPBr)

In a four-necked flask, 1-bromo-3-iodobenzene (15.0 g, 53.0 mmol), carbazole (8.70 g, 52.0 mmol), copper powder (10.1 g, 159.0 mmol), potassium carbonate (22 0.0 g, 159.0 mmol) and dimethylformamide (DMF) (120 mL) were added, heated to 130 ° C. with vigorous stirring under a nitrogen stream, and allowed to react for 24 hours. After completion of the reaction, the reaction solution was diluted with ethyl acetate and filtered through celite. The filtrate was poured into water, extracted with ethyl acetate, and washed with saturated brine. It dehydrated with anhydrous magnesium sulfate and the solvent was removed by an evaporator.
Purification was performed by a column chromatography method (developing solvent ratio: n-hexane / toluene = 6/1) to obtain a colorless viscous target product. Yield: 13.7 g, 81.8%.

四つ口フラスコに９−（３−ブロモフェニル）−９Ｈ−カルバゾール（９．８６ｇ，３０．６ｍｍｏｌ）、ビス（ピナコラート）ジボラン（８．５５ｇ，３３．７ｍｍｏｌ）、酢酸カリウム（９．０１ｇ，９１．８ｍｍｏｌ）、トリス（ジベンジリデンアセトン）
ジパラジウム（０）〔Ｐｄ_２（ｄｂａ）_３〕（０．８４１ｇ，０．９１８ｍｍｏｌ）、トリシクロヘキシルホスフィン（１．０３ｇ，３．６７ｍｍｏｌ）と無水１，４−ジオキサン（２００ｍＬ）を入れて、窒素気流下８０℃で２４時間反応させた。その後、反応溶液に水を注ぎ，酢酸エチルで抽出し、飽和食塩水で洗浄した。無水硫酸マグネシウムで脱水し、溶媒をエバポレーターで除去した。
精製はカラムクロマトグラフィー法〔展開溶媒：トルエン／ｎ−ヘキサン＝２／１（２回）〕を行い、白色固体の目的生成物を得た。収率：９．２９ｇ，８２．２％ (2) Synthesis of 9- {3- [4,4,5,5-tetramethyl- (1,3,2) dioxaborolan-2-yl] -phenyl} -9H-carbazole (mCzPDOB)

In a four-necked flask, 9- (3-bromophenyl) -9H-carbazole (9.86 g, 30.6 mmol), bis (pinacolato) diborane (8.55 g, 33.7 mmol), potassium acetate (9.01 g, 91 .8 mmol), Tris (dibenzylideneacetone)
Add dipalladium (0) [Pd ₂ (dba) ₃ ] (0.841 g, 0.918 mmol), tricyclohexylphosphine (1.03 g, 3.67 mmol) and anhydrous 1,4-dioxane (200 mL), and add nitrogen. The reaction was performed at 80 ° C. for 24 hours under an air stream. Thereafter, water was poured into the reaction solution, extracted with ethyl acetate, and washed with saturated brine. It dehydrated with anhydrous magnesium sulfate and the solvent was removed by an evaporator.
Purification was carried out by a column chromatography method [developing solvent: toluene / n-hexane = 2/1 (twice)] to obtain the desired product as a white solid. Yield: 9.29 g, 82.2%

四つ口フラスコに３，５−ジブロモピリジン（０．７１１ｇ，３．０ｍｍｏｌ）、ｍＣｚＰＤＯＢ（２．６６ｇ，７．２ｍｍｏｌ）、テトラキス（トリフェニルホスフィン）パラジウム〔Ｐｄ（ＰＰｈ_３）_４〕（１３９ｍｇ，０．１２ｍｍｏｌ）、トルエン／エタノール（２／１，１５０ｍＬ）と２Ｍ Ｋ_２ＣＯ_３（５０ｍＬ）を入れて、窒素気流下９０℃で２４時間反応させた。反応終了後、反応溶液を水に注ぎ、クロロホルムで抽出し、飽和食塩水で洗浄した。無水硫酸マグネシウムで脱水し、溶媒をエバポレーターで除去した。
精製はカラムクロマトグラフィー法（展開溶媒：クロロホルム）を行い、白色粉末の目的生成物を得た。収率：１．６９ｇ，９８．８％。
図１に３５ＤＣｚＰＰｙの吸収曲線を、図２に３５ＤＣｚＰＰｙのフォトルミネッセンス（ＰＬ）曲線を示す。表１に３５ＤＣｚＰＰｙの電気化学特性を、表２に３５ＤＣｚＰＰｙの熱特性を示す。（表１および表２は実施例１にまとめて掲げる。） (3) Synthesis of 3,5-bis (3-9H-carbazol-9-yl-phenyl) pyridine (35DCzPPy)

In a four-necked flask, 3,5-dibromopyridine (0.711 g, 3.0 mmol), mCzPDOB (2.66 g, 7.2 mmol), tetrakis (triphenylphosphine) palladium [Pd (PPh ₃ ) ₄ ] (139 mg, 0.12 mmol), toluene / ethanol (2/1, 150 mL) and 2M K ₂ CO ₃ (50 mL) were added and reacted at 90 ° C. for 24 hours under a nitrogen stream. After completion of the reaction, the reaction solution was poured into water, extracted with chloroform, and washed with saturated brine. It dehydrated with anhydrous magnesium sulfate and the solvent was removed by an evaporator.
Purification was performed by column chromatography (developing solvent: chloroform) to obtain the desired product as a white powder. Yield: 1.69 g, 98.8%.
FIG. 1 shows an absorption curve of 35DCzPPy, and FIG. 2 shows a photoluminescence (PL) curve of 35DCzPPy. Table 1 shows the electrochemical characteristics of 35DCzPPy, and Table 2 shows the thermal characteristics of 35DCzPPy. (Tables 1 and 2 are listed together in Example 1. )

四つ口フラスコに２，６−ジブロモピリジン（０．７１１ｇ，３．０ｍｍｏｌ）、ｍＣｚＰＤＯＢ（２．６６ｇ，７．２ｍｍｏｌ）、Ｐｄ（ＰＰｈ_３）_４（１３９ｍｇ，０．１２ｍｍｏｌ）、トルエン／エタノ−ル（２／１，１５０ｍＬ）と２Ｍ Ｋ_２ＣＯ_３（５０ｍＬ）を入れて、窒素気流下９０℃で２４時間反応させた。反応終了後、反応溶液を水に注ぎ、クロロホルムで抽出し、飽和食塩水で洗浄した。無水硫酸マグネシウムで脱水し、溶媒をエバポレーターで除去した。
精製はカラムクロマトグラフィー法（以下の混合割合の混合溶媒を用いて、１回目〜４回目までの展開を行った。展開溶媒比：クロロホルム／ｎ−ヘキサン＝１／２；２／３；１／１；２／１）を行い、白色粉末の目的生成物を得た。収率：１．７１ｇ，９９．９ｍｏｌ％
図１に２６ＤＣｚＰＰｙの吸収曲線を、図２に２６ＤＣｚＰＰＰｙのフォトルミネッセンス（ＰＬ）曲線を示す。表１に２６ＤＣｚＰＰｙの電気化学特性を、表２に２６ＤＣｚＰＰｙの熱特性を示す（表１および表２は実施例１にまとめて掲げる。）。 Reference example 2
Synthesis of 2,6-bis (3-9H-carbazol-9-yl-phenyl) pyridine (26DCzPPy)

In a four-necked flask, 2,6-dibromopyridine (0.711 g, 3.0 mmol), mCzPDOB (2.66 g, 7.2 mmol), Pd (PPh ₃ ) ₄ (139 mg, 0.12 mmol), toluene / ethanol- (2 / 1,150 mL) and 2M K ₂ CO ₃ (50 mL) were added and reacted at 90 ° C. for 24 hours under a nitrogen stream. After completion of the reaction, the reaction solution was poured into water, extracted with chloroform, and washed with saturated brine. It dehydrated with anhydrous magnesium sulfate and the solvent was removed by an evaporator.
Purification was performed by column chromatography (mixed solvents having the following mixing ratios were used for the first to fourth development. Developing solvent ratio: chloroform / n-hexane = 1/2; 2/3; 1 / 1; 2/1) to obtain the desired product as a white powder. Yield: 1.71 g, 99.9 mol%
FIG. 1 shows an absorption curve of 26DCzPPy, and FIG. 2 shows a photoluminescence (PL) curve of 26DCzPPy. Table 1 shows the electrochemical characteristics of 26DCzPPy, and Table 2 shows the thermal characteristics of 26DCzPPy (Tables 1 and 2 are listed together in Example 1 ).

四つ口フラスコに２−メチル−４，６−ジクロロピリミジン（０．３６０ｇ， ２．２１ｍｍｏｌ）、ｍＣｚＰＤＯＢ（１．９６ｇ，５．３１ｍｍｏｌ）、ビス（トリフェニルホスフィン）パラジウムジクロライド｛ＰｄＣｌ_２（ＰＰｈ_３）_２｝（７０ｍｇ，０．１０ｍｍｏｌ）、１，４−ジオキサン（１２０ｍＬ）と２Ｍ Ｋ_２ＣＯ_３（３０ｍＬ）を入れて、窒素気流下９０℃で２４時間反応させた。反応終了後、反応溶液を水に注ぎ、クロロホルムで抽出し、飽和食塩水で洗浄した。無水硫酸マグネシウムで脱水し、溶媒をエバポレーターで除去した。
精製はカラムクロマトグラフィー法（以下の混合割合の混合溶媒を用いて、１回目と２回目の展開溶媒を行った。展開溶媒比：クロロホルム／ｎ−ヘキサン＝２／１；４／１）を行い、白色粉末の目的生成物を得た。収率：１．２１ｇ，９４．９％ Example 1
Synthesis of 2-methyl-4,6-bis (3-9H-carbazol-9-yl-phenyl) pyrimidine (DCzPMPm)

In a four-necked flask, 2-methyl-4,6-dichloropyrimidine (0.360 g, 2.21 mmol), mCzPDOB (1.96 g, 5.31 mmol), bis (triphenylphosphine) palladium dichloride {PdCl ₂ (PPh _{3 2} } (70 mg, 0.10 mmol), 1,4-dioxane (120 mL) and 2M K ₂ CO ₃ (30 mL) were added and reacted at 90 ° C. for 24 hours under a nitrogen stream. After completion of the reaction, the reaction solution was poured into water, extracted with chloroform, and washed with saturated brine. It dehydrated with anhydrous magnesium sulfate and the solvent was removed by an evaporator.
The purification was carried out by column chromatography (first and second developing solvents using a mixed solvent having the following mixing ratio. Developing solvent ratio: chloroform / n-hexane = 2/1; 4/1). The desired product was obtained as a white powder. Yield: 1.21 g, 94.9%

Ｉｐ：イオン化ポテンシャル
Ｅｇ：エネルギーギャップ
Ｅａ：エレクトロンアフィニティ（電子親和力）
エネルギーギャップ（Ｅｇ）については、蒸着機で作成した薄膜を紫外−可視吸光度計で薄膜の吸収曲線を測定する。その薄膜の短波長側の立ち上がりのところに接線を引き、求まった交点の波長Ｗ（ｎｍ）を次の式に代入し目的の値を求める。それによって得た値がＥｇになる。
Ｅｇ＝１２４０÷Ｗ
例えば接線を引いて求めた値Ｗ（ｎｍ）が４７０ｎｍだったとしたらこの時のＥｇの値は
Ｅｇ＝１２４０÷４７０＝２．６３（ｅＶ）
と言うことになる。
ＩＰ（イオン化ポテンシャル）はイオン化ポテンシャル測定装置（例えば理研計器ＡＣ−３）を使用して測定し、測定するサンプルがイオン化を開始したところの電圧（ｅＶ）の値を読む。
Ｅａ（電子親和力）は、ＩｐからＥｇを引いた値である。

FIG. 1 shows a UV absorption curve of DCzPMPm, and FIG. 2 shows a photoluminescence (PL) curve of DCzPMPm. Table 1 shows the electrochemical properties of DCzPMPm, and Table 2 shows the thermal properties of DCzPMPm.

Ip: Ionization potential
Eg: Energy gap
Ea: Electron affinity (electron affinity)
Regarding the energy gap (Eg), an absorption curve of the thin film prepared with a vapor deposition machine is measured with an ultraviolet-visible absorptiometer. A tangent line is drawn at the short-wavelength rising edge of the thin film, and the target wavelength is obtained by substituting the obtained wavelength W (nm) of the intersection into the following equation. The value obtained thereby becomes Eg.
Eg = 1240 ÷ W
For example, if the value W (nm) obtained by drawing the tangent is 470 nm, the value of Eg at this time is
Eg = 1240 ÷ 470 = 2.63 (eV)
It will be said.
IP (ionization potential) is measured using an ionization potential measuring device (for example, Riken Keiki AC-3), and the value of the voltage (eV) at which the sample to be measured starts ionization is read.
Ea (electron affinity) is a value obtained by subtracting Eg from Ip.

またそれぞれのホール輸送層に用いた３，３′′′−ビス（Ｎ，Ｎ−ジ−ｐ−トリル）−１，１′：２′，１′′：２′′，１′′′−クォーターフェニル（３ＤＴＡＰＢＰ）の構造式を以下に示す。

それぞれの電子輸送層に用いた３，３′，５，５′−テトラ〔３−（ピリジン−３−イル）フェニル〕−１，１′−ビフェニル（ｔｅｔｒａ−ｍＰｙＰｈＢＰ）の構造式を以下に示す。

Example 2, Reference Examples 3 to 4 and Comparative Example 1
Host material of Reference Example 1 3,5-bis (3-9H- carbazol-9-yl-phenyl) - pyridine (35DCzPPy), of Reference Example 2 2,6-bis (3-9H- carbazol-9-yl - Example 2 and Reference Example 3 below using phenyl) pyridine (26DCzPPy) and 2-methyl-4,6-bis (3-9H-carbazol-9-yl-phenyl) pyrimidine (DCzPMPm) of Example 1 respectively. ˜4 blue phosphorescent devices were prepared. For comparison, 4,4 ″ ″-bis (9H-carbazol-9-yl) -1,1 ′: 2 ′, 1 ″: 2 ″, 1 ″ ″-quarterphenyl (4CzPBP) is used for the host layer. The blue phosphor element of Comparative Example 1 used was made and the performance was evaluated. The structural formula of 4CzPBP is shown below.

In addition, 3,3 ″ ″-bis (N, N-di-p-tolyl) -1,1 ′: 2 ′, 1 ″: 2 ″, 1 ″ ″ − used for each hole transport layer. The structural formula of quarterphenyl (3DTAPBP) is shown below.

The structural formula of 3,3 ′, 5,5′-tetra [3- (pyridin-3-yl) phenyl] -1,1′-biphenyl (tetra-mPyPhBP) used for each electron transport layer is shown below. .

Device configuration comparison example 1
Ref. 1. ○: ITO / TPDPES (20 nm) / 3DTAPBP (30 nm) / 4CzPBP: FIrpic (13 wt%) (10 nm) / tetra-mPyPhBP (40 nm) / LiF (0.5 nm) / Al (100 nm);
Reference example 3
Device1. ◇: ITO / TPDPES (20 nm) / 3DTAPBP (30 nm) / 35 DCzPPy: FIrpic (13 wt%) (10 nm) / tetra-mPyPhBP (40 nm) / LiF (0.5 nm) / Al (100 nm);
Reference example 4
Device2. Δ: ITO / TPDPES (20 nm) / 3DTAPBP (30 nm) / 26 DCzPPy: FIrpic (13 wt%) (10 nm) / tetra-mPyPhBP (40 nm) / LiF (0.5 nm) / Al (100 nm);
Example 2
Device3. □: ITO / TPDPES (20 nm) / 3DTAPBP (30 nm) / DCzPMPm: FIrpic (13 wt%) (10 nm) / tetra-mPyPhBP (40 nm) / LiF (0.5 nm) / Al (100 nm).
The current density-voltage characteristics of these elements are shown in FIG.
The luminance-voltage characteristics are shown in FIG.
The power efficiency vs. voltage characteristics are shown in FIG.
The current efficiency vs. voltage characteristics are shown in FIG.
The power efficiency-luminance characteristics are shown in FIG.
The external quantum efficiency-luminance characteristics are shown in FIG.
The EL spectrum is shown in FIG.
The EL spectrum (enlarged) is shown in FIG.
Each is shown.

Ｐ．Ｅ．＝Ｐｏｗｅｒ Ｅｆｆｉｃｉｅｎｃｙ：電力効率
Ｑ．Ｅ．＝Ｑｕａｎｔｕｍ Ｅｆｆｉｃｉｅｎｃｙ：外部量子効率
Ｃｕｒｒｅｎｔ ｄｅｎｓｉｔｙ：電流密度

表３は、各電子輸送材料を用いた素子を作成したときの輝度１００ｃｄ／ｍ^２における素子にかかる電圧、電流密度、電力効率、外部量子効率を列挙している。表４は１０００ｃｄ／ｍ^２における素子にかかる電圧、電流密度、電力効率、外部量子効率を列挙している。
３５ＤＣｚＰＰｙについては４ＣｚＰＢＰに比べて電流密度が大きいので電子の移動度が大きいと考えられる。しかし電力効率、外部量子効率が劣るのは、素子中でのホールと電子のキャリアバランスが適正でないからで、これは素子の膜厚を検討すれば改善されると考えられる。２６ＤＣｚＰＰｙとＤＣｚＰＭＰｍについては、電力効率、量子効率から４ＣｚＰＢＰと同等もしくはそれ以上の性能を有するものと判断できる。 The electrochemical characteristics at 100 cd / m ² of these elements are shown in Table 3, and the electrochemical characteristics at 1000 cd / m ² are shown in Table 4.

P. E. = Power Efficiency: Power efficiency Q. E. = Quantum Efficiency: The external quantum efficiency Current density: current density

Table 3 lists the voltage, current density, power efficiency, and external quantum efficiency applied to the device at a luminance of 100 cd / m ² when a device using each electron transport material is created. Table 4 lists the voltage, current density, power efficiency, and external quantum efficiency applied to the device at 1000 cd / m ² .
Since 35DCzPPy has a higher current density than 4CzPBP, it is considered that electron mobility is large. However, the reason why the power efficiency and the external quantum efficiency are inferior is that the carrier balance between holes and electrons in the device is not appropriate, and this is considered to be improved by examining the film thickness of the device. About 26DCzPPy and DCzPMPm, it can be judged from the power efficiency and the quantum efficiency that the performance is equal to or higher than that of 4CzPBP.

The UV absorption curves of 35DCzPPy of Reference Example 1, 26DCzPPy of Reference Example 2, and DCzPMPm of Example 1 are shown. Photoluminescence curves of 35DCzPPy of Reference Example 1, 26DCzPPy of Reference Example 2, and DCzPMPm of Example 1 are shown. The current density-voltage characteristics of Example 2, Reference Examples 3 to 4 and Comparative Example 1 are shown. The luminance-voltage characteristics of Example 2, Reference Examples 3 to 4 and Comparative Example 1 are shown. The power efficiency-voltage characteristics of Example 2, Reference Examples 3 to 4 and Comparative Example 1 are shown. The current efficiency-voltage characteristics of Example 2, Reference Examples 3 to 4 and Comparative Example 1 are shown. The power efficiency-luminance characteristics of Example 2, Reference Examples 3 to 4 and Comparative Example 1 are shown. The external quantum efficiency-luminance characteristic of Example 2, Reference Examples 3-4, and Comparative Example 1 is shown. The EL spectra of Example 2, Reference Examples 3 to 4 and Comparative Example 1 are shown. The EL spectrum (expansion) of Example 2, Reference Examples 3-4, and Comparative Example 1 is shown. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention. Sectional drawing which shows an example of the organic electroluminescent element in this invention.

1 Substrate 2 Anode (ITO)
3 Light emitting layer 4 Cathode 5 Hole transport layer (hole transport layer)
6 Electron transport layer 7 Hole injection layer (hole injection layer)
8 Electron injection layer 9 Hole blocking layer (hole blocking layer)

Claims (3)

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

(Where Q is

In ^{and, R 1 to 4} and R ¹⁹ are hydrogen and straight-chain or branched alkyl group selected from the group consisting of groups having 1 to 6 carbon ^{atoms, R 20} is a straight-chain or branched having 1 to 6 carbon atoms R ^5-12 is hydrogen, a linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkoxy group having 1 to 6 carbon atoms, and a linear chain having 1 to 6 carbon atoms or Each group is independently selected from the group consisting of branched alkylamino groups. )   A host material comprising the bicarbazole derivative according to claim 1.   An organic electroluminescence device using the bicarbazole derivative according to claim 1.

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