JP6975959B2 - Arylamine derivatives, hole transport materials using them, and organic EL devices - Google Patents

Description

The present invention relates to an arylamine derivative having a high triplet energy, a hole transport material using the arylamine derivative, and an organic EL device.

In an organic EL element, by applying a voltage between a pair of electrodes, holes from the anode and electrons from the cathode are injected into a light emitting layer containing an organic compound as a light emitting material, and the injected electrons and holes are discharged. By recombination, excitons are formed in the luminescent organic compound, and light emission can be obtained from the excited organic compound.

One of the means for improving the practicality of such an organic EL element is to increase the luminous efficiency. The excitons organic compound forms, there are singlet excitons (E _S1) and triplet exciton (E _T1), and the fluorescence emission from singlet excitons (E _S1), triplet excitons (E _{There is phosphorescent emission from T1} ), but the statistical generation ratio of these in the element is E _S1 : E _T1 = 1: 3, and the internal quantum efficiency of 25% is the limit for organic EL elements using fluorescent emission. It is said that. Therefore, in order to improve the conversion efficiency from electrons to photons (internal quantum efficiency), a phosphorescent material capable of converting the triplet excited state into light emission has been developed, and recently, an organic EL using this phosphorescent light emission has been developed. The element has been reported.

The phosphorescent material includes metal complexes such as iridium, platinum, renium, and osmium, but from the viewpoint of light emission characteristics and stability, Ir (ppy) ₃ (tris (2-phenylpyridinato) iridium (III) ); Iridium having a chelate-type organic ligand represented by Ir (Fppy) ₃ (tris [2- (2,4-difluorophenyl) pyridine] iridium (III); blue material) Complexes are known, and by doping the host material with these metal complexes, the carrier density is increased, the charge transfer property is improved, and excitons are generated.

The use of Thermally Activated Delayed Fluorescence (TADF) is also important for improving the performance of organic EL devices. Although the TADF material is a fluorescent material, it is theoretically possible to realize 100% exciton generation probability like the phosphorescent material, which is useful for improving efficiency. Furthermore, it is possible to reduce the development cost for molecular design that does not require precious metals such as iridium and platinum. Therefore, by developing a light-emitting material using this TADF, it is considered that a low-cost and high-efficiency light-emitting element can be obtained.

On the other hand, as the host material, various carrier transport materials such as a material having electron transport property and a material having hole transport property can be used. However, for example, α-NPD, which is a typical hole transport material, has high durability but low triplet energy (T ₁ = 2.28 eV), and is not suitable for phosphorescence or TADF organic EL devices. Therefore, the development of wide-gap hole transport materials with high triplet energy is being studied. In 2013, Fukagawa et al. Developed DBTPB in which dibenzothiophene was introduced at the end of an arylamine derivative, which made the green phosphorescent element about 1.5 times more efficient than α-NPD and about 2 times longer life. (Non-Patent Document 1). However, its T ₁ is about 2.37 eV, and it _{can be used as a typical green phosphorescent dopant such as Ir (ppy) 3} (T ₁ = 2.53 eV), blue phosphorescent light, or a green / blue TADF dopant. Insufficient for utilization, the development of hole transport materials with high durability and high T _{1 remains a challenge.}

H. Fukagawa et al., Appl. Phys. Chem., 2013, 103, 143306

An object of the present invention is to provide an arylamine derivative having high triplet energy, which can be a host material for an organic EL element, and a hole transport material and an organic EL element using the arylamine derivative.

一般式（１）中、Ａｒ¹〜Ａｒ⁵は、それぞれ独立に、置換基を有していてもよいアリール基、又は下記一般式（２）で表される置換基である。

一般式（２）中、Ｒ¹〜Ｒ⁵は、それぞれ独立に、水素原子、直鎖若しくは分岐鎖の炭素原子数１〜６のアルキル基、直鎖若しくは分岐鎖の炭素原子数１〜６のアルコキシ基、直鎖若しくは分岐鎖の炭素原子数１〜６のモノアルキルアミノ基、又は、直鎖若しくは分岐鎖の炭素原子数１〜６のジアルキルアミノ基であり、Ｘは酸素原子、硫黄原子、又は−ＣＲ⁶Ｒ⁷−基（Ｒ⁶及びＲ⁷−は、それぞれ独立に、水素原子、直鎖若しくは分岐鎖の炭素原子数１〜６のアルキル基、直鎖若しくは分岐鎖の炭素原子数１〜６のアルコキシ基、直鎖若しくは分岐鎖の炭素原子数１〜６のモノアルキルアミノ基、又は、直鎖若しくは分岐鎖の炭素原子数１〜６のジアルキルアミノ基である。）である。
Ｘは、酸素原子又は硫黄原子であることが好ましい。
Ｘは、酸素原子又は硫黄原子であり、かつ、一般式（１）中、Ｒ¹〜Ｒ⁵は水素原子又はフェニル基であることが好ましい。
本発明のホール輸送材料は、上記アリールアミン誘導体を用いたものであることを特徴とする。
本発明の有機ＥＬ素子は、上記アリールアミン誘導体を用いたものであることを特徴とする。 The present invention comprises the following matters.
The arylamine derivative of the present invention is characterized by being represented by the following general formula (1).

In the general formula (1), Ar ^{1 to} Ar ⁵ are aryl groups that may independently have substituents, or substituents represented by the following general formula (2).

In the general formula (2), R ^{1 to} R ⁵ each independently have an alkyl group having 1 to 6 carbon atoms in a hydrogen atom, a straight chain or a branched chain, and 1 to 6 carbon atoms in a straight chain or a branched chain. An alkoxy group, a monoalkylamino group having 1 to 6 carbon atoms in a linear or branched chain, or a dialkylamino group having 1 to 6 carbon atoms in a linear or branched chain, where X is an oxygen atom or a sulfur atom. Or −CR ⁶ R ⁷ − groups (R ⁶ and R ⁷ − are independently hydrogen atoms, linear or branched alkyl groups having 1 to 6 carbon atoms, and linear or branched chains having 1 carbon atom. It is an alkoxy group of ~ 6, a monoalkylamino group having 1 to 6 carbon atoms in a linear or branched chain, or a dialkylamino group having 1 to 6 carbon atoms in a linear or branched chain).
X is preferably an oxygen atom or a sulfur atom.
It is preferable that X is an oxygen atom or a sulfur atom, and in the general formula (1), R ^{1 to} R ⁵ are hydrogen atoms or phenyl groups.
The whole transport material of the present invention is characterized by using the above arylamine derivative.
The organic EL device of the present invention is characterized by using the above arylamine derivative.

The arylamine derivative of the present invention has a crosslinked biphenyl moiety, specifically dibenzofuran, or dibenzothiophene in the terminal moiety and central skeleton, so that it has _{high thermal stability of T g} > 100 ° C. or higher, and T ₁ > 2. It can also have a high triplet energy of 6 eV or more, and enables high efficiency and long life of phosphorescent or TADF organic elements.
In addition to being suitably used as a hole transport material, the arylamine derivative of the present invention may be dispersed in another organic layer of an organic EL element, for example, a light emitting layer together with a light emitting material, or may be used as an electron transport material. You may use it.

FIG. 1 ^{represents a 1} HNMR spectrum of HTM3. FIG. 2 ^{represents the 1} HNMR spectrum of HTM4. FIG. 3 ^{represents the 1} HNMR spectrum of HTM5. FIG. 4 shows the ¹ HNMR spectrum of HTM6. FIG. 5 shows the ¹ HNMR spectrum of HTM7. FIG. 6 ^{represents the 1} HNMR spectrum of HTM8. FIG. 7 shows the PYS measurement results of HTM3 to HTM6. FIG. 8 shows the UV-vis absorption spectra of HTM3 to HTM6. FIG. 9 shows the PL spectra of HTM3 to HTM6. FIG. 10 shows JV characteristics (a), JV characteristics (linear) (b), LV characteristics (c), and CE of an element using DBTPB, HTM4, and HTM6 for the hole transport layer (HTL). -Represents the L characteristic (d). FIG. 11 shows the PE-L characteristics (e), EQE-L characteristics (f), EL spectrum (g), and device life (h) of a device using DBTPB, HTM4, or HTM6 for the hole transport layer (HTL). show. FIG. 12 shows JV characteristics (a), JV characteristics (linear) (b), LV characteristics (c), and CE-L of an element using DBTPB or HTM6 for the hole transport layer (HTL). It represents the characteristic (d), the PE-L characteristic (e), and the EQE-L characteristic (f). FIG. 13 shows the EL spectrum of an element using DBTPB or HTM6 for the hole transport layer (HTL). FIG. 14 shows the configuration of the organic EL element of the embodiment.

一般式（１）中、Ａｒ¹〜Ａｒ⁵は、それぞれ独立に、置換基を有していてもよいアリール基、又は下記一般式（２）で表される置換基である。 Hereinafter, the present invention will be described in detail.
[Arylamine derivative]
The arylamine derivative of the present invention is represented by the following general formula (1).

In the general formula (1), Ar ^{1 to} Ar ⁵ are aryl groups that may independently have substituents, or substituents represented by the following general formula (2).

一般式（２）中、Ｒ¹〜Ｒ⁵は、それぞれ独立に、水素原子、直鎖若しくは分岐鎖の炭素原子数１〜６のアルキル基、直鎖若しくは分岐鎖の炭素原子数１〜６のアルコキシ基、直鎖若しくは分岐鎖の炭素原子数１〜６のモノアルキルアミノ基、又は、直鎖若しくは分岐鎖の炭素原子数１〜６のジアルキルアミノ基であり、Ｘは酸素原子、硫黄原子、又は−ＣＲ⁶Ｒ⁷−基（Ｒ⁶及びＲ⁷−は、それぞれ独立に、水素原子、直鎖若しくは分岐鎖の炭素原子数１〜６のアルキル基、直鎖若しくは分岐鎖の炭素原子数１〜６のアルコキシ基、直鎖若しくは分岐鎖の炭素原子数１〜６のモノアルキルアミノ基、又は、直鎖若しくは分岐鎖の炭素原子数１〜６のジアルキルアミノ基である。）である。

In the general formula (2), R ^{1 to} R ⁵ each independently have an alkyl group having 1 to 6 carbon atoms in a hydrogen atom, a straight chain or a branched chain, and 1 to 6 carbon atoms in a straight chain or a branched chain. An alkoxy group, a monoalkylamino group having 1 to 6 carbon atoms in a linear or branched chain, or a dialkylamino group having 1 to 6 carbon atoms in a linear or branched chain, where X is an oxygen atom or a sulfur atom. Or −CR ⁶ R ⁷ − groups (R ⁶ and R ⁷ − are independently hydrogen atoms, linear or branched alkyl groups having 1 to 6 carbon atoms, and linear or branched chains having 1 carbon atom. It is an alkoxy group of ~ 6, a monoalkylamino group having 1 to 6 carbon atoms in a linear or branched chain, or a dialkylamino group having 1 to 6 carbon atoms in a linear or branched chain).

For Ar ^{1 to} Ar ⁵ , the aryl group which may have a substituent is an aromatic substituent having 6 to 22 carbon atoms. The aromatic substituent may be either a hydrocarbon ring or a heterocycle, and may be either a monocyclic ring or a condensed ring.
Of ^{Ar 1 ~Ar 5, Ar 1,} Ar 2, Ar 4 and Ar ⁵ is one having groups a bond, specifically, a phenyl group, a biphenyl group, a naphthyl group, anthracenyl group, phenanthrenyl group , Triphenylenyl group, terphenyl group, dibenzofuranyl group, dibenzothiophenyl group, carbazole group, indolocarbazole group and the like. Of these, a dibenzofuranyl group and a dibenzothiophenyl group are preferable, and a 1-dibenzofuranyl group and a 1-dibenzothiophenyl group are more preferable.
Ar ³ is a group having two binders, specifically, a phenylene group, a biphenylene group, a naphthaleneylene group, an anthrasenylene group, a phenanthrenylene group, a triphenyleneylene group, a terphenylene group, a dibenzofuranylene group, Examples thereof include a dibenzothiophenylene group, a carbazole group, an indolocarbazole group and the like. Of these, a dibenzofuranylene group and a dibenzothiophenylene group are preferable, and a 3,6-dibenzofuranylene group and a 3,6-dibenzothiophenylene group are more preferable.
Examples of the substituent that the aryl group may have include an alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a phenanthrolyl group, an acetyl group, a cyano group and the like.

For R ^{1 to} R ⁵ , the alkyl groups having 1 to 6 carbon atoms in the linear or branched chains include, specifically, a methyl group, an ethyl group, a propyl group, a 2-propyl group, a butyl group, and an isobutyl group. And t-butyl group and the like.
Alkoxy groups having 1 to 6 carbon atoms in a linear or branched chain include alkoxy groups having 1 to 6 carbon atoms, specifically, a methoxy group, an ethoxy group, a propoxy group, a 2-propoxy group, and a butoxy group. Examples thereof include an isobutoxy group and a t-butoxy group.
The monoalkylamino group having 1 to 6 carbon atoms in the linear or branched chain includes, for example, a methylamino group, an ethylamino group, a 1-propylamino group, an isopropylamino group, a cyclopropylamino group, and a 1-butylamino group. , Isobutylamino group, s-butylamino group, t-butylamino group, cyclobutylamino group, 1-pentylamino group, 2-pentylamino group, 3-pentylamino group, isopentylamino group, neopentylamino group, Examples thereof include 1-hexylamino group, 2-hexylamino group, 3-hexylamino group, piperidinyl group and the like.
Examples of the dialkylamino group having 1 to 6 carbon atoms in the linear or branched chain include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, a dipentylamino group, and a dihexylamino group.
Of these, R ^{1 to} R ⁵ are more preferably hydrogen atoms or phenyl groups.

X is an oxygen atom, a sulfur atom, or -CR ⁶ R ⁷ - is a group. In −CR ⁶ R ⁷ − groups, R ⁶ and R ⁷ − are independently hydrogen atoms, linear or branched alkyl groups having 1 to 6 carbon atoms, and linear or branched chains having 1 carbon atom. It is an alkoxy group of ~ 6, a monoalkylamino group having 1 to 6 carbon atoms in a linear or branched chain, or a dialkylamino group having 1 to 6 carbon atoms in a linear or branched chain.
The above-mentioned alkyl group, alkoxy group, monoalkylamino group or dialkylamino group are the same as those described above for ^{R 1 to} R ^5.

The arylamine derivative has a π-conjugated system. It is known that molecules having a π-conjugated system have a light absorption band in the visible region, and many of them can function as dyes. Furthermore, the energy gap can be adjusted by appropriately adding a functional group to such a molecule to change its electronic properties. That is, in the present invention, the arylamine derivative, by molecular design to minimize the energy gap between the singlet excited state (E _S1) and a triplet excited state (E _T1), once it moved to the triplet excited state The energy can be returned to the singlet excited state again, and highly efficient fluorescence can be extracted. Therefore, the arylamine derivative of the present invention is suitably used as a green fluorescent material, for example, in a green phosphorescent device using a _{phosphorescent light emitting material Ir (ppy) 3 having a peak wavelength of 514 nm.}

The arylamine derivative represented by the general formula (1) is more preferably a compound represented by the following structural formula.

The arylamine derivative of the present invention can be produced, for example, by the method shown below. The manufacturing method of HTM-4 is shown as an example.

After stirring 4-bromodibenzofuran and aniline in dehydrated 1,4-dioxane in the presence of Pd (0) and a base, 1,3-bis (2) as an N-heterocyclic carbene (NHC) ligand. , 6-Diisopropylphenyl) Add imidazolinium chloride to give 4-phenylaminodibenzofuran. Then, 2 equivalents of 4-phenylaminodibenzofuran and 2,8-dibromodibenzothiophene were stirred in dehydrated toluene in the presence of a base, and then Pd (0) and tri-t-butylphosphonium tetrafluoroborate were added. Then, by further stirring, HTM-4 is obtained in a good yield.
The arylamine derivative of the present invention can be produced by various known methods in addition to the above methods.

[Hole transport material, organic EL element]
The hole transport material and the organic EL device of the present invention use the above arylamine derivative.
The organic EL element has a structure in which one or more organic layers are laminated between electrodes. For example, (i) electrode 2 / hole transport layer 4 / light emitting layer 5 / electron transport layer 7 / electrode 2', or (Ii) It has a structure in which the electrode 2 / hole transport layer 4 / light emitting layer 5 / electron transport layer 7 / electron injection layer / electrode 2'are laminated in this order. FIG. 14 shows the layer structure of the organic EL element of the embodiment, in which an electrode 2 is formed on a substrate 1, and a hole injection transport layer 3, a hole transport layer 4, a light emitting layer 5, and holes are formed on the electrode 2. The blocking layer 6, the electron transport layer 6, and the electrode 2'show a structure in which they are laminated in this order. The organic layer refers to a layer other than the electrode, that is, a hole injection transport layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and the like.

The substrate 1 is transparent and smooth, and has a total light transmittance of at least 70%. Specifically, it 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.

The thin films such as the electrode 2, the hole injection transport layer 3, the hole transport layer 4, the light emitting layer 5, the hole blocking layer 6, the electron transport layer 7, and the electrode 2'formed on the substrate 1 are formed by a vacuum deposition method or a coating method. It is laminated with. When the vacuum vapor deposition method is used, the vapor deposition is usually heated in an atmosphere reduced to ^{10 -3 Pa or less.} The film thickness of each layer varies depending on the type of layer and the material used, but usually, the electrodes 2 and 2'are about 100 nm, and the other organic layer including the light emitting layer 5 is less than 50 nm.

The electrode 2 is usually an anode, has a large work function, and usually has a total light transmittance of 80% or more. Specifically, in order to transmit the light emitted from the anode, transparent conductive ceramics such as indium tin oxide (ITO) and ZnO, transparent conductive polymers such as PEDOT / PSS and polyaniline, and other transparent conductive materials are used. Used. The film thickness of the anode is usually 10 to 200 nm.

As with other light emitting layers used in organic EL devices, it is preferable to use a host compound together with the light emitting material in the light emitting layer 5. Examples of the light emitting material include tris (2-phenylpyridinato) iridium (III) (Ir (ppy) ₃ ), which is a phosphorescent light emitting material, and bis [2- (4,6-difluorophenyl) pyridinato-C2. N] (picolinato) iridium (III) (FIrpic), Tris [1-phenylisoquinolin-C2, N] iridium (III) (Ir (piq) ₃ ), and a thermalally activated delayed fluorescent material (4s, 6s). -2,4,5,6-tetra (9H-carbazole-9-yl) isophthalonitrile (4CzIPN), 10,10'-(4,4'-sulfonylbis (4,1-phenylene)) bis (9) , 9-dimethyl-9,10-dihydroacridin)) (DMAC-DPS) and the like. Host compounds include, for example, bis [2- (diphenylphosphino) phenyl] ether oxide (DPEPO), 3,6-bis (diphenylphorholyl) -9-phenylcarbazole (PO9), 4,4'-bis. (N-carbazolyl) -1,1'-biphenyl (CBP), 3,3'-bis (N-carbazolyl) -1,1'-biphenyl (mCBP), tris (4-carbazoyl-9-ylphenyl) amine (TCTA), 2,8-bis (diphenylphosphoryl) dibenzothiophene (PPT), adamantan anthracene (Ad-Ant), rubrene, and 2,2'-bi (9,10-diphenylanthracene) (TPBA), etc. Can be mentioned.

A hole injection transport layer 3 and a hole transport layer 4 are provided between the anode and the light emitting layer 5 in order to efficiently transport holes from the anode to the light emitting layer.
Examples of the hole injection transport material constituting the hole injection transport layer 3 include (poly (allylen ether ketone) -containing triphenylamine (KLHIP: PPBI), hexaazatriphenylene carbonitrile (HATCN), PEDOT: PSS and the like. The hole injection transport layer 3 exerts an effect of lowering the driving voltage of the organic EL element. The thickness of the hole injection transport layer 3 is usually 1 to 20 nm.

The electrode 2'is usually a cathode. In order to efficiently transport electrons from the cathode to the light emitting layer 5, a hole blocking layer 6 and an electron transporting layer 7 are provided between the electrode 2'and the light emitting layer 5. Examples of the electron transport material forming the electron transport layer 7 include 8-hydroxyquinolinolatrithium (Liq) and 4,6-bis (3,5-di (pyridine-3-yl) phenyl) -2-methyl. Pyrimidine (B3PymPm), 4,6-bis (3,5-di (pyridine-4-yl) phenyl) -2-phenylpyrimidin (B4PyPPm), 2- (4-biphenylyl) -5- (pt-butyl) Phenyl) -1,3,4-oxadiazole (tBu-PBD), 1,3-bis [5- (4-t-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), 1,3 5-Tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi), 3- (4-biphenylyl) -4-phenyl-5- (4-t-butylphenyl) -1,2,4 -Triazole (TAZ) and the like can be mentioned. Of these, TPBi and TAZ are electron transport materials having excellent hole blocking properties. The film thicknesses of the hole blocking layer 6 and the electron transporting layer 7 can be appropriately changed depending on the desired design, but are usually 3 to 50 nm.

As the electrode 2', one having a low work function (4 eV or less) and chemically stable is used. Specifically, a cathode material such as an Al, MgAg alloy, or an alloy of Al and an alkali metal such as AlLi or AlCa is used. These cathode materials are formed by, for example, a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, or an ion plating method. The thickness of the cathode is usually 10 nm to 1 μm, preferably 50 to 500 nm.

In addition, layers such as a hole blocking layer 6, an electron blocking layer, and an exciton blocking layer are further formed as needed.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

[Synthesis of arylamine derivatives]
The equipment and measurement conditions used to identify the compound are as follows.
(1) ¹ H Nuclear Magnetic Resonance Method (NMR)
JEMOL Ltd., 400MHz, JNM-EX270FT-NMR
(2) Mass spectrometry (MS)
JMS-K9 [Desktop GCQMS] manufactured by JEOL Ltd.

[Synthesis Example 1] Synthesis of 1,4-phenylaminodibenzofuran

In a 25 ml three-necked flask, 5.0 g (20.3 mmol) of 4-bromodibenzofuran, 2.3 g (25.2 mmol) of aniline, 5.05 g (52.7 mmol) of sodium t-butoxide (t-BuONa), and dehydration 1, 100 ml of 4-dioxane was added and nitrogen bubbling was performed for 1 hour. Then, bis (dibenzylideneacetone) palladium (0) (Pd (dba) ₂ ) 581 mg (1.01 mmol) and 1,3-bis (2,6-diisopropylphenyl) imidazolinium chloride 859 mg (2.02 mmol) were added. In addition, the mixture was heated under reflux for 2 hours with stirring under a nitrogen stream. After confirming the consumption of the raw material by TLC, the formation of the target product was confirmed by MS, the reaction solution was returned to room temperature, 15 ml of water was added, and the mixture was stirred. Then, the organic layer was extracted with diethyl ether, washed with saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated to obtain a brown viscous body. The obtained viscous body was dissolved in 200 ml of a toluene / hexane mixed solvent (1: 1), suction filtered through silica gel (stacked on a glass filter for about 4 cm), and concentrated to obtain a yellowish white solid. The obtained solid was recrystallized and purified using ethanol to obtain a white solid. The target product was identified by MS and ¹ H-NMR.
Yield 4.53g, yield 86%
MS: [M] = 259.3m / z

[Synthesis Example 2] Synthesis of 1,4-phenylaminodibenzothiophene

To a 25 mL three-necked flask, 1.00 g (3.80 mmol) of 4-bromodibenzothiophene, 450 μl (4.94 mmol) of aniline, 950 mg (9.89 mmol) of sodium t-butoxide, and 20 ml of dehydrated toluene were added, and nitrogen bubbling was performed for 1 hour. rice field. There, tris (dibenzylideneacetone) dipalladium (0) (Pd ₂ (dba) ₃ ) 170 mg (0.19 mmol), tri-t-butylphosphonium tetrafluoroborate ([(t-Bu) ₃ PH] ⁺ BF). ₄ ^-) 110 mg of (0.38 mmol) followed by heating to reflux for 2 hours. When the reaction mixture was confirmed by TLC and Mass, the raw materials disappeared and the peak of the target product was obtained. The reaction mixture was returned to room temperature, extracted with toluene, washed with brine, dried over anhydrous magnesium sulfate, and the solvent was distilled off. The obtained residue was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 7/3) to obtain 951 mg (3.45 mmol) of 4-phenylaminodibenzothiophene, which is the target product, in a yield of 91%. .. The target product was identified by MS and ¹ H-NMR.

[Example 1] Synthesis of HTM3

To a 50 ml four-necked flask, add 2.75 g (10 mmol) of 4-phenylaminodibenzothiophene, 1.63 g (5.0 mmol) of 2,8-dibromodibenzofuran, 2.5 g (26 mmol) of sodium t-butoxide, and 50 ml of dehydrated toluene. Nitrogen bubbling for 1 hour. _{Then, Pd 2 (dba) 3 460mg} (0.5mmol), tri -t- butyl phosphonium tetrafluoroborate ^{_{(t-Bu 3 PH + BF}} 4 -) stirring 290 mg (1.0 mmol) was added to a nitrogen stream While heating and refluxing for 53 hours. The formation of the target product was confirmed by TLC and MS. After cooling the reaction solution to room temperature, the organic layer was extracted with toluene, washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated to obtain a brown viscous body. The obtained viscous body was dissolved in 10 ml of toluene and packed in a column. As it was, it was purified by silica gel column chromatography (developing solvent: toluene / hexane = 1/4) to obtain the desired product.
Yield 1.92g, yield 54%
MS: [M ⁺ ] = 714.7m / z
FIG. 1 shows the measurement results ^{of 1 1 HNMR.}

[Example 2] Synthesis of HTM4

1.16 g (4.5 mmol) of 4-phenylaminodibenzofuran, 0.51 g (1.5 mmol) of 2,8-dibromodibenzothiophene, 1.13 g (11.7 mmol) of t-BuONa, dehydrated toluene in a 25 ml four-necked flask. 20 ml was added and nitrogen bubbling was performed for 1 hour. Then, Pd ₂ (dba) ₃ 210 mg (0.23 mmol) and tri-t-butylphosphonium tetrafluoroborate 130 mg (0.45 mmol) were added, and the mixture was heated under reflux under a nitrogen stream for 13 hours. The formation of the target product was confirmed by TLC and MS, and the reaction solution was returned to room temperature. Then, the organic layer was extracted with toluene, washed with saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated to obtain a brown viscous body. The obtained viscous body was dissolved in 10 ml of toluene and packed in a silica gel column. As it was, it was purified by silica gel column chromatography (developing solvent: toluene / hexane = 1/3 (2.5 L)) to obtain 0.46 g of the target HTM4 in a yield of 44%.
MS: [M ⁺ ] = 699.4m / z
FIG. 2 shows the measurement results ^{of 1 1 HNMR.}

[Example 3] Synthesis of HTM5

In a 25 ml four-necked flask, 0.52 g (2.0 mmol) of 4-phenylaminodibenzofuran, 0.33 g (1.0 mmol) of 2,8-dibromodibenzofuran, 500 mg (5.2 mmol) of sodium t-butoxide, and 10 ml of dehydrated toluene are placed. In addition, nitrogen bubbling was performed for 1 hour. _{Then, Pd 2 (dba) 3 92mg} (0.10mmol), was added tri -t- butyl phosphonium tetrafluoroborate 58 mg (0.20 mmol), the mixture was stirred while heating under reflux for 12 hours under a nitrogen stream. The formation of the target product was confirmed by TLC and MS. After cooling the reaction solution to room temperature, the organic layer was extracted with toluene, washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated to obtain a brown viscous body. The obtained viscous body was dissolved in 5 ml of toluene and packed in a column. As it was, it was purified by silica gel column chromatography (developing solvent: toluene / hexane = 1/4) to obtain 0.51 g of the target HTM5 in a yield of 75%.
MS: [M ⁺ ] = 683.7m / z
FIG. 3 shows the measurement results ^{of 1 1 HNMR.}

[Example 4] Synthesis of HTM6

2.75 g (10.0 mmol) of 4-phenylaminodibenzothiophene, 1.71 g (5.0 mmol) of 2,8-dibromodibenzodiophene, 2.50 g (26.0 mmol) of sodium t-butoxide, in a 50 ml three-necked flask. 50 ml of dehydrated toluene was added and nitrogen bubbling was performed for 1 hour. Then, Pd ₂ (dba) ₃ 460 mg (0.50 mmol) and tri-t-butylphosphonium tetrafluoroborate 290 mg (1.0 mmol) were added, and the mixture was heated under reflux with stirring under a nitrogen stream for 50 hours. The formation of the target product was confirmed by TLC and MS. After cooling the reaction solution to room temperature, the organic layer was extracted with toluene, washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated to obtain a brown viscous body. The obtained viscous body was dissolved in 5 ml of toluene and packed in a column. As it was, it was purified by silica gel column chromatography (developing solvent: toluene / hexane = 1/4) to obtain 3.33 g of the target HTM6 in a yield of 91%.
MS: [M ⁺ ] = 731.5m / z
FIG. 4 shows the measurement results ^{of 1 1 HNMR.}

[Example 5] Synthesis of HTM7

4-Phenylaminodibenzofuran 520 mg (2.01 mmol), 4,4 "-dibromo-2', 3', 5', 6'-tetraphenyl-p-terphenyl 690 mg (1.00 mmol) in a 25 mL four-necked flask. , Sodium t-butoxide 500 mg (5.20 mmol) and dehydrated toluene 10 ml were added and nitrogen bubbling was carried out for 1 hour. Tris (dibenzilidenacetone) dipalladium (0) 92 mg (0.100 mmol), tri-t-butyl. 58 mg (0.200 mmol) of phosphonium tetrafluoroborate was added, and the mixture was stirred at reflux for 2.5 hours. When the reaction mixture was confirmed by TLC and MS, the raw materials disappeared and the peak of the desired product was obtained. The mixture was returned to room temperature, passed through silica gel, and the insoluble portion was filtered off. The obtained residue was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/2), and the target product, HTM7, was 570 mg. (0.54 mmol), obtained in a yield of 54%.
FIG. 5 shows the measurement results ^{of 1 1 HNMR.}

[Example 6] Synthesis of HTM8

4-Phenylaminodibenzothiophene 550 mg (2.00 mmol), 4,4 "-dibromo-2', 3', 5', 6'-tetraphenyl-p-terphenyl 690 mg (1.00 mmol) in a 25 mL four-necked flask. ), Sodium t-butoxide 500 mg (5.20 mmol) and dehydrated toluene 10 ml were added, and nitrogen bubbling was carried out for 1 hour. Tris (dibenzilidenacetone) dipalladium (0) 92 mg (0.100 mmol), tri-t. -Butylphosphonium tetrafluoroborate 58 mg (0.200 mmol) was added, and the mixture was stirred at reflux for 1.5 hours. When the reaction mixture was confirmed by TLC and MS, the raw materials disappeared and the peak of the desired product was obtained. The reaction mixture was returned to room temperature, passed through silica gel, and the insoluble part was filtered off. The obtained residue was purified by silica gel column chromatography (hexane: dichloromethane = 3: 2) to obtain HTM8, which is the target product. It was obtained in 05 g (0.97 mmol) and a yield of 97%.
FIG. 6 shows the measurement results ^{of 1 1 HNMR.}

ＨＭＴ３〜ＨＴＭ７のＴ_1cal.は２．７５ｅＶ以上であり、高い三重項エネルギーを持つことが示唆された。 [Evaluation of arylamine derivatives]
[Molecular orbital calculation result]
_{The HOMO, LUMO, and T 1} of HMT3 to HTM8 obtained in Examples 1 to 6 were estimated by DFT calculation (Gaussian03W, B3LYP / 6-311 + G (d, p) // 6-311G). The results are shown below.

The T _{1 cal.} Of HMT3 to HTM7 was 2.75 eV or more, suggesting that they have high triplet energy.

[Evaluation of thermal properties]
The equipment and measurement method for thermal property evaluation are as follows.
(1) Melting point (T _m )
_{The sample is enclosed in an aluminum pan, and the glass transition temperature (T g} ) and crystallization temperature (T g) and crystallization temperature (T g) and crystallization temperature (T g) in nitrogen gas at a heating rate of 10 ° C./min using a differential scanning calorimeter (manufactured by Perkin Elmer Japan Co., Ltd .; DSCDTA). Tc) and melting point (T _m ) were measured.
(2) Decomposition point (T _d5 )
Place the sample on an aluminum pan and measure the _{5% weight decay temperature (T d5} ) in nitrogen gas at a heating rate of 10 ° C / min using a differential thermogravimetric analyzer (manufactured by Perkin Elmer Japan Co., Ltd .; TGA diamond). bottom.
The results of the above thermophysical properties after sublimation purification of HMT3 to HTM6 obtained in Examples 1 to 4 are shown below.
It can be seen that HMT3 to HTM6 have a T _g of 118 ° C. or higher and have high thermal stability.

[Evaluation of optical characteristics]
The equipment and measurement conditions used for the optical characteristic evaluation are as follows.
(1) Ultraviolet / visible (UV-vis) spectrophotometer UV-3150 manufactured by Shimadzu Corporation
Measurement conditions; Scan speed Medium speed, Measurement range 200 to 800 nm Sampling pitch 0.5 nm, Slit width 0.5 nm
(2) Photoluminescence (PL) measuring device Fluoro MAX-2 manufactured by HORIBA, Ltd.
The PL spectrum and the time-resolved PL spectrum (PL transient spectrum) using a streak camera (C4334 manufactured by Hamamatsu Photonics Co., Ltd.) were measured at room temperature (300K) and low temperature (5K).
(3) Photoelectron yield spectroscopy (PYS) device Ionization potential measuring device manufactured by Sumitomo Heavy Industries, Ltd. Ionization potential (Ip) was measured in vacuum using an ionization potential measuring device.
Electron affinity _{(E a)} was calculated by estimating the energy gap _{(E g)} than the absorption edge of the UV-vis absorption spectra.

_{For HMT3 to HTM6 obtained in Examples 1 to 4, the ionization potential (I p} ) and band were obtained based on the measurement results of PYS (FIG. 7), UV-vis absorption spectrum (FIG. 8), and PL spectrum (FIG. 9). The gap energy (E _g ), electron affinity (E _a ), and absorption maximum (λ _PL ) of the PL spectrum were determined. The results are shown in Table 3.

[Manufacturing and evaluation of organic EL elements]
The equipment used to evaluate the light emission characteristics of the organic EL element is as follows.
Equipment; Hamamatsu Photonics Co., Ltd. PHOTONIC MULTI-CHANGEANALYZER PMA-1

A schematic cross-sectional view of the device is shown in FIG. 14, and the materials used are shown below.

<Host mCBP element>
A green phosphorescent device having the following structure was produced. In addition, HTL represents a hole transport layer, and the inside of parentheses represents a film thickness (nm).
ITO / KLHIP: PPBI (20) / HTL (20) / mCBP: Ir (ppy) 3 6wt% (30) / TPBi (50) / Liq (1) / Al
HTL is DBTPB, HTM4, or HTM6.
The results of device characteristic evaluation are shown in Table 4.

At 100 cd / m ² and 1000 cd / m ² , HTM4 showed almost the same external quantum efficiency (EQE) as DBTPB. On the other hand, HTM6 showed higher EQE than DBTPB at both ^{100 cd / m 2} and 1000 cd / m ^2. Looking at the JV characteristics (FIGS. 10A and 10B), the rising voltage of both HTM4 and HTM6 is high. This is because HTM4 (I _p = 5.67 eV) and HTM6 (I _{p = 5.72 eV) have a deeper I p} than DBTPB (I _p = 5.5 eV), so that the hole injection property from the hole injection layer is poor. It is thought that it became. In HTM4 and HTM6, it is considered that HTM6 _{has better matching of HOMO with mCBP (I p} = 6.00 eV) and better hole injection into the light emitting layer, so that the voltage is lowered. On the other hand, at high current densities, HTM4 and HTM6 showed higher JV characteristics than DBTPB, and ^{at a drive voltage of 1000 cd / m 2} , HTM6 showed a lower drive voltage than DBTPB. This suggests that HTM4 and HTM6 have higher hole transportability than DBTPB. Further, as a result of the device life evaluation, HTM4 and HTM6 showed a device life of about 1.5 times that of DBTPB (FIG. 11 (h)). From this, it is considered that the new hole transport materials HTM4 and HTM6 have higher chemical stability than the existing DBTPB.

<Host DBT-TRZ element>
A green phosphorescent device having the following structure was produced. HTL represents the hole transport layer, and the inside of the parentheses represents the film thickness (nm).
ITO / KLHIP: PPBI (20) / HTL (20) / DBT-TRZ: Ir (ppy) 3 6wt% (30) / TPBi (50) / Liq (1) / Al
HTL is DBTPB or HTM6.
The results of device characteristic evaluation are shown in Table 5.

素子特性評価の結果、駆動電圧においては立ち上がり、１００ｃｄ／ｍ²時においてＨＴＭ６では高電圧化がみられた（図１２（ｃ））。これは、ＨＴＭ６（Ｉ_p＝５．７２ ｅＶ）はＤＢＴＰＢ（Ｉ_p＝５．５ｅＶ）よりもＩ_pが深いため、ホール注入層からのホール注入性が悪くなったためと考えられる。しかしながら、ＥＱＥにおいてはＨＴＭ６はＤＢＴＰＢよりも高い効率を示した（表５）。これは、ＤＢＴＰＢのＴ₁（２．３７ｅＶ）がＩｒ（ｐｐｙ）₃（Ｔ₁＝２．５３ｅＶ）よりも低く励起子の閉じ込めが不十分であるのに対し、ＨＴＭ６はＴ₁（Ｅ_Tcal＝２．７９ｅＶ）が高いためであると考えられる。

As a result of the element characteristic evaluation, the drive voltage increased, and the HTM6 increased the voltage at ^{100 cd / m 2 (FIG. 12 (c)).} _{This, HTM6 (I p = 5.72 eV} ) , since deep is I _p than DBTPB (I _p = 5.5eV), hole injection from the hole injection layer is considered due to worse. However, in EQE, HTM6 showed higher efficiency than DBTPB (Table 5). This is because T ₁ (2.37 eV) of _{DBTPB is lower than Ir (ppy) 3} (T ₁ = 2.53 eV) and exciton confinement is insufficient, whereas T ₁ (E Tcal =) of _{HT M6.} It is considered that this is because 2.79eV) is high.

1 Substrate 2, 2'Electrode 3 Hole injection transport layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Power supply

Claims (3)

Arylamine derivative represented by the following structural formula;

A hole transport material using the arylamine derivative according to claim 1. Arylamine derivative as claimed in claim 1, or an organic EL device using the hole transport material according to claim 2.

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