WO2014042006A1 - Novel thieno-indole derivative and organic electroluminescent element using said derivative - Google Patents

Abstract

This thieno-indole derivative is represented by general formula (1). In general formula (1), Ar¹ is an aromatic hydrocarbon group, at least one of X¹ and X² is a group having an aromatic tertiary amino structure, and the other groups can be hydrogen atoms. This compound has, in connection with an aromatic tertiary amino structure being introduced to a thieno-indole ring structure, (A) good hole injection characteristics, (B) high hole mobility, (C) excellent electron blocking capability, (D) stable thin film state, and (E) excellent heat resistance; and is useful as a hole transport material to be used in organic electroluminescent elements.

Description

Novel thienoindole derivatives and organic electroluminescence devices using the derivatives

The present invention relates to a novel compound (thienoindole derivative) suitable for an organic electroluminescence element which is a self-luminous element suitable for various display devices and an organic electroluminescence element comprising an organic layer containing the compound.

Since organic electroluminescence elements (hereinafter sometimes referred to as organic EL elements) are self-luminous elements, they are brighter and more visible than liquid crystal elements, and can be clearly displayed. I came.

In 1987, Eastman Kodak's C.I. W. Tang et al. Have made a practical organic EL device using an organic material by developing a laminated structure device in which various roles are assigned to each material. This laminated structure element is constituted by laminating a phosphor capable of transporting electrons and an aromatic amine compound capable of transporting holes, and both charges are transferred to the phosphor layer. By injecting light into the light source, high luminance of 1000 cd / m ² or more can be obtained at a voltage of 10 V or less.

Up to now, many improvements have been made for practical use of organic EL elements. For example, various roles are further subdivided, and high efficiency is achieved by an electroluminescent device in which an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially provided on the substrate. And durability has been achieved.

In addition, the use of triplet excitons has been attempted for the purpose of further improving the luminous efficiency, and the use of phosphorescent emitters has been studied.
An element utilizing light emission by thermally activated delayed fluorescence (TADF) has also been developed. In 2011, Adachi et al. Of Kyushu University realized an external quantum efficiency of 5.3% with a device using a thermally activated delayed fluorescent material (see, for example, Non-Patent Document 1).

The light emitting layer can also be prepared by doping a charge transporting compound generally called a host material with a phosphor or a phosphorescent light emitter. The selection of the organic material in the organic EL element greatly affects various characteristics such as efficiency and durability of the element.

In the organic EL element, the light injected from both electrodes is recombined in the light emitting layer to obtain light emission. However, it is important how efficiently both holes and electrons are transferred to the light emitting layer. For example, the probability of recombination of holes and electrons is improved by increasing the hole injection property and the electron blocking property of blocking electrons injected from the cathode, and further excitons generated in the light emitting layer. By confining, high luminous efficiency can be obtained. Therefore, the role of the hole transport material is important, and there is a demand for a hole transport material that has high hole injectability, high hole mobility, high electron blocking properties, and high durability against electrons. ing.

Also, the heat resistance and amorphous nature of the material are important for the lifetime of the element. In a material having low heat resistance, thermal decomposition occurs even at a low temperature due to heat generated when the element is driven, and the material is deteriorated. In the case of a material having low amorphous property, the thin film is crystallized even in a short time, and the element is deteriorated. For this reason, the material used is required to have high heat resistance and good amorphous properties.

As hole transport materials used in organic EL devices, N, N′-diphenyl-N, N′-di (α-naphthyl) benzidine (hereinafter abbreviated as NPD) and various aromatic amine derivatives are known. (For example, refer to Patent Document 1 and Patent Document 2).
NPD has a good hole transport capability, but its glass transition point (Tg), which is an index of heat resistance, is as low as 96 ° C., and device characteristics are degraded due to crystallization under high temperature conditions (for example, Non-patent document 2).
In addition, among the aromatic amine derivatives described in Patent Document 1 and Patent Document 2, there are those having an excellent mobility of hole mobility of 10 ⁻³ cm ² / Vs or more, but the electron blocking property. Insufficient amount of electrons pass through the light-emitting layer, and improvement in luminous efficiency cannot be expected.For higher efficiency, the electron blocking property is higher, and the thin film is more stable and heat resistant. High materials were demanded.

As compounds having improved characteristics such as heat resistance and hole injection properties, in Patent Documents 3 and 4, an arylamine compound A having a substituted thienoindole structure and an arylamine compound B having a substituted carbazole structure represented by the following formulas: Has been proposed.

Patent Document 5 discloses an arylamine compound C having a substituted thienoindole structure represented by the following formula, and has been proposed for use as an organic transistor due to its mobility and stability.

However, in the device using the compounds A and B for the hole injection layer or the hole transport layer, although the light emission efficiency and the like have been improved, it cannot be said that it is still sufficient, and the voltage reduction and the current efficiency are also sufficient. However, there is a need for a compound that can further increase the luminous efficiency.
In addition, there is no example in which a substituted thienoindole derivative such as Compound C is used in an organic EL device, and its effectiveness has not been confirmed.

JP-A-8-48656 Japanese Patent No. 3194657 JP 2010-205815 A WO2008 / 62636 JP 2010-205982 A

Therefore, the object of the present invention can be suitably used as a material for producing a high-efficiency, high-durability organic electroluminescence device, has excellent hole injection / transport performance, and has an electronic device capability. In addition, it is to provide a novel organic compound having high stability in a thin film state and further excellent in heat resistance.
Another object of the present invention is to provide an organic electroluminescence device comprising an organic layer containing the above organic compound.

The present inventors have shown that the aromatic tertiary amine structure has a high hole injection / transport capability, the thienoindole ring structure has an electron blocking property, and such a partial structure has Focusing on the good heat resistance and thin film stability, various compounds having a thienoindole ring structure are designed and chemically synthesized, and various organic electroluminescence devices are prototyped using the compounds. As a result of earnestly evaluating the characteristics, it was confirmed that high efficiency and excellent durability were obtained, and the present invention was completed.

According to the present invention, a thienoindole derivative represented by the following general formula (1) is provided.

Where
Ar ¹ represents an aromatic hydrocarbon group or an aromatic heterocyclic group,
R ¹ to R ⁴ are each a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, carbon An alkenyl group having 2 to 6 atoms, an alkyloxy group having 1 to 6 carbon atoms, a cycloalkyloxy group having 5 to 10 carbon atoms, an aromatic hydrocarbon group, an aromatic heterocyclic group or an aryloxy group, R ¹ to R ³ may be bonded to each other via a single bond, an optionally substituted methylene group, an oxygen atom or a sulfur atom to form a ring;
X ¹ and X ² are a hydrogen atom, a deuterium atom, respectively, provided that at least one of them is a monovalent group represented by the following structural formula (2).
Fluorine atom, chlorine atom, cyano group, nitro group, alkyl group having 1 to 6 carbon atoms, cycloalkyl group having 5 to 10 carbon atoms, alkenyl group having 2 to 6 carbon atoms, 1 to 6 carbon atoms Alkyloxy group of 5 to 5 carbon atoms
10 cycloalkyloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, aryloxy groups, or monovalent groups represented by the following structural formula (2).

Where
A ¹ represents a divalent aromatic hydrocarbon group, a divalent aromatic heterocyclic group or a single bond,
Ar ² and Ar ³ each represent an aromatic hydrocarbon group or an aromatic heterocyclic group, and Ar ² and Ar ³ are a single bond, a methylene group which may have a substituent, an oxygen atom Alternatively, they may be bonded to each other via a sulfur atom to form a ring, and when A ¹ is a divalent aromatic hydrocarbon group, A ¹ and Ar ² have a single bond or a substituent. And may be bonded to each other via a methylene group, an oxygen atom or a sulfur atom which may be formed to form a ring.

According to the present invention, in the organic electroluminescence device having a pair of electrodes and at least one organic layer sandwiched therebetween,
At least one layer of the organic layer contains the thienoindole derivative, and an organic electroluminescence device is provided.

Furthermore, the organic EL device of the present invention has, for example, a hole transport layer, an electron blocking layer, a hole injection layer, or a light emitting layer as the organic layer containing the thienoindole derivative.

The thienoindole derivative represented by the general formula (1) described above is a novel compound, and has a structure in which an aromatic tertiary amino group (disubstituted aromatic amino group) is introduced into the thienoindole ring. It has the following characteristics.
(A) Good hole injection characteristics.
(B) The mobility of holes is large.
(C) Excellent electron blocking ability.
(D) The thin film state is stable.
(E) Excellent heat resistance.

Accordingly, the thienoindole derivative of the present invention is useful as a hole transporting substance used in an organic EL device, and since the thin film state is safe, it is particularly used as an organic layer provided in the organic EL device. The following characteristics can be imparted to the EL element.
(F) High luminous efficiency and power efficiency.
(G) The light emission start voltage is low.
(H) The practical drive voltage is low.
(I) The device life is long (high durability is shown).

For example, an organic EL device in which a hole injection layer and / or a hole transport layer is formed using the thienoindole derivative of the present invention has a high hole injection / mobility, a high electron blocking property, and an electron Because of its high stability against light, it is possible to confine excitons generated in the light emitting layer, further improve the probability of recombination of holes and electrons, obtain high luminous efficiency, and lower the driving voltage. In addition, durability can be improved.

Moreover, in the organic EL device having an electron blocking layer using the thienoindole derivative of the present invention, the driving voltage is low while having high luminous efficiency due to excellent electron blocking ability and excellent hole transportability, Current resistance is improved, and the maximum light emission luminance is improved.

Furthermore, the thienoindole derivative of the present invention has excellent hole transport properties and a wide band gap as compared with conventional materials, and therefore can be used as a host material for the light emitting layer. By supporting a fluorescent light-emitting body or phosphorescent light-emitting body called a dopant and using it as a light-emitting layer, the driving voltage of the organic EL element can be lowered and the light emission efficiency can be improved.
In particular, among the thienoindole derivatives of the present invention, those in which A ¹ and Ar ² in the structural formula (2) form a ring (for example, Compound 18 described later) are described in Examples 3 and 4 described later. As shown in the above, the glass transition point is high, the thin film stability is excellent, the work function is also large, and the hole transport ability is particularly good.

As described above, the thienoindole derivative of the present invention is extremely useful as a constituent material of a hole injection layer, a hole transport layer, an electron blocking layer or a light emitting layer of an organic EL device, has excellent electron blocking ability, and has a thin film state. It is stable and excellent in heat resistance, and can improve the light emission efficiency and power efficiency of the organic EL element, lower the practical drive voltage, lower the light emission start voltage, and increase the durability.

1 is a ¹ H-NMR chart of the compound of Example 1 (Compound 10). FIG. 2 is a ¹ H-NMR chart of the compound of Example 2 (Compound 18). FIG. The figure which shows an example of the layer structure of an organic EL element.

The thienoindole derivative of the present invention is represented by the following general formula (1), and an aromatic tertiary amino group (—NAr ² Ar ³ ) represented by the structural formula (2) described later on the thienoindole ring. ) Has a structure in which at least one is bonded.

<Group Ar ¹ >
In the above general formula (1), Ar ¹ bonded to the nitrogen atom of the thienoindole ring represents an aromatic hydrocarbon group or an aromatic heterocyclic group. Such an aromatic hydrocarbon group or aromatic heterocyclic group may have a monocyclic structure or a condensed polycyclic structure.
Examples of these aromatic groups include phenyl group, biphenylyl group, terphenylyl group, naphthyl group, anthryl group, phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, perylenyl group, fluoranthenyl group, triphenylenyl group, pyridyl group. , Furyl group, pyrrolyl group, thienyl group, quinolyl group, isoquinolyl group, benzofuranyl group, benzothienyl group, indolyl group, carbazolyl group, benzoxazolyl group, benzothiazolyl group, quinoxalyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl Group, dibenzothienyl group, carbolinyl group and the like.
In the above aromatic group, the aromatic heterocyclic group includes a sulfur-containing aromatic heterocyclic group such as thienyl group, benzothienyl group, benzothiazolyl group, dibenzothienyl group; furyl group, benzofuranyl group, benzoxazolyl And oxygen-containing aromatic heterocyclic groups such as a dibenzofuranyl group.

The above aromatic group may have a substituent. These substituents include deuterium atom; cyano group; nitro group; halogen atom such as fluorine atom, chlorine atom, bromine atom, iodine atom; methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl. A straight-chain or branched alkyl group having 1 to 6 carbon atoms such as a group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group; methyloxy group, ethyloxy group A linear or branched alkyloxy group having 1 to 6 carbon atoms such as propyloxy group; an alkenyl group such as vinyl group or allyl group; an aryloxy group such as phenyloxy group or tolyloxy group; a benzyloxy group; Arylalkyloxy groups such as phenethyloxy group; phenyl group, biphenylyl group, terphenylyl group, Aromatic hydrocarbon groups such as butyl, anthracenyl, phenanthryl, fluorenyl, indenyl, pyrenyl, perylenyl, fluoranthenyl, triphenylenyl; pyridyl, thienyl, furyl, pyrrolyl, quinolyl , Aromatic groups such as isoquinolyl group, benzofuranyl group, benzothienyl group, indolyl group, carbazolyl group, benzoxazolyl group, benzothiazolyl group, quinoxalyl group, benzoimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, carbolinyl group A heterocyclic group; an aryl vinyl group such as a styryl group or a naphthyl vinyl group; an acyl group such as an acetyl group or a benzoyl group;
In addition, these substituents may further have a substituent, and examples of the substituent include the same substituents that Ar ¹ may have.

<Groups R ¹ to R ⁴ >
In the general formula (1), R ¹ to R ⁴ are each a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an alkyl group having 1 to 6 carbon atoms, or the number of carbon atoms. A cycloalkyl group having 5 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkyloxy group having 1 to 6 carbon atoms, a cycloalkyloxy group having 5 to 10 carbon atoms, an aromatic hydrocarbon group, an aromatic complex Represents a cyclic group or an aryloxy group.

In the above R ¹ to R ⁴ , an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, and an alkyloxy group having 1 to 6 carbon atoms Specific examples of the cycloalkyloxy group having 5 to 10 carbon atoms include the following. The above alkyl group, alkenyl group, and alkyloxy group may be linear or branched.
An alkyl group;
Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group and the like.
A cycloalkyl group;
A cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group and the like.
An alkenyl group;
Vinyl group, allyl group, isopropenyl group, 2-butenyl group and the like.
An alkyloxy group;
Methyloxy group, ethyloxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, tert-butyloxy group, n-
Pentyloxy group, n-hexyloxy group, cyclopentyloxy group and the like.
A cycloalkyloxy group;
A cyclohexyloxy group, a cycloheptyloxy group, a cyclooctyloxy group, a 1-adamantyloxy group, a 2-adamantyloxy group, and the like.

The alkyl group, cycloalkyl group, alkenyl group, alkyloxy group and cycloalkyloxy group described above may further have a substituent. The substituent is the same as the substituent which the aromatic group represented by Ar ¹ may have (excluding the alkyl group, arylvinyl group and acyl group).

The aromatic hydrocarbon group and aromatic heterocyclic group in R ¹ to R ⁴ are the same groups as the substituents exemplified for Ar ¹ described above, and among the aromatic heterocyclic groups, a thienyl group, a benzothienyl group are included. Sulfur-containing aromatic heterocyclic groups such as a group, benzothiazolyl group and dibenzothienyl group are preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group represented by R ¹ to R ⁴ may further have a substituent.
As the substituent, in addition to the substituent that the aromatic group represented by Ar ¹ may have, a trifluoromethyl group; an aralkyl group such as a benzyl group, a naphthylmethyl group, and a phenethyl group; a dimethylamino group; A dialkylamino group such as a diethylamino group; a disubstituted amino group substituted with an aromatic hydrocarbon group such as a diphenylamino group or a dinaphthylamino group; a diaralkylamino group such as a dibenzylamino group or a diphenethylamino group; Disubstituted amino groups substituted with aromatic heterocyclic groups such as pyridylamino groups and dithienylamino groups; Dialkenylamino groups such as diallylamino groups; Alkyl groups, aromatic hydrocarbon groups, aralkyl groups, aromatic heterocyclic groups Or a di-substituted amino group substituted with two kinds of substituents selected from alkenyl groups.

Examples of the aryloxy group in R ¹ to R ⁴ include phenyloxy group, biphenylyloxy group, terphenylyloxy group, naphthyloxy group, anthryloxy group, phenanthryloxy group, fluorenyloxy group, index Examples thereof include a nyloxy group, a pyrenyloxy group, and a perylenyloxy group.
These aryloxy groups may also have a substituent, and examples of the substituent include the same substituents as the aromatic group represented by Ar ¹ .

Among the above R ¹ to R ⁴ , R ¹ to R ³ and the substituents thereof are bonded via a single bond, a methylene group (which may have a substituent such as a methyl group), an oxygen atom or a sulfur atom. They may combine with each other to form a ring.

<Groups X ¹ and X ² >
In the general formula (1), X ¹ and X ² are each a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, an alkyl group having 1 to 6 carbon atoms, or the number of carbon atoms A cycloalkyl group having 5 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkyloxy group having 1 to 6 carbon atoms, a cycloalkyloxy group having 5 to 10 carbon atoms, an aromatic hydrocarbon group, an aromatic complex A cyclic group or an aryloxy group, or a monovalent group represented by the following structural formula (2), wherein at least ^one of X ¹ and X ^{2 is} a monovalent group represented by the following structural formula (2) ( A group having a tertiary amino structure).

A group A ¹ ;
In the structural formula (2), A ¹ is a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group (a group formed by removing two hydrogen atoms from an aromatic hydrocarbon or an aromatic heterocyclic ring). Or represents a single bond.
The following rings can be illustrated as specific examples of the ring structure of the aromatic hydrocarbon ring and aromatic heterocyclic ring that the above divalent group has.
An aromatic hydrocarbon ring;
Benzene, biphenyl, terphenyl, tetrakisphenyl, naphthalene, anthracene, acenaphthalene, fluorene, phenanthrene, indane, pyrene.
Aromatic heterocycles;
Pyridine, pyrimidine, triazine, pyrrole, furan, thiophene,
Quinoline, isoquinoline, benzofuran, benzothiophene, indoline, carbazole, carboline, benzoxazole, benzothiazole,
Quinoxaline, benzimidazole, pyrazole, dibenzofuran, dibenzothiophene, naphthyridine, phenanthroline, acridinine.
In the present invention, a divalent aromatic hydrocarbon group is preferable, and a divalent aromatic hydrocarbon group having a benzene ring is particularly preferable.

Further, the divalent aromatic hydrocarbon group and aromatic heterocyclic group represented by A ¹ may further have a substituent, and the substituent that Ar ¹ described above may have as the substituent. The same thing can be mentioned.
Further, the above divalent aromatic hydrocarbon group is bonded to the group Ar ² described later via a methylene group, oxygen atom, sulfur atom or single bond which may have a substituent such as an alkyl group. May form a ring. In particular, those in which a divalent aromatic hydrocarbon group is bonded to the group Ar ² to form a ring are excellent in thin film stability and exhibit particularly excellent hole transport ability. A typical example of such a ring is a carbazole ring.

The groups Ar ² and Ar ³ ;
In the structural formula (2), Ar ² and Ar ³ represent an aromatic hydrocarbon group and an aromatic heterocyclic group.
Specific examples of such aromatic groups (aromatic hydrocarbon groups and aromatic heterocyclic groups) include the same groups as those of Ar ^{1 in the} general formula (1).
Ar ² and Ar ³ are bonded to each other through a methylene group, an oxygen atom, a sulfur atom or a single bond, which may have a substituent such as an alkyl group, and form a ring together with the nitrogen atom of the amino group. It may be formed.
Furthermore, although A ¹ and Ar ² exist as groups independent of each other, when A ¹ is a divalent aromatic hydrocarbon group, A ¹ and Ar ² are a single bond, a methylene group, oxygen It can also be bonded to each other via an atom or sulfur atom to form a ring.

<Specific examples of thienoindole derivatives>
The thienoindole derivative of the present invention represented by the above general formula (1) has an aromatic tertiary amino structure (—NAr ² Ar ³ ) derived from the group X ¹ or X ^2. Corresponding to the structures of ¹ and X ² , only the group X ² has a structure represented by the structural formula (2) (A type), and only the group X ¹ is represented by the structural formula (2). Group (B type) and groups X ¹ and X ² both have a structure represented by structural formula (2) (C type). .

Type A thienoindole derivatives;
This type of compound is represented by the following general formula (1-1).

Where
Ar ¹ , R ¹ to R ⁴ , X ¹ , A ¹ , Ar ² and Ar ³ are as described in the general formula (1) and the structural formula (2) (provided that in X ¹ ,
The group represented by Structural Formula (2) is excluded).

In the present invention, among the A-type thienoindole derivatives represented by the above general formula (1-1), those represented by the following general formula (1a), that is, the 2-position of the thienoindole ring (next to the sulfur atom) In which a group having an aromatic tertiary amino structure (—NAr ² Ar ³ ) is bonded.

Where
Ar ¹ to Ar ³ , R ¹ to R ⁴ , A ¹ and X ¹ are defined by the general formula (1-1)
).
Among such A-type thienoindole derivatives in which A ¹ and Ar ² are bonded to form a ring (for example, compounds 17-19, 36-38, 50, 55, 60 described later) are thin films. It is particularly suitable in terms of stability and hole transport capability.

B type thienoindole derivatives;
This type of compound is represented by the following general formula (1-2).

Where
Ar ¹ , R ¹ to R ⁴ , X ² , A ¹ , Ar ² and Ar ³ are as described in the general formula (1) and the structural formula (2) (provided that, in X ² ,
The group represented by Structural Formula (2) is excluded).

In the present invention, among the thienoindole derivatives represented by the above general formula (1-2), a compound represented by the following general formula (1b), that is, an aromatic tertiary amino structure (- Those having a group having NAr ¹ Ar ² ) are preferred.

Where
Ar ¹ to Ar ³ , R ¹ to R ⁴ , A ¹ and X ² are defined by the general formula (1-2)
).
Also, in such B-type thienoindole derivatives, those in which A ¹ and Ar ² are bonded to form a ring (for example, compounds 42 and 54 described later) have thin film stability and hole transport ability. This is particularly preferable.

C-type thienoindole derivatives;
In this type, both of the groups X ¹ and X ² are groups represented by the structural formula (2) (groups having an aromatic tertiary amino structure). ).

Where
Ar ¹ to Ar ³ , R ¹ to R ⁴ and A ¹ are as described in the general formula (1) and the structural formula (2).
Here, the plurality of A ¹ , Ar ² , and Ar ³ may be the same or different.

In the present invention, among the C-type thienoindole derivatives represented by the general formula (1-3), the group having an aromatic tertiary amino structure (—NAr ² Ar ³ ) is the 2-position of the thienoindole ring. A carbon atom adjacent to the sulfur atom and a structure bonded to the 7-position, specifically, a thienoindole derivative represented by the following general formula (1c) is preferable.

Where
Ar ¹ to Ar ³ , R ¹ to R ⁴ and A ¹ are as described in the general formula (1-3).
In addition, among such C-type thienoindole derivatives, those in which A ¹ and Ar ² are bonded to form a ring (for example, compound 16 described below) are thin film stability and hole transport capability. And is particularly suitable.

<Synthesis of thienoindole derivatives>
The thienoindole derivative of the present invention is a novel compound and can be synthesized, for example, as follows.
First, a thienoindole having an aryl group introduced into the 4-position nitrogen atom and having groups R ¹ to R ⁴ corresponding to the general formula (1) is used as a starting material, and this thienoindole is converted to bromine or N-bromo. was brominated by like succinimide, to synthesize a bromo substituted compound of bromine is introduced into a predetermined position (a position to be bonded to the group X1 or X ^2). Here, by changing the bromination reagent and conditions, bromo-substituted products and di-substituted products having different substitution positions can be obtained.

Further, various boronic acids or boronic esters synthesized by the reaction of halogen-substituted triarylamines with pinacolborane, bis (pinacolato) diboron, etc. (for example, J. Org. Chem., 60, 7508 (1995)). Prepare a reference). By subjecting this boronic acid or boronic ester to a bromo-substituted thienoindole as described above, a cross-coupling reaction such as Suzuki coupling (see, for example, Chem. Rev., 95, 2457 (1995)). These thienoindole derivatives can be synthesized.

Further, by reacting the above bromo-substituted thienoindole with pinacolborane, bis (pinacolato) diboron or the like, a boronic acid or a boronic acid ester corresponding to the thienoindole derivative of the general formula (1) is synthesized. The thienoindole derivative of the present invention can also be synthesized by reacting boronic acid or a boronic acid ester with a halogen-substituted product of triarylamine by a cross-coupling reaction such as Suzuki coupling.

Note that these compounds can be purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization using a solvent, crystallization methods, and the like. The compound is identified by NMR analysis.

<Preferred examples of thienoindole derivatives>
Specific examples of preferable compounds among the thienoindole derivatives represented by the general formula (1) described above are shown below, but the present invention is not limited to these compounds.

The above-described thienoindole derivative of the present invention has a glass transition point (Tg) and a melting point higher than those of conventionally known hole transport materials, can form a thin film excellent in heat resistance, and stably maintains the thin film state. be able to. In addition, the electron blocking ability is high. For example, when a deposited layer having a film thickness of 100 nm is formed using the thienoindole derivative of the present invention and the work function is measured, an extremely high value is shown.
In the thienoindole derivative of the present invention, the A type exhibits the most excellent performance as a material for an organic EL device.

<Organic EL device>
The organic EL element provided with the organic layer formed using the thienoindole derivative of the present invention described above has a structure shown in FIG. 3, for example.
That is, a transparent anode 2, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer on a glass substrate 1 (a transparent substrate such as a transparent resin substrate may be used). 7 and a cathode 8 are provided.
Of course, the organic EL element to which the thienoindole derivative of the present invention is applied is not limited to the above layer structure, and an electron blocking layer or a light emitting layer 5 is provided between the hole transport layer 4 and the light emitting layer 5. A hole blocking layer or the like can be provided between the electron transport layer 6 and the electron transport layer 6. Further, a simple layer structure in which the electron injection layer 7 and the hole injection layer 3 are omitted can be obtained. For example, in the above multilayer structure, some layers can be omitted. For example, a simple layer structure in which the anode 2, the hole transport layer 3, the light emitting layer 5, the electron transport layer 6, and the cathode 8 are provided on the substrate 1 can be used.

That is, the thienoindole derivative of the present invention has an organic layer (for example, a hole injection layer 3, a hole transport layer 4, an electron blocking layer not shown, or a light emitting layer) provided between the anode 2 and the cathode 8. It is suitably used as a forming material of 5).

In the above organic EL element, the transparent anode 2 may be formed of a known electrode material, and an electrode material having a large work function such as ITO or gold is formed on the substrate 1 (transparent substrate such as a glass substrate). It is formed by vapor deposition.

Further, the hole injection layer 3 provided on the transparent anode 2 can be formed using the above-described thienoindole derivative of the present invention, or may be formed using a conventionally known material, for example, the following materials. it can.
Porphyrin compounds represented by copper phthalocyanine;
Starburst type triphenylamine derivatives;
Materials such as various triphenylamine tetramers;
Acceptor heterocyclic compounds such as hexacyanoazatriphenylene;
Coating type polymer materials such as poly (3,4-ethylenedioxythiophene) (PEDOT), poly (styrene sulfonate) (PSS) and the like.

The layer (thin film) using the above materials can be formed by a known method such as a spin coating method or an ink jet method in addition to the vapor deposition method.

The hole transport layer 4 provided on the hole injection layer 3 can also be formed by using the above-described thienoindole derivative of the present invention, and a conventionally known hole transport material as described below. It can also be formed using.
Benzidine derivatives such as
N, N′-diphenyl-N, N′-di (m-tolyl) benzidine (hereinafter abbreviated as TPD);
N, N′-diphenyl-N, N′-di (α-naphthyl) benzidine (hereinafter abbreviated as NPD);
N, N, N ′, N′-tetrabiphenylylbenzidine;
Amine-based derivative 1,1-bis [4- (di-4-tolylamino) phenyl] cyclohexane (hereinafter abbreviated as TAPC);
Various triphenylamine trimers and tetramers;
The above-mentioned coating type polymer material that is also used as a hole injection layer;

Such a compound for the hole transport layer may be formed by itself, but may be formed by mixing two or more kinds. In addition, a multilayer film in which a plurality of layers are formed using one or more of the above-described compounds and such layers are stacked can be used as a hole transport layer.

Moreover, it can also be set as the layer which served as the positive hole injection layer 3 and the positive hole transport layer 4, and such a positive hole injection / transport layer can be formed by coating using polymeric materials, such as PEDOT. it can.

In addition, in the hole transport layer 4 (the same applies to the hole injection layer 3), it is possible to use a material which is usually used for the layer and further P-doped with trisbromophenylamine hexachloroantimony or the like. Further, the hole transport layer 4 (or the hole injection layer 3) can be formed using a polymer compound having a TPD basic skeleton.

Furthermore, an electron blocking layer (not shown) (which can be provided between the light emitting layer 5 and the hole transport layer 3) can be formed using the thienoindole derivative of the present invention having an electron blocking action. Also, it can be formed using a known electron blocking compound such as a carbazole derivative or a compound having a triphenylsilyl group and a triarylamine structure. Specific examples of the compound having a carbazole derivative and a triarylamine structure are as follows.
<Carbazole derivative>
4,4 ′, 4 ″ -tri (N-carbazolyl) triphenylamine (hereinafter abbreviated as TCTA);
9,9-bis [4- (carbazol-9-yl) phenyl]
Fluorene;
1,3-bis (carbazol-9-yl) benzene (hereinafter abbreviated as mCP);
2,2-bis (4-carbazol-9-ylphenyl) adamantane (hereinafter abbreviated as Ad-Cz);
<Compound having a triarylamine structure>
9- [4- (carbazol-9-yl) phenyl] -9- [4- (triphenylsilyl) phenyl] -9H-fluorene;

The electron blocking layer is formed by using one or more of the thienoindole compounds of the present invention and the above-mentioned known hole transport materials alone, or one or more of these hole transport materials. It is also possible to form a plurality of layers by using a multilayer film in which such layers are stacked as an electron blocking layer.

As the light-emitting layer 5 of the organic EL element, in addition to metal complexes of quinolinol derivatives such as Alq ₃ , various metal complexes such as zinc, beryllium, and aluminum, anthracene derivatives, bisstyrylbenzene derivatives, pyrene derivatives, oxazole derivatives, poly A light-emitting material such as a paraphenylene vinylene derivative can be used.

Moreover, the light emitting layer 5 can also be comprised with a host material and a dopant material.
As a host material in this case, a thiazole derivative, a benzimidazole derivative, a polydialkylfluorene derivative, or the like can be used in addition to the above light-emitting material, in addition to the thienoindole derivative of the present invention.
As the dopant material, quinacridone, coumarin, rubrene, perylene and derivatives thereof, benzopyran derivatives, rhodamine derivatives, aminostyryl derivatives, and the like can be used.

Such a light-emitting layer 5 can also have a single-layer configuration using one or more of the light-emitting materials, or a multilayer structure in which a plurality of layers are stacked.

Furthermore, the light emitting layer 5 can also be formed using a phosphorescent light emitting material as the light emitting material.
As the phosphorescent material, a phosphorescent material of a metal complex such as iridium or platinum can be used. For example, green phosphorescent emitters such as Ir (ppy) ₃ , blue phosphorescent emitters such as FIrpic and FIr6, red phosphorescent emitters such as Btp ₂ Ir (acac), and the like can be used. The material is used by doping into a hole injecting / transporting host material or an electron transporting host material.

Examples of the hole injection / transport host material include thienoindole derivatives of the present invention, carbazole derivatives such as 4,4′-di (N-carbazolyl) biphenyl (hereinafter abbreviated as CBP), TCTA, and mCP. Can be used.
As an electron transporting host material, p-bis (triphenylsilyl) benzene (hereinafter abbreviated as UGH2), 2,2 ′, 2 ″-(1,3,5-phenylene) -tris ( 1-phenyl-1H-benzimidazole) (hereinafter abbreviated as TPBI) and the like can be used.

In addition, it is preferable to dope the host material with a phosphorescent light emitting material by co-evaporation in the range of 1 to 30 weight percent with respect to the entire light emitting layer in order to avoid concentration quenching.

In addition, a material that emits delayed fluorescence, such as a CDCB derivative (for example, PIC-TRZ, CC2TA, PXZ-TRZ, 4CzIPN) as disclosed in Non-Patent Document 1 described above, can be used as the light emitting material. is there.

The hole blocking layer (not shown in FIG. 3) that can be provided between the light emitting layer 5 and the electron transport layer 6 can be formed using a compound having a known hole blocking action.
Examples of known compounds having such hole blocking action include phenanthroline derivatives such as bathocuproin (hereinafter abbreviated as BCP), aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenol In addition to metal complexes of quinolinol derivatives such as rate (hereinafter abbreviated as BAlq), various rare earth complexes, triazole derivatives, triazine derivatives, oxadiazole derivatives, and the like can be given.
These materials can also be used for forming the electron transport layer 6 described below, and the hole blocking layer and the electron transport layer 6 can be used in combination.

Such a hole blocking layer can also have a single layer or multilayer structure, and each layer is formed using one or more of the compounds having the hole blocking action described above.

The electron transport layer 6 is an electron transport compound known per se, for example, metal complexes of quinolinol derivatives including Alq ₃ and BAlq, various metal complexes, triazole derivatives, triazine derivatives, oxadiazole derivatives, thiadiazole Derivatives, carbodiimide derivatives, quinoxaline derivatives, phenanthroline derivatives, silole derivatives and the like are used.
The electron transport layer 6 can also have a single layer or multilayer structure, and each layer is formed using one or more of the electron transport compounds described above.

Furthermore, the electron injection layer 7 is also known per se, for example, an alkali metal salt such as lithium fluoride or cesium fluoride, an alkaline earth metal salt such as magnesium fluoride, or a metal oxide such as aluminum oxide. Can be formed.

As the cathode 8 of the organic EL element, an electrode material having a low work function such as aluminum, or an alloy having a lower work function such as a magnesium silver alloy, a magnesium indium alloy, or an aluminum magnesium alloy is used as the electrode material.

The organic EL device in which at least one of the organic layers (for example, the hole injection layer 3, the hole transport layer 4, the electron blocking layer or the light emitting layer 5) is formed using the thienoindole derivative of the present invention has a luminous efficiency and It has high power efficiency, low practical driving voltage, low light emission starting voltage, and extremely excellent durability.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the following examples.

<Example 1>
Synthesis of bis (biphenyl-4-yl)-[4- {4- (biphenyl-4-yl) thieno [3,2-b] indol-2-yl} phenyl] amine; (Synthesis of Compound 10)

2-Bromo-4- (biphenyl-4-yl) thieno [3,2-b]
Indole 11.3g,
Bis (biphenyl-4-yl)-{4- (4,4,5,5-
Tetramethyl- [1,3,2] dioxaboran-2-yl) phenyl}
16.7 g of amine,
130 ml of a mixed solvent of toluene / ethanol (4/1, v / v),
21 ml of 2M potassium carbonate aqueous solution,
Was added to a reaction vessel purged with nitrogen, and nitrogen gas was aerated for 30 minutes while irradiating ultrasonic waves.
Next, 0.67 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring under reflux for 27.5 hours. After cooling to room temperature and adding 100 ml of methanol, the precipitated crude product was collected by filtration.
This crude product was added to 500 ml of toluene, dissolved by heating to 80 ° C., and subjected to adsorption purification using 19 g of silica gel. After concentration under reduced pressure, bis (biphenyl-4-yl)-[4- {4- (biphenyl-4-yl) thieno [ 17.6 g (yield 87%) of a yellow powder of 3,2-b] indol-2-yl} phenyl] amine (Compound 10) was obtained.

The structure of the obtained yellow powder was identified using NMR. ^The results of ¹ H-NMR measurement are shown in FIG.

^The following 36 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 7.93 (2H)
7.82-7.60 (16H)
7.54-7.38 (8H)
7.30-7.19 (10H)

<Example 2>
Synthesis of 3- {4- (9,9-dimethyl-9H-fluoren-2-yl) thieno [3,2-b] indol-2-yl} -9-phenylcarbazole;
(Synthesis of Compound 18)

2-Bromo-4- (9,9-dimethyl-9H-fluorene-2-
Il) Thieno [3,2-b] indole 14.7 g,
10.9 g of (9-phenyl-9H-carbazol-3-yl) boronic acid
190 ml of a mixed solvent of toluene / ethanol (4/1, v / v),
25 ml of 2M aqueous potassium carbonate solution,
Was added to a reaction vessel purged with nitrogen, and nitrogen gas was aerated for 30 minutes while irradiating ultrasonic waves.
Next, 0.76 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring under reflux for 5.5 hours. The organic layer was collected by allowing to cool to room temperature and performing a liquid separation operation, followed by dehydration with anhydrous magnesium sulfate and concentration under reduced pressure to obtain a crude product.
The crude product was purified by column chromatography (carrier: silica gel, eluent: heptane / toluene) and then repeated crystallization using a mixed solvent of toluene / methanol to give 3- {4- (9,9- 15.3 g (yield 76%) of yellowish white powder of dimethyl-9H-fluoren-2-yl) thieno [3,2-b] indol-2-yl} -9-phenylcarbazole (Compound 18) was obtained. .

The structure of the obtained yellowish white powder was identified using NMR. ^The results of ¹ H-NMR measurement are shown in FIG.

^The following 30 hydrogen signals were detected by ¹ H-NMR (DMSO-d6).
δ (ppm) = 8.72 (1H)
8.36 (1H)
8.12 (1H)
7.9-7.90 (2H)
7.89-7.80 (2H)
7.74-7.52 (8H)
7.50-7.22 (9H)
1.62 (6H)

<Example 3>
(Measurement of glass transition temperature)
For the thienoindole derivatives obtained in Examples 1 and 2, the melting point and glass transition point were determined with a high-sensitivity differential scanning calorimeter (manufactured by Bruker AXS, DSC3100S).
The results were as follows.
Melting point Glass transition point Compound of Example 1 264 ° C 130 ° C
Compound of Example 2 242 ° C 129 ° C
From this, the thienoindole derivative has a glass transition point of 100 ° C. or higher, which indicates that the thin film state is stable.

<Example 4>
Using the thienoindole derivative obtained in Examples 1 and 2, a deposited film having a film thickness of 100 nm was prepared on an ITO substrate, and the work was performed with an ionization potential measuring apparatus (Sumitomo Heavy Industries, Ltd., PYS-202). The function was measured.
Work function Compound of Example 1 5.55 eV
Compound of Example 2 5.72 eV
From the above results, the thienoindole derivative of the present invention shows a favorable energy level as compared with a work function of 5.54 eV possessed by general hole transport materials such as NPD and TPD. It can be seen that it has a hole transport capability.

<Example 5>
(Characteristic evaluation of organic EL elements)
An organic EL device having the structure shown in FIG. 3 was prepared, comprising a hole transport layer formed using the thienoindole derivative (Compound 10) obtained in Example 1.

Specifically, the glass substrate 1 on which ITO having a thickness of 150 nm was formed was washed with an organic solvent, and then the surface was washed by oxygen plasma treatment. Thereafter, the glass substrate with the ITO electrode is mounted in a vacuum vapor deposition machine, and the pressure is reduced to 0.001 Pa or less. In this state, a hole having a thickness of 20 nm is injected so as to cover the transparent anode 2 using the compound 63 having the following structural formula. Layer 3 was formed.

On the hole injection layer 3 thus formed, the thienoindole derivative (compound 10) obtained in Example 1 was deposited to form a hole transport layer 4 having a thickness of 40 nm.
On this hole transport layer 4, a compound 64 and a compound 65 having the following structural formula are used, and binary deposition is performed at a deposition rate at which the deposition rate ratio is Compound 64: Compound 65 = 5: 95. A 30 nm light emitting layer 5 was formed.

Next, Alq ₃ was used to form an electron transport layer 6 having a thickness of 30 nm on the light emitting layer 5.
Further, lithium fluoride was used to form an electron injection layer 7 having a thickness of 0.5 nm on the electron transport layer 6.
Finally, aluminum was vapor-deposited to a thickness of 150 nm to form the cathode 8 to obtain an organic EL element having the structure shown in FIG.

Table 1 summarizes the measurement results of the light emission characteristics of the organic EL device produced as described above when a DC voltage was applied in the atmosphere at room temperature.

<Comparative Example 1>
Instead of the thienoindole derivative of Example 1 (Compound 10), an organic EL was produced in the same manner as in Example 5 except that the hole transport layer 4 having a film thickness of 40 nm was formed using Compound A having the following structural formula. An element was produced.

For the organic EL device thus obtained, the light emission characteristics were measured in the same manner as in Example 5, and the results are also shown in Table 1.

<Comparative Example 2>
Instead of the thienoindole derivative of Example 1 (Compound 10), the hole transport layer 4 having a thickness of 40 nm was formed using Compound B having the following structural formula. An EL element was prepared, and the obtained organic EL element was measured for light emission characteristics in the same manner as in Example 5. The results are also shown in Table 1.

<Comparative Example 3>
Instead of the thienoindole derivative of Example 1 (Compound 10), an organic EL device was produced in the same manner as in Example 5 except that the hole transport layer 4 having a film thickness of 40 nm was formed using a compound 66 having the following structural formula. The device was fabricated, and the obtained organic EL device was measured for light emission characteristics in the same manner as in Example 5. The results are also shown in Table 1.

As shown in Table 1, the driving voltage when a current density of 10 mA / cm ² was passed was 5.18 V for an organic EL element using Compound A and 5.62 V for an organic EL element using Compound B. In contrast, the organic EL device using the compound of Example 1 (Compound 10) has a low voltage of 4.78 V.
In terms of power efficiency, the organic EL element using Compound A is 5.20 lm / W, the organic EL element using Compound B is 5.06 lm / W, and the organic EL element using Compound 66 is 5.06 lm / W. Compared to W, the organic EL device using the compound of Example 1 (Compound 10) was greatly improved to 6.06 lm / W.

As is apparent from the above results, the organic EL device using the thienoindole derivative of the present invention is more efficient than the organic EL devices using the compounds A and B and the compound 66, which are known materials. As a result, it was found that an improvement in the drive voltage and a decrease in the practical drive voltage can be achieved.

Further, the light emission starting voltage was measured for the organic EL devices obtained in Example 5 and Comparative Examples 1 to 3, and the results are shown below.
Organic EL device Compound Luminescence start voltage [V]
Example 5 Compound 10 2.7
Comparative Example 1 Compound A 2.9
Comparative Example 2 Compound B 2.9
Comparative Example 3 Compound 66 2.8

As can be seen from this result, the organic EL device using the compounds A and B and the compound 66 has a higher emission starting voltage than the organic EL device using the thienoindole derivative (compound 10) of the present invention.

The compound having a thienoindole derivative of the present invention is excellent as a compound for an organic EL device because it has a high hole transport capability, an excellent electron blocking capability, and a stable thin film state. By producing an organic EL device using the compound, high luminous efficiency and power efficiency can be obtained, practical driving voltage can be lowered, and durability can be improved. For example, it has become possible to develop home appliances and lighting.

1: Glass substrate 2: Transparent anode 3: Hole injection layer 4: Hole transport layer 5: Light emitting layer 6: Electron transport layer 7: Electron injection layer 8: Cathode

Claims (15)

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

   

   Where
   Ar ¹ represents an aromatic hydrocarbon group or an aromatic heterocyclic group,
   R ¹ to R ⁴ are each a hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano group, nitro group, alkyl group having 1 to 6 carbon atoms, cycloalkyl group having 5 to 10 carbon atoms, carbon 2-6 atoms
   An alkenyl group having 1 to 6 carbon atoms, a cycloalkyloxy group having 5 to 10 carbon atoms, an aromatic hydrocarbon group, an aromatic heterocyclic group or an aryloxy group, and R ¹ to R ³ may be bonded to each other via a single bond, an optionally substituted methylene group, an oxygen atom or a sulfur atom to form a ring,
   X ¹ and X ² are each a hydrogen atom, provided that at least one of them is a monovalent group represented by the following structural formula (2).
   Deuterium atom, fluorine atom, chlorine atom, cyano group, nitro group, alkyl group having 1 to 6 carbon atoms, cycloalkyl group having 5 to 10 carbon atoms, alkenyl group having 2 to 6 carbon atoms, number of carbon atoms An alkyloxy group having 1 to 6 carbon atoms, a cycloalkyloxy group having 5 to 10 carbon atoms, an aromatic hydrocarbon group, an aromatic heterocyclic group or an aryloxy group, or a monovalent group represented by the following structural formula (2) Is,
   

   

   Where
   A ¹ represents a divalent aromatic hydrocarbon group, a divalent aromatic heterocyclic group or a single bond,
   Ar ² and Ar ³ each represent an aromatic hydrocarbon group or an aromatic heterocyclic group, and Ar ² and Ar ³ are a single bond, a methylene group which may have a substituent, an oxygen atom or A ring may be bonded to each other via a sulfur atom, and when A ¹ is a divalent aromatic hydrocarbon group, A ¹ and Ar ² are a single bond or a substituent. A ring may be formed by bonding to each other via a methylene group, an oxygen atom or a sulfur atom which may have.
2. The thienoindole derivative according to claim 1, wherein in the structural formula (2), A ¹ and Ar ² form a ring.
3. The thienoindole derivative according to claim 2, wherein the ring formed by A ¹ and Ar ² is a carbazole ring.
4. ^2. The thienoindole derivative according to claim 1, wherein, in the general formula (1), only X ² of X ¹ and X ² is a group represented by the structural formula (2).
5. The following general formula (1a);
   

   

   Where
   Ar ¹ to Ar ³ , R ¹ to R ⁴ , A ¹ and X ¹ have the same meanings as described in the general formula (1) and the structural formula (2).
   The thienoindole derivative of Claim 4 represented by these.
6. The thienoindole derivative according to claim 5, wherein in the general formula (1a), A ¹ and Ar ² form a ring.
7. In Formula (1), of X ¹ and X ^2, thieno indole derivative according to claim 1 only X ¹ is a group represented by the structural formula (2).
8. The following general formula (1b);
   

   

   Where
   Ar ¹ to Ar ³ , R ¹ to R ⁴ , X ² and A ¹ have the meanings described in the general formula (1) and the structural formula (2).
   The thienoindole derivative according to claim 7 represented by
9. The thienoindole derivative according to claim 1, wherein in the general formula (1), both X ¹ and X ² are groups represented by the structural formula (2).
10. The following general formula (1c);
    

    

    Where
    Ar ¹ to Ar ³ , R ¹ to R ^4, and A ¹ have the same meanings as described in the general formula (1) and the structural formula (2), and a plurality of A ¹ , Ar ² , Ar ³ May be the same or different,
    The thienoindole derivative of Claim 9 represented by these.
11. In an organic electroluminescence device having a pair of electrodes and at least one organic layer sandwiched therebetween,
    At least one layer of the organic layer contains the thienoindole derivative according to claim 1.
12. The organic electroluminescence device according to claim 11, wherein the organic layer containing the thienoindole derivative is a hole transport layer.
13. The organic electroluminescence device according to claim 11, wherein the organic layer containing the thienoindole derivative is an electron blocking layer.
14. The organic electroluminescence device according to claim 11, wherein the organic layer containing the thienoindole derivative is a hole injection layer.
15. The organic electroluminescence device according to claim 11, wherein the organic layer containing the thienoindole derivative is a light emitting layer.

Images