WO2014038417A1

WO2014038417A1 - Novel benzothienoindole derivative and organic electroluminescent element in which novel benzothienoindole derivative is used

Info

Publication number: WO2014038417A1
Application number: PCT/JP2013/072677
Authority: WO
Inventors: 長岡　誠; 幸喜加瀬; 重草野
Original assignee: 保土谷化学工業株式会社
Priority date: 2012-09-07
Filing date: 2013-08-26
Publication date: 2014-03-13
Also published as: TW201418260A; JPWO2014038417A1; JP2014101374A

Abstract

This benzothienoindole derivative is represented by general formula (1). This compound has a benzothienoindole ring structure, and has the following characteristics (A)-(E) due to the benzothienoindole ring structure. (A) the hole injection characteristics are good; (B) the hole mobility is high; (C) the electron blocking ability is excellent; (D) the thin film state is stable; and (E) the heat resistance is excellent. This benzothienoindole derivative is useful as a hole transport material that is used in organic EL elements.

Description

Novel benzothienoindole derivative and organic electroluminescence device using the derivative

The present invention relates to a compound (benzothienoindole derivative) suitable for an organic electroluminescence element which is a self-luminous element suitable for various display devices, and an organic electroluminescence element provided with 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 formed by laminating a phosphor capable of transporting electrons and an aromatic amine compound capable of transporting holes, and is 1000 cd / m ² at a voltage of 10 V or less. The above high brightness can be obtained.

Up to now, many improvements have been made for practical use of organic EL elements. For example, an element having a structure in which various roles are further subdivided and 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 a substrate is known. Such an element achieves high efficiency and durability.

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 an organic EL element, charges injected from both electrodes recombine in the light emitting layer to emit light, but it is important to efficiently transfer both holes and electrons to the light emitting layer. For example, the probability of recombination of holes and electrons is improved by increasing the hole injection property and blocking the electron 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.

Examples of hole transport materials that have been used in organic EL devices so far include N, N′-diphenyl-N, N′-di (α-naphthyl) benzidine (hereinafter abbreviated as NPD) and various aromatic amines. Derivatives were known (see, for example, 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 deteriorated due to crystallization under high temperature conditions.
In addition, among the aromatic amine derivatives described in Patent Document 1 and Patent Document 2, there are those having excellent mobility such as hole mobility of 10 ⁻³ cm ² / Vs or more. Insufficiency, part of the electrons pass through the light-emitting layer, and no improvement in light emission efficiency can be expected. For higher efficiency, the electron blocking property is higher, and the thin film is more stable and heat resistant. A material with high properties was demanded.

As compounds having improved properties such as heat resistance, hole injection properties, and electron blocking properties, Patent Documents 3 and 4 describe arylamine compound A having a substituted thienoindole structure represented by the following formula and aryl having a substituted carbazole structure. Amine compound B has been proposed.

However, devices using these compounds in the hole injection layer or hole transport layer have been improved in heat resistance and light emission efficiency, but are still not sufficient. The efficiency was not sufficient, and there was a problem with amorphousness. For this reason, there has been a demand for further lower drive voltage and higher light emission efficiency while enhancing amorphousness.

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

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 benzothienoindole ring structure has an electron blocking property, and such a partial structure. Paying attention to the good heat resistance and thin film stability of, we designed and chemically synthesized various compounds with benzothienoindole ring structure, and prototyped various organic electroluminescence devices using the compounds, As a result of diligent evaluation of device characteristics, it was confirmed that high efficiency and excellent durability were obtained, and the present invention was completed.

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

Where
Ar ¹ to Ar ^{3 each} represents an aromatic hydrocarbon group or an aromatic heterocyclic group,
Ar ² and Ar ³ may be bonded to each other via a single bond, a methylene group which may have a substituent, an oxygen atom or a sulfur atom to form a ring,
R ¹ to R ⁷ are a hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano group, nitro group, alkyl group having 1 to 6 carbon atoms, or 5 to 10 carbon atoms.
Cycloalkyl group, alkenyl group having 2 to 6 carbon atoms, 1 carbon atom
An alkyloxy group having 6 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, wherein R ¹ to R ⁴ or R ⁵ to R ⁷ are , A single bond, a methylene group which may have a substituent, an oxygen atom or a sulfur atom may be bonded to each other to form a ring,
A ¹ represents a divalent aromatic hydrocarbon group, a divalent aromatic heterocyclic group or a single bond, and A ¹ represents a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group. In some cases, A ¹ and Ar ³ may be bonded to each other via a single bond, a methylene group which may have a substituent, an oxygen atom or a sulfur atom 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 includes the triphenylene derivative, and an organic electroluminescence device is provided.

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 benzothienoindole derivative.

The benzothienoindole derivative of the present invention 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 benzothienoindole ring. In relation to such a structure, 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 (exhibiting excellent amorphous properties).
(E) Excellent heat resistance.

Therefore, the benzothienoindole 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 stable, it is used as an organic layer particularly provided in the organic EL device, The following characteristics can be imparted to the organic 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 benzothienoindole derivative of the present invention has a high hole injection / transfer rate, a high electron blocking property, Since the stability to electrons is high, excitons generated in the light-emitting layer can be confined, and the probability of recombination of holes and electrons is improved, and high luminous efficiency is exhibited. Further, the driving voltage is lowered, and the durability can be improved.

The organic EL device having an electron blocking layer formed using the benzothienoindole derivative of the present invention is driven while having high luminous efficiency due to excellent electron blocking ability and excellent hole transportability. The voltage is low, the current resistance is improved, and the maximum light emission luminance is improved.

Furthermore, since the benzothienoindole derivative of the present invention has excellent hole transportability and a wide band gap compared to conventional materials, it can be used as a host material for the light emitting layer, For example, 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.

Thus, the benzothienoindole derivative of the present invention is extremely useful as a constituent material for the hole injection layer, hole transport layer, electron blocking layer, or light emitting layer of the organic EL device, and the light emission efficiency and power of the organic EL device. Efficiency can be improved, practical drive voltage can be lowered, and durability can be increased.

1 is a ¹ H-NMR chart of the compound of Example 1 (Compound 7). FIG. 2 is a ¹ H-NMR chart of the compound of Example 2 (Compound 9). FIG. 2 is a ¹ H-NMR chart of the compound of Example 3 (Compound 36). FIG. FIG. 3 is a ¹ H-NMR chart of the compound of Example 4 (Compound 8). FIG. 3 is a ¹ H-NMR chart of the compound of Example 5 (Compound 15). FIG. 2 is a ¹ H-NMR chart of the compound of Example 6 (Compound 79). FIG. 3 is a ¹ H-NMR chart of the compound of Example 7 (Compound 80). FIG. 2 is a ¹ H-NMR chart of the compound of Example 8 (Compound 6). 2 is a ¹ H-NMR chart of the compound of Example 9 (Compound 81). FIG. 2 is a ¹ H-NMR chart of the compound of Example 10 (Compound 73). FIG. The figure which shows an example of the structural formula of an organic EL element.

The benzothienoindole derivative of the present invention is represented by the following general formula (1), and a group having an aromatic tertiary amino structure (NAr ² Ar ³ ) is introduced into the benzothienoindole ring.

<Group Ar ¹ to Ar ³ >
In the above general formula (1), Ar ¹ bonded to the nitrogen atom of the benzothienoindole 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 such aromatic groups (aromatic hydrocarbon groups and aromatic heterocyclic groups) include phenyl, biphenylyl, terphenylyl, naphthyl, anthryl, phenanthryl, fluorenyl, indenyl, 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, Examples thereof include a benzothiazolyl group, a quinoxalyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, and a carbolinyl group.

Among these, phenyl group, biphenylyl group, terphenylyl group, naphthyl group, anthryl group, phenanthryl group, fluorenyl group, pyrenyl group, perylenyl group, triphenylenyl group, thienyl group, benzofuranyl group, benzothienyl group, carbazolyl group, dibenzofuran group. Nyl group and dibenzothienyl group are preferable, and phenyl group, biphenylyl group, fluorenyl group, benzothienyl group, carbazolyl group, and dibenzothienyl group are more preferable.

Moreover, said 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 an allyl group; an aryloxy group such as a phenyloxy group or a tolyloxy group; a benzyloxy group or a phenethyloxy group Arylalkyloxy groups such as phenyl group, biphenylyl group, terphenylyl group, naphthyl group, ant Aromatic hydrocarbon groups such as senyl group, phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, perylenyl group, fluoranthenyl group, triphenylenyl group; pyridyl group, thienyl group, furyl group, pyrrolyl group, quinolyl group, isoquinolyl group , Aromatic heterocyclic groups such as benzofuranyl group, benzothienyl group, indolyl group, carbazolyl group, benzoxazolyl group, benzothiazolyl group, quinoxalyl group, benzoimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, carbolinyl group Aryl vinyl groups such as styryl group and naphthyl vinyl group; acyl groups such as acetyl group and benzoyl group;
Further, these substituents may further have the substituents exemplified above.

In the above general formula (1), the substituents Ar ² and Ar ³ possessed by the amino group introduced into the benzothienoindole ring are also aromatic hydrocarbon groups as in the above-described substituent Ar ^1. Or represents an aromatic heterocyclic group. Specific examples and suitable examples thereof are also the same as those mentioned for the group Ar ¹ .
Ar ² and Ar ³ may be bonded to each other via a single bond, a methylene group which may have a substituent such as a methyl group, an oxygen atom or a sulfur atom to form a ring ( For example, compounds 45, 46, 54 to 56, 63, 64 described later) and these groups are preferably independent of each other.

Ar ³ may be bonded to A ¹ described later to form a ring. This structure will be described later.

<Groups R ¹ to R ⁷ >
In the general formula (1), groups R ¹ to R ⁷ bonded to the benzene ring in the basic skeleton of the benzothienoindole ring are each a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, Groups, alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 5 to 10 carbon atoms, alkenyl groups having 2 to 6 carbon atoms, alkyloxy groups having 1 to 6 carbon atoms, and 5 to 10 carbon atoms. A cycloalkyloxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group or an aryloxy group.

Specific examples of the alkyl group, cycloalkyl group, alkenyl group, alkyloxy group, and cycloalkyloxy group in the above R ¹ to R ⁷ include the following. In addition, other than the cycloalkyl group and the cycloalkyloxy 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 and the like.
A cycloalkyloxy group;
A cyclopentyloxy 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 (except for the alkyl group, arylvinyl group and acyl group).

The aromatic hydrocarbon group and aromatic heterocyclic group in R ¹ to R ⁷ are the same as those exemplified for Ar ¹ described above. In particular, the aromatic hydrocarbon group is preferably a phenyl group, biphenylyl group, fluorenyl group or the like, and the aromatic heterocyclic group is a sulfur-containing aromatic heterocyclic ring such as a thienyl group, a benzothienyl group, a benzothiazolyl group, or a dibenzothienyl group. Groups are preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group represented by R ¹ to R ⁷ may further have a substituent. Examples of the substituent include the same substituents that Ar ¹ may have.

In the above R ¹ to R ⁷ , the aryloxy group includes a phenyloxy group, a biphenylyloxy group, a terphenylyloxy group, a naphthyloxy group, an anthryloxy group, a phenanthryloxy group, a fluorenyloxy group, Indenyloxy group, pyrenyloxy group, perylenyloxy group and the like can be mentioned.
These aryloxy groups may also have a substituent, and examples of the substituent include the same substituents that Ar ¹ may have.

In R ¹ to R ⁷ described above, R ¹ to R ⁴ or R ⁵ to R ⁷ are bonded to each other through a single bond, a methylene group which may have a substituent, an oxygen atom or a sulfur atom. A ring may be formed, but these groups are preferably independent of each other without being bonded to each other.

<A ^1>
In the general formula (1), A ¹ bonded to the indole ring represents a divalent aromatic hydrocarbon group, a divalent aromatic heterocyclic group or a single bond.
The divalent aromatic hydrocarbon group and the divalent aromatic heterocyclic group mean a divalent group formed by removing two hydrogen atoms from an aromatic hydrocarbon ring and an aromatic heterocyclic ring.
Specific examples of such a divalent aromatic hydrocarbon group and a divalent aromatic heterocyclic group include the following.
A divalent aromatic hydrocarbon group;
Phenylene group, biphenylene group, terphenylene group, tetrakisphenylene group, naphthylene group, anthrylene group, phenanthrylene group, fluorenylene group, phenanthrolylene group, indenylene group, pyrenylene group, peryleneylene group, fluoranthenylene group, trifluorone group Nilenylene group and the like.
A divalent aromatic heterocyclic group;
Pyridinylene group, pyrimidinylene group, quinolylene group, isoquinolylene group, indoleylene group, carbazolylene group, quinoxalylylene group, benzimidazolylene group, pyrazolylene group, naphthyridinylene group, phenanthrolinylene group, acridinylene group, benzothienylene group, benzothienylene group, benzothienylene group , Dibenzothienylene group and the like.

The divalent aromatic hydrocarbon group and divalent aromatic heterocyclic group represented by A ¹ may further have a substituent. Examples of such a substituent include the same substituents that the group Ar ¹ may have.

In the present invention, A ¹ is a single bond or a phenylene group, biphenylene group, terphenylene group, naphthylene group, anthrylene group, phenanthrylene group, fluorenylene group, carbazolylene group, thienylene group, benzothienylene group, dibenzothienylene group. In particular, a phenylene group, a biphenylene group, and a fluorenylene group are preferable.

Furthermore, in the above general formula (1), the divalent aromatic group (aromatic hydrocarbon group or aromatic heterocyclic group) in A ¹ may have a substituent such as a single bond or a methyl group. It can also be bonded to the aforementioned group Ar ³ through a good methylene group, oxygen atom or sulfur atom to form a ring (for example, compounds 36, 38 to 42, 47 to 53, 58, 62 to be described later). 65, 67, 68, 72-78).

A ¹ described above is preferably bonded to the 3-position carbon atom of the benzothienoindole ring, and the benzothienoindole derivative having such a structure is represented by the following general formula (1a).

In the formula, Ar ¹ to Ar ³ , R ¹ to R ⁷ and A ¹ are as described in the general formula (1).

In the benzothienoindole derivative of the present invention represented by the above general formula (1), the compound represented by the following general formula (2) is particularly excellent in heat resistance and excellent in thin film stability. It has properties.

In the formula, Ar ¹ , Ar ² and R ¹ to R ⁷ are each represented by the general formula (1)
As described in
A ² is a divalent aromatic hydrocarbon group in the general formula (1) or 2
A part of a valent aromatic heterocyclic group (that is, a part of A ¹ ),
R ⁸ to R ¹¹ are each a hydrogen atom or A described in the general formula (1)
r ³ represents a substituent that may be present;
R ¹² to R ¹⁴ represent a hydrogen atom or a substituent that the above divalent aromatic hydrocarbon group or divalent aromatic heterocyclic group may have,
R ⁸ to R ¹¹ or R ¹² to R ¹⁴ are preferably independent from each other, but are bonded to each other via a single bond, an optionally substituted methylene group, an oxygen atom or a sulfur atom. To form a ring.
In the above general formula (2), specific examples of A ² (bridge group) which is a part of A ¹ include a single bond, a phenylene group, a biphenylene group, a naphthylene group, a phenanthrylene group, a fluorenylene group, a carbazolylene group, Examples thereof include a thienylene group, a benzothienylene group, and a dibenzothienylene group, and a phenylene group is particularly preferable.

That is, in the benzothienoindole derivative represented by the general formula (2), the group Ar ³ in the general formula (1) is a benzothienyl group, and the thiophene ring in the benzothienyl group is bonded via a single bond. Te has bound molecular structure to the benzene ring is part of a group a ^1, when viewed as a whole molecule, having a symmetrical structure in which two benzothienopyridine indole rings are linked by a bridge絡基a ² Yes. That is, although it seems to be due to such a symmetrical structure, such a compound has an advantage that it is excellent in heat resistance and stable in a thin film state.

In the above general formula (2), the bridging group A ² is preferably bonded to the 3 and 3 ′ carbon atoms of the benzothienoindole ring as in the general formula (1a) described above. It is preferable to have a structure represented by the following general formula (2a).

In the formula, Ar ¹ , Ar ² , R ¹ to R ¹⁴ and A ² are as described in the general formula (2).
That is, such compounds (for example, compounds 73 and 74 described later) have high molecular symmetry, and as shown in Example 10 described later, the glass transition point is not measured, and extremely high heat resistance is obtained. Show.

<Synthesis of benzothienoindole derivatives>
The benzothienoindole derivative of the present invention is a novel compound and can be synthesized, for example, as follows.
First, benzothienoindole in which the 10th position of benzothienoindole is substituted with an aryl group is used as a starting material, and brominated by reacting with bromine, N-bromosuccinimide, etc. Is synthesized.
Furthermore, boronic acid or boronic acid ester synthesized by the reaction of bromo-substituted triarylamine with pinacolborane or bis (pinacolato) diboron (see, for example, J. Org. Chem., 60, 7508 (1995)) Prepare. By subjecting this boronic acid or boronic ester to a bromo-substituted benzothienoindole as described above, a cross-coupling reaction such as Suzuki coupling (see, for example, Chem. Rev., 95, 2457 (1995)) The desired benzothienoindole derivative can be synthesized.
Further, the benzothienoindole substituted at the 10-position with an aryl group is further brominated to introduce a bromo group at a position other than the 3-position, and a cross-coupling reaction similar to the above is performed, whereby the bridging group A ¹ It is possible to synthesize benzothienoindole derivatives having different bonding positions.

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 can be identified by NMR analysis.

<Preferred examples of benzothienoindole derivatives>
Specific examples of preferable compounds among the benzothienoindole derivatives represented by the general formula (1) are shown below, but the present invention is not limited to these compounds.
In the following examples, compounds 1 to 4 are missing numbers.

The above-described benzothienoindole 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. can do. 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 benzothienoindole derivative of the present invention and the work function is measured, a very high value is shown.

<Organic EL device>
The organic EL element provided with the organic layer formed using the benzothienoindole derivative of the present invention described above has, for example, the structure shown in FIG.
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 benzothienoindole 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 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 5 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, the substrate 1 may have 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.

That is, the benzothienoindole derivative of the present invention is 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 preferably used as a material for forming the layer 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 benzothienoindole derivative of the present invention, or a conventionally known material such as the following material. You can also.
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 using the above-described benzothienoindole derivative of the present invention, and the conventionally known hole transport as described below. It can also be formed using a material.
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 benzothienoindole derivative of the present invention having an electron blocking action. However, it can also 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 benzothienoindole compounds of the present invention and the known hole transport materials as described above, and one or more of these hole transport materials. A plurality of layers can be formed using seeds, and a multilayer film in which such layers are stacked can be used 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, in addition to the above luminescent material, a thiazole derivative, a benzimidazole derivative, a polydialkylfluorene derivative, or the like can be used in addition to the benzothienoindole 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 benzothienoindole 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.

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

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.

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

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- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) phenyl} amine;
(Synthesis of Compound 7)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 4.0 g,
7.2 g of bis (biphenyl-4-yl)-{4- (4,4,5,5-tetramethyl- [1,3,2] dioxaboran-2-yl) phenyl} amine,
150 ml of a mixed solvent of toluene / ethanol (4/1, v / v),
30 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, 0.4 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 70 ° C. for 5.5 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation. The organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product.
The crude product is purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane), and then dispersed and washed twice with ethyl acetate, whereby bis (biphenyl-4-yl)-{4 5.3 g of a pale yellow powder of-(10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) phenyl} amine (compound 7) (yield 72.1% )

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

^The following 34 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 7.92 (1H)
7.86 (1H)
7.71-7.67 (4H)
7.62-7.53 (13H)
7.38 (4H)
7.30-7.24 (4H)
7.21-7.17 (7H)

<Example 2>
(Biphenyl-4-yl)-(9,9-dimethyl-9H-fluoren-2-yl)-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indole- Synthesis of 3-yl) phenyl} amine;
(Synthesis of Compound 9)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 4.0 g,
(Biphenyl-4-yl)-(9,9-dimethyl-9H-fluoren-2-yl)-{4- (4,4,5,5-tetramethyl- [1,3,2
] Dioxaboran-2-yl) phenyl} amine 7.2 g,
150 ml of a mixed solvent of toluene / ethanol (4/1, v / v),
30 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, 0.4 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 70 ° C. for 4 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation. The organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product.
The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane), and then crystallization purification using a mixed solvent of toluene / methanol was repeated twice to obtain (biphenyl-4-yl). )-(9,9-dimethyl-9H-fluoren-2-yl)-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) phenyl} 6.6 g (yield 85.7%) of a pale yellow powder of amine (Compound 9) was obtained.

^The following 38 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 7.93 (1H)
7.86 (1H)
7.70-7.65 (6H)
7.62-7.55 (9H)
7.41 (1H)
7.38 (2H)
7.35 (1H)
7.30-7.18 (10H)
7.08 (1H), 1.42 (6H)

<Example 3>
Synthesis of 10-phenyl-3- (9-phenyl-9H-carbazol-3-yl) -10H-benzo [4,5] thieno [3,2-b] indole;
(Synthesis of Compound 36)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 4.0 g,
9-phenyl-3- (4,4,5,5-tetramethyl- [1,3
, 2] dioxaboran-2-yl) -9H-carbazole 4.7 g,
75 ml of a mixed solvent of toluene / ethanol (4/1, v / v),
15 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, 0.4 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 70 ° C. for 9 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation. The organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product.
The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene / cyclohexane), and then purified by recrystallization using n-butanol twice to obtain 10-phenyl-3- (9-phenyl). 4.6 g (yield 80.4%) of a pale yellow powder of -9H-carbazol-3-yl) -10H-benzo [4,5] thieno [3,2-b] indole (Compound 36) 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 24 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 8.44 (1H)
8.21 (1H)
7.93 (1H)
7.90 (1H)
7.75-7.67 (7H)
7.66-7.59 (5H)
7.48 (1H)
7.43 (1H)
7.39 (1H)
7.36 (1H)
7.29 (2H)
7.23 (1H)
7.20 (1H)

<Example 4>
(9,9-dimethyl-9H-fluoren-2-yl)-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) phenyl} -phenyl Synthesis of amines;
(Synthesis of Compound 8)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 9.0 g,
(9,9-Dimethyl-9H-fluoren-2-yl)-[4- (4
, 4,5,5-tetramethyl- [1,3,2] dioxaborane-2-
Yl) phenyl] -phenylamine 12.7 g,
160 ml of 1,4-dioxane,
40 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, 0.3 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 84 ° C. for 4.5 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation. The organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product.
The crude product was dissolved in toluene by heating and purified by adsorption using silica gel, followed by dispersion washing using methanol, followed by crystallization purification using a mixed solvent of toluene / methanol twice, and methanol. (9,9-dimethyl-9H-fluoren-2-yl)-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] A pale yellowish white powder of 9.1 g (yield 57.9%) of indol-3-yl) phenyl} -phenylamine (Compound 8) was obtained.

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

^The following 34 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 7.93 (1H)
7.86 (1H)
7.68 (5H)
7.63 (2H)
7.55 (4H)
7.40 (1H)
7.29-7.21 (8H)
7.13 (4H)
7.02 (2H)
1.40 (6H)

<Example 5>
(Biphenyl-4-yl)-(4-tert-butylphenyl)-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) phenyl} amine Synthesis of
(Synthesis of Compound 15)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 5.0 g,
(Biphenyl-4-yl)-(4-tert-butylphenyl)-{
4- (4,4,5-trimethyl- [1,3,2] dioxaborane-2-
Yl) phenyl} amine 7.3 g,
160 ml of 1,4-dioxane,
40 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, 0.5 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 85 ° C. for 4 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation. The organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product.
The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane), followed by crystallization purification using a mixed solvent of ethyl acetate / n-hexane, and a mixed solvent of toluene / methanol. By performing crystallization purification, (biphenyl-4-yl)-(4-tert-butylphenyl)-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indole 5.7 g (64% yield) of pale yellowish white powder of -3-yl) phenyl} amine (Compound 15) was obtained.

^The following 38 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 7.93 (1H)
7.86 (1H)
7.70 (4H)
7.59 (3H)
7.52 (6H)
7.38 (2H)
7.34 (2H)
7.27 (3H)
7.20 (1H)
7.13 (4H)
7.08 (2H)
1.33 (9H)

<Example 6>
Synthesis of [4- {10- (9,9-dimethyl-9H-fluoren-2-yl) -10H-benzo [4,5] thieno [3,2-b] indol-3-yl} phenyl] -diphenylamine ;
(Synthesis of Compound 79)

3-bromo-10- (9,9-dimethyl-9H-fluoren-2-yl) -10H-benzo [4,5] thieno [3,2-b] indole 9.0 g,
{4- (4,4,5,5-tetramethyl- [1,3,2] dioxaboran-2-yl) phenyl} -diphenylamine 6.5 g,
110 ml of 1,4-dioxane,
27 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, 0.5 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 81 ° C. for 5 hours. After cooling to room temperature and collecting the precipitated crude product by filtration, it was dissolved by heating in toluene and subjected to adsorption purification using silica gel.
Subsequently, after carrying out dispersion washing using methanol, crystallization purification using a mixed solvent of toluene / methanol is repeated twice, whereby [4- {10- (9,9-dimethyl-9H-fluorene- 6.8 g (yield 56.7%) of a light gray white powder of 2-yl) -10H-benzo [4,5] thieno [3,2-b] indol-3-yl} phenyl] -diphenylamine (Compound 79) )

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

^The following 34 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 8.10 (1H)
7.96 (1H)
7.92-7.87 (2H)
7.83 (1H)
7.73 (1H)
7.67 (1H)
7.57 (4H)
7.39 (3H)
7.30 (1H)
7.27-7.19 (5H)
7.14-7.06 (6H)
6.99 (2H)
1.59 (6H)

<Example 7>
(9,9-dimethyl-9H-fluoren-2-yl)-[4- {10- (9,9-dimethyl-9H-fluoren-2-yl) -10H-benzo [4,5] thieno [3 Synthesis of 2-b] indol-3-yl} phenyl] -phenylamine;
(Synthesis of Compound 80)

6.9 g of 3-bromo-10- (9,9-dimethyl-9H-fluoren-2-yl) -10H-benzo [4,5] thieno [3,2-b] indole,
(9,9-Dimethyl-9H-fluoren-2-yl)-[4- (4
8.8 g of 4,5,5-tetramethyl- [1,3,2] dioxaboran-2-yl) phenyl] -phenylamine,
84 ml of 1,4-dioxane,
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, 0.2 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 85 ° C. for 4 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation. The organic layer was dehydrated with anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a crude product.
The crude product is dissolved in toluene by heating and subjected to adsorption purification using silica gel, followed by dispersion washing using methanol, crystallization purification using a mixed solvent of ethyl acetate / n-hexane, and a mixed solvent of toluene / methanol. (9,9-dimethyl-9H-fluoren-2-yl)-[4- {10- (9,9-dimethyl-9H-fluoren-2-yl) -10H -7.0 g (yield 64.8%) of white powder of -benzo [4,5] thieno [3,2-b] indol-3-yl} phenyl] -phenylamine (compound 80) was obtained.

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

^The following 42 hydrogen signals were detected by ¹ H-NMR (THF-d ₈ ).
δ (ppm) = 8.08 (1H)
7.94 (1H)
7.88 (1H)
7.71 (1H)
7.67 (1H)
7.65 (1H)
7.61 (1H)
7.58-7.54 (4H)
7.40-7.35 (4H)
7.29-7.11 (11H)
7.02-6.97 (2H)
1.57 (6H)
1.39 (6H)

<Example 8>
Synthesis of (biphenyl-4-yl)-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) phenyl} -phenylamine;
(Synthesis of Compound 6)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 7.0 g,
(Biphenyl-4-yl)-{4- (4,4,5,5-tetramethyl- [1,3,2] dioxaboran-2-yl) phenyl} -phenylamine 9.1 g,
105 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, 0.6 g of tetrakis (triphenylphosphine) palladium was added and heated, followed by stirring at 70 ° C. for 13 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation. A crude product was obtained by concentration under reduced pressure.
The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane) and then purified by crystallization using a mixed solvent of toluene / n-hexane to give (biphenyl-4-yl). )-{4- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) phenyl} -phenylamine ((Compound 6), 6.4 g of white powder ( Yield 55.9%).

^The following 30 hydrogen signals were detected by ¹ H-NMR (CDCl ₃ ).
δ (ppm) = 7.91-7.86 (2H)
7.68-7.42 (15H)
7.32-7.14 (12H)
7.06-7.02 (1H)

<Example 9>
Synthesis of {7- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) -9,9-dimethylfluorenyl-2-yl} -diphenylamine;
(Synthesis of Compound 81)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 10.0 g,
{7- (4,4,5,5-tetramethyl- [1,3,2] dioxaboran-2-yl) -9,9-dimethylfluorenyl-2-yl} -diphenylamine 14.2 g,
90 ml of a mixed solvent of THF / ethanol (7/2, v / v),
40 ml of 2M potassium carbonate aqueous solution,
0.9 g of tetrakis (triphenylphosphine) palladium,
Was added to a reaction vessel purged with nitrogen, heated, and stirred at 75 ° C. for 20 hours. After cooling to room temperature, the organic layer was collected by a liquid separation operation, and concentrated under reduced pressure to obtain a crude product.
The crude product was purified by crystallization using a mixed solvent of dichloromethane / methanol, then dissolved in toluene by heating, and the insoluble material was removed by filtration, followed by concentration. {7- (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) -9 by crystallization from methanol and recrystallization with toluene twice. , 9-dimethylfluorenyl-2-yl} -diphenylamine (Compound 81) (8.2 g, yield 46.8%) was obtained.

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

^The following 34 hydrogen signals were detected by ¹ H-NMR (CDCl ₃ ).
δ (ppm) = 7.92-7.87 (2H)
7.72-7.52 (11H)
7.34-7.11 (12H)
7.07-6.98 (3H)
1.45 (6H)

<Example 10>
Synthesis of 1,4-bis (10-phenyl-10H-benzo [4,5] thieno [3,2-b] indol-3-yl) benzene;
(Synthesis of Compound 73)

3-Bromo-10-phenyl-10H-benzo [4,5] thieno [3
, 2-b] indole 40.0 g,
Bispinacolate diboron 32.2g,
20.8 g of potassium acetate,
400 ml of toluene,
1,1-bis {(diphenylphosphino) ferrocene} palladium (II) dichloride-dichloromethane adduct 2.6 g,
Was added to a reaction vessel purged with nitrogen, heated, and stirred at 75 ° C. for 20 hours. After cooling to room temperature and removing insolubles by filtration, the organic layer was collected by a liquid separation operation and then concentrated to obtain a crude product.
The crude product was purified by column chromatography (carrier: silica gel, eluent: dichloromethane / n-heptane) and then crystallized with heptane to give 3- (4,4,5,5-tetramethyl- [1, 33.6 g of 3,2] dioxaboran-2-yl) -10-phenyl-10H-benzo [4,5] thieno [3,2-b] indole was obtained.

The resulting 3- (4,4,5,5-tetramethyl- [1,3,2] dioxabolan-2-yl) -10-phenyl-10H-benzo [4,5]
Thieno [3,2-b] indole 14.2 g,
1,4-dibromobenzene 10 g,
108 ml of a mixed solvent of THF / ethanol (7/2, v / v),
38 ml of 2M aqueous potassium carbonate solution,
0.9 g of tetrakis (triphenylphosphine) palladium,
Was added to a reaction vessel purged with nitrogen and heated, and stirred at 75 ° C. for 9 hours. After cooling to room temperature, methanol was added and the precipitate was collected by filtration. The precipitate was dissolved by heating in 1,2-dichlorobenzene, the insoluble matter was removed by filtration, and then concentrated to obtain a crude product.
The crude product was recrystallized twice using a mixed solvent of THF / acetone, and then further recrystallized twice using toluene, whereby 1,4-bis (10-phenyl-10H-benzo [4 , 5] thieno [3,2-b] indol-3-yl) benzene (Compound 73), 13.2 g (yield 76.8%) of an off-white powder.

^The following 28 hydrogen signals were detected by ¹ H-NMR (CDCl ₃ ).
δ (ppm) = 7.94-7.87 (4H)
7.68-7.53 (17H)
7.34-7.17 (7H)

<Example 11>
(Measurement of glass transition temperature)
For the benzothienoindole derivatives obtained in Examples 1 to 10, the glass transition point was determined by a high-sensitivity differential scanning calorimeter (manufactured by Bruker AXS, DSC3100S).
The results were as follows.
Glass transition point
Compound of Example 1 133.5 ° C.
Compound of Example 2 144.6 ° C
Compound of Example 3 117.7 ° C
Compound of Example 4 129.5 ° C
Compound of Example 5 131.9 ° C
Compound of Example 6 135.3 ° C
Compound of Example 7 151.1 ° C
Compound of Example 8 116.3 ° C
Compound of Example 9 130.0 ° C
Compound of Example 10 Not observed

According to the above glass transition temperature measurement results, the benzothienoindole compound of the present invention has a glass transition point of 100 ° C. or higher or was not observed. This result shows that the state of the deposited film formed using the benzothienoindole compound of the present invention is stable.

<Example 12>
Using the benzothienoindole derivatives obtained in Examples 1 to 10, a deposited film with a film thickness of 100 nm was prepared on an ITO substrate, and an ionization potential measuring device (PYS-202 type, manufactured by Sumitomo Heavy Industries, Ltd.). ) To measure the work function.
Work function Compound of Example 1 5.57 eV
Compound of Example 2 5.54 eV
Compound of Example 3 5.57 eV
Compound of Example 4 5.63 eV
Compound of Example 5 5.58 eV
Compound of Example 6 5.66 eV
Compound of Example 7 5.56 eV
Compound of Example 8 5.68 eV
Compound of Example 9 5.64 eV
NPD 5.54eV

From the above results, the benzothienoindole derivative of the present invention shows a suitable energy level as compared with the work function of 5.5 eV which is possessed by general hole transport materials such as NPD and TPD, It turns out that it has a hole transport capability.

<Example 13>
(Characteristic evaluation of organic EL elements)
An organic EL device having the structure shown in FIG. 11 was prepared, comprising a hole transport layer formed using the benzothienoindole derivative (Compound 7) 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. Then, this glass substrate with an ITO electrode was mounted in a vacuum vapor deposition machine and the pressure was reduced to 0.001 Pa or less. Subsequently, a hole injection layer 3 having a thickness of 20 nm was formed so as to cover the transparent electrode 2 using a compound 82 having the following structural formula.

On the hole injection layer 3 formed in this manner, the benzothienoindole derivative (compound 7) obtained in Example 1 was deposited to form a hole transport layer 4 having a thickness of 40 nm.
On the hole transport layer 4, a compound 83 and a compound 84 having the following structural formula are used, and binary deposition is performed at a deposition rate at which a deposition rate ratio is 83:95:95. A 30 nm light emitting layer 5 was formed.

Next, an electron transport layer 6 having a film thickness of 30 nm was formed on the light emitting layer 5 using Alq ₃ .
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 device having the structure shown in FIG.

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

<Example 14>
Except that the 40 nm-thick hole transport layer 4 was formed using the compound (Compound 9) of Example 2 instead of the benzothienoindole derivative (Compound 7) of Example 1, it was exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Example 15>
Except for forming the 40 nm-thick hole transport layer 4 by using the compound of Example 3 (Compound 36) instead of the benzothienoindole derivative (Compound 7) of Example 1, it was exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Example 16>
Except that the 40-nm-thick hole transport layer 4 was formed using the compound of Example 4 (Compound 8) instead of the benzothienoindole derivative (Compound 7) of Example 1, it was exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Example 17>
Except for using the compound (Compound 15) of Example 5 instead of the benzothienoindole derivative (Compound 7) of Example 1, the hole transport layer 4 having a thickness of 40 nm was formed to be exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Example 18>
Except that the 40-nm-thick hole transport layer 4 was formed using the compound of Example 6 (Compound 79) instead of the benzothienoindole derivative (Compound 7) of Example 1, it was exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Example 19>
Except for using the compound (Compound 80) of Example 7 instead of the benzothienoindole derivative (Compound 7) of Example 1, the hole transport layer 4 having a thickness of 40 nm was formed, and exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Example 20>
Except that the 40-nm-thick hole transport layer 4 was formed using the compound of Example 8 (Compound 6) instead of the benzothienoindole derivative (Compound 7) of Example 1, it was exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Example 21>
Except that the 40-nm-thick hole transport layer 4 was formed using the compound of Example 9 (Compound 81) instead of the benzothienoindole derivative (Compound 7) of Example 1, it was exactly the same as Example 13. Thus, an organic EL element was produced. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

<Comparative Example 1>
For comparison, in place of the benzothienoindole derivative (Compound 7) of Example 1, the following structural formula B was used to form a hole transport layer 4 having a thickness of 40 nm. Similarly, an organic EL device was produced.

Table 1 summarizes the measurement results of the issuance characteristics of the produced organic EL elements when a DC voltage was applied at room temperature in the atmosphere.

<Comparative Example 2>
Instead of the benzothienoindole derivative (Compound 7) of Example 1, an organic EL device was produced in the same manner as Example 13 except that the hole transport layer 4 having a film thickness of 40 nm was formed using the following structural formula 85. Was made. The obtained organic EL device was measured for light emission characteristics in the same manner as in Example 13, and the results are shown in Table 1.

As shown in Table 1, the driving voltage when a current density of 10 mA / cm ² was passed was 5.62 V for an organic EL element using Compound B and 4.87 V for an organic EL element using Compound 85. On the other hand, in the organic EL devices using the compounds of Examples 1 to 9 of the present invention, the voltage was decreased from 4.63 to 4.80 V. In terms of power efficiency, the compounds of Examples 1 to 9 of the present invention were used for 5.06 lm / W of the organic EL device using Compound B and 5.06 lm / W of the organic EL device using Compound 85. The conventional organic EL device was improved from 5.16 to 5.57 lm / W.

As is clear from the above results, the organic EL device using the benzothienoindole derivative of the present invention is improved in power efficiency as compared with the organic EL device using the known compound B or compound 85, It was found that a decrease in practical driving voltage can be achieved.

Further, with respect to the organic EL devices obtained in Examples 13 to 21, Comparative Example 1 and Comparative Example 2, the light emission starting voltage was measured, and the results are shown below.
Organic EL device Compound Luminescence start voltage [V]
Example 13 Compound 7 2.7
Example 14 Compound 9 2.7
Example 15 Compound 36 2.7
Example 16 Compound 8 2.7
Example 17 Compound 15 2.8
Example 18 Compound 79 2.8
Example 19 Compound 80 2.7
Example 20 Compound 6 2.7
Example 21 Compound 81 2.7
Comparative Example 1 Compound B 2.9
Comparative Example 2 Compound 85 2.8

As can be seen from the results, each of the organic EL devices using the benzothienoindole derivatives (compounds of Examples 1 to 9) of the present invention as compared with the organic EL devices using the conventionally known compounds B and 85, respectively. Has a low emission start voltage.

The benzothienoindole derivative of the present invention is excellent as a compound for an organic EL device because it has a high hole transport ability, an excellent electron blocking ability, 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.

DESCRIPTION OF SYMBOLS 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

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

Where
Ar 1 to Ar 3 represent an aromatic hydrocarbon group or an aromatic heterocyclic group, and Ar 2 and Ar 3 are a single bond or an optionally substituted methylene group, oxygen atom or sulfur atom. May be linked together to form a ring,
R 1 to R 7 are 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 atom Alkenyl group having 2 to 6 carbon atoms, alkyloxy group having 1 to 6 carbon atoms, and 5 to 1 carbon atoms
A cycloalkyloxy group of 0, an aromatic hydrocarbon group, an aromatic heterocyclic group or an aryloxy group, wherein R 1 to R 4 or R 5 to
R 7 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,
A 1 represents a divalent aromatic hydrocarbon group, a divalent or aromatic heterocyclic group represents a single bond, A 1 is a divalent aromatic hydrocarbon group or a divalent Kaoru aromatic heterocyclic group In this case, A 1 and Ar 3 are a single bond,
A ring may be formed by bonding to each other via a methylene group, an oxygen atom or a sulfur atom which may have a substituent.
The group A 1 is bonded to the 3-position carbon atom, and the following general formula (1a):

Where
Ar 1 to Ar 3 , R 1 to R 7 and A 1 have the same meanings as described in the general formula (1).
The benzothienoindole derivative of Claim 1 represented by these.
The Ar 3 is a benzothienyl group, the thiophene ring in the benzothienyl group has a structure bonded to the A 1 through a single bond, and the following general formula (2):

Where
Ar 1 , Ar 2 , R 1 to R 7 have the same meanings as described in the general formula (1),
A 2 is a part of A 1 and represents a divalent aromatic hydrocarbon group, a divalent aromatic heterocyclic group or a single bond,
R 8 ~ R 14 is a hydrogen atom, a deuterium atom, a fluorine atom, EnsoHara child, a cyano group, a nitro group, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having a carbon number of 5-10, carbon atoms Alkenyl groups having 2 to 6 carbon atoms, alkyloxy groups having 1 to 6 carbon atoms, and 5 to 5 carbon atoms
10 cycloalkyloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups or aryloxy groups, wherein R 8 to R 11 or R 12 to R 14 may have a single bond or a substituent. It may be bonded to each other via a methylene group, an oxygen atom or a sulfur atom to form a ring.
The benzothienoindole derivative of Claim 1 represented by these.
The following general formula (2a):

Where
Ar 1 , Ar 2 , R 1 to R 14, and A 2 represent the above general formula (2)
Meaning as described in the
The benzothienoindole derivative of Claim 3 represented by these.
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 benzothienoindole derivative according to claim 1.
6. The organic electroluminescence device according to claim 5, wherein the organic layer containing the benzothienoindole derivative is a hole transport layer.
6. The organic electroluminescence device according to claim 5, wherein the organic layer containing the benzothienoindole derivative is an electron blocking layer.
6. The organic electroluminescence device according to claim 5, wherein the organic layer containing the benzothienoindole derivative is a hole injection layer.
The organic electroluminescent device according to claim 5, wherein the organic layer containing the benzothienoindole derivative is a light emitting layer.