JP5167747B2 - Charge transport material for low molecular weight coating type organic electroluminescent device, composition for organic electroluminescent device, thin film for organic electroluminescent device, and organic electroluminescent device - Google Patents

Description

  The present invention relates to a charge transport material used when forming an organic layer of an organic electroluminescence device by a wet film forming method such as coating, a composition for an organic electroluminescence device containing the charge transport material, and the organic electroluminescence device The present invention relates to an organic electroluminescent device having a layer formed of a composition for use.

In recent years, an electroluminescent element (organic electroluminescent element) using an organic thin film has been developed. Examples of the method for forming the organic thin film include a vacuum deposition method and a wet film formation method. The wet film formation method does not require a vacuum process, is easy to increase in area, and has an advantage that it is easy to mix a plurality of materials having various functions into one layer (coating liquid). .
Polymer materials such as poly (p-phenylene vinylene) derivatives and polyfluorene derivatives are mainly used as materials for the light-emitting layer formed by the wet film formation method. There's a problem.

・ It is difficult to control the degree of polymerization and molecular weight distribution of polymer materials.
・ Deterioration due to terminal residues occurs during continuous driving.
・ High purity of the material itself is difficult and contains impurities.
Due to the above-described problems, an element using a wet film formation method is inferior in driving stability as compared with an element using a vacuum deposition method, and has not reached a practical level except for a part.

  As an attempt to solve the above problems, Patent Document 1 uses an organic thin film formed by a wet film-forming method by mixing a plurality of low-molecular materials (charge transporting materials and light-emitting materials) instead of a polymer compound. The organic electroluminescent elements described above are described, and the following compounds H-1 and H-2 are used as hole transporting charge transporting materials.

  In addition, in an organic electroluminescent device using an organic thin film made of a plurality of low-molecular materials formed by a wet film forming method, Non-Patent Document 1 discloses a device using phosphorescence emission in order to increase the luminous efficiency of the device. The following compounds H-3 and H-4 are used for the charge transport materials described.

However, the compounds H-1, H-2, H-3, and H-4 have low solubility in solvents. For this reason, it is necessary to use a halogen-based solvent such as chloroform as a coating solvent, but the halogen-based solvent has a large environmental load and has a practical problem. Furthermore, since there is a high possibility that the material is deteriorated by impurities contained in the halogen-based solvent, it is considered that an element formed by a wet film formation method using a halogen-based solvent does not have sufficient driving stability. Further, the compounds H-1, H-2, H-3, and H-4 are very easily crystallized, and it is difficult to obtain a uniform amorphous film by the wet film forming method. In the case where a phosphorescent material is used as the light-emitting material, compound H-1 has a low triplet excitation level, and thus light emission of an organic electroluminescent element formed using a composition containing compound H-1 and the phosphorescent material. Efficiency is considered low.
Japanese Patent Laid-Open No. 11-238359 Japanese Journal of Applied Physics Vol.44, No.1B, 2005, pp.626-629

  The present invention relates to a light emitting layer formed by a wet film formation method, and in an organic electroluminescent element having a light emitting layer whose light emitting material is a low molecular material, a layer made of a low molecular material (hereinafter referred to as a low molecular organic layer). It is an object of the present invention to provide an organic electroluminescence device that is difficult to crystallize, has high luminous efficiency, low driving voltage, and excellent driving stability including heat resistance.

  As a result of intensive studies to solve the above problems, the present inventors have expressed the following formula (I) as a charge transport material used for forming a low molecular organic layer of an organic electroluminescent element by a wet film forming method. The organic electroluminescent device manufactured using a wet film-forming method can form a film that has a partial structure that has high heat resistance, triplet excitation level, and high solubility and is difficult to crystallize. The present inventors have found that a highly practical organic electroluminescence device having high luminous efficiency, low driving voltage and excellent driving stability including heat resistance can be obtained even when used in the present invention.

  That is, the present invention relates to a charge transport material for a low molecular weight coating type organic electroluminescence device, comprising the compound having a partial structure represented by the following formula (I), and a composition for an organic electroluminescence device containing the charge transport material. And organic electroluminescent devices.

(In formula (I), ring A may have a substituent.)
Moreover, this invention discovered the following novel compound excellent in heat resistance and solubility as a compound which forms the organic layer of an organic electroluminescent element, and reached | attained this invention.
That is, the present invention resides in an organic compound represented by the following formula (III).

(In Formula (III), Ring B, Ring C, and Ring D each independently represent a benzene ring that may have a substituent other than the —NR ₁ R ₂ group. Ring B ′ and Ring D 'Represents an independently substituted benzene ring, and R ₁ and R ₂ each represents an arbitrary substituent, and R ₁ and R ₂ are bonded to form a ring. A plurality of R ₁ and R ₂ contained in one molecule may be the same or different from each other, provided that at least one of the —NR ₁ R ₂ groups has the above formula ( And n and m each represent an integer of 0 to 3.)

  The charge transport material having a compound having a partial structure represented by the above formula (I) of the present invention has a high triplet excitation level, high heat resistance, and excellent solubility in a solvent. By using this charge transport material, it is possible to form a film that is difficult to crystallize, has excellent thermal stability, and has excellent light emitting characteristics by a wet film forming method. An organic electroluminescent element having a layer formed by a wet film-forming method using this charge transport material has a low driving voltage and excellent driving stability including heat resistance.

Furthermore, the organic compound represented by the above formula (III) of the present invention has very high heat resistance and is excellent in solubility in a solvent. Therefore, using this organic compound, it is possible to form a film that is difficult to crystallize, has excellent thermal stability, and excellent emission characteristics by a wet film formation method.
The organic electroluminescent device according to the present invention is a flat panel display (for example, for OA computers or wall-mounted televisions), an in-vehicle display device, a light source utilizing characteristics as a mobile phone display or a surface light emitter (for example, a light source of a copying machine, a liquid crystal). It can be applied to backlight sources for displays and instruments, display panels, and indicator lights, and its technical value is great.

Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. It is not specified in the contents.
[Charge transport material]
The present invention relates to a charge transport material for a low molecular weight coating type organic electroluminescence device, comprising a compound having a partial structure represented by the following formula (I).

  In the present invention, an organic electroluminescent element having a light emitting layer formed by a wet film forming method and having a light emitting material made of a low molecular material is referred to as a low molecular coating type organic electroluminescent element.

(In formula (I), ring A may have a substituent.)
The charge transport material for a low molecular weight coating type organic electroluminescence device of the present invention (hereinafter, appropriately referred to as the charge transport material of the present invention) has a partial structure represented by the formula (I). By having the partial structure represented by this formula (I), it has excellent charge (hole) transport ability, high triplet excitation level, high heat resistance, and solubility in a solvent. Excellent. Therefore, it can be used for an organic layer of an organic electroluminescent element formed by a wet film forming method, and is particularly preferably used for a light emitting layer by a wet film forming method together with a low molecular light emitting material.
In the present invention, the wet film forming method is a method in which a film is formed by applying a composition by spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, ink jet method or the like.

The charge transport material of the present invention is a low molecular weight material, and its molecular weight is 5000 or less, preferably 4000 or less, more preferably 3000 or less, particularly preferably 2000 or less, and usually 400 or more, preferably 500 or more, More preferably, it is 600 or more.
If the molecular weight exceeds the upper limit, purification may become difficult due to the high molecular weight of impurities, and if the molecular weight is lower than the lower limit, the glass transition temperature, melting point, vaporization temperature, etc. will decrease, and heat resistance will be significantly impaired. There is a risk of being.

  The charge transport material of the present invention usually has a glass transition temperature of 50 ° C. or higher, but from the viewpoint of heat resistance and the process of the wet film forming method, the glass transition temperature is preferably 120 ° C. or higher, and 150 ° C. More preferably, it is the above. The upper limit of the glass transition temperature is usually about 400 ° C. The charge transport material of the present invention usually has a vaporization temperature of 300 ° C. or higher and 800 ° C. or lower. The charge transport material of the present invention preferably has no crystallization temperature between the glass transition temperature and the vaporization temperature.

The substituent which ring A in formula (I) may have is usually a substituent having a molecular weight of 300 or less, and the substituent is formed by linking two or more substituents exemplified below. There may be. Hereinafter, specific examples of the substituent are exemplified.
An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, and a tert-butyl group.)
An alkenyl group which may have a substituent (preferably an alkenyl group having 2 to 9 carbon atoms, such as vinyl, allyl, 1-butenyl group and the like).
An alkynyl group which may have a substituent (preferably an alkynyl group having 2 to 9 carbon atoms, such as ethynyl and propargyl groups).
An aralkyl group which may have a substituent (preferably an aralkyl group having 7 to 15 carbon atoms, such as a benzyl group).
An alkoxy group that may have a substituent (preferably an alkoxy group having 1 to 8 carbon atoms that may have a substituent, such as methoxy, ethoxy, and butoxy groups).
An aryloxy group which may have a substituent (preferably an aromatic hydrocarbon group having 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy group, etc.) )
An aromatic hydrocarbon group which may have a substituent (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, etc. And monovalent groups derived from 5- or 6-membered monocyclic rings or 2 to 5 condensed rings.)
An aromatic heterocyclic group which may have a substituent (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrrolo) Imidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, Monovalent groups derived from 5- or 6-membered monocyclic or 2-4 condensed rings such as pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring Can be mentioned.)
Examples of the substituent of the substituent exemplified above include those exemplified above.

From the standpoint of further improving solubility and amorphousness, the substituent of the benzene ring of ring A is preferably an alkyl group which may have a substituent, more preferably a methyl group, an ethyl group, n A lower alkyl group such as a -propyl group, 2-propyl group, n-butyl group, isobutyl group, tert-butyl group, and more preferably a methyl group or an ethyl group.
From the viewpoint of improving the electrochemical durability and the heat resistance, the benzene ring of the ring A is preferably unsubstituted or the ring A preferably has an aromatic hydrocarbon group as a substituent. A phenyl group is preferred as the aromatic hydrocarbon group.

If the charge transport material of the present invention is a compound having a partial structure represented by the above formula (I), it usually has an excellent charge (hole) transport ability, a high triplet excitation level, and a high level. Although it has heat resistance and excellent solubility in a solvent, in order to have higher solubility, a compound having a partial structure represented by the following formula (II) is preferable. In particular, the partial structure represented by the above formula (I) is more preferably linked by a group formed by linking one or more of the partial structures represented by the following formula (II). In particular, in order to improve durability against repeated electrical one-electron oxidation and neutralization, a 3,6-diphenyl-N-carbazolyl group represented by the general formula (I) is represented by the following formula (II). A partial structure introduced by m-position linkage in combination with the partial structure to be formed is preferred. From the viewpoint of improving solubility, it is preferable to have two or more m-phenylene groups represented by the formula (II) in the molecule as a partial structure. However, if these m-phenylene groups are excessively contained, the heat resistance is lowered. There is a fear.

  In particular, the charge transport material of the present invention is preferably a compound having a partial structure represented by the following formula (II-1) or (II-2).

式（ＩＩ−１）または（ＩＩ−２）で表される部分構造は、置換基を有していてもよい。該置換基としては、下記環Ｂ、環Ｃ、環Ｄ、環Ｂ’および環Ｄ’のベンゼン環が有していてもよい任意の置換基として例示したものが挙げられる。

The partial structure represented by the formula (II-1) or (II-2) may have a substituent. Examples of the substituent include those exemplified as the optional substituents that the benzene ring of the following ring B, ring C, ring D, ring B ′ and ring D ′ may have.

In addition, in order to have higher durability, in addition to the partial structure represented by the formula (I), a compound having one or more carbazolyl groups may further have an electrically stable site in one molecule. It is preferable that the heat resistance is improved by introducing a carbazolyl group, so that thermal deterioration during driving can be improved.
Furthermore, the charge transport material of the present invention is an electrochemical compound that is composed of only a partial structure selected from the group consisting of a benzene ring, an aromatic heterocycle having a nitrogen atom as a hetero atom, and a nitrogen atom. It is preferable for improving stability and triplet excitation level.

The charge transport material of the present invention preferably has no group containing a hetero atom other than a nitrogen atom. In particular, the charge transport material of the present invention is most preferably a compound composed only of a partial structure selected from the group consisting of a benzene ring, an aromatic heterocycle having a nitrogen atom as a hetero atom, and a nitrogen atom.
In addition, a compound composed only of a benzene ring, an aromatic heterocycle having a nitrogen atom as a heteroatom, and a partial structure selected from the group consisting of nitrogen atoms is an aromatic heterocycle having a nitrogen atom as a benzene ring and a heteroatom. A compound formed by bonding only a ring or an atom selected from the group consisting of a ring and a nitrogen atom. That is, it means that an alkyl group, an alkoxy group, an aryloxy group and the like are not included in this compound.

In addition, the charge transport material of the present invention preferably has an odd number of groups (partial structures) represented by the formula (I) in one molecule in terms of higher durability, and more preferably only one. It is preferable to have. Moreover, it is preferable that it has two or more partial structures shown by general formula (I) at the point which has high solubility and high heat resistance.
As described above, the charge transport material of the present invention preferably further has an unsubstituted carbazolyl group in addition to the group represented by the general formula (I). It is preferable that the ratio of the group represented and the unsubstituted carbazolyl group be the same. Here, the abundance ratio of the group represented by the general formula (I) and the unsubstituted carbazolyl group in one molecule is (the molecular weight of the group represented by the general formula (I) (molecular weight 318) or unsubstituted. Carbazolyl group molecular weight (molecular weight 166)) / 1 molecular weight × 100%. Further, “similar” means that the difference in the respective existence ratios is within ± 5%. By using a charge transport material that satisfies the above-mentioned existence ratio, a long-life device can be obtained. Similarly, the number of the group represented by the general formula (I) and the unsubstituted carbazolyl group in one molecule is the group represented by the general formula (I): the unsubstituted carbazolyl group = 1: 2. In order to obtain a device having a long lifetime, it is particularly preferable that it is present at a ratio of
Among them, the charge transport material of the present invention has a particularly excellent charge (hole) transport ability, a high triplet excitation level, high heat resistance, and excellent solubility in a solvent. It is preferable to consist of an organic compound represented by the formula (III).

  In addition, the compound represented by the following formula (III) is a novel compound, not only as a charge transport material, but also for various light emitting materials, solar cell materials, battery materials (electrolyte, electrode, separation membrane, stabilizer, etc.) ), Medical use, coating material, coating material, organic semiconductor material, toiletry material, antistatic material, thermoelectric element material and the like.

(In Formula (III), Ring B, Ring C, and Ring D each independently represent a benzene ring that may have a substituent other than the —NR ₁ R ₂ group. Ring B ′ and Ring D 'Represents an independently substituted benzene ring, and R ₁ and R ₂ each represents an arbitrary substituent, and R ₁ and R ₂ are bonded to form a ring. A plurality of R ₁ and R ₂ contained in one molecule may be the same or different from each other, provided that at least one of the —NR ₁ R ₂ groups has the above formula ( And n and m each represent an integer of 0 to 3.)
In the formula (III), at least one of the —NR ₁ R ₂ groups is a group represented by the formula (I), and the other —NR ₁ R ₂ group is an unsubstituted carbazolyl group. preferable.

Ring B, ring C and ring D in the formula (III) each independently represent a benzene ring which may have a substituent other than the —NR ₁ R ₂ group. Ring B ′ and ring D ′ each independently represent a benzene ring which may have a substituent.
The optional substituents that the benzene ring of ring B, ring C, ring D, ring B ′ and ring D ′ may have are usually substituents having a molecular weight of 300 or less. Examples of the substituent are mentioned. The substituent may be formed by linking two or more substituents exemplified below. Hereinafter, specific examples of the substituent are exemplified.

An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, and a tert-butyl group.)
An alkenyl group which may have a substituent (preferably an alkenyl group having 2 to 9 carbon atoms, such as vinyl, allyl, 1-butenyl group and the like).
An alkynyl group which may have a substituent (preferably an alkynyl group having 2 to 9 carbon atoms, such as ethynyl and propargyl groups).
An aralkyl group which may have a substituent (preferably an aralkyl group having 7 to 15 carbon atoms, such as a benzyl group).
An alkoxy group that may have a substituent (preferably an alkoxy group having 1 to 8 carbon atoms that may have a substituent, such as methoxy, ethoxy, and butoxy groups).
An aryloxy group which may have a substituent (preferably an aromatic hydrocarbon group having 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy group, etc.) )
An aromatic hydrocarbon group which may have a substituent (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, etc. And monovalent groups derived from 5- or 6-membered monocyclic rings or 2 to 5 condensed rings.)
An aromatic heterocyclic group which may have a substituent (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrrolo) Imidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, Monovalent groups derived from 5- or 6-membered monocyclic or 2-4 condensed rings such as pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring Can be mentioned.)
Examples of the substituent of the substituent exemplified above include those exemplified above.

  From the viewpoint of improving electrochemical durability and improving heat resistance, the substituents of the benzene ring of ring B, ring C, ring D, ring B ′ and ring D ′ each have a substituent. An aromatic hydrocarbon group that may be substituted is preferable, and a phenyl group that may have a substituent is more preferable. More preferably, it is an unsubstituted phenyl group, or a mono- or di-substituted phenyl group (provided that this number is the substituent for ring B, ring C, ring D, ring B ′ and ring D ′ in formula (III)). Is a number not included.)

From the viewpoint of further improving the solubility and the amorphousness, the substituent of the benzene ring of ring B, ring C, ring D, ring B ′ and ring D ′ may be an alkyl which may have a substituent. Group, more preferably a lower alkyl group such as a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, an n-butyl group, an isobutyl group, or a tert-butyl group, more preferably a methyl group or an ethyl group. .

N and m each represent an integer of 0 to 3, and may be the same or different. n and m are preferably n = m = 0 or 1, and more preferably n = m = 0.
Ring B, ring C, ring D, ring B ′ and ring D ′ are preferably formed by connecting the respective rings at the meta position. That is, it is preferable that Ring B, Ring C, Ring D, Ring B ′ and Ring D ′ are connected to a group represented by the above formula (II).

  The charge transport material of the present invention has a particularly high heat resistance, n = m = 0, and ring B, ring C, and ring D are connected as represented by the following formula (IV). It is preferable that

In the formula (III), R ₁ and R ₂ each represent an arbitrary substituent, and may be the same or different from each other. The substituent is usually a substituent having a molecular weight of 300 or less, and specific examples thereof include the substituents exemplified below. The substituent may be formed by linking two or more substituents exemplified below. Hereinafter, specific examples of the substituent are exemplified.
An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, and a tert-butyl group.)
An alkenyl group which may have a substituent (preferably an alkenyl group having 2 to 9 carbon atoms, such as vinyl, allyl, 1-butenyl group and the like).
An alkynyl group which may have a substituent (preferably an alkynyl group having 2 to 9 carbon atoms, such as ethynyl and propargyl groups).
An aralkyl group which may have a substituent (preferably an aralkyl group having 7 to 15 carbon atoms, such as a benzyl group).
An acyl group which may have a substituent (preferably an acyl group having 2 to 10 carbon atoms which may have a substituent, such as formyl, acetyl and benzoyl groups)
An alkoxycarbonyl group which may have a substituent (preferably an alkoxycarbonyl group having 2 to 10 carbon atoms which may have a substituent, such as a methoxycarbonyl group and an ethoxycarbonyl group)
Aryloxycarbonyl group which may have a substituent (preferably an alkylcarbonyloxy group having 2 to 10 carbon atoms which may have a substituent, such as an acetoxy group)
Halogen atom (especially fluorine atom or chlorine atom)
Carboxy group Aromatic hydrocarbon group which may have a substituent (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring And monovalent groups derived from a 5- or 6-membered monocyclic ring or a 2-5 condensed ring).
An aromatic heterocyclic group which may have a substituent (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrrolo) Imidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, Monovalent groups derived from 5- or 6-membered monocyclic or 2-4 condensed rings such as pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring Can be mentioned.)
Examples of the substituent that each group described above may have include an alkyl group having about 1 to 6 carbon atoms; an aryl group containing an alkoxy group having about 1 to 6 carbon atoms and an aromatic hydrocarbon group having about 6 to 10 carbon atoms. An oxy group; an alkylamino group having at least one alkyl group having about 1 to 6 carbon atoms: an aromatic hydrocarbon group having about 6 to 20 carbon atoms, an alkylthio group having about 1 to 6 carbon atoms, and about 6 to 10 carbon atoms An arylthio group having an aromatic hydrocarbon group, an acyl group having about 2 to 20 carbon atoms, and the like.

R ₁ and R ₂ are more preferably an aromatic hydrocarbon group which may have a substituent or an aromatic which may have a substituent from the viewpoint of charge transportability, electrochemical durability and heat resistance. An aromatic hydrocarbon group which may have a substituent is most preferable.
Specific examples of the —NR ₁ R ₂ group include the followings because the charge transportability and electrical redox durability are improved, or a moderately wide redox potential difference is obtained.

Among them, a1, a2, a3 and a7 are preferable, and a1, a2 and a7 are more preferable.
On the other hand, in the charge transport material of the present invention, R ₁ and R ₂ are bonded to each other from the viewpoint of suppressing non-radiative deactivation (thermal deactivation) of excitons due to unnecessary molecular motion and improving emission quantum efficiency. A compound which forms a ring with N atom is preferred. The —NR ₁ R ₂ group (hereinafter referred to as “cyclic-NR ₁ R ₂ group”) in which R ₁ and R ₂ are combined to form a ring is conjugated with an unshared electron pair on the N atom contained in itself. It is preferable to have a π electron, and the group as a whole is preferably an aromatic group (aromatic hydrocarbon group or aromatic heterocyclic group). Particularly preferred is an N-carbazolyl group, and most preferred is a 3,6-diphenyl-N-carbazolyl group which may have the same substituent as in the above formula (I). Specific examples of more preferable cyclic -NR ₁ R ₂ groups are shown below, but the present invention is not limited thereto.

In addition, these cyclic —NR ₁ R ₂ groups may have an arbitrary substituent, and examples thereof may include ring B, ring C, ring D, ring B ′ and ring D ′. The group mentioned above is mentioned as a substituent.

  Specific examples preferable as the charge transport material of the present invention are shown below, but the present invention is not limited thereto.

The compound represented by the formula (III) can be synthesized by selecting a raw material according to the structure of the target compound and using a known method. For example, it can be synthesized by the following method.
(a) Diarylamino group, carbazolyl group (R ¹ R ² N-), etc. with respect to the fluorine atom of the raw material (XArX (F)) (X = Br, I) having a fluorine atom as a substituent (the fluorine atom Hydrogen in a solvent such as tetrahydrofuran, dioxane, ether, N, N-dimethylformamide under a dry gas atmosphere and / or an inert gas atmosphere. A strong base (about 1.1 to 10 equivalents with respect to fluorine atoms) such as sodium halide, tert-butoxypotassium, and n-butyllithium is reacted for 1 to 60 hours under heating and reflux. The obtained compound (XAr (-NR ¹ R ² ) X) and the diarylamino group and carbazolyl group (R ¹ 'R ² ' N-) to be further introduced are combined with copper powder, copper wire, copper halide (CuX ( X = Cl, Br, I)), copper oxide (CuO)
Copper catalysts (about 0.1 to 5 equivalents to the starting halogen atom) and basic substances such as potassium carbonate, calcium carbonate, potassium phosphate, cesium carbonate, tert-butoxy sodium (based on the starting halogen atom) In the presence of 1 to 10 equivalents), in an inert gas stream, in a solvent-free or aromatic solvent such as nitrobenzene, in a solvent such as tetraglyme and polyethylene glycol, in a temperature range of 20 to 300 ° C., 1 to 60 A method of stirring and mixing for hours.

(b) Or the obtained compound (XAr (-NR ¹ R ² ) X) and the diarylamino group and carbazolyl group (R ¹ 'R ² ' N-) to be further introduced are combined with Pd ₂ (dba) ₃ (Pd = Palladium, dba = dibenzylite acetone), Pd (dba) ₂ , palladium acetate and other bivalent palladium catalysts and BINAP (= 2,2-bis (diphenylphosphino-1,1'-binaphthyl), tri ( tert-butyl) phosphine,
Combination of ligands such as triphenylphosphine, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) butane, dppf (= 1,1'-bis (diphenylphosphino) ferrocene) Or a catalyst (about 0.001 to 1 equivalent to the halogen atom of the starting material) such as a zero-valent palladium complex such as Pd (PPh) ₄ or a palladium chloride complex such as PdCl ₂ (dppf) ₂ , and tert- Tetrahydrofuran, dioxane, dimethoxyethane, N, N- in the presence of a basic substance such as butoxykari, tert-butoxy sodium, potassium carbonate, cesium carbonate or triethylamine (usually 1.1 to 10 equivalents relative to the halogen atom of the starting material). Stir in a solvent such as dimethylformamide, dimethyl sulfoxide, xylene, toluene, etc. at 30 to 200 ° C. for 1 to 60 hours. Method.

(c) or the intermediate compound (XAr (—NR ¹ R ² ) X) obtained above using diarylaminophenylboronic acid, carbazolephenylboronic acid or the like as a starting material and tetrakis (triphenylphosphine) palladium, etc. In the presence of a palladium catalyst (about 1 to 5 mol%), a base such as cesium carbonate, potassium phosphate, sodium carbonate (about 1.5 to 5 times equivalent to the halogen atom of the halide), toluene-ethanol, toluene- Water, tetrahydrofuran, dioxane, dimethoxyethane, N, N-dimethylformamide, or the like, or a mixed solvent system thereof (the boronic acid concentration is about 1 to 100 mmol%) in an inert gas atmosphere for about 5 to 24 hours, Method by heating to reflux.
In addition to the above, known methods can be applied, and amine groups can be introduced by the method described in the “4th edition experimental chemistry course 20” (edited by the Japan Science Society, Maruzen), Chapter 6 (Amine), etc. Applicable.

Next, the composition for organic electroluminescent elements will be described.
The composition for organic electroluminescent elements to which this exemplary embodiment is applied contains at least the charge transport material described above. Usually, it contains a solvent, preferably a light emitting material.
(1) Solvent Various solvents can be applied as the solvent contained in the composition for organic electroluminescent elements of the present invention, and the solvent is not particularly limited. For example, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene and tetralin; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene and anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole and other aromatic ethers; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic esters such as ethyl, propyl benzoate and n-butyl benzoate; ketones having an alicyclic ring such as cyclohexanone and cyclooctanone; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; methyl ethyl ketone and cyclohexano Alcohol having an alicyclic ring such as ruthenium or cyclooctanol; Aliphatic alcohol such as butanol or hexanol; Aliphatic ether such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether or propylene glycol-1-monomethyl ether acetate (PGMEA); Ethyl acetate And aliphatic esters such as n-butyl acetate, ethyl lactate and n-butyl lactate.

Of these, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetralin and the like are preferable in that they have low water solubility and are not easily altered.
Since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, the presence of moisture in the composition causes moisture to remain in the dried film, degrading the device characteristics. The possibility is considered and it is not preferable.

  Examples of the method for reducing the amount of water in the composition include nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, use of a solvent having low water solubility, and the like. In particular, it is preferable to use a solvent having low water solubility because the solution film can prevent whitening by absorbing moisture in the atmosphere during the wet film forming process. From such a viewpoint, the composition for an organic electroluminescent device of the present invention contains, for example, a solvent having a water solubility at 25 ° C. of 1% by weight or less, preferably 0.1% by weight or less. The content is preferably 10% by weight or more.

  Further, in order to reduce a decrease in film formation stability due to evaporation of the solvent from the composition during wet film formation, the solvent of the composition for organic electroluminescent elements has a boiling point of 100 ° C. or higher, preferably a boiling point of 150. It is effective to use a solvent having a boiling point of 200 ° C. or higher, more preferably 200 ° C. or higher. In order to obtain a more uniform film, it is necessary for the solvent to evaporate from the liquid film immediately after film formation at an appropriate rate. For this purpose, the boiling point is usually 80 ° C. or higher, preferably 100 ° C. or higher. It is effective to use a solvent having a boiling point of 120 ° C. or more, usually less than 270 ° C., preferably less than 250 ° C., more preferably less than 230 ° C.

A solvent that satisfies the above-described conditions, that is, the conditions of solute solubility, evaporation rate, and water solubility may be used alone, or two or more kinds of solvents may be mixed and used.
(2) Light-Emitting Material The light-emitting material refers to a component that mainly emits light in the organic electroluminescent device, and corresponds to the light-emitting layer dopant component of the organic electroluminescent device. Of the amount of light (unit: cd / m ² ) emitted from the composition for organic electroluminescent elements, it is usually 10% to 100%, preferably 20% to 100%, more preferably 50% to 100%, most preferably. If 80% to 100% is identified as luminescence from a component material, it is defined as a luminescent material.

The composition for an organic electroluminescent device of the present invention is preferably used for an organic electroluminescent device in which a luminescent material is a low molecular material and a layer containing the luminescent material is formed by a wet film forming method. Although the composition for organic electroluminescent elements of the present invention contains a light emitting material and is usually used for forming a light emitting layer, it may be used for other layers such as a hole transport layer.
As the luminescent material, any known material can be applied, and a fluorescent luminescent material or a phosphorescent luminescent material can be used alone or in combination. A phosphorescent luminescent material is preferable from the viewpoint of internal quantum efficiency.

For the purpose of improving the solubility in a solvent, the symmetry and rigidity of the light emitting material molecule may be reduced, or a lipophilic substituent such as an alkyl group may be introduced.
Examples of the fluorescent material that emits blue light include perylene, pyrene, anthracene, phenanthrene, naphthalene, chrysene, fluorene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof. Examples of the fluorescent material that gives green light emission include quinacridone derivatives and coumarin derivatives. Examples of the fluorescent material that gives yellow light include rubrene and perimidone derivatives. Examples of the fluorescent material that emits red light include DCM compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, and the like.

Examples of the phosphorescent material include organometallic complexes containing a metal selected from Groups 7 to 11 of the periodic table.
Preferred examples of the metal in the phosphorescent organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Preferred examples of these organometallic complexes include compounds represented by the following general formula (3) or the following general formula (4).

ML ″ _(q−j) L ′ _j (3)
(In General Formula (3), M represents a metal, q represents a valence of the metal, L ″ and L ′ represent a bidentate ligand, and j represents 0, 1 or 2. )

(In General Formula (4), M ^d represents a metal, T represents carbon or nitrogen. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is nitrogen, R ⁹⁴ and R ⁹⁵ is not.
Hereinafter, the compound represented by the general formula (3) will be described.
In General Formula (3), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.

  In the general formula (3), bidentate ligands L ″ and L ′ each represent a ligand having the following partial structure.

L ′ is particularly preferably the following from the viewpoint of the stability of the complex.

In the partial structures of L ″ and L ′, the ring A1 represents an aromatic hydrocarbon group or an aromatic heterocyclic group, which may have a substituent. The ring A2 is a nitrogen-containing aromatic group. Represents a heterocyclic group, and these may have a substituent.
When the rings A1 and A2 have a substituent, preferred substituents include halogen atoms such as fluorine atoms; alkyl groups such as methyl groups and ethyl groups; alkenyl groups such as vinyl groups; methoxycarbonyl groups and ethoxycarbonyl groups. Alkoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diarylamino groups such as diphenylamino groups; carbazolyl groups; An acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group; an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, and a phenanthyl group.

  More preferable examples of the compound represented by the general formula (3) include compounds represented by the following general formulas (3a), (3b), and (3c).

(In general formula (3a), M ^a represents the same metal as M, w represents the valence of the metal, and ring A1 represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

(In the general formula (3b), M ^b represents the same metal as M, w represents the valence of the above metal, and ring A1 is an aromatic hydrocarbon group or substituted which may have a substituent. Represents an aromatic heterocyclic group which may have a group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.)

(In general formula (3c), M ^c represents the same metal as M, w represents the valence of the above metal, j represents 0, 1 or 2. Furthermore, ring A1 and ring A1 ′ represent Each independently represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently Represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.
In the above general formulas (3a), (3b), and (3c), the group of ring A1 and ring A1 ′ is preferably, for example, a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group, a furyl group, a benzoic group. Examples include thienyl group, benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group, carbazolyl group and the like.

In addition, the group of ring A2 and ring A2 ′ is preferably a pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, benzimidazole group, quinolyl group, isoquinolyl group, quinoxalyl group, A phenanthridyl group and the like can be mentioned.
Furthermore, the substituents that the compounds represented by the general formulas (3a), (3b), and (3c) may have include halogen atoms such as fluorine atoms; alkyl groups such as methyl groups and ethyl groups; vinyls Alkenyl groups such as methoxy groups; alkoxycarbonyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkyls such as dimethylamino groups and diethylamino groups An amino group; a diarylamino group such as a diphenylamino group; a carbazolyl group; an acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group;

These substituents may be connected to each other to form a ring. As a specific example, a substituent of the ring A1 and a substituent of the ring A2 are bonded, or a substituent of the ring A1 ′ and a substituent of the ring A2 ′ are bonded. Two fused rings may be formed. Examples of such a condensed ring group include a 7,8-benzoquinoline group.
Among them, as a substituent of ring A1, ring A1 ′, ring A2 and ring A2 ′, more preferably an alkyl group, an alkoxy group, an aromatic hydrocarbon group, a cyano group, a halogen atom, a haloalkyl group, a diarylamino group, a carbazolyl group Is mentioned.

In general formula (3a), (3b), preferably as ^{M a, M b, M c} in (3c), ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold.
Specific examples of the organometallic complexes represented by the general formulas (3), (3a), (3b), and (3c) are shown below, but are not limited to the following compounds (in the following, Ph is phenyl Represents a group).

Among the organometallic complexes represented by the above general formulas (3), (3a), (3b), and (3c), in particular, as the ligand L ″ and / or L ′, a 2-arylpyridine-based ligand, That is, a compound having 2-arylpyridine, a compound in which an arbitrary substituent is bonded thereto, and a compound in which an arbitrary group is condensed to this is preferable.
Next, the compound represented by the general formula (4) will be described.

In the general formula (4), M ^d represents a metal, and specific examples thereof include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.
In the general formula (4), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, or a carboxyl group. Represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group.

Further, when T is carbon, R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, as described above, when T is nitrogen, there is no R ⁹⁴ or R ⁹⁵ .
R ^{92 to} R ⁹⁵ may further have a substituent. In this case, the substituent which may further be present is not particularly limited, and any group can be used as the substituent.

Furthermore, R ^{92 to} R ⁹⁵ may be connected to each other to form a ring, and this ring may further have an arbitrary substituent.
Specific examples (T-1, T-10 to T-15) of the organometallic complex represented by the general formula (4) are shown below, but are not limited to the following exemplified compounds. In the following, Me represents a methyl group, and Et represents an ethyl group.

Moreover, as an organometallic complex, the compounds described in WO2005 / 019373 can also be used.
By forming the organic electroluminescent element composition of the present invention as described above on a substrate or an organic layer of an organic electroluminescent element formed on the substrate using a wet film forming method, A thin film for an electroluminescent element can be obtained.
3. Organic Electroluminescent Device Next, the organic electroluminescent device will be described.
The organic electroluminescence device to which the present embodiment is applied has at least an anode, a cathode, and a light emitting layer provided between both electrodes on a substrate, and the composition for organic electroluminescence device of the present invention is used. It has the layer formed using, It is characterized by the above-mentioned. This layer is a layer formed by a wet film forming method, and this layer is particularly preferably an organic light emitting layer.

FIG. 3 is a schematic cross-sectional view showing a structural example suitable for an organic electroluminescent element to which the present exemplary embodiment is applied. In FIG. 3, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 light emitting layer (organic light emitting layer), 8 is a hole blocking layer, 7 is an electron transport layer, 5 is an electron injection layer, and 6 is a cathode. Represents each.
[1] Substrate The substrate 1 serves as a support for the organic electroluminescence device, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, polysulfone or the like is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.
[2] Anode An anode 2 is provided on the substrate 1. The anode 2 plays a role of hole injection into a layer on the light emitting layer side (hole injection layer 3 or light emitting layer 4 or the like).

This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline. In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution It is also possible to form the anode 2 by dispersing it and applying it onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992). The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired. The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above. For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is treated with ultraviolet (UV) / ozone, or with oxygen plasma or argon plasma. It is preferable to do.
[3] Hole Injection Layer Since the hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 4, the hole injection layer 3 preferably contains a hole transporting compound. The hole injection layer 3 preferably contains a hole transporting compound, and more preferably contains a hole transporting compound and an electron accepting compound. The hole injection layer 3 preferably contains a cation radical compound, and more preferably contains a cation radical compound and a hole transporting compound. Furthermore, the hole injection layer 3 may contain a binder resin that does not easily trap charges and a coating property improving agent as necessary.

However, as the hole injection layer 3, only the electron-accepting compound is formed on the anode 2 by a wet film formation method, and the organic electroluminescent element composition of the present embodiment is directly applied and laminated thereon. It is also possible. In this case, a part of the composition of the present embodiment interacts with the electron-accepting compound, so that a layer having excellent hole injecting property is formed.
(Hole transporting compound)
As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable. Examples of the hole transporting compound include aromatic amine compounds, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, and the like. Of these, aromatic amine compounds are preferred from the viewpoints of amorphousness and visible light transmittance. An aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine. The kind of the aromatic tertiary amine compound is not particularly limited, but a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (polymerized hydrocarbon compound in which repeating units are linked) is more preferable from the viewpoint of the surface smoothing effect. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following general formula (V).

(In the general formula (V), Ar ²¹ and Ar ²² are each independently an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Ar ^{23 to} Ar ²⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. Y represents a linking group selected from the following group of linking groups, and among Ar ^{21 to} Ar ²⁵ , two groups bonded to the same N atom are bonded to each other to form a ring. May be.)

(In the above formulas, Ar ^{31 to} Ar ⁴¹ are each independently an aromatic hydrocarbon ring which may have a substituent, or 1 derived from an aromatic heterocyclic ring which may have a substituent. R represents a hydrogen atom or an arbitrary substituent. R ⁵¹ and R ⁵² each independently represents a hydrogen atom or an arbitrary substituent.
As Ar ^{21 to} Ar ²⁵ and Ar ^{31 to} Ar ⁴¹ , any monovalent or divalent group derived from any aromatic hydrocarbon ring or aromatic heterocyclic ring is applicable. These may be the same or different from each other. Moreover, you may have arbitrary substituents. The groups derived from the aromatic hydrocarbon rings and / or aromatic heterocycles of Ar ^{21 to} Ar ²⁵ and Ar ^{31 to} Ar ⁴¹ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. Ar ²¹ and Ar ²² are preferably monovalent groups derived from a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, or a pyridine ring from the viewpoint of the solubility, heat resistance, and hole injection / transport properties of the polymer compound. More preferred are a phenyl group and a naphthyl group. Ar ^{23 to} Ar ²⁵ are preferably divalent groups derived from a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring from the viewpoint of heat resistance and hole injection / transport properties including redox potential. A group, a biphenylene group, and a naphthylene group are more preferable. Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the general formula (V) include those described in WO2005 / 089024. The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. When two or more hole transporting compounds are contained, the combination thereof is arbitrary, but one or more aromatic tertiary amine polymer compounds and one or two other hole transporting compounds are used. It is preferable to use the above together.
(Electron-accepting compound)
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound which is the compound of these is more preferable. Examples include onium salts substituted with organic groups such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, iron (III) chloride (Japanese Patent Laid-Open No. 11-251067)
, Inorganic compounds having high valence such as ammonium peroxodisulfate, cyano compounds such as tetracyanoethylene, aromatic boron compounds such as tris (pentafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365), fullerene derivatives, iodine, etc. Can be mentioned. Of the above compounds, onium salts substituted with organic groups and high valent inorganic compounds are preferred because of their strong oxidizing power, and organic groups are substituted because they are soluble in various solvents and applicable to wet coating. Preferred are onium salts, cyano compounds, and aromatic boron compounds. Specific examples of an onium salt substituted with an organic group, a cyano compound, and an aromatic boron compound suitable as an electron-accepting compound include those described in WO 2005/089024, and suitable examples thereof are also the same. Although the compound (A-2) represented by the following structural formula is mentioned, it is not limited to them at all.

The hole injection layer 3 is formed on the anode 2 by a wet film forming method or a vacuum deposition method. In the case of layer formation by a wet film formation method, one or more predetermined amounts of each of the above-described materials (hole transporting compound, electron accepting compound, cation radical compound) do not become a charge trap if necessary. Add binder resin and coatability improver, dissolve in solvent, prepare coating solution, by wet film forming method such as spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, inkjet method etc. It is applied on the anode 2 and dried to form the hole injection layer 3. As the solvent used for the layer formation by the wet film forming method, any solvent can be used as long as it can dissolve the above-mentioned materials (hole transporting compound, electron accepting compound, cation radical compound). Is not particularly limited, but generates a deactivated substance or deactivated substance that may deactivate each material (hole transporting compound, electron accepting compound, cation radical compound) used for the hole injection layer 3 What does not contain a thing is preferable. An ether solvent or an ester solvent is preferable. The film thickness of the hole injection layer 3 thus formed is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. The hole injection layer 3 may be omitted.

[4] Hole Transport Layer A hole transport layer is provided on the hole injection layer 3. As conditions required for the material of the hole transport layer, it is necessary that the material has a high hole injection efficiency from the anode 2 and can efficiently transport the injected holes. For this purpose, the ionization potential is low, the transparency to visible light is high, the hole mobility is high, the stability is high, and impurities that become traps are unlikely to be generated during manufacturing or use. Required. Further, in order to come into contact with the light emitting layer 4, it is required not to quench the light emitted from the light emitting layer 4 or to form an exciplex with the light emitting layer 4 to reduce the efficiency. In addition to the above general requirements, when the application for in-vehicle display is considered, the element is further required to have heat resistance. Therefore, a material having a glass transition temperature of 80 ° C. or higher, more preferably 85 ° C. or higher is preferable.

Such a hole transporting material is 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl, similar to the hole transporting material used for the host material of the light emitting layer 4. Aromatic diamines containing two or more representative tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234811), 4,4 ′, 4 ″ -tris (1 -Aromatic amine compounds having a starburst structure such as naphthylphenylamino) triphenylamine (J. Lumin., 72-74, 985, 1997), aromatic amine compounds comprising tetramers of triphenylamine (Chem. Commun., 2175, 1996), spiro compounds such as 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene (Syn) h. Metals, 91, 209, 1997), carbazole derivatives such as 4,4′-N, N′-dicarbazole biphenyl, etc. These compounds may be used alone. In addition to the above compounds, polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Laid-Open No. 7-53953), tetraphenylbenzidine may be used as the material for the hole transport layer in addition to the above compounds. Polymer materials such as polyarylene ether sulfone (Polym. Adv. Tech., 7, p. 33, 1996) containing a hole transport layer may be formed by spraying, printing, spin coating, Ordinary coating methods such as dip coating method and die coating method, wet film forming methods such as various printing methods such as inkjet method and screen printing method, It can be formed by a dry film formation method such as an air evaporation method, etc. In the case of a wet film formation method, a binder resin or coating property that does not become a hole trap if necessary, to one or more of hole transport materials. An additive such as an improver is added and dissolved in an appropriate solvent to prepare a coating solution, which is coated on the anode 2 by a method such as spin coating, and dried to form a hole transport layer. Examples of the binder resin include polycarbonate, polyarylate, polyester, etc. Since the binder resin decreases the hole mobility when the addition amount is large, it is desirable that the binder resin is less, and usually the content in the hole transport layer is 50% by weight. The following is preferred.
In addition, you may use the composition for organic electroluminescent elements of this invention in order to form a positive hole transport layer.
The thickness of the hole transport layer is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less. In order to uniformly form such a thin film, a vacuum deposition method is generally used.

[5] Light emitting layer (organic light emitting layer)
A light emitting layer 4 is usually provided on the hole transport layer. In the present invention, the light emitting layer 4 is a layer formed by a wet film formation method using a composition containing a low molecular light emitting material. A main light emitting source excited by recombination of holes injected from the anode 2 through the hole injection layer 3 and electrons injected from the cathode 9 through the electron injection layer 5 between the electrodes to which an electric field is applied; It is a layer. The light-emitting layer 4 preferably contains a light-emitting material (dopant) and one or more host materials, and uses the composition for organic electroluminescent elements containing the charge transport material of the present invention and a low-molecular light-emitting material. Thus, it is preferably formed by a wet film formation method.

  The light emitting layer 4 may contain other materials and components as long as the performance of the organic electroluminescent element of the present embodiment is not impaired. In general, when the same material is used in the organic electroluminescent element, the thinner the film thickness between the electrodes, the larger the effective electric field, so that the injected current increases, so the driving voltage decreases. For this reason, the driving voltage of the organic electroluminescence device decreases when the total film thickness between the electrodes is thin, but if it is too thin, a short circuit occurs due to the protrusion caused by the electrode such as ITO. Necessary. In the present embodiment, in addition to the light emitting layer 4, when an organic layer such as a hole injection layer 3 and an electron injection layer 5 described later is provided, the light emitting layer 4, the hole injection layer 3, and the electron injection layer 5 The total film thickness combined with the organic layer is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, usually 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less. In addition, when the conductivity of the hole injection layer 3 other than the light emitting layer 4 and the electron injection layer 5 described later is high, the amount of charge injected into the light emitting layer 4 increases. It is also possible to reduce the drive voltage while increasing the thickness to reduce the thickness of the light emitting layer 4 and maintaining the total thickness to some extent. Therefore, the film thickness of the light emitting layer 5 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less. When the element of the present embodiment has only the light emitting layer 4 between the anode 2 and the cathode 9, the thickness of the light emitting layer 4 is usually 30 nm or more, preferably 50 nm or more, usually 500 nm or less, preferably Is 300 nm or less.

[6] Hole blocking layer When a phosphorescent dye is used as the light emitting material or a fluorescent light emitting material that emits blue light is used, it is effective to provide the hole blocking layer 8. The hole blocking layer 8 has a function of confining holes and electrons in the light emitting layer 4 and improving luminous efficiency. That is, the hole blocking layer 8 is generated by blocking the holes moving from the light emitting layer 4 from reaching the electron transport layer 7, thereby increasing the recombination probability with electrons in the light emitting layer 4. There is a role of confining excitons in the light emitting layer 4 and a role of efficiently transporting electrons injected from the electron transport layer 7 in the direction of the light emitting layer 4. The hole blocking layer 8 prevents the holes moving from the anode 2 from reaching the cathode 6 and can efficiently transport the electrons injected from the cathode 6 toward the light emitting layer 4. The compound is laminated on the light emitting layer 4 so as to be in contact with the interface of the light emitting layer 4 on the cathode 6 side. The physical properties required for the material constituting the hole blocking layer 8 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high. Examples of the material of the hole blocking layer 8 that satisfies such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Mixed ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, styryls such as distyrylbiphenyl derivatives Compounds (JP-A-11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7- 41759) and phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297). Furthermore, a compound having at least one pyridine ring substituted at the 2,4,6-positions described in WO2005 / 022962 is also preferable as the hole blocking material. The film thickness of the hole blocking layer 8 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. The hole blocking layer 8 can be formed by the same method as the hole injection layer 3, but usually a vacuum deposition method is used.

[7] Electron Transport Layer The electron transport layer 7 is provided between the light emitting layer 4 and the electron injection layer 5 for the purpose of further improving the light emission efficiency of the device. The electron transport layer 7 is formed of a compound capable of efficiently transporting electrons injected from the cathode 6 between electrodes to which an electric field is applied in the direction of the light emitting layer 4. As an electron transport compound used for the electron transport layer 7, the electron injection efficiency from the cathode 6 or the electron injection layer 5 is high, and the injected electrons can be efficiently transported with high electron mobility. It must be a compound. Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, di- Styryl biphenyl derivative, silole derivative, 3- or 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compound No. 207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide, n-type sulfide Examples include zinc and n-type zinc selenide. The lower limit of the thickness of the electron transport layer 7 is usually 1 nm, preferably about 5 nm, and the upper limit is usually about 300 nm, preferably about 100 nm. The electron transport layer 7 is formed by laminating on the light emitting layer 4 by a wet film forming method or a vacuum deposition method in the same manner as the hole injection layer 3. Usually, a vacuum deposition method is used.

[8] Electron Injection Layer The electron injection layer 5 serves to efficiently inject electrons injected from the cathode 6 into the light emitting layer 4. In order to perform electron injection efficiently, the material for forming the electron injection layer 5 is preferably a metal having a low work function, and an alkali metal such as sodium or cesium, or an alkaline earth metal such as barium or calcium is used. The film thickness of the electron injection layer 5 is preferably 0.1 to 5 nm. Also, an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO ₃ may be inserted at the interface between the cathode 9 and the light emitting layer 4 or the electron transport layer 7 described later. This is an effective method for improving the efficiency of the device (Appl. Phys. Lett., 70, 152, 1997; Japanese Patent Laid-Open No. 10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997). Year; SID 04 Digest, page 154). Further, organic electron transport materials represented by metal complexes such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and aluminum complexes of 8-hydroxyquinoline described later are doped with alkali metals such as sodium, potassium, cesium, lithium and rubidium. (Described in Japanese Patent Application Laid-Open No. 10-270171, Japanese Patent Application Laid-Open No. 2002-1000047, Japanese Patent Application Laid-Open No. 2002-1000048, and the like), the electron injecting / transporting property is improved and excellent film quality can be achieved. Therefore, it is preferable. The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less. The electron injection layer 5 is formed by laminating on the light emitting layer 4 by a wet film forming method or a vacuum deposition method in the same manner as the light emitting layer 4. In the case of the vacuum evaporation method, the evaporation source is put into a crucible or metal boat installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with an appropriate vacuum pump, and then the crucible or metal boat is By heating and evaporating, the electron injection layer 5 is formed on the substrate placed facing the crucible or metal boat. The alkali metal is deposited using an alkali metal dispenser in which nichrome is filled with an alkali metal chromate and a reducing agent. By heating the dispenser in a vacuum container, the alkali metal chromate is reduced and the alkali metal is evaporated. In the case of co-evaporating the organic electron transport material and the alkali metal, the organic electron transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. Each crucible and dispenser are simultaneously heated and evaporated to form an electron injection layer 5 on the substrate 1 placed facing the crucible and dispenser. At this time, co-evaporation is uniformly performed in the film thickness direction of the electron injection layer 5, but there may be a concentration distribution in the film thickness direction. The electron injection layer 5 may be omitted.

[9] Cathode The cathode 6 plays a role of injecting electrons into a layer (such as the electron injection layer 5 or the light emitting layer 4) on the light emitting layer 4 side. The material used for the cathode 6 can be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, and tin, magnesium, indium, calcium, aluminum A suitable metal such as silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy. The film thickness of the cathode 6 is usually the same as that of the anode 2. For the purpose of protecting the cathode 6 made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

[10] Other Constituent Layers While the description has been given centering on the element having the layer structure shown in FIG. 1, in the present embodiment, between the anode 2 and the cathode 6 and the light emitting layer 4 in the organic electroluminescent element. May have any layer as long as its performance is not impaired, and any layer other than the light emitting layer 4 may be omitted. For example, the electron transport layer 7 and the hole blocking layer 8 may be appropriately provided as necessary. 1) Only the electron transport layer, 2) Only the hole blocking layer, and 3) The hole blocking layer / electron transport layer There are usages such as stacking, 4) not using, etc.

  For the same purpose as the hole blocking layer 8, it is also effective to provide an electron blocking layer (not shown) between the hole injection layer 3 and the light emitting layer 4. The electron blocking layer increases the probability of recombination with holes in the light emitting layer 4 by blocking electrons moving from the light emitting layer 4 from reaching the hole injection layer 3, There is a role of confining in the light emitting layer 4 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 4. The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). In addition, when the light emitting layer 4 is formed by a wet film forming method, it is preferable that the electron blocking layer is also formed by a wet film forming method because the device manufacturing becomes easy. For this reason, it is preferable that the electron blocking layer also has wet film formation compatibility. Examples of the material used for such an electron blocking layer include dioctyl typified by F8-TFB in addition to the organic electroluminescent element composition described above. And a copolymer of fluorene and triphenylamine (described in WO 2004/084260).

The structure opposite to that shown in FIG. 1, that is, the cathode 6, the electron injection layer 5, the light emitting layer 4, the hole injection layer 3, and the anode 2 can be laminated on the substrate 1 in this order. It is also possible to provide an organic electroluminescent element between two substrates, at least one of which is highly transparent. Furthermore, a structure in which a plurality of layers shown in FIG. 1 are stacked (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interfacial layer (between the light emitting units) (when the anode is ITO and the cathode is Al, the two layers), for example, V ₂ O ₅ is used as the charge generation layer (CGL). This is more preferable from the viewpoint of luminous efficiency and driving voltage.

  The organic electroluminescence device to which the present embodiment is applied applies to any of a single device, a device having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix. be able to.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.
In the following, the glass transition temperature was determined by DSC measurement, the vaporization temperature was determined by TG-DTA measurement, and the melting point was determined by DSC measurement or TG-DTA measurement.
[Example 1: Synthesis and solubility measurement of charge transport material (IA) of the present invention]

3,6-dibromocarbazole (8 g), phenylboronic acid (7.8 g) was dissolved in ethylene glycol dimethyl ether (80 ml), an aqueous solution in which 13.6 g of potassium carbonate was dissolved in 40 ml of water was degassed, and then added to the system. The entire system is degassed, purged with nitrogen, and heated and stirred. Tetrakis (triphenylphosphine) palladium (0) (1.42 g) was added at an internal temperature of 60 ° C., and then reacted for 9 hours under heating and reflux. After cooling, the mixture was concentrated, water and chloroform were added to the system, and the organic layer was extracted.

  The organic layer was dried over magnesium sulfate, further concentrated, and crystallized with methanol. Thereafter, the residue was purified by column chromatography, recrystallized from methanol, and dried to obtain 3,6-diphenylcarbazole target product 1 (3.2 g).

  Under a stirring atmosphere in a nitrogen stream at room temperature, sodium hydride (purity> 55%; 0.278 g) in a suspension of N, N-dimethylformamide (20 ml) was subjected to 3,6-diphenylcarbazole target compound 1 (2 0.008 g) was added and this was stirred at 80 ° C. for 50 minutes. 1,3-Dibromo-5-fluorobenzene (0.95 ml) was poured into the obtained solution, and the mixture was stirred for 2.3 hours under heating and reflux. Ice water and methanol are added to the resulting solution, followed by filtration and washing with methanol. The resulting solid content is extracted with toluene, the extract is filtered, the filtrate is concentrated, and the residue is concentrated with silica gel column chromatography and methanol. The product was purified by suspension washing to obtain crystals of the target product 2 (3.173 g).

Under a nitrogen atmosphere, tetrakis (triphenylphosphine) palladium ((3.152 g), 3- (N-carbazolyl) phenylboronic acid (4.910 g) and dimethoxyethane (17.1 ml) were mixed with a mixed solution. 0) (0.527 g) was added, and then an aqueous solution (14.3 ml) of potassium carbonate (3.939 g) was added, followed by stirring under heating and refluxing for 5.5 hours. Methylene chloride was added to the resulting solution, which was washed twice with an aqueous sodium hydrogen carbonate solution, dehydrated with anhydrous magnesium sulfate, filtered, and the filtrate was concentrated. The obtained residue was purified by silica gel column chromatography and suspension washing with methanol to obtain the desired product 3 (3.793 g). Further, a part (1.998 g) of this was purified by sublimation under a high vacuum at a maximum heating temperature of 450 ° C. to obtain a high-purity target 3 (charge transport material (IA) of the present invention) (1
. 84 g) was obtained. In the formula (IA), Ph represents a phenyl group.

DEI-MS m / z = 877 (M +)
The glass transition temperature of this product was 161 ° C., the crystallization temperature and the melting point were not observed, and the vaporization start temperature was 564 ° C.

The solubility of the charge transport material (IA) of the present invention in toluene was examined, and the results are shown in Table 1. As shown in Table 1, the charge transport material (IA) showed high solubility in toluene and a high glass transition temperature (Tg).
[Example 2: Synthesis and solubility measurement of charge transport material (IB) of the present invention]

  55% sodium hydride (0.819 g, 18.8 mmol) dispersed in oil was suspended in dry DMF (86 mL), and diphenylcarbazole: target 1 (5.00 g, 15.7 mmol) was added in small portions. . The mixture was warmed to 80 ° C. and 3-bromofluorobenzene (11.0 g, 62.6 mmol) was added dropwise. After dropping, the solution was stirred for 5.5 hours while refluxing. The reaction mixture was poured into ice water, and the precipitated solid was collected by filtration. The obtained solid was purified by recrystallization to obtain 3,6-diphenyl-9- (3-bromophenyl) carbazole: target product 4 (4.33 g, 58%).

  Under a nitrogen atmosphere, 3,6-diphenyl-9- (3-bromophenyl) carbazole: target product 4 (4.31 g, 9.08 mmol), bispinacolato diboron (2.77 g, 10.9 mmol), potassium acetate [1,1′-bis (diphenylphosphino) ferrocene] dichloropalladium (II) complex dichloromethane adduct (0.22 g, 0.27 mmol) was added to a DMSO solution (45 mL) of (3.03 g, 30.87 mmol). It was. After stirring at 80 ° C. for 8 hours, the reaction mixture was poured into water, extracted with toluene (300 mL × 2), dried over anhydrous magnesium sulfate, concentrated under reduced pressure, filtered with activated clay. The solvent of the filtrate was distilled off under reduced pressure, and the residue was recrystallized to obtain the target compound 5 (3.27 g, 69%).

Under a nitrogen atmosphere, 2M sodium carbonate aqueous solution (25 mL) was added to a solution of target product 5 (2.00 g, 3.84 mmol), target product 2 (655 mg, 1.63 mmol) in toluene (50 mL) and ethanol (10 mL). Further nitrogen bubbling was performed for 15 minutes, and tetrakistriphenylphosphine palladium (0) (444 mg, 0.38 mmol) was added at once. The reaction mixture was stirred at reflux for 12 hours, allowed to cool to room temperature, poured into water, and extracted with dichloromethane (50 mL × 2). The organic layer was washed with a saturated aqueous sodium chloride solution (50 mL), dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain the intended product 6 (IB) (520 mg). In formula (IB), Ph represents a phenyl group.

When this was subjected to mass spectrometry, the molecular ion peak was 1029 (M ⁺ ).
The glass transition temperature of this product was 190 ° C., the crystallization temperature and melting point were not observed, and the vaporization start temperature was 576 ° C.

  The solubility of the charge transport material (IB) of the present invention in toluene was examined, and the results are shown in Table 1. As shown in Table 1, the charge transport material (IB) exhibited a sufficiently high solubility in toluene for film formation and a very high glass transition temperature (Tg).

[Example 3: Synthesis and solubility measurement of charge transport material (IC) of the present invention]

  Under a nitrogen atmosphere, diiodobenzene (8.5 g, 25.9 mmol), 3-bromophenylboronic acid (10.4 g, 51.8 mmol) in toluene (50 mL) -ethanol (12.5 mL) in 2M sodium carbonate An aqueous solution (25 mL) was added, nitrogen bubbling was further performed for 15 minutes, and tetrakistriphenylphosphine palladium (0) (1.8 g, 1.5 mmol) was added at once. The reaction mixture was stirred for 8 hours under reflux, allowed to cool to room temperature, poured into water, and extracted with toluene (50 mL × 3). The organic layer was washed with a saturated aqueous sodium chloride solution (50 mL × 2), dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain the intended product 7 (1.4 g).

The target product 7 (1.0 g, 2.6 mmol), 4,4,5,5-tetramethyl-2- (3- (3,7-diphenylcarbazol-9-yl) phenyl) 1,3 under nitrogen atmosphere , 2-
Dioxoborolane: The target compound 5 (3.22 g, 6.17 mmol) dimethoxyethane (3
(2 mL) aqueous sodium carbonate solution (15 mL) was added to the solution, nitrogen bubbling was further performed for 15 minutes, and tetrakistriphenylphosphine palladium (0) (144 mg, 0.13 mmol) was added all at once. The reaction mixture was stirred at reflux for 12 hours, allowed to cool to room temperature, poured into water, and extracted with dichloromethane (50 mL × 2). The organic layer was washed with a saturated aqueous sodium chloride solution (50 mL), dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain the desired product 8 (IC) (1.7 g).

When this was subjected to mass spectrometry, the molecular ion peak was 1016 (M +).
The glass transition temperature of this product was 163 ° C., the crystallization temperature and the melting point were not observed, and the vaporization start temperature was 564 ° C.

The solubility of the charge transport material (IC) of the present invention in toluene was examined, and the results are shown in Table 1. As shown in Table 1, the charge transport material (IC) exhibited sufficient solubility for film formation in toluene and had a high glass transition temperature (Tg).
[Example 4: Synthesis and solubility measurement of charge transport material (ID) of the present invention]

  Dry N, N-dimethylformamide (172 ml) was added to 60% sodium hydride (2.01 g), and the atmosphere in the system was replaced with nitrogen. Under a nitrogen atmosphere, 3,6-diphenylcarbazole: target product 1 (8.6 g) was added and heated to 80 ° C. At that temperature, 1,3-dibromo-5-fluorobenzene (13.67 g) was added, stirred for 6 hours under reflux with heating, and allowed to cool to room temperature.

A methanol aqueous solution was added to the reaction solution, and the precipitated crystals were collected by filtration. The crystals were dissolved in methylene chloride, washed with water, and the organic layer was concentrated. The resulting crude product was purified by column chromatography (n-hexane / methylene chloride = 4/1) to obtain the desired product 9 (9.95 g, yield 67%) as white crystals.

  In a nitrogen stream, carbazole (7.00 g), 3-bromoiodobenzene (14.2 g), copper powder (2.66 g), potassium carbonate (5.79 g), and tetraglyme (10 ml) were heated to 140 ° C. The mixture was stirred for 5 hours and allowed to cool to room temperature. After completion of the reaction, chloroform was added to the reaction solution, and insoluble matters were separated by filtration. Chloroform contained in the filtrate was distilled off under reduced pressure and purified by silica gel column chromatography (n-hexane / toluene = 4/1). The target product 10 (10.5 g, yield 78%) was obtained as a colorless viscous liquid by drying under reduced pressure.

  While cooling with an ethanol bath at −60 to −65 ° C. in a nitrogen stream, a solution of the target product 10 (9.06 g) in anhydrous tetrahydrofuran (400 ml) was added with a normal hexane solution of 1.54 M normal butyl lithium (27.4 ml). Was added dropwise over 7 minutes, followed by stirring for 40 minutes. Thereafter, the mixture was stirred at room temperature for 2.2 hours, 1N aqueous hydrochloric acid solution (45 ml) was added, and the mixture was further stirred for 30 minutes. Tetrahydrofuran was distilled off from the resulting solution under reduced pressure, diethyl ether (400 ml) and saturated brine (100 ml) were added and shaken, and the organic layer was separated and washed with saturated brine. It was. Anhydrous magnesium sulfate and activated clay were added to the obtained organic layer, stirred, filtered and concentrated. The obtained solid was suspended and washed with water and normal hexane, and then purified by reprecipitation from ethanol-normal hexane to obtain the intended product 11 (4.03 g).

  While bubbling nitrogen through a solution of 1-bromo-3-iodobenzene (22.2 g), target compound 11 (18.8 g), toluene (288 ml), ethanol (72 ml), tetrakis (triphenylphosphine) palladium (1 .51 g) was added. An aqueous solution in which sodium carbonate (34.67 g) previously substituted with nitrogen was dissolved in water (144 ml) was added dropwise, and the mixture was stirred at reflux for 2.5 hours. The mixture was allowed to cool to room temperature, water was added, and the mixture was extracted with methylene chloride. The organic layer was concentrated and purified by column chromatography (n-hexane / methylene chloride = 3/1), hexane was added to the concentrated solution, and the precipitated crystals were recovered to obtain the target compound 12 (21.93 g, Yield 84%) was obtained as white crystals.

  Dehydrated tetrahydrofuran (5 ml) and iodine (small amount) were added to magnesium (0.73 g) under a nitrogen stream. To this solution, a solution of the target compound 12 (8 g) in dehydrated tetrahydrofuran (60 ml) was added dropwise, and the mixture was stirred for 6 hours under reflux. The reaction mixture was cooled to 40 ° C., trimethyl borate (6.26 g) was slowly added dropwise, and the mixture was further stirred for 1 hr. Water and 1N hydrochloric acid are added to the reaction solution, and the mixture is filtered. The filtrate is extracted with methylene chloride, the organic layer is washed and concentrated, and the residue is purified by column chromatography (methylene chloride / ethyl acetate = 2/1). This gave the target product 13 (2.21 g, yield 30%) as white crystals.

  A solution of the target product 9 (1.17 g), the target product 13 (2.0 g), and ethylene glycol dimethyl ether (20 ml) was degassed. Under a nitrogen atmosphere, tetrakis (triphenylphosphine) palladium (0.13 g) was added, and an aqueous solution (4.1 ml) of potassium carbonate (1.17 g) previously passed through nitrogen was added dropwise. The mixture was stirred for 9 hours under reflux with heating, allowed to cool to room temperature, water was added and extracted with methylene chloride, and the organic layer was washed with water and concentrated. The residue was purified by silica gel column chromatography (n-hexane / methylene chloride = 3/1 to 2/1) to obtain the target product 14 (ID) (1.74 g, yield 80%) as white crystals. . 1.07 g of this white crystal was further dried under reduced pressure at a high temperature (˜300 ° C.), and 1.01 g of a white solid was recovered.

From DEI-MS (m / z = 1030), it was confirmed to be the target product 14 (ID).
The vaporization temperature of this product was 570 ° C., and the glass transition temperature was 142 ° C.
The solubility of the charge transport material (ID) of the present invention in toluene was examined, and the results are shown in Table 1. As shown in Table 1, the charge transport material (ID) showed very high solubility in toluene, and the glass transition temperature was higher than that of the comparative compound (X-C).

[Example 5: Synthesis and solubility measurement of charge transport material (IE) of the present invention]

Acetic acid (140 ml) was added to 1,3-diacetylbenzene (8.0 g) and benzaldehyde (10.46 g), and sulfuric acid (15.8 ml) was added dropwise to the system stirred at 35 ° C. After stirring for 5 hours, methanol (80 ml) and water (40 ml) were added to the system to precipitate crystals. After the crystals were separated by filtration, the crystals were further washed with methanol to obtain the target product 15 (yield 7.3 g, yield 43.7%) as light yellow crystals.

Target 15 (7g), 3-bromophenacyl bromide (22.06g), ammonium acetate (79.4g)
Was dissolved in acetic acid (300 g) and dimethylformamide (180 ml), and reacted for 9 hours at 130 ° C. with superheating.
The mixture was allowed to cool, and 100 ml of ethanol and 250 ml of water were added to the system to precipitate crystals. The crystals were washed with methanol and washed with methylene chloride, and the target product 16 (yield 3.15 g) was obtained as pale yellow crystals.
Yield 22%) was obtained.

Toluene (40 ml) is added to the target product 16 (3.0 g) and target product 1 (3.31 g) sodium-tert-butoxide (1.83 g) obtained above and stirred. Tris (dibenzylideneacetone) dipalladium (0) chloroform (0.447 g) is dissolved in toluene (8 ml), a solution to which tri-tert-butylphosphine (0.437 g) is added is added, and the reaction is carried out for 9 hours under reflux with heating. After completion of the reaction, insolubles were removed, concentrated, washed with hanging, and purified by column chromatography to obtain the intended product 17 (2.7 g). From DEI-MS (m / z = 1170 (M +)), it was confirmed to be the target product 17 (IE). As a result of DSC measurement, the glass transition temperature (Tg) of this product was 187 ° C., and the vaporization start temperature was 573 ° C.
The solubility of the charge transport material (IE) of the present invention in toluene was examined, and the results are shown in Table 1. As shown in Table 1, the charge transport material (IE) showed very high solubility in toluene, and the glass transition temperature was higher than that of the comparative compound (X-D).

[Comparative Example 1: Solubility Measurement and Glass Transition Temperature of Comparative Example Compound (X-A)]
The solubility of the comparative compound (X-A) shown below in toluene was examined, and the results are shown in Table 1. As shown in Table 1, the solubility of the comparative compound (X-A) in toluene was very low. In addition, the glass transition temperature of the comparative compound (X-A) was 97 ° C.
[Comparative Example 2: Solubility Measurement and Glass Transition Temperature of Comparative Compound (X-B)]
The solubility of the comparative compound (X-B) in toluene was examined, and the results are shown in Table 1. As shown in Table 1, the solubility of the comparative compound (X-B) in toluene was high. The glass transition temperature of the comparative compound (X-B) was 147 ° C.

[Comparative Example 3: Solubility Measurement and Glass Transition Temperature of Comparative Example Compound (X-C)]
The solubility of the comparative compound (X-C) in toluene was examined, and the results are shown in Table 2. As shown in Table 2, the solubility of the comparative compound (X-C) in toluene was scarce.

  The glass transition temperature of the comparative compound (X-C) was 112 ° C.

[Comparative Example 4: Solubility Measurement and Glass Transition Temperature of Comparative Example Compound (X-D)]
The solubility of the comparative compound (X-D) in toluene was examined, and the results are shown in Table 1. The glass transition temperature of the comparative compound (X-D) was 142 ° C.

[Example 6: Production and evaluation of organic electroluminescence device using composition for organic electroluminescence device of the present invention containing charge transport material (IA)]
An organic electroluminescent element having the structure shown in FIG. 3 was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 having a thickness of 150 nm (sputtered film; sheet resistance 15 Ω) is patterned into a 2 mm wide stripe using normal photolithography and hydrochloric acid etching. Thus, an anode 2 was formed. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.
Next, the hole injection layer 3 was formed by a wet film formation method as follows. As a material for the hole injection layer 3, a non-conjugated polymer compound (PB-1 (weight average molecular weight: 26500, number average molecular weight: 12000)) having an aromatic amino group having the structural formula shown below and the structure shown below Using the electron-accepting compound (A-1) of the formula, spin coating was performed under the following conditions.

Spin coating conditions Solvent Anisole Coating solution concentration PB-1 2.0% by weight
A-1 0.4% by weight
Spinner speed 2000rpm
Spinner rotation time 30 seconds Drying conditions 230 ° C. × 3 hours A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

  Subsequently, the light emitting layer 4 was formed by a wet film forming method as follows. As a material for the light emitting layer 4, the charge transport material (IA) of the present invention having the following structural formula synthesized in Example 1 is used as a solvent together with the iridium complex (D-1) having the structural formula shown below as a solvent. The composition for organic electroluminescent elements used was prepared, and spin-coated under the following conditions using this composition for organic electroluminescent elements.

Spin coating conditions Solvent Xylene Concentration in composition IA 2.5% by weight
D-1 0.13 wt%
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 130 ° C x 60 minutes (under reduced pressure)
A uniform thin film having a thickness of 26 nm was formed by the above spin coating.

Next, a pyridine derivative (HB-1) shown below is used as the hole blocking layer 8 with a crucible temperature 292.
The film was laminated with a film thickness of 5 nm at a deposition rate of 0.09 to 0.1 nm / second at ˜298 ° C. The degree of vacuum during the deposition was 1.3 × 10 ⁻⁴ Pa (about 1.0 × 10 ⁻⁶ Torr).

Next, an aluminum 8-hydroxyquinoline complex (ET-1) shown below was deposited as an electron transport layer 7 on the hole blocking layer 8 in the same manner. At this time, the crucible temperature of the aluminum 8-hydroxyquinoline complex is controlled within a range of 472 to 456 ° C., and the degree of vacuum during the deposition is 1.1 to 1.3 × 10 ⁻⁴ Pa (about 0.8 to 1. 0 × 10 ⁻⁶ Torr), the deposition rate was 0.1 to 0.16 nm / second, and the film thickness was 30 nm.

The substrate temperature during vacuum deposition of the hole blocking layer 8 and the electron transport layer 7 was kept at room temperature.
Here, the element that has been deposited up to the electron transport layer 7 is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide striped shadow mask is used as a cathode deposition mask. In close contact with the element so as to be orthogonal to each other, it is installed in another vacuum deposition apparatus, and the degree of vacuum in the apparatus is 1.4 × 10 ⁻⁶ Torr (about 1.8 × 10 ⁻⁴ Pa) in the same manner as the organic layer. ) Exhaust until below.

Next, lithium fluoride (LiF) is deposited on the electron transport layer 7 as the electron injection layer 5 by using a molybdenum boat, a deposition rate of 0.01 nm / second, and a degree of vacuum of 1.5 × 10 ⁻⁶ Torr (
The film was formed on the electron transport layer 7 with a film thickness of 0.5 nm at about 2.1 × 10 ⁻⁴ Pa).
Next, aluminum is heated as a cathode 6 on the electron injection layer 5 by a molybdenum boat, a deposition rate of 0.1 to 0.55 nm / second, and a degree of vacuum of 2.0 × 10 ⁻⁶ Torr (about 2. 7 × 10 ⁻⁴ Pa) to form an aluminum layer having a thickness of 80 nm to complete the cathode 6.

The substrate temperature during the deposition of the electron transport layer 7 and the cathode 6 was kept at room temperature.
As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained. The light emission characteristics of this element are as follows.
Luminance / current: 15.9 [cd / A] (@ 100 cd / m ² )
Voltage: 8.1 [V] (@ 100 cd / m ² )
Luminous efficiency: 6.2 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 514.0 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.315, 0.622).

[Example 7: Production and evaluation of organic electroluminescence device using composition for organic electroluminescence device of the present invention containing charge transport material (IB)]
An organic electroluminescent element was produced in the same manner as in Example 6 except that the light emitting layer 4 was formed by a wet film forming method as follows.
A composition for an organic electroluminescence device using toluene as a solvent together with the iridium complex (D-1) having the structural formula shown below and the iridium complex (D-1) having the structural formula shown below was prepared. Spin coating was performed using the composition for electroluminescent elements under the following conditions, and a uniform thin film having a thickness of 44 nm was formed.

Spin coating conditions Solvent Toluene Concentration in composition IB 1.5% by weight
D-1 0.08 wt%
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 100 ° C x 60 minutes (under reduced pressure)
The light emitting characteristics of the obtained device are as follows.

Luminance / current: 7.9 [cd / A] (@ 100 cd / m ² )
Voltage: 8.7 [V] (@ 100 cd / m ² )
Luminous efficiency: 2.9 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 516.4 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.315, 0.626).
[Example 8: Production and evaluation of organic electroluminescence device using composition for organic electroluminescence device of the present invention having charge transport material (ID)]
An organic electroluminescent element was produced in the same manner as in Example 6 except that the light emitting layer 4 was formed by a wet film forming method as follows.

  A composition for an organic electroluminescent device using toluene as a solvent together with the iridium complex (D-1) of the structural formula shown above, the charge transport material (ID) of the present invention having the structural formula shown below, This organic electroluminescent element composition was spin coated under the following conditions to form a uniform thin film having a thickness of 35 nm.

I-D
Spin coating conditions Solvent Xylene Concentration in composition ID 2.0% by weight
D-1 0.1 wt%
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 130 ° C x 60 minutes (under reduced pressure)
The light emitting characteristics of the obtained device are as follows.

Luminance / current: 10.9 [cd / A] (@ 100 cd / m ² )
Voltage: 7.4 [V] (@ 100 cd / m ² )
Luminous efficiency: 4.6 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 514.0 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.310, 0.625).

From this result, the organic electroluminescent device using the charge transport materials (IA), (IB), and (ID) of the present invention as the host material is the charge transport material (IA), (I Both -B) and (ID) have excellent charge transport properties and do not easily crystallize, so that it was confirmed that uniform light emission was obtained, the light emission efficiency was high, and the device could be driven at a low voltage.
The results of measuring the half-life of the organic electroluminescent elements produced in Examples 6 to 8 are shown in Table 3 below. The ratio of the group represented by the formula (I) (3,6-diphenylcarbazolyl group) present in one molecule and the unsubstituted carbazolyl group (in this case, the molecular weight of each partial structure was divided by one molecular weight) It was found that the molecular structure having the same ratio) has a longer durability, that is, a longer life than a molecular structure having a large proportion of 3,6-diphenylcarbazolyl groups.

From this, it was found that the number of substitution of 3,6-diphenylcarbazolyl group in one molecule is smaller than that of carbazolyl group, which is effective for improving durability.

[Example 9: Production and evaluation of organic electroluminescence device using composition for organic electroluminescence device of the present invention having charge transport material (IE)]
An organic electroluminescent element having the structure shown in FIG. 3 was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 having a thickness of 150 nm (sputtered film; sheet resistance 15 Ω) is patterned into a 2 mm wide stripe using normal photolithography and hydrochloric acid etching. Thus, an anode 2 was formed. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

Next, the hole injection layer 3 was formed by a wet film formation method as follows. As a material for the hole injection layer 3, a non-conjugated polymer compound (PB-2 (weight average molecular weight: 29400, number average molecular weight: 12600)) having an aromatic amino group having the structural formula shown below and the description in Example 6 Was spin-coated under the following conditions using the electron-accepting compound (A-1) shown in FIG.

Spin coating conditions Solvent Ethyl benzoate Coating solution concentration PB-2 2.0% by weight
A-1 0.4% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 260 ° C. × 3 hours A uniform thin film having a thickness of 30 nm was formed by the above spin coating.
Subsequently, the light emitting layer 4 was formed by a wet film forming method as follows.
The charge transport material (IE) of the present invention having the structural formula shown below is a solvent together with the iridium complex (D-1) having the structural formula shown above and the hole transporting material (F-1) having the structural formula shown below. A composition for an organic electroluminescent device using xylene as a starting material was prepared and spin-coated using the composition for an organic electroluminescent device under the following conditions to form a uniform thin film having a thickness of 50 nm.

IE
Spin coating conditions Solvent Xylene Concentration in composition IE 1.0% by weight
F-1 1.0% by weight
D-1 1.0% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 130 ° C x 60 minutes (under reduced pressure)
The hole blocking layer, the electron transport layer, and the cathode layer were formed in the same manner as in Example 6. The light emitting characteristics of the obtained device are as follows.
Luminance / current: 28 [cd / A] (@ 100 cd / m ² )
Voltage: 7.1 [V] (@ 100 cd / m ² )
Luminous efficiency: 12.4 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 513.0 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.308, 0.623).
From this result, the organic electroluminescence device using the charge transport material (IE) of the present invention as a host material is excellent in charge transport property and does not easily crystallize, so that uniform light emission can be obtained and the light emission efficiency. Therefore, it was confirmed that it can be driven at a low voltage.

It is typical sectional drawing which showed an example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Light emitting layer 5 Electron injection layer 6 Cathode 7 Electron transport layer 8 Hole blocking layer 9 Electron blocking layer

Claims (6)

An organic compound represented by the following formula (III).

(In Formula (III), Ring B, Ring C, and Ring D each independently represent a benzene ring that may have a substituent other than the —NR ₁ R ₂ group. Ring B ′ and Ring D 'Represents an independently substituted benzene ring, and R ₁ and R ₂ each represents an arbitrary substituent, and R ₁ and R ₂ are bonded to form a ring. A plurality of R ₁ and R ₂ contained in one molecule may be the same or different from each other, provided that at least one of the —NR ₁ R ₂ groups has the above formula ( I and n are groups represented by I), and n and m each represents an integer of 0 to 3.)   An organic compound, wherein the organic compound according to claim 1 is a charge transport material for a low molecular weight coating type organic electroluminescence device.   The composition for organic electroluminescent elements containing the organic compound and solvent of Claim 2. Furthermore, the composition for organic electroluminescent elements of Claim 3 containing a phosphorescence-emitting material.   The thin film for organic electroluminescent elements formed by the wet film-forming method using the composition for organic electroluminescent elements of Claim 3 or 4.   5. An organic electroluminescence device having an anode, a cathode, and a light emitting layer provided between both electrodes on a substrate, wherein the wet electro-deposition method using the composition for an organic electroluminescence device according to claim 3 or 4 An organic electroluminescence device having a layer formed by glue.

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