JP5141051B2 - Organic compound, composition for organic electroluminescent device, thin film for organic electroluminescent device, and organic electroluminescent device - Google Patents

Description

The present invention relates to an organic compound having a hole transporting property and an organic electroluminescence device using the organic compound.
The present invention also relates to an organic electroluminescent element composition containing the organic compound and an organic electroluminescent element thin film formed from the organic electroluminescent element composition.

In recent years, an electroluminescent element (organic electroluminescent element) using an organic material instead of an inorganic material such as ZnS has been developed. In general, a hole injection layer is provided between the anode and the light emitting layer in order to increase the efficiency and life of the electroluminescent device.
In addition, by forming the hole injection layer by a wet film-forming method, the heat resistance and surface flatness of the device are improved compared to the case of forming by a vacuum vapor deposition method, the emission luminance is lowered, and constant current driving is performed. It has been reported that the voltage rise at the time, the occurrence of non-light emitting portions (dark spots), and the like are suppressed.

  For example, Patent Document 1 and Patent Document 2 report that a high-molecular-weight hole-transporting compound is dissolved in an organic solvent together with an electron-accepting compound, and a hole injection layer is formed by a wet film forming method. However, since the hole transporting compound used in Patent Document 1 and Patent Document 2 is a polymer, the molecular weight is not single but has a distribution. Usually, the molecular weight distribution of a polymer changes every time it is produced, and the difference in molecular weight distribution leads to a difference in performance. Therefore, it is difficult to produce a polymer having stable performance. Furthermore, for example, a polymer having a high molecular weight having an average molecular weight exceeding 10,000 is difficult to remove impurities such as inorganic substances.

On the other hand, Patent Document 3 reports that a hole transporting compound having a molecular weight of less than 2,000 is dissolved in an organic solvent together with an electron accepting compound, and a hole injection layer is formed by a wet film forming method. However, it is considered that the compounds exemplified in Patent Document 3 do not have sufficient film forming properties.
JP-A-11-283750 JP 2000-36390 A JP 2004-158216 A

  The present invention is not a conventional high-molecular-weight hole-transporting compound, but a compound having a relatively large molecular weight that is less likely to cause an impurity problem, has a good film forming property, and is long when used in an organic electroluminescent device. An organic compound having a hole transporting property, a composition for an organic electroluminescent device containing the organic compound, a thin film for an organic electroluminescent device, and a long film using the organic compound It is an object to provide a long-life organic electroluminescent device.

  As a result of intensive studies by the present inventors, it has been found that an organic compound having the following specific aromatic amine structure has a good film forming property and can provide a long-life organic electroluminescence device.

（式（Ｉ）中、Ａｒ^１〜Ａｒ^１８は、それぞれ独立に、６員環の単環または２〜５縮合環から成る芳香族炭化水素基を表す。
Ｑ ^１ は、下記の連結基群Ｑ’の中から選ばれる連結基を表す。
Ｑ ^２ 〜Ｑ ^５ は、−Ｏ−Ａｒ ^２１ −Ｃ（＝Ｏ）−Ａｒ ^２２ −Ｏ−を表す。
ｍおよびｎは、１である。）
＜連結基群Ｑ’＞

（式中、Ａｒ^２１〜Ａｒ^２２は、それぞれ独立に、６員環の単環または２〜５縮合環から成る芳香族炭化水素基を表す。） The present invention has been achieved based on such findings, and the gist of the present invention resides in an organic compound (claim 1) represented by the following formula (I).

(In formula (I), Ar ^{1 to} Ar ¹⁸ each independently represents an aromatic hydrocarbon group composed of a 6-membered monocyclic ring or a 2-5 condensed ring .
Q ¹ represents a linking group selected from the group of linkage groups Q below SL '.
Q < ² > -Q < ⁵ > represents -O-Ar < ²¹ > -C (= O) -Ar < ²² > -O-.
m and n are 1 . )
<Linking group Q '>

(In the formula, Ar ^{21 to} Ar ²² each independently represents an aromatic hydrocarbon group composed of a 6-membered monocyclic ring or a 2-5 condensed ring.)

Another gist of the present invention resides in a composition for an organic electroluminescence device containing the organic compound (Claim 3 ).

Still another subject matter of the present invention resides in a thin film for an organic electroluminescent element (Claim 6 ) formed by a wet film-forming method using the composition for an organic electroluminescent element.

Still another subject matter of the present invention is an organic electroluminescence device having an anode, a cathode and an organic layer provided between both electrodes on a substrate, wherein the organic layer has a layer containing this organic compound as the organic layer. It exists in an electroluminescent element (Claim 7 ).

Since the organic compound of the present invention is not a polymer but a compound having a single molecular weight, it can be easily purified and can be stably produced. In addition, since the molecular weight is relatively large and the structure is not rigid, it has sufficient solubility and the surface flatness during film formation is improved.
For this reason, the organic electroluminescence device manufactured using the organic compound of the present invention has reduced emission luminance, voltage rise, non-emission portion (dark spot), short-circuit defects, etc. during constant current driving, Long-life element.

Therefore, the organic electroluminescent device manufactured using the organic compound of the present invention is a light source (for example, a light source of a copying machine) that makes use of the characteristics of a flat panel display (for example, for OA computers or wall-mounted televisions) or a surface light emitter. In addition, its technical value is high when applied to backlight sources for liquid crystal displays and instruments), display panels, and marker lamps.
Further, the organic compound of the present invention has essentially excellent solubility, film-forming property and electrochemical durability, so that it is not limited to an organic electroluminescent device, but also an electrophotographic photoreceptor, a photoelectric conversion device, It can also be used effectively for organic solar cells, organic rectifying elements and the like.

  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.

（式（Ｉ）中、Ａｒ^１〜Ａｒ^１８は、それぞれ独立に、置換基を有していてもよい芳香族炭化水素基または置換基を有していてもよい芳香族複素環基を表す。Ａｒ^１〜Ａｒ^１８は、それぞれ互いに結合して環を形成していてもよい。
Ｑ^１〜Ｑ^５は、それぞれ独立に、−Ｏ−基を含む連結基を表す。
ｍおよびｎは、それぞれ独立に、０または１である。） [Organic compounds]
The organic compound of the present invention is represented by the following formula (I).

(In formula (I), Ar ^{1 to} Ar ¹⁸ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ^{1 to} Ar ¹⁸ may be bonded to each other to form a ring.
Q ^{1 to} Q ⁵ each independently represent a linking group containing an —O— group.
m and n are each independently 0 or 1. )

{Ar ^{1 to} Ar ¹⁸ }
Ar ^{1 to} Ar ¹⁸ are an aromatic hydrocarbon group or an aromatic heterocyclic group, and each may be the same or different and may have a substituent.

  Examples of the aromatic hydrocarbon group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, and fluoranthene ring. Examples thereof include monovalent or divalent groups derived from a 6-membered monocyclic ring or a 2-5 condensed ring.

  Examples of the aromatic heterocyclic group include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolo Pyrazole 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, pyrimidine ring, triazine Ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. Derived include monovalent or divalent radical.

Ar ^{1 to} Ar ¹⁸ may be one in which one type or two or more types of aromatic hydrocarbon groups and / or aromatic heterocyclic groups are linked by a direct bond.

Ar ^{1 to} Ar ¹⁸ are each independently preferably a group derived from a benzene ring which may have a substituent, or a group in which two benzene rings are linked by a direct bond (biphenylene group or biphenyl group). More preferably, it is a phenyl group.

Examples of the substituent that Ar ^{1 to} Ar ¹⁸ may have include one or more selected from the following substituent group Z.

<Substituent group Z>
Preferably an alkyl group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, such as a methyl group and an ethyl group;
An alkenyl group having preferably 2 to 11 carbon atoms, more preferably 2 to 5 carbon atoms, such as a vinyl group;
Preferably an alkynyl group having 2 to 11 carbon atoms, more preferably 2 to 5 carbon atoms, such as an ethynyl group;
Preferably an alkoxy group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methoxy group and an ethoxy group;
An aryloxy group having preferably 4 to 25 carbon atoms, more preferably 5 to 14 carbon atoms, such as a phenoxy group, a naphthoxy group, and a pyridyloxy group;
An alkoxycarbonyl group having preferably 2 to 11 carbon atoms, more preferably 2 to 7 carbon atoms, such as a methoxycarbonyl group and an ethoxycarbonyl group;
A dialkylamino group having preferably 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, such as a dimethylamino group and a diethylamino group;
A diarylamino group having preferably 10 to 30 carbon atoms, more preferably 12 to 22 carbon atoms, such as a diphenylamino group, a ditolylamino group, or an N-carbazolyl group;
An arylalkylamino group having preferably 6 to 25 carbon atoms, more preferably 7 to 17 carbon atoms, such as a phenylmethylamino group;
Preferably an acyl group having 2 to 10 carbon atoms, preferably 2 to 7 carbon atoms, such as an acetyl group and a benzoyl group;
Halogen atoms such as fluorine atoms and chlorine atoms;
Preferably a haloalkyl group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, such as a trifluoromethyl group;
Preferably an alkylthio group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methylthio group and an ethylthio group;
A phenylthio group, a naphthylthio group, a pyridylthio group and the like, preferably an arylthio group having 4 to 25 carbon atoms, more preferably 5 to 14 carbon atoms;
A silyl group having preferably 2 to 33 carbon atoms, more preferably 3 to 26 carbon atoms, such as a trimethylsilyl group and a triphenylsilyl group;
Preferably a C2-C33, more preferably C3-C26 siloxy group such as a trimethylsiloxy group, a triphenylsiloxy group;
A cyano group;
An aromatic hydrocarbon group having preferably 6 to 30 carbon atoms, more preferably 6 to 18 carbon atoms, such as a phenyl group and a naphthyl group;
An aromatic heterocyclic group having preferably 3 to 28 carbon atoms, more preferably 4 to 17 carbon atoms, such as thienyl group and pyridyl group

The substituent for Ar ^{1 to} Ar ¹⁸ may be a group having a crosslinkable group. Examples of the crosslinkable group include groups selected from the following crosslinkable group group T. The following crosslinkable group ^may also be directly coupled to Ar 1 ^{to Ar 18,} it may be bonded to ^Ar 1 ^{to Ar 18} through the group described in the substituent group Z. In particular, a divalent group formed by linking 1 to 30 groups selected from an —O— group, a —C (═O) — group, or an (optionally substituted) —CH ₂ — group. ^through, it is preferable to bind to Ar 1 ^{to Ar 18.}

(Crosslinkable group T)

In the above ^formulas, R 51 ^{to R 55} each independently represents a hydrogen atom or an alkyl group. Specific examples of the alkyl group are the same as the specific examples of the alkyl group exemplified in the substituent group Z. Ar ⁵⁶ represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Specific examples of the aromatic hydrocarbon group and the aromatic heterocyclic group are the same as the specific examples of the aromatic hydrocarbon group and the aromatic heterocyclic group exemplified in the substituent group Z. In addition, examples of the substituent of the aromatic hydrocarbon group and the aromatic heterocyclic group include the groups described in the substituent group Z.

  The molecular weight of each of the substituents is preferably 400 or less, more preferably about 250 or less.

^{Q 1 ^~Q 5}
Q ^{1 to} Q ⁵ each independently represent a linking group containing an —O— group.
If the coupling group containing -O- group is illustrated, the coupling group chosen from the following coupling group group Q 'will be mentioned. In particular, all of Q ^{1 to} Q ⁵ are preferably linking groups selected from the following linking group group Q ′.

（式中、Ａｒ^２１〜Ａｒ^３２は、それぞれ独立に、置換基を有していてもよい芳香族炭化水素基または置換基を有していてもよい芳香族複素環基を表す。Ｒ^３１およびＲ^３２は、それぞれ独立に、水素原子または置換基を表す。Ｒ^３３〜Ｒ^３５は２価の基を表す。） <Linking group Q '>

(In the formula, Ar ^{21 to} Ar ³² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ³¹ and R ³² independently represents a hydrogen atom or a substituent, and R ^{33 to} R ³⁵ each represents a divalent group.)

In the linking group group Q ′, Ar ^{21 to} Ar ³² may be an aromatic hydrocarbon group or an aromatic heterocyclic group, each of which may be the same or different and has a substituent. It may be.
Specific examples and preferred examples of the aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{21 to} Ar ³² are the same as the specific examples and preferred examples of Ar ^{1 to} Ar ¹⁸ . Moreover, the substituent which may have is also the same as the substituent which Ar < ¹ > -Ar < ¹⁸ > may have.

R ³¹ and R ³² are a hydrogen atom or a substituent, and may be the same as or different from each other. Here, examples of substituents applicable as R ³¹ and R ³² include alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups. Can be mentioned. Examples of the aromatic hydrocarbon group and the aromatic heterocyclic group include those exemplified as specific examples of Ar ^{1 to} Ar ¹⁸ . Examples of the alkyl group, alkenyl group, alkynyl group, and alkoxy group include those exemplified in the substituent group Z.

R ^{33 to} R ³⁵ are divalent groups. Here, if illustrate a divalent group applicable to R ³³ to R ^35, an alkylene group, an alkenylene group, an alkynylene group, a divalent group derived from an aromatic hydrocarbon ring, 2 derived from an aromatic heterocyclic Valent groups, and one kind or two or more kinds of divalent groups can be linked and used. Examples of the aromatic hydrocarbon group and the aromatic heterocyclic group include those exemplified as specific examples of Ar ^{1 to} Ar ¹⁸ . Examples of the alkylene group, alkenylene group, and alkynylene group include the divalent groups exemplified in the substituent group Z.

Ar ^{1 to} Ar ¹⁸ may be bonded to each other to form a ring. Examples of the ring formed include a carbazole ring, a carboline ring, a phenoxazine ring, a phenothiazine ring, a dibenzofuran ring, a xanthene ring, an oxanthrene ring, Examples include a phenoxathiin ring.

{M and n}
m and n are each independently 0 or 1. Both m and n are preferably 1 in order to further improve the surface flatness during film formation.

{Molecular weight}
The molecular weight of the organic compound of the present invention represented by the formula (I) is usually 800 or more, preferably 1400 or more, more preferably 2000 or more, usually 10,000 or less, preferably 7000 or less, more preferably 4000 or less. If the upper limit is exceeded, purification may be difficult, and if the lower limit is not reached, the surface flatness during film formation may not be sufficiently improved.

{Preferred example}
Specific examples of the organic compound of the present invention are shown below, but the present invention is not limited to these.

{Synthesis method}
The organic compound of the present invention includes, for example, a diamino compound represented by H ₂ N—Ar ¹ -Q ¹ -Ar ⁴ —NH ₂ and a halide represented by Ar ^a Ar ^b NQ ^a -Ar ^c -X. (Ar ¹ , Ar ⁴ , Q ¹ are synonymous with those in formula (I), and Ar ^a , Ar ^b are the same as those in formula (I). ⁸ , Ar ⁹ , Ar ¹¹ , Ar ¹² , Ar ¹⁴ , Ar ¹⁵ , Ar ¹⁷ , Ar ¹⁸ are synonymous, and Ar ^c is synonymous with Ar ⁷ , Ar ¹⁰ , Ar ¹³ , Ar ¹⁶ in formula (I). Q ^a has the same meaning as Q ² , Q ³ , Q ⁴ and Q ⁵ in formula (I), and X represents a halogen atom. Usually, this reaction is carried out in the presence of a base such as potassium carbonate, tert-butoxy sodium or triethylamine, and if necessary, can also be carried out in the presence of a transition metal catalyst such as copper or a palladium complex. When the four Ar ^a Ar ^b NQ ^a -Ar ^c groups are the same, they can also be synthesized in one step.

  Moreover, like the following reaction formula, the organic compound of the present invention represented by the formula (I-1) can be synthesized from a tetrahydroxy compound and a halide. Usually, this reaction is carried out in the presence of a base such as potassium carbonate, tert-butoxy sodium or triethylamine, and if necessary, can also be carried out in the presence of a transition metal catalyst such as copper or a palladium complex.

In the above reaction formula, Q ¹ and Ar ^{1 to} Ar ¹⁸ are synonymous with those in the formula (I), X represents a halogen atom such as F, Cl, Br, I, etc., and G ^{2 to} G ⁵ are independent of each other. Represents a direct bond or a divalent group. Examples of the arbitrary divalent group include a divalent group obtained by removing one —O— group from the group represented by the linking group group Q ′.

  Moreover, the organic compound of this invention represented by Formula (I-2) is synthesize | combined from a tetrahalide and a hydroxy body like the following reaction formula, for example. Usually, this reaction is carried out in the presence of a base such as potassium carbonate, tert-butoxy sodium or triethylamine, and if necessary, can also be carried out in the presence of a transition metal catalyst such as copper or a palladium complex.

In the above reaction formula, Q ¹ and Ar ^{1 to} Ar ¹⁸ are synonymous with those in the formula (I), X represents a halogen atom such as F, Cl, Br, I, etc., and G ^{2 to} G ⁵ are independent of each other. Represents a direct bond or any divalent group. Examples of the arbitrary divalent group include a divalent group obtained by removing one —O— group from the group represented by the linking group group Q ′.

[Composition for organic electroluminescence device]
Next, the composition for organic electroluminescent elements of the present invention will be described.
The composition for organic electroluminescent elements of the present invention contains the organic compound of the present invention. Usually, the composition for organic electroluminescent elements of the present invention contains a solvent, and preferably further contains an electron-accepting compound. Moreover, the organic electroluminescent element composition may contain various additives such as a leveling agent and an antifoaming agent.

  Since the thin film formed using the composition for organic electroluminescent elements of the present invention is excellent in heat resistance and charge transportability, the thin film is composed of an electrophotographic photosensitive member, an organic electroluminescent element, a photoelectric conversion element, and an organic solar battery. , And can be suitably used for an organic rectifying element and the like, and particularly preferably used for an organic electroluminescent element. Moreover, it is preferable to use the thin film obtained by forming the composition for organic electroluminescent elements of this invention by the wet film-forming method as an organic layer of an organic electroluminescent element.

{solvent}
The solvent contained in the composition for organic electroluminescent elements of the present invention is not particularly limited as long as it is a solvent that dissolves the organic compound of the present invention contained in the composition for organic electroluminescent elements of the present invention. Here, the solvent that dissolves the organic compound is a solvent that normally dissolves the organic compound in an amount of 0.05% by weight or more, preferably 0.5% by weight or more, and more preferably 1% by weight or more. Since these organic compounds have high solvent solubility, various solvents are applicable.

  In particular, in an organic electroluminescent device, a hole injection layer containing an electron-accepting compound should be formed in order to increase the hole injection / transport property and lower the driving voltage of the organic electroluminescent device. Is preferred. For this reason, in the composition for organic electroluminescent elements for forming the hole injection layer of the organic electroluminescent element by a wet film forming method, the solvent used is 0.005% by weight of the electron-accepting compound. It is preferably dissolved above, more preferably 0.05% by weight or more, and even more preferably 0.5% by weight or more.

  Furthermore, as will be described later, the solvent used for forming the hole injection layer of the organic electroluminescent element by a wet film-forming method is the organic compound of the present invention contained in the composition for organic electroluminescent element of the present invention. A hole-transporting compound such as the above, an electron-accepting compound, a deactivating substance that deactivates a cation radical of a hole-transporting compound generated from a mixture thereof, or a substance that does not generate a deactivating substance is preferable.

  Note that the cation radical of the hole transporting compound, the electron accepting compound, or the hole transporting compound resulting from the mixture thereof may be altered. This alteration is considered to be caused by interaction such as charge transfer with other compounds contained in the same layer formed in the organic electroluminescence device. When these are altered, there is a problem that hole injection / transport properties of a layer formed of these materials and the like are lowered. Many of these alterations are considered to be caused by the solvent or impurities contained in the solvent, and in order to form a layer having a high hole injection / transport property, as a solvent of the composition for organic electroluminescent elements, It is necessary to select an appropriate solvent that must not be. In addition, due to the above-described alteration, there is a tendency that impurities are likely to be generated in the composition for organic electroluminescent elements prepared for the wet film forming method, and the storage stability of the composition for organic electroluminescent elements is reduced. There is a point.

  Preferred solvents that satisfy the above conditions include, for example, ether solvents and ester solvents. Specifically, examples of the ether solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1, 3 -Aromatic ethers such as dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole and the like. Examples of ester solvents include aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and benzoic acid. Examples include aromatic esters such as n-butyl. These solvents may be used alone or in combination of two or more.

  The concentration of these solvents in the composition for organic electroluminescent elements is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and usually 99.999% by weight or less, preferably 99%. It is .99% by weight or less, and more preferably 99.9% by weight or less.

  In addition to the solvents described above, various other solvents may be included as necessary as the solvent. Examples of such other solvents include aromatic hydrocarbon solvents such as benzene, toluene and xylene, amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, and dimethyl sulfoxide. . However, aromatic hydrocarbon solvents such as benzene, toluene and xylene have low ability to dissolve cation radicals of hole transporting compounds, electron accepting compounds, and hole transporting compounds resulting from the mixture thereof. It is preferable to use a mixture with a system solvent, an ester solvent or the like.

As a hole-transporting compound such as the organic compound of the present invention, an electron-accepting compound, a deactivating substance that deactivates the cation radical of the hole-transporting compound resulting from a mixture thereof, or a compound that generates such a deactivating substance Examples thereof include alcohol solvents such as ethyl alcohol.
That is, when a layer containing a hole transporting compound such as the organic compound of the present invention and an electron accepting compound is formed by a wet film forming method using the composition for an organic electroluminescent element of the present invention, When these are contained in the composition for a light emitting device, the electron-accepting compound reacts with a solvent that easily undergoes oxidation, such as the alcohol solvent.

In addition, a hole-transporting compound such as the organic compound of the present invention, an electron-accepting compound, a deactivating substance that deactivates the cation radical of the hole-transporting compound resulting from a mixture thereof, or such a deactivating substance is generated. Examples of the compound include a protonic acid and a halogen solvent. Specifically, examples of the protonic acid include inorganic acids such as hydrochloric acid and hydrobromic acid; and organic acids such as formic acid, acetic acid, and lactic acid. Examples of the halogen-based solvent include a chlorine solvent, a bromine-containing solvent, and an iodine-containing solvent.

  For example, when a layer is formed by a wet film forming method using a composition for an organic electroluminescent device containing a hole transporting compound such as the organic compound of the present invention and an electron accepting compound, the organic electroluminescent device is used. If an organic acid or halogen-based solvent is contained in the composition, for example, the organic acid reacts with the hole injection / transport site and transforms into an ammonium salt. Pouring / transporting properties are reduced. In addition, when a halogen-based solvent is contained, these halogen-based solvents often contain a corresponding acid, and this acid, like the above-mentioned organic acid, is used for hole injection / transport. Since the property site is altered, the hole injection / transport property of the obtained layer also deteriorates. In addition, it is not preferable that halides are mixed even in terms of a large environmental load.

  In addition, since an organic electroluminescent element is formed by laminating a plurality of layers made of organic compounds, each layer is required to be a uniform layer. When a layer is formed by a wet film formation method, moisture is mixed into the solution for forming the layer (composition), so that moisture is mixed into the coating film and the uniformity of the film is impaired. The water content in the product is preferably as low as possible.

  Specifically, when a layer is formed by a wet film forming method using the composition for organic electroluminescent elements of the present invention, the amount of water contained in the composition for organic electroluminescent elements is 1% by weight or less, Preferably it is 0.1 weight% or less, More preferably, it is 0.05 weight% or less.

  In general, since organic electroluminescent elements use many materials such as cathodes that deteriorate significantly due to moisture, the presence of moisture in the composition for organic electroluminescent elements is not preferable from the viewpoint of element degradation. .

  Examples of the method for reducing the amount of water in the composition for organic electroluminescent elements include methods such as nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, and use of a solvent with low water solubility. . In particular, it is preferable to use a solvent having low water solubility because the formed film can prevent whitening by absorbing moisture in the atmosphere during the wet film forming process.

  From such a point of view, when the composition for organic electroluminescent elements of the present invention is used, particularly for use in forming a film by a wet film forming method, the composition for organic electroluminescent elements is, for example, at 25 ° C. It is preferable to contain 10% by weight or more of a solvent having a water solubility of 1% by weight or less, preferably 0.1% by weight or less. In addition, it is more preferable if the solvent which satisfy | fills this water solubility condition is 30 weight% or more in an organic electroluminescent element composition, and it is especially preferable if it is 50 weight% or more.

{Electron-accepting compound}
Next, the electron-accepting compound that is preferably contained in the composition for organic electroluminescent elements of the present invention will be described.

  The electron-accepting compound is preferably a compound having an oxidizing power and an ability to accept one electron from a hole-transporting compound such as the organic compound of the present invention. Specifically, a compound having an electron affinity of 4 eV or more. Is preferable, and a compound which is a compound of 5 eV or more is more preferable.

  Examples include onium salts substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, iron (III) chloride (JP-A-11-251067), ammonium peroxodisulfate and the like. Examples thereof include valent inorganic compounds, cyano compounds such as tetracyanoethylene, aromatic boron compounds such as tris (pentafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365), fullerene derivatives, iodine and the like.

  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. In particular, an onium salt substituted with an organic group is preferable, and an iodonium salt is particularly preferable.

  Specific examples of the organic group-substituted onium salts, cyano compounds, and aromatic boron compounds suitable as the electron-accepting compound include those described in WO 2005/089024, and the preferred examples thereof are also the same. It is not limited to them at all.

  An electron-accepting compound may be used individually by 1 type, and 2 or more types may be mixed and used for it.

{Hole transporting compound}
The composition for organic electroluminescent elements of the present invention may contain a hole transporting compound in addition to the organic compound of the present invention described above. The hole transporting compound will be described below.

  As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 5.5 eV is preferable in terms of hole transporting property. For example, an aromatic amine compound, a phthalocyanine derivative or a porphyrin derivative, a diarylamino group is used. Examples include 8-hydroxyquinoline derivative metal complexes and oligothiophene derivatives.

  Moreover, as said hole transportable compound, the hole transportable compound which is easy to melt | dissolve in a various solvent is preferable.

  As the aromatic tertiary amine compound, for example, a binaphthyl compound (Japanese Patent Laid-Open No. 2004-014187) and an asymmetric 1,4-phenylenediamine compound (Japanese Patent Laid-Open No. 2004-026732) are preferable. In addition, compounds that have been conventionally used as a hole injecting / transporting thin film forming material in an organic electroluminescence device may be appropriately selected from compounds that are easily dissolved in various solvents.

  Examples of conventionally known compounds that have been utilized as hole injection / transport thin film forming materials include tertiary aromatic amine units such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane. Two or more tertiary amines typified by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl; aromatic diamine compounds linked to each other (JP-A-59-194393); An aromatic amine compound having two or more condensed aromatic rings substituted with a nitrogen atom (Japanese Patent Laid-Open No. 5-234681); a derivative of triphenylbenzene and an aromatic triamine compound having a starburst structure (US Pat. No. 4 923,774); aromatic diamine compounds such as N, N′-diphenyl-N, N′-bis (3-methylphenyl) biphenyl-4,4′-diamine (US Pat. No. 4,764,625); α, α, α ′, α′-tetramethyl-α, α′-bis (4-di (p-tolyl) aminophenyl) -p-xylene 3-269084); a sterically asymmetric triphenylamine derivative as a whole molecule (JP-A-4-129271); a compound in which a pyrenyl group is substituted with a plurality of aromatic diamino groups (JP-A-4-175395) ); Aromatic diamine compounds in which tertiary aromatic amine units are linked by an ethylene group (JP-A-4-264189); Aromatic diamines having a styryl structure (JP-A-4-290851); Aromatic thiophene groups Compound in which tertiary amine units are linked (JP-A-4-304466); Starburst type aromatic triamine compound (JP-A-4-308688) Benzylphenyl compound (JP-A-4-364153); a compound in which a tertiary amine is linked by a fluorene group (JP-A-5-25473); a triamine compound (JP-A-5-239455); bisdipyridylaminobiphenyl ( JP-A-5-320634); N, N, N-triphenylamine derivatives (JP-A-6-1972); aromatic diamines having a phenoxazine structure (JP-A-7-138562); diaminophenylphenol Nantridine derivatives (JP-A-7-252474); hydrazone compounds (JP-A-2-315991); silazane compounds (US Pat. No. 4,950,950); silanamine derivatives (JP-A-6-49079) ); Phosphamine derivatives (JP-A-6-25659); Quinaclide Compounds. Preferred examples of the phthalocyanine derivative or porphyrin derivative include porphyrin, 5,10,15,20-tetraphenyl-21H, 23H-porphyrin, 5,10,15,20-tetraphenyl-21H, 23H-porphyrin cobalt. (II), 5,10,15,20-tetraphenyl-21H, 23H-porphyrin copper (II), 5,10,15,20-tetraphenyl-21H, 23H-porphyrin zinc (II), 5,10, 15,20-tetraphenyl-21H, 23H-porphyrin vanadium (IV) oxide, 5,10,15,20-tetra (4-pyridyl) -21H, 23H-porphyrin, 29H, 31H-phthalocyanine copper (II), phthalocyanine Zinc (II), phthalocyanine titanium, phthalocyanine oxy Magnesium, phthalocyanine lead, phthalocyanine copper (II), 4,4 ', 4 ", 4' '' - tetraaza-29H, 31H-phthalocyanine, and the like.

  Specific examples of preferred oligothiophene derivatives include α-terthiophene and derivatives thereof, α-sexithiophene and derivatives thereof, and oligothiophene derivatives containing a naphthalene ring (Japanese Patent Laid-Open No. 6-256341).

  These hole transporting compounds may be used in combination of two or more as required.

{Material concentration and compounding ratio}
The solid content concentration of the organic compound of the present invention, the electron-accepting compound of the present invention, and components that can be added as necessary (hole transporting compound, leveling agent, etc.) in the composition for organic electroluminescent elements of the present invention is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, further preferably 0.5% by weight or more, most preferably 1% by weight or more, usually 80% by weight Hereinafter, it is preferably 50% by weight or less, more preferably 40% by weight or less, further preferably 30% by weight or less, and most preferably 20% by weight or less. When this concentration is below the lower limit, it is difficult to form a thick film when forming a thin film, and when it exceeds the upper limit, it is difficult to form a thin film.

  In the composition for organic electroluminescent elements of the present invention, the weight mixing ratio of electron accepting compound / organic compound of the present invention is usually 0.1 / 99.9 or more, more preferably 0.5 / 99. 0.5 or more, more preferably 1/99 or more, most preferably 2/98 or more, usually 90/10 or less, more preferably 70/30 or less, and even more preferably 50/50 or less. It is. If this ratio falls below the lower limit or exceeds the upper limit, the hole injection property and heat resistance may be reduced.

{Preparation method}
The composition for organic electroluminescent elements of the present invention is prepared by dissolving a solute comprising the organic compound of the present invention, an electron accepting compound and components that can be added as necessary in a suitable solvent. In order to shorten the time required for the dissolution step and to keep the solute concentration in the composition uniform, the solute is usually dissolved while stirring the liquid. The dissolution step may be performed at room temperature, but when the dissolution rate is slow, it can be heated and dissolved. After completion of the dissolution step, a filtration step such as filtering may be performed as necessary.

{Properties, properties, etc. of composition for organic electroluminescence device}
<Moisture concentration>
In the case of producing an organic electroluminescent element by forming a layer by a wet film forming method using the composition for organic electroluminescent element of the present invention, if water is present in the composition for organic electroluminescent element to be used, the formed film Since moisture is mixed and the uniformity of the film is impaired, the water content in the composition for organic electroluminescent elements of the present invention is preferably as low as possible. In general, since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, when moisture is present in the composition for organic electroluminescent devices, moisture remains in the dried film. However, there is a possibility of deteriorating the characteristics of the element, which is not preferable.

  Specifically, the amount of water contained in the composition for organic electroluminescent elements of the present invention is usually 1% by weight or less, preferably 0.1% by weight or less, more preferably 0.01% by weight or less.

  As a method for measuring the moisture concentration in the composition for organic electroluminescent elements, the method described in Japanese Industrial Standard “Method for Measuring Moisture of Chemical Products” (JIS K0068: 2001) is preferable. For example, the Karl Fischer reagent method (JIS K0211). -1348) and the like.

<Uniformity>
The composition for organic electroluminescent elements of the present invention is preferably in a uniform liquid state at room temperature in order to improve stability in a wet film forming process, for example, ejection stability from a nozzle in an ink jet film forming method. . The uniform liquid at normal temperature means that the composition is a liquid composed of a uniform phase and does not contain a particle component having a particle size of 0.1 μm or more in the composition.

<Physical properties>
Regarding the viscosity of the composition for organic electroluminescent elements of the present invention, when the viscosity is extremely low, for example, coating surface non-uniformity due to excessive liquid film flow in the film forming process, nozzle ejection failure in ink jet film formation, etc. are likely to occur. In the case of extremely high viscosity, nozzle clogging or the like in ink jet film formation is likely to occur. For this reason, the viscosity at 25 ° C. of the composition of the present invention is usually 1 mPa · s or more, preferably 3 mPa · s or more, more preferably 5 mPa · s or more, and usually 1000 mPa · s or less, preferably 100 mPa · s or less. More preferably, it is 50 mPa · s or less.

  In addition, when the surface tension of the organic electroluminescent element composition of the present invention is high, the wettability of the liquid for film formation with respect to the substrate is lowered, the leveling property of the liquid film is poor, and the film formation surface is disturbed during drying. Since the problem of becoming easy occurs, the surface tension at 20 ° C. of the composition of the present invention is usually less than 50 mN / m, preferably less than 40 mN / m.

  Furthermore, when the vapor pressure of the composition for organic electroluminescent elements of the present invention is high, problems such as changes in solute concentration due to evaporation of the solvent tend to occur. For this reason, the vapor pressure at 25 ° C. of the composition of the present invention is usually 50 mmHg or less, preferably 10 mmHg or less, more preferably 1 mmHg or less.

{Storage method of composition for organic electroluminescence device}
The composition for an organic electroluminescent element of the present invention is preferably filled in a container capable of preventing the transmission of ultraviolet rays, for example, a brown glass bottle, and sealed and stored. The storage temperature is usually −30 ° C. or higher, preferably 0 ° C. or higher, and usually 35 ° C. or lower, preferably 25 ° C. or lower.

[Thin film for organic electroluminescence device]
The thin film for an organic electroluminescent device of the present invention formed by a wet film formation method using the composition for an organic electroluminescent device of the present invention is a film that is difficult to crystallize, has excellent luminescent properties and heat resistance, and is usually organic. Used as a layer between the cathode and anode of the electroluminescent device.

  Here, the wet film-forming method in the present invention refers to a coating method such as a spin coating method, a spray coating method, a dip coating method, a die coating method, a flexographic printing method, a screen printing method, and an inkjet method. It is used to form a film.

  For the purpose of reducing residual solvent and moisture, it is preferable to heat and dry after coating. The heating time is usually 1 minute or longer, preferably 24 hours or shorter. Although it does not specifically limit as a heating means, Means such as mounting the laminated body which has the formed layer on a hotplate, or heating in oven is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.

  The film thickness of the organic electroluminescent element thin film of the present invention is appropriately determined depending on the application, and is, for example, usually 10 nm or more, preferably 20 nm or more, usually 300 nm or less, preferably 200 nm or less, or usually 30 nm or more, preferably 50 nm or more, usually 500 nm or less, preferably 300 nm or less.

[Organic electroluminescence device]
The organic electroluminescent element of the present invention has an anode, a cathode, and an organic layer provided between the two electrodes, and the organic layer includes a layer containing the organic compound of the present invention. The layer containing the organic compound of the present invention preferably further contains an electron accepting compound. The organic electroluminescent element of the present invention is particularly preferably an organic electroluminescent element having a layer formed by a wet film formation method using the composition for organic electroluminescent elements of the present invention.

  The layer containing the organic compound of the present invention between the anode and the cathode is preferably a hole injection layer and / or a hole transport layer. In particular, when the organic compound of the present invention is used as a hole injection layer formed by a wet film-forming method at a position in contact with the anode, the surface roughness of the anode is reduced, and short circuit defects are prevented during device fabrication. It is preferable because the advantage of this layer is effective. In addition, the organic compound of the present invention has a suitable ionization potential, exhibits high redox stability and high hole injection / transport properties, and is preferable as a hole injection / transport material for organic electroluminescence devices. Of course, you may use the organic compound of this invention for a light emitting layer. The organic electroluminescent element of the present invention preferably has a light emitting layer as an organic layer, and this light emitting layer is a layer containing a low molecular compound formed by a wet film forming method. Here, the low molecular compound is a compound other than a polymer having a repeating unit produced by repeating the same reaction or a similar reaction, and the molecular structure is substantially single and the molecular structure is represented by the chemical formula. It is a compound that can be defined uniquely.

  FIG. 1 is an example of a schematic cross-sectional view showing a structural example suitable for the organic electroluminescence device of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a light emitting layer, 5 represents a hole blocking layer, 6 represents an electron transport layer, 7 represents an electron injection layer, and 8 represents a cathode.

[1] Substrate The substrate 1 serves as a support for the organic electroluminescent element, and quartz or glass plates, metal plates, metal foils, plastic films, sheets, and the like are used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone 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 (such as the hole injection layer 3 or the light emitting layer 4).

  The anode 2 is usually made of metal such as aluminum, gold, silver, nickel, palladium, platinum, metal oxide such as oxide of indium and / or tin, metal halide such as copper iodide, carbon black, or poly It is composed of conductive polymers such as (3-methylthiophene), polypyrrole, and polyaniline.

The anode 2 is usually formed by sputtering or vacuum deposition. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing and coating the substrate 1. Further, 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 is usually 5 nm or more, preferably 10 nm or more, and 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.

  The surface of the anode is treated with ultraviolet (UV) / ozone, oxygen plasma, or argon plasma for the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve hole injection. Is preferred.

[3] Hole Injection Layer The hole injection layer 3 is formed on the anode 2 by a wet film formation method or a vacuum deposition method. 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 the organic compound of the present invention.

  In particular, it is possible to produce an organic electroluminescent device that can be driven at a low voltage, has high luminous efficiency, and has high heat resistance. The resulting organic electroluminescent device has a reduced luminance and increased voltage when driven at a constant current. Since the generation of non-light emitting portions (dark spots), short-circuit defects, and the like can be suppressed, the hole injection layer 3 is preferably formed by a wet film formation method using the composition for organic electroluminescent elements of the present invention. Examples of the wet film forming method include spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, and ink jet method.

  In the hole injection layer 3, a cation radical obtained by removing one electron from an electrically neutral compound accepts one electron from a nearby electrically neutral compound, whereby holes move. When the cation radical compound is not included in the hole injection layer 3 when the element is not energized, the cation radical of the hole transport compound is generated when the hole transport compound gives electrons to the anode 2 during energization, Holes are transported by transferring electrons between the cation radical and an electrically neutral hole transporting compound.

  When the hole injection layer 3 contains a cation radical compound, cation radicals necessary for hole transport are present at a concentration higher than that generated by oxidation by the anode 2, and the hole transport performance is improved. It is preferable that the hole injection layer 3 contains a cation radical compound.

  Here, the cation radical compound is a cation radical that is a chemical species obtained by removing one electron from a hole transporting compound, and an ionic compound composed of a counter anion, and already has holes (free carriers) that are easy to move. Yes.

  Also, by mixing an electron-accepting compound with a hole-transporting compound such as the organic compound of the present invention, one-electron transfer from the hole-transporting compound to the electron-accepting compound occurs, and the above cation radical compound is generated. To do. For this reason, it is preferable that the hole injection layer 3 contains a hole transporting compound such as the organic compound of the present invention and an electron accepting 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.

  Alternatively, as the hole injection layer 3, only an electron-accepting compound may be formed on the anode 2 by a wet film forming method, and the organic electroluminescent element composition of the present invention may be directly applied and laminated thereon. Is possible. In this case, when a part of the composition for organic electroluminescent elements of the present invention interacts with the electron accepting compound, a layer excellent in hole injecting property is formed.

[4] Light-Emitting Layer The light-emitting layer 4 is formed on the hole injection layer 3. The light emitting layer 4 is a layer containing a light emitting material, and between the electrodes to which an electric field is applied, holes injected from the anode 2 through the hole injection layer 3 and electrons injected from the cathode 8 through the electron transport layer 5 It is a layer that is excited by recombination and becomes a main light emitting source.

The light emitting layer 4 preferably contains a light emitting material (dopant) and one or more host materials. The light emitting layer 4 may be a layer produced by a vacuum deposition method or a layer produced by a wet film formation method, but is preferably formed by a wet film formation method.
In the case of forming by a wet film forming method, the light emitting layer 4 is obtained by dissolving a light emitting material or a host material in a solvent to prepare a light emitting layer forming composition and forming the composition by a wet film forming method. . As a solvent, what was illustrated as a solvent contained in the composition for organic electroluminescent elements of the said invention is mentioned.

  The light emitting layer 4 can also be made of a polymer light emitting material such as a polyfluorene derivative or a poly (p-phenylene vinylene) derivative.

  The thickness of the light emitting layer 4 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less.

The light emitting material mainly refers to a component that emits light, and corresponds to a dopant component in an organic electroluminescent element. Of the amount of light emitted from the organic electroluminescent device (unit: cd / m ² ), usually 10 to 100%, preferably 20 to 100%, more preferably 50 to 100%, most preferably 80 to 100%. When it is identified as light emission from a component material, it is defined as a light emitting material.

  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, it is also important to reduce the symmetry and rigidity of the light emitting material molecule or introduce a lipophilic substituent such as an alkyl group.

  Examples of fluorescent dyes that emit blue light include perylene, pyrene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof. Examples of the green fluorescent dye include quinacridone derivatives and coumarin derivatives. Examples of yellow fluorescent dyes include rubrene and perimidone derivatives. Examples of red fluorescent dyes 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 (VIII-1) or the following general formula (VIII-2).
ML _(q−j) L ′ _j (VIII-1)
(In General Formula (VIII-1), M represents a metal, q represents the valence of the metal, L and L ′ represent a bidentate ligand, and j represents 0, 1 or 2. .)

（一般式（VIII−２）中、Ｍ^ｄは金属を表し、Ｔは炭素又は窒素を表す。Ｒ⁹²〜Ｒ⁹⁵は、それぞれ独立に置換基を表す。ただし、Ｔが窒素の場合は、Ｒ⁹⁴およびＲ⁹⁵は無い。）

(In the general formula (VIII-2), M ^d represents a metal, T represents carbon or nitrogen. R ^{92 to} R ⁹⁵ each independently represent a substituent. However, when T is nitrogen, R ^d represents R. ⁹⁴ and R ⁹⁵ are not available.)

Hereinafter, the compound represented by formula (VIII-1) will be described first.
In general formula (VIII-1), 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.
Moreover, the bidentate ligands L and L ′ in the general formula (VIII-1) each represent a ligand having the following partial structure.

As L ′, the followings are particularly preferable 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, and these may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group, and these may have a substituent.

  When ring A1 and ring 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, ethoxycarbonyl groups and the like Alkoxycarbonyl 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 Acyl groups such as acetyl groups; haloalkyl groups such as trifluoromethyl groups; cyano groups; aromatic hydrocarbon groups such as phenyl groups, naphthyl groups, and phenanthyl groups.

  More preferable examples of the compound represented by the general formula (VIII-1) include compounds represented by the following general formulas (VIII-1a), (VIII-1b), and (VIII-1c).

（一般式（VIII−１ａ）中、Ｍ^ａはＭと同様の金属を表し、ｗは上記金属の価数を表す。また、環Ａ１は置換基を有していてもよい芳香族炭化水素基を表し、環Ａ２は置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In General Formula (VIII-1a), M ^a represents the same metal as M, w represents the valence of the metal, and ring A1 is an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

（一般式（VIII−１ｂ）中、Ｍ^ｂはＭと同様の金属を表し、ｗは上記金属の価数を表す。また、環Ａ１は置換基を有していてもよい芳香族炭化水素基又は置換基を有していてもよい芳香族複素環基を表し、環Ａ２は置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In the general formula (VIII-1b), M ^b represents the same metal as M, w represents the valence of the metal. Further, the ring A1 is an aromatic optionally substituted hydrocarbon group Or, it represents an aromatic heterocyclic group which may have a substituent, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

（一般式（VIII−１ｃ）中、Ｍ^ｃはＭと同様の金属を表し、ｗは上記金属の価数を表す。また、ｊは０、１又は２を表す。さらに、環Ａ１および環Ａ１’は、それぞれ独立に、置換基を有していてもよい芳香族炭化水素基又は置換基を有していてもよい芳香族複素環基を表す。また、環Ａ２および環Ａ２’は、それぞれ独立に、置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In the general formula (VIII-1c), M ^c represents the same metal as M, w represents the valence of the metal, and j represents 0, 1 or 2. Furthermore, ring A1 and ring A1 Each independently represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group, and ring A2 and ring A2 ′ each represent Independently, it represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

  In the general formulas (VIII-1a), (VIII-1b), and (VIII-1c), the group of the ring A1 and the ring A1 ′ is preferably, for example, a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group. Group, furyl group, benzothienyl 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 (VIII-1a), (VIII-1b), and (VIII-1c) may have include halogen atoms such as fluorine atoms; methyl groups, ethyl groups Alkenyl groups such as vinyl groups; Alkenyl groups such as vinyl 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; And dialkylamino groups such as diethylamino group; diarylamino groups such as diphenylamino group; carbazolyl groups; acyl groups such as acetyl group; haloalkyl groups such as trifluoromethyl group; cyano groups and the like.

  When the said substituent is an alkyl group, the carbon number is 1 or more and 6 or less normally. Furthermore, when the substituent is an alkenyl group, the carbon number is usually 2 or more and 6 or less. When the substituent is an alkoxycarbonyl group, the carbon number is usually 2 or more and 6 or less. Further, when the substituent is an alkoxy group, the carbon number is usually 1 or more and 6 or less. Moreover, when a substituent is an aryloxy group, the carbon number is 6 or more and 14 or less normally. Furthermore, when the substituent is a dialkylamino group, the carbon number is usually 2 or more and 24 or less. Further, when the substituent is a diarylamino group, the carbon number is usually 12 or more and 28 or less. Furthermore, when the substituent is an acyl group, the carbon number is usually 1 or more and 14 or less. Moreover, when a substituent is a haloalkyl group, the carbon number is 1 or more and 12 or less normally.

  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 (VIII-1a), (VIII -1b), (VIII-1c) in ^{M a,} M b, preferably as ^{M c,} ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or Gold is mentioned.

  Specific examples of the organometallic complex represented by the general formula (VIII-1), (VIII-1a), (VIII-1b) or (VIII-1c) are shown below, but are not limited to the following compounds. None (in the following, Ph represents a phenyl group).

  Among the organometallic complexes represented by the general formulas (VIII-1), (VIII-1a), (VIII-1b), and (VIII-1c), in particular, the ligand L and / or L ′ is 2- An arylpyridine-based ligand, that is, a compound having 2-arylpyridine, one having an arbitrary substituent bonded thereto, and one obtained by condensing an arbitrary group thereto is preferable.

Next, the compound represented by the general formula (VIII-2) will be described.
In the general formula (VIII-2), M ^d represents a metal, and specific examples include metals described above as the metal to periodic table 7 is selected from Group 11. 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 (VIII-2), 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, A carboxyl group, 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 is represented.

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, R ⁹⁴ and R ⁹⁵ are absent.

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 (VIII-2) 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.

The phosphorescent material is usually used by mixing with a host material.
As the host material, any known material can be applied. Examples of applicable compounds include the following, and of course, the organic compound of the present invention can also be used.

  Examples of carbazole compounds (including triarylamine compounds) include JP-A-63-235946, JP-A-2-285357, JP-A-2-261889, JP-A-3-230584, and JP-A-3230584. JP-A-3-232856, JP-A-5-263073, JP-A-6-312979, JP-A-7-053950, JP-A-8-003547, JP-A-9-157743, JP-A-9- No. 268283, JP-A-9-165573, JP-A-9-249876, JP-A-9-310066, JP-A-10-041069, JP-A-10-168447, European Patent No. 847228 , JP-A-10-208880, JP-A-10-226785, JP-A-10-312 73, JP-A-10-316658, JP-A-10-330361, JP-A-11-144866, JP-A-11-144867, JP-A-11-144873, JP-A-11-149987 Gazette, JP-A-11-167990, JP-A-11-233260, JP-A-11-241662, WO-00 / 70655, U.S. Pat. No. 6,562,982, JP-A-2003-040844, JP-A-2001-313179, JP-A-2001-257076, Japanese Patent Application No. 2003-202925, Japanese Patent Application No. 2003-204940, Japanese Patent Application No. 2003-299512, etc. Compound etc. are mentioned.

  Examples of the phenylanthracene derivative include compounds described as charge transport materials in JP-A No. 2000-344691.

  Furthermore, examples of the starburst type compound of condensed ring arylene include compounds described as charge transport materials in JP-A No. 2001-192651, JP-A No. 2002-324677, and the like.

  Examples of the condensed ring imidazole compound include “Appl. Phys. Lett., 78, 1622, 2001”, JP 2001-335776 A, JP 2002-338579 A, and JP 2002-319491 A. JP-A 2002-367785, JP-A 2002-367786, and the like include compounds described as charge transport materials.

  Furthermore, examples of the azepine-based compound include compounds described as charge transport materials in JP-A No. 2002-2335075 and the like.

  In addition, examples of the condensed triazole-based compound include compounds described as charge transporting materials in JP-A No. 2002-356489 and the like.

  Further, examples of the propeller-type arylene compound include compounds described in JP-A-2003-027048 as charge transport materials.

  Examples of the monotriarylamine type compounds include compounds described as charge transport materials in JP-A No. 2002-17583, JP-A No. 2002-249765, JP-A No. 2002-324676, and the like.

  Furthermore, examples of the arylbenzidine compounds include compounds described as charge transport materials in JP-A No. 2002-329577 and the like.

  Examples of the triaryl boron compound include compounds described as charge transport materials in JP-A Nos. 2003-031367 and 2003-031368.

  Further, examples of the indole compounds include compounds described in JP 2002-305084 A, JP 2003-008866 A, JP 2002-015871 A, and the like as charge transport materials.

  Examples of indolizine compounds include compounds described as charge transport materials in JP-A No. 2000-311787.

  Furthermore, examples of the pyrene compound include compounds described as charge transport materials in JP-A No. 2001-118682 and the like.

  Examples of the dibenzoxazole (or dibenzothiazole) compound include compounds described as charge transport materials in JP-A No. 2002-231453.

  Further, examples of the bipyridyl compounds include compounds described as charge transport materials in JP-A No. 2003-123983 and the like.

  Examples of the pyridine-based compound include compounds described as charge transport materials in JP-A-2005-276801, JP-A-2005-268199, and the like.

  Among these, carbazole compounds (including triarylamine compounds), condensed arylene starburst compounds, condensed imidazole compounds, from the viewpoint of excellent emission characteristics when using an organic electroluminescent device, Propeller type arylene compounds, monotriarylamine type compounds, indole compounds, indolizine compounds, bipyridyl compounds, pyridine compounds and the like are preferable.

  Furthermore, from the viewpoint of driving life when using an organic electroluminescent device, a carbazole compound, a bipyridyl compound, and a pyridine compound are more preferable, a mixture of a carbazole compound and a bipyridyl compound, or a carbazole compound and It is most preferable to use a mixture of pyridine compounds.

  It is also preferable to employ a compound having both a carbazolyl group and a pyridyl group.

  For the purpose of improving the solubility in a solvent, it is also important to reduce the symmetry and rigidity of the molecule or to introduce a lipophilic substituent such as an alkyl group.

  The compound used as the host material has a glass transition point of usually 70 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 130 ° C. or higher, and most preferably 150 ° C. or higher. This is because if the glass transition point is too low, the heat resistance of the organic electroluminescent device may be lowered and the driving life may be shortened.

  The compound used as the host material has a molecular weight of usually 10,000 or less, preferably 5000 or less, more preferably 3000 or less, and usually 100 or more, preferably 300 or more, more preferably 500 or more. When the molecular weight is less than 100, the heat resistance is remarkably lowered, gas generation is caused, the film quality is deteriorated when the film is formed, or the morphology of the organic electroluminescent element is changed due to migration or the like. This is not preferable. When the molecular weight exceeds 10,000, it is not preferable because purification of the host material is difficult or time is required for dissolution in a solvent.

  The compound used as the host material desirably has a band gap of usually 3.0 V or higher, preferably 3.2 V or higher, more preferably 3.5 V or higher. Blue fluorescent light-emitting materials or phosphorescent light-emitting materials, especially green to blue light-emitting materials have a large band gap. When an organic electroluminescent element is produced using this phosphorescent light-emitting material, the host material surrounding the phosphorescent light-emitting material is: This is because, in general, it is preferable that the phosphorescent material has a bandgap that is equal to or larger than that of the phosphorescent material in terms of luminous efficiency and life as an organic electroluminescent element.

  The light emitting layer 4 may further contain other materials and components as long as the performance of the present invention 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 invention, in addition to the light emitting layer 4, when the organic layer such as the hole injection layer 3 and the electron transport layer 5 described later is provided, the light emitting layer 4 and other organic materials such as the hole injection layer 3 and the electron transport layer 5 The total film thickness combined with the 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 7 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 thickness of the light emitting layer 4 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less.

[5] Hole blocking layer The hole blocking layer 5 has a function of confining holes and electrons in the light emitting layer 4 and improving the light emission efficiency. That is, the hole blocking layer 5 is generated by increasing the probability of recombination with electrons in the light emitting layer 4 by blocking the holes moving from the light emitting layer 4 from reaching the electron transport layer 6. 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 6 in the direction of the light emitting layer 4.

  The hole blocking layer 5 prevents the holes moving from the anode 2 from reaching the cathode 8 and can efficiently transport the electrons injected from the cathode 8 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 on the cathode 8 side of the light emitting layer 4.

  The physical properties required of the material constituting the hole blocking layer 5 include high electron mobility, low hole mobility, large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.

  Examples of the hole blocking layer material satisfying such conditions include mixed arrangements of bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, styryl compounds such as distyrylbiphenyl derivatives ( 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 5 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 5 can also be formed by the same method as the hole injection layer 3, but a vacuum deposition method is usually used.

  The electron transport layer 6 and the hole blocking layer 5 described later may be appropriately provided as necessary. 1) Only the electron transport layer, 2) Only the hole block layer, and 3) The hole block layer / electron transport layer There are usages such as stacking, 4) not using, etc.

[6] Electron Transport Layer The electron transport layer 6 is provided between the light emitting layer 4 and the electron injection layer 7 for the purpose of further improving the light emission efficiency of the device.

  The electron transport layer 6 is formed of a compound that can efficiently transport electrons injected from the cathode 8 between the electrodes to which an electric field is applied in the direction of the light emitting layer 4. As the electron transporting compound used for the electron transport layer 6, the electron injection efficiency from the cathode 8 or the electron injection layer 7 is high, and the injected electrons having high electron mobility can be efficiently transported. 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, 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 6 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 6 is formed by laminating on the light emitting layer 4 by a wet film formation method or a vacuum deposition method in the same manner as the hole injection layer 3. Usually, a vacuum deposition method is used.

[7] Electron Injection Layer The electron injection layer 7 serves to efficiently inject electrons injected from the cathode 8 into the light emitting layer 4. In order to perform electron injection efficiently, the material for forming the electron injection layer 7 is preferably a metal having a low work function, and alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium are used.

  The film thickness of the electron injection layer 7 is preferably 0.1 to 5 nm.

Further, it is possible to insert an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO _{3 at} the interface between the cathode 8 and the light emitting layer 4 or the electron transport layer 6. (Appl. Phys. Lett., 70, 152, 1997; JP-A-10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997); SID 04 Digest, page 154).

  Furthermore, organic metal 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 JP-A-10-270171, JP-A 2002-1000047, JP-A 2002-1000048, and the like) makes it possible to improve electron injection / transport properties and achieve excellent film quality. 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 7 is formed by laminating on the light emitting layer 4 by a wet film forming method or a vacuum vapor 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 Heat and evaporate to form an electron injection layer 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 heated simultaneously to evaporate to form an electron injection layer on the substrate placed facing the crucible and dispenser.

  At this time, co-evaporation is uniformly performed in the film thickness direction of the electron injection layer 7, but there may be a concentration distribution in the film thickness direction.

[8] Cathode The cathode 8 plays a role of injecting electrons into a layer on the light emitting layer side (such as the electron injection layer 7 or the light emitting layer 4). The material used for the cathode 8 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, A suitable metal such as aluminum or 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 8 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

  As described above, the element having the layer structure shown in FIG. 1 has been mainly described. However, the above description is provided as long as the performance is not impaired between the anode 2 and the cathode 8 and the light emitting layer 4 in the organic electroluminescent element of the present invention. In addition to the layers, any layer may be included, and any layer other than the light emitting layer 4 may be omitted.

  For example, it is also effective to provide an electron blocking layer between the hole injection layer 3 and the light emitting layer 4 for the same purpose as the hole blocking layer 5. 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). Further, when the light emitting layer 4 is formed by a wet film forming method, it is preferable to form the electron blocking layer 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. As a material used for such an electron blocking layer, in addition to the charge transport material of the present invention, dioctylfluorene represented by F8-TFB and And a copolymer of triphenylamine (described in WO 2004/084260).

  The structure opposite to that shown in FIG. 1, that is, a cathode 8, an electron injection layer 7, an electron transport layer 6, a hole blocking layer 5, a light emitting layer 4, a hole injection layer 3, and an anode 2 are laminated on the substrate 1 in this order. As described above, the organic electroluminescent element of the present invention can be provided between two substrates, at least one of which is highly transparent.

Further, 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 present invention can be applied to any of an organic electroluminescent element having a single element, an element having a structure arranged in an array, and a structure having an anode and a cathode arranged in an XY matrix.

  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.

[Synthesis example of organic compounds]
The synthesis example of the organic compound of this invention is shown below.

(Synthesis Example 1) Objects 1 to 5

  In a nitrogen stream, 4,4′-diaminodiphenyl ether (4.00 g), 4-iodoanisole (28.1 g), copper (5.08 g), potassium carbonate (16.6 g), tetraglyme (50 ml) The mixture was stirred for 9 hours while being heated to ° C. After allowing to cool, chloroform (200 ml) was added and stirred, and then insoluble matters were filtered off, and the filtrate was concentrated. The obtained solid was suspended and washed with ethanol to obtain the desired product 1 (10.3 g).

  The target product 1 (5.21 g) and dichloromethane (160 ml) were cooled to 0 ° C. in a nitrogen stream, and a 1M methylene chloride solution of boron tribromide (50 ml) was added dropwise, followed by stirring for 30 minutes. The mixture was warmed to room temperature, sodium bicarbonate water was added, and the mixture was extracted with ethyl acetate. The organic layer was concentrated and purified by silica gel column chromatography (hexane / ethyl acetate = 1/1) to obtain (4.60 g). Obtained.

  In a nitrogen stream, 4-iodoanisole (15.7 g), 4,4′-difluorobenzophenone (31.2 g), potassium carbonate (29.6 g), and N-methylpyrrolidone (NMP) (70 ml) were added at 140 ° C. The mixture was stirred for 3 hours under heating. After allowing to cool, water was added and stirred, followed by extraction with toluene and chloroform. After the organic layer was concentrated, the obtained precipitate was suspended and washed with methanol to obtain the desired product 3 (22.9 g).

  In a nitrogen stream, the target product 3 (22.0 g), diphenylamine (9.79 g), copper (6.69 g), potassium carbonate (21.8 g), and tetraglyme (20 ml) were heated to 190 ° C. Stir for hours. After allowing to cool, chloroform (200 ml) was added and stirred, and then insoluble matters were filtered off, and the filtrate was concentrated. The obtained solid was suspended and washed with methanol to obtain the desired product 4 (12.1 g).

In a nitrogen stream, target 2 (2.26 g), target 4 (9.50 g), potassium carbonate (6.60 g), and NMP (40 ml) were stirred at 150 ° C. for 8 hours. After allowing to cool, activated clay and chloroform were added and stirred, insoluble matter was filtered off, and the filtrate was concentrated. The resulting precipitate was washed in suspension with methanol / water mixture, methanol, and acetone in order, then purified by silica gel column chromatography (methylene chloride: ethyl acetate), dissolved in methylene chloride, and reprecipitated in methanol. By doing this, the target object 5 (6.21 g) was obtained. By MALDI-MS (m / z = 2325 (M ⁺ )), it was confirmed to be the intended product 5.

(Synthesis Example 2) Target products 6 to 8

  In a nitrogen stream, 4-aminophenol (4.40 g), 4,4′-difluorobenzophenone (4.00 g), potassium carbonate (10.1 g), and NMP (80 ml) were heated to 140 ° C. for 3 hours. Stir. After allowing to cool, water was added and stirred, followed by extraction with toluene and ethyl acetate. After the organic layer was concentrated, the obtained precipitate was suspended and washed with an ethanol / water mixture to obtain the desired product 6 (4.21 g).

  In a nitrogen stream, the target compound 4 (4.80 g) synthesized in Synthesis Example 1 and 4-iodophenol (2.40 g), potassium carbonate (2.87 g), and NMP (25 ml) were heated to 150 ° C. Stir for 8 hours. After allowing to cool, activated clay and toluene were added and stirred, insoluble matter was filtered off, water was added to the filtrate, and the organic layer was concentrated. The obtained precipitate was dissolved in methylene chloride and then reprecipitated in methanol twice to obtain the target product 7 (3.76 g).

In a nitrogen stream, target 6 (0.301 g), target 7 (3.50 g), copper (0.385 g), potassium carbonate (1.68 g), and tetraglyme (15 ml) were heated to 200 ° C. And stirred for 9 hours. After allowing to cool, activated clay and chloroform were added and stirred, insoluble matter was filtered off, and the filtrate was concentrated. The obtained solid was suspended and washed with methanol, purified by silica gel column chromatography (methylene chloride: ethyl acetate), dissolved in methylene chloride, and reprecipitated in methanol to obtain the target compound 8 (1 .20 g) was obtained. By MALDI-MS (m / z = 2520 (M ⁺ )), it was confirmed to be the target product 8.

[Production of organic electroluminescence device]
Example 1
The organic electroluminescent element shown in FIG. 1 was produced.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 with a thickness of 120 nm (manufactured by Sanyo Vacuum Co., Ltd., sputtered film product) using ordinary photolithography technology and hydrochloric acid etching Then, the anode 2 was formed by patterning into stripes having a width of 2 mm. The patterned ITO substrate is cleaned in the order of ultrasonic cleaning with an aqueous surfactant solution, water cleaning with ultrapure water, ultrasonic cleaning with ultrapure water, and water cleaning with ultrapure water, followed by drying with compressed air, and finally UV irradiation. Ozone cleaning was performed.

  First, the organic compound of the present invention represented by the following structural formula (P1) (target product 5 synthesized in Synthesis Example 1) and 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluoro) represented by the structural formula (A1). A composition for an organic electroluminescent device containing phenyl) borate and ethyl benzoate in the following composition was prepared. This composition for organic electroluminescent elements was formed into a film by spin coating under the following conditions. Thereafter, the formed film was baked in the atmosphere at 230 ° C. for 3 hours to obtain a hole injection layer 3 having a thickness of 30 nm.

<Composition for organic electroluminescence device>
Solvent Ethyl benzoate Concentration P1: 2.0% by weight
A1: 0.8% by weight

<Film formation conditions>
Spinner speed 1500rpm
Spinner rotation time 30 seconds Spin coating atmosphere In air Next, a composition for forming a light emitting layer containing organic compounds (C1) and (C2) represented by the following structural formula and xylene was prepared. This light emitting layer forming composition was formed on the hole injection layer 3 by spin coating under the following conditions. Thereafter, the formed film was baked in a vacuum at 130 ° C. for 1 hour to obtain a light emitting layer 4 having a thickness of 30 nm.

<Composition for light emitting layer formation>
Solvent Xylene Concentration C1: 2.0 wt%
C2: 0.1% by weight

<Film formation conditions>
Spinner speed 1000rpm
Spinner rotation time 30 seconds Spin coat atmosphere In nitrogen

Next, the substrate on which the hole injection layer 3 and the light emitting layer 4 are applied and formed is placed in a vacuum deposition apparatus, and after the apparatus is roughly evacuated by an oil rotary pump, the degree of vacuum in the apparatus is 1.6. It exhausts using a cryopump until it becomes less than * 10 <^-4> Pa, The organic compound shown by the following structural formula (C3) is formed into a film on the light emitting layer 4 with a vacuum evaporation method, The hole-blocking layer 5 with a film thickness of 5 nm Got. The degree of vacuum during deposition was 1.6 × 10 ⁻⁴ Pa, and the deposition rate was controlled in the range of 0.4 to 0.7 K / sec.

Next, tris (8-hydroxyquinolinate) aluminum was heated and evaporated to form an electron transport layer 6 having a thickness of 30 nm on the hole blocking layer. The degree of vacuum during vapor deposition was controlled in the range of 1.5 to 1.6 × 10 ⁻⁴ Pa and the vapor deposition rate in the range of 0.4 to 1.2 kg / sec.
The substrate temperature during vacuum deposition of the hole blocking layer 5 and the electron transport layer 6 was kept at room temperature.

Here, the element on which the electron transport layer 6 has been deposited is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide stripe-shaped shadow mask is used as a cathode deposition mask. The device was in close contact with each other so as to be orthogonal to each other, placed in another vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus was 1.9 × 10 ⁻⁴ Pa or less in the same manner as the organic layer.

As the electron injection layer 7, first, lithium fluoride (LiF) is controlled using a molybdenum boat at a deposition rate of 0.12 liters / second and a degree of vacuum of 2.4 × 10 ⁻⁴ Pa. A film was formed on the electron transport layer 6.

Next, aluminum is similarly heated as a cathode 8 by a molybdenum boat and controlled at a deposition rate of 0.5 to 5.0 kg / sec and a degree of vacuum of 3.0 to 7.0 × 10 ⁻⁴ Pa to a film thickness of 80 nm. An aluminum layer was formed. The substrate temperature during the deposition of the electron injection layer 7 and the cathode 8 was kept at room temperature.

Subsequently, in order to prevent the element from being deteriorated by moisture in the atmosphere during storage, a sealing process was performed by the method described below.
In a nitrogen glove box, a photocurable resin (30Y-437 manufactured by ThreeBond Co., Ltd.) with a width of about 1 mm is applied to the outer periphery of a 23 mm × 23 mm glass plate, and a moisture getter sheet (Dynic Corporation) is applied to the center. Made). On this, the board | substrate which complete | finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened.

  As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained.

Table 1 shows the normalized driving life when the initial luminance of the obtained organic electroluminescent element is 2500 cd / m ² .

(Comparative Example 1)
In Example 1, as a composition for forming a hole injection layer, a hole transporting polymer compound having a repeating structure represented by the following structural formula (P1) (weight average molecular weight 29400, number average molecular weight 12600), 1 except that the 30-nm-thick hole injection layer 3 was formed using a composition containing the compound represented by the structural formula (A1) and ethyl benzoate in the following composition. The organic electroluminescent element shown in FIG.

<Composition for forming hole injection layer>
Solvent Ethyl benzoate Concentration P2: 2.0% by weight
A1: 0.8% by weight

Table 1 shows the normalized driving life when the initial luminance of the obtained organic electroluminescent element is 2500 cd / m ² .

  As is apparent from Table 1, the organic electroluminescence device produced using the composition for organic electroluminescence device containing the organic compound of the present invention has achieved a long life.

(Example 2)
The organic electroluminescent element shown in FIG. 1 was produced in the same manner as in Example 1 except that the formation of the hole injection layer and the light emitting layer was changed as follows.

  First, an organic compound of the present invention represented by the following structural formula (P3) (target product 8 synthesized in Synthesis Example 2) and 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluoro) represented by the structural formula (A1). A composition for an organic electroluminescent device containing phenyl) borate and ethyl benzoate in the following composition was prepared. This composition for organic electroluminescent elements was formed into a film by spin coating under the following conditions. Thereafter, the formed film was baked in the atmosphere at 230 ° C. for 3 hours to obtain a hole injection layer 3 having a thickness of 25 nm.

<Composition for organic electroluminescence device>
Solvent Ethyl benzoate Concentration P3: 2.0% by weight
A1: 0.8% by weight

<Film formation conditions>
Spinner speed 1500rpm
Spinner rotation time 30 seconds Spin coat atmosphere In air

  Next, a composition for forming a light emitting layer containing organic compounds (C4), (C2) and toluene represented by the following structural formula was prepared. This light emitting layer forming composition was formed by spin coating under the following conditions. Thereafter, the formed film was baked in a vacuum at 100 ° C. for 1 hour to obtain a light emitting layer 4 having a thickness of 65 nm.

<Composition for light emitting layer formation>
Solvent Toluene Concentration C4: 2.0% by weight
C2: 0.1% by weight

<Film formation conditions>
Spinner speed 1500rpm
Spinner rotation time 30 seconds Spin coat atmosphere In nitrogen

Table 2 shows the normalized driving life when the initial luminance of the obtained organic electroluminescent element is 2500 cd / m ² .

(Comparative Example 2)
In Example 2, as a composition for forming a hole injection layer, a hole transporting polymer compound having a repeating structure represented by the following structural formula (P4) (p: q = 1: 1, weight average molecular weight 26500, Number average molecular weight 12000), a composition containing the compound represented by the above structural formula (A1) and anisole in the following composition was formed by spin coating under the following conditions. The organic electroluminescent element shown in FIG. 1 was produced in the same manner as in Example 2 except that after baking at 230 ° C. for 3 hours, a hole injection layer 3 having a thickness of 30 nm was obtained.

<Composition for forming hole injection layer>
Solvent Anisole Concentration P4: 2.0% by weight
A1: 0.4% by weight

<Film formation conditions>
Spinner speed 2000rpm
Spinner rotation time 30 seconds Spin coat atmosphere In air

Table 2 shows the normalized driving life when the initial luminance of the obtained organic electroluminescent element is 2500 cd / m ² .

  As is apparent from Table 2, the organic electroluminescent device produced using the composition according to the present invention has achieved a long lifetime.

It is typical sectional drawing which showed an 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 Hole blocking layer 6 Electron transport layer 7 Electron injection layer 8 Cathode

Claims (9)

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

(In formula (I), Ar ^{1 to} Ar ¹⁸ each independently represents an aromatic hydrocarbon group composed of a 6-membered monocyclic ring or a 2-5 condensed ring .
Q ¹ represents a linking group selected from the group of linkage groups Q below SL '.
Q < ² > -Q < ⁵ > represents -O-Ar < ²¹ > -C (= O) -Ar < ²² > -O-.
m and n are 1 . )
<Linking group Q '>

(In the formula, Ar ^{21 to} Ar ²² each independently represents an aromatic hydrocarbon group composed of a 6-membered monocyclic ring or a 2-5 condensed ring.) The organic compound according to claim 1, wherein in the formula (I), Ar ^{1 to} Ar ¹⁸ are a group consisting of a benzene ring. The composition for organic electroluminescent elements containing the organic compound of Claim 1 or 2 . Furthermore, the composition for organic electroluminescent elements of Claim 3 containing an electron-accepting compound. The composition for organic electroluminescent elements according to claim 4 , wherein the electron-accepting compound is an iodonium salt. The thin film for organic electroluminescent elements formed by the wet film-forming method using the composition for organic electroluminescent elements as described in any one of Claims 3 thru | or 5 . An organic electroluminescent element having an anode, a cathode and an organic layer provided between both electrodes on a substrate, wherein the organic layer has a layer containing the organic compound according to claim 1 or 2 as the organic layer. Light emitting element. The organic electroluminescent element according to claim 7 , wherein the layer containing the organic compound according to claim 1 or 2 is a layer formed by a wet film forming method. The organic electroluminescent element according to claim 7 or 8 , wherein the organic layer has a light emitting layer, and the light emitting layer is a layer formed by depositing a low molecular compound by a wet film forming method.

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