JP4876390B2 - Composition, charge transport material, organic electroluminescent device and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve hole injection and transportation in the hole injection and transportation layer or luminous layer using an aromatic diamine containing compound, and improve solubility of the aromatic diamine containing compound into a solvent. <P>SOLUTION: This is a composition which contains a high molecular weight compound having the weight-average molecular weight of 3,000-1,000,000 and a repeating unit as expressed by a general formula (1) and a low molecular weight component corresponding to a molecular weight of a compound as expressed by a general formula (2). The composition has an integral value of 3% or less of a peak integral value corresponding to a molecular weight of a specific component (low molecular weight component area ratio) against the integral value of the total molecular weight distribution in the molecular weight distribution determined by SEC (size exclusion chromatography) measurement. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a composition containing an aromatic diamine-containing polymer compound, a charge transport material using the composition, an organic electroluminescent device, and a method for producing the 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. When used as an organic electroluminescent device, the high luminous efficiency is one of the important factors. Regarding the luminous efficiency, a hole transport layer composed of an aromatic diamine compound, aluminum of 8-hydroxyquinoline, and the like. The organic electroluminescence device provided with a light emitting layer composed of a complex is greatly improved.

A method of forming the hole transport layer as described above by a wet film forming method has been reported. In general, a layer containing a hole transport material or an electron-accepting compound of an organic electroluminescence device is formed by a wet film forming method, so that the heat resistance and surface of the device are compared with those formed by a vacuum deposition method. It is said that there are excellent advantages such as improved flatness.
For example, Patent Document 1 reports that an organic electroluminescent element using an aromatic diamine-containing polymer compound having a high glass transition temperature as a hole transport layer is formed by a wet film forming method. However, there is a problem that the compound does not dissolve unless it is a polar solvent or a halogen-based solvent having high water solubility.

In addition, the reason why the driving voltage of the organic electroluminescent element is increased is that the contact between the anode and the hole transport layer is considered to be insufficient. Means for improving the contact between the anode and the hole transport layer by providing a hole injection layer containing an electron-accepting compound and reducing the driving voltage have been studied. As an example, Patent Document 2 discloses a method in which a hole injection layer is formed by a spin coating method, which is a kind of wet film-forming method, using a 1,2-dichloroethane solution containing an aromatic diamine-containing polymer compound. Is described.

  In Patent Document 3, a 1,4-phenylenediamine-containing polymer compound that is a hole transporting material and tris (4-bromophenyl) ammonium hexachloroantimonate (TBPAH) or tris (penta) that are electron accepting compounds. A method is described in which a hole injection / transport layer is formed by spin coating using a solution of fluorophenyl) borane (PPB) dissolved in cyclohexanone or ethyl benzoate.

When an aromatic diamine-containing compound is used for the hole injection / transport layer as described above, a device having improved heat resistance can be provided. However, the hole injection / transport properties of the hole injection / transport layer and the solubility of the aromatic diamine-containing compound in the solvent are considered to be further studied since the wet film formation method is used. It was. In the hole injection / transport layer with low hole injection / transport properties, when used as an organic electroluminescent device, holes are not efficiently injected into the light-emitting layer, so drive voltage, light emission efficiency, and drive stability There is a high possibility of adversely affecting sex. In addition, when the solubility is low, it is difficult to form a layer using a wet film forming method.
JP-A-9-188756 JP 2000-36390 A Japanese Patent Laid-Open No. 2003-213002

  An object of the present invention is to improve hole injection / transport properties in a hole injection / transport layer or a light emitting layer using an aromatic diamine-containing polymer compound. Another object is to improve the solubility of the aromatic diamine-containing polymer compound in a solvent.

  As a result of intensive studies by the present inventors, the cause of the decrease in hole injection / transport is considered to be due to the presence of a specific low molecular weight component such as a cyclic dimer in the aromatic diamine-containing polymer compound. It was. The low molecular weight component traps charges, so that the charge mobility is lowered and the hole injection / transport property is lowered. Therefore, it has been found that the problem of the present invention can be solved by reducing the low molecular weight component, and the present invention has been achieved. It was also found that the solubility of the aromatic diamine-containing compound in the solvent can be improved by reducing the low molecular weight component.

That is, the present invention provides a high molecular weight compound having a weight average molecular weight of 3,000 to 1,000,000 and having a repeating unit represented by the following general formula (1) and a compound represented by the following general formula (2): And a compound represented by the following general formula (2) with respect to an integral value of the entire molecular weight distribution in a molecular weight distribution determined by SEC (size exclusion chromatography) measurement: In the composition , the ratio of the integrated values of the peaks corresponding to the low molecular weight components containing (hereinafter referred to as the low molecular weight component area ratio) is 3% or less.
The present invention also relates to a charge transport material comprising the composition, an organic electroluminescent device having a layer containing the composition, a composition for an organic electroluminescent device comprising the composition and a solvent, And, using the reprecipitation method, the purified product of the reprecipitation method and the solvent to be the precipitating agent are mixed to form a mixture, and the liquid layer portion in the mixture is removed and purified within 30 minutes. It exists in the manufacturing method of this composition.

(In the formula, Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.
Ar ^{3 to} Ar ⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. .
X represents a linking group selected from the following linking group group X ¹ . )
Linking group X ¹

(In the formula, Ar ^{11 to} Ar ²⁸ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. R ³¹ and R ³² each independently represent Represents a hydrogen atom or an arbitrary substituent.

Where Ar ¹  And Ar ²  , Ar ³  ~ Ar ⁵  And X have the same meanings as in general formula (1).

The composition of the present invention is excellent in charge transport properties (hole injection / transport properties) because low molecular weight components such as cyclic dimers that cause charge trapping are reduced. In addition, the compound has a higher solubility in various organic solvents by reducing low molecular weight components, and is used as a hole injection / transport material for organic electroluminescent devices formed by a wet film formation method. preferable. Moreover, since it has a high glass transition temperature compared with the thing containing a low molecular weight component, it is further excellent in heat resistance.

Moreover, the composition (coating liquid) further containing a solvent in the composition of the present invention makes it possible to form a layer by a wet film forming method without altering the components in the coating liquid. According to the organic electroluminescent element manufactured using the composition of the present invention, an element in which a decrease in luminance during continuous driving is reduced is provided.
Accordingly, the organic electroluminescent device manufactured using the composition of the present invention is a light source (for example, a light source of a copying machine) utilizing characteristics of a flat panel display (for example, for an OA computer or a wall-mounted television) or a surface light emitter. LCD backlights and instrument backlights)
Application to display panels and marker lamps is conceivable, and the technical value is particularly great as an in-vehicle display element that requires high heat resistance.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.
First, the composition of the present invention will be described.
The composition of the present invention has a weight average molecular weight of 3,000 to 1,000,000, a high molecular weight compound having a repeating unit represented by the following general formula (1), and the following general formula (2). In a molecular weight distribution determined by SEC (size exclusion chromatography) measurement, a composition containing a low molecular weight component corresponding to the molecular weight of the compound having the following general formula (2 The peak integral value (hereinafter referred to as the low molecular weight component area ratio) corresponding to the molecular weight of the compound represented by (3) is 3% or less.

(In the formula, Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.
Ar ^{3 to} Ar ⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. .
X represents a linking group selected from the following linking group group X ¹ . )
Linking group X ¹

(In the formula, Ar ^{11 to} Ar ²⁸ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. R ³¹ and R ³² each independently represent Represents a hydrogen atom or an arbitrary substituent.
In the composition of the present invention, Ar ^{1 to} Ar ⁵ in the low molecular weight component represented by the general formula (2) are Ar ¹ to Ar selected from the high molecular weight compound having a repeating unit represented by the general formula (1). Corresponds to Ar ⁵ . And the integrated value (low molecular weight area ratio) of the peak corresponding to the molecular weight of the compound represented by the general formula (2) is 3% with respect to the integrated value of the entire molecular weight distribution of the composition of the present invention.
The following.

  That is, in the composition of the present invention, the compound of the general formula (2) is a compound in which two of the repeating units of the general formula (1) are bonded cyclically, and the repeating units are bonded cyclically. In the case of bonding in a ring-opened state, or in the case of multiple types of repeating units, that is, in the case of copolymerization, two different types of repeating units are bonded. It is difficult to separate and identify them.

  Therefore, in the composition of the present invention, these various combinations are quantitatively captured as a group of peaks corresponding to the molecular weight of the compound represented by the general formula (2) by the SEC technique. The integrated value of the peak corresponding to the molecular weight of the compound represented by the general formula (2) with respect to the integrated value of the entire molecular weight distribution corresponding to the entire composition is set to a narrowed range of 3% or less. It is stipulated.

Ar ^{1 to} Ar ⁵ and Ar ^{11 to} Ar ²⁸ may be any aromatic hydrocarbon group or aromatic heterocyclic group, and each may be the same or different, and any substitution It may have a group.
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 ^{3 to} Ar ⁵ and Ar ^{11 to} Ar ¹⁵ , Ar ^{17 to} Ar ²⁰ , Ar ^{22 to} Ar ²⁵ , Ar ²⁷ , and Ar ²⁸ are one kind or two or more kinds of aromatic hydrocarbon groups and / or aromatic complexes. A ring group can be connected and used.
R ³¹ and R ³² may be a hydrogen atom or an arbitrary substituent, and may be the same as or different from each other. Examples of the applicable substituent include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a silyl group, a siloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group.

As a substituent which Ar < ¹ > -Ar < ⁵ > and Ar < ¹¹ > -Ar < ²⁸ > may have, the 1 type (s) or 2 or more types of the following substituent group Z are mentioned, for example.
[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 it is C1-C10, such as a methoxy group and an ethoxy group, More preferably, it is C1-C6
An alkoxy group of
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, and 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;
A haloalkyl group having preferably 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 ring group having preferably 6 to 30 carbon atoms, more preferably 6 to 18 carbon atoms, such as a phenyl group and a naphthyl group;
Preferably an aromatic heterocyclic group having 3 to 28 carbon atoms, more preferably 4 to 17 carbon atoms, such as a thienyl group, a pyridyl group, etc. The molecular weight of each of the substituents is preferably 400 or less, and more preferably about 250 or less.

From the viewpoint of solubility, heat resistance, hole injection / transport properties, Ar ¹ and Ar ² are preferably monovalent groups derived from a benzene ring, naphthalene ring, phenanthrene ring, thiophene ring, or pyridine ring, phenyl group, A naphthyl group is more preferable.
In view of heat resistance and hole injection / transport properties including redox potential, Ar ^{3 to} Ar ⁵ are preferably divalent groups derived from a benzene ring, a naphthalene ring, an anthracene ring, or a phenanthrene ring, a phenylene group, More preferred are a biphenylene group and a naphthylene group.

  Further, the composition of the present invention has a very high hole injection / transport property, so that the general formula (1) is represented by the following general formula (1 ′) and the general formula (2) is represented by the following general formula ( 2 ′) is preferable, and the above general formula (1) is more preferably the following general formula (3), and the above general formula (2) is more preferably the following general formula (4).

In formula, R < ¹ > -R < ⁵ > represents an arbitrary substituent each independently. p and q each independently represent an integer of 0 to 5. r, s, and t each independently represent an integer of 0-4. X has the same meaning as in general formula (1).
Specific examples of R ^{1 to} R ⁵ are the same as the examples of the substituent that Ar ^{1 to} Ar ⁵ may have, that is, the substituent group Z described above.

Wherein, Y represents a linking group selected from the group of linkage groups X ² below.
Linking group X ²

Ar ^{11 to} Ar ¹⁷ are the same as Ar ^{11 to} Ar ¹⁷ described above.

In formula, Y is synonymous with the thing in General formula (3).

  Specific examples of preferable repeating units of the composition of the present invention are shown below, but the present invention is not limited thereto.

Among the above specific examples, P-1 to P-11, P-13 to P-18, P-20, P-21, P-23, and P-25 are more preferable in terms of heat resistance and charge transportability. , P-26 repeating units, and more preferably P-1, P-3, P-4, P-6, P-9, and P-10 repeating units. More preferably, it is a repeating unit of P-1 to P-11, P-13 to P-18, P-20, P-21, P-23, P-25, P-26, and more preferably P- 1, P-3, P-4, P-6, P-9, and P-10, and most preferably P-1 and P-4.

  The high molecular weight compound having a repeating unit represented by the general formula (1) (hereinafter simply referred to as a high molecular weight compound) contains two or more types of repeating units represented by the general formula (1) as necessary. It may be a compound. In addition, the compound represented by the general formula (2) may have a different general formula (1) as a unit. Furthermore, the composition of the present invention may contain other various repeating units as long as the performance of the composition of the present invention is not impaired.

The composition of the present invention is useful when an organic electroluminescent device having a weight average molecular weight of 3,000 to 1,000,000 is used. Further, when the layer containing this composition is formed by a wet coating method, a layer having a weight average molecular weight of about 10,000 or more and 200,000 or less is preferable from the viewpoint of solubility and heat resistance.
In the molecular weight distribution determined by SEC (size exclusion chromatography) measurement, the composition containing the repeating unit represented by the general formula (1) of the present invention has a molecular weight of the compound represented by the general formula (2). The ratio of the integrated value of the peak corresponding to the total molecular weight distribution to the integrated value of the total molecular weight distribution (low molecular weight component area ratio) is 3% or less, but from the viewpoint of solubility, film-forming property, hole injection / transport property 1.5% or less, preferably 0.001% or more, more preferably 0.7% or less, and still more preferably 0.3% or less. Usually, the low molecular weight area ratio before being reduced by purification or the like is 4 to 7%, and depending on conditions, it may be as large as 15%.

  The peak corresponding to the molecular weight of the compound represented by the general formula (2) is not only the peak indicating the compound represented by the general formula (2) but also the same position as the compound represented by the general formula (2). It means the thing including the peak of the compound that appears. For example, a cyclic dimer represented by the general formula (2), a chain dimer in which the cyclic dimer is opened, and the like are represented by two different general formulas (1). A cyclic dimer and a chain dimer having a structure represented by the general formula (2) are also included. However, it is usually expected to be a cyclic dimer substantially represented by the general formula (2).

Here, in the molecular weight distribution determined by the low molecular weight component area ratio, that is, SEC (size exclusion chromatography) measurement, the integrated value of the peak corresponding to the molecular weight of the compound represented by the general formula (2) is the entire molecular weight distribution. A method of calculating the ratio of the integral value of will be described.
First, SEC measurement conditions are shown. The column is TSKgel GMH _XL x 2 manufactured by Tosoh Corporation or a column having a resolution equal to or higher than that, that is, particle size: 9 mm, column size: 7.8 m
m Inside diameter x 30 cm x 2 and guaranteed theoretical plate number: about 14000 TP / 30 cm, column temperature is 40 ° C. The moving bed is selected from tetrahydrofuran and chloroform that do not adsorb to the filler, and the flow rate is 1.0 ml / min. The injection concentration is 0.1% by weight, and the injection amount is 0.10 ml. RI is used as a detector. The molecular weight distribution is determined by converting the elution time of the sample into the molecular weight using a calibration curve calculated from the elution time of polystyrene (standard sample) having a known molecular weight. In the SEC measurement, the elution time is shorter for the high molecular weight component, and the elution time is longer for the low molecular weight component. In the SEC measurement of the composition containing the repeating unit represented by the general formula (1) of the present invention, a peak corresponding to the molecular weight of the compound represented by the general formula (2) is observed in about 18 minutes to 19 minutes. Is done. After elution of the component corresponding to the molecular weight of the compound represented by the general formula (2), the refractive index indicated by the detector becomes constant, and the elution time when the refractive index of the solvent used in the moving bed is approximately equal to the peak end is defined as the peak end. To do. When the elution time at the peak end is converted into a molecular weight, logM is about 2.4 to 2.8.

Here, the low molecular weight component area ratio is the integrated value (area) of the low molecular weight side from the peak top of the peak corresponding to the molecular weight of the compound represented by the general formula (2) in the molecular weight distribution determined by the above method. A value obtained by doubling A) by the integral value (area B) of the entire molecular weight distribution.
That is,
Low molecular weight component area ratio = 2 × (area A) / (area B)
And expressed as a percentage,
Low molecular weight component area ratio (%) = 2 × (area A) / (area B) × 100
It becomes.

  The molecular weight of the compound represented by the general formula (2) is calculated according to the repeating unit actually selected from the repeating units represented by the general formula (1) used. In the molecular weight distribution curve by SEC measurement, a peak corresponding to the molecular weight value is observed, but some of the substituents may react depending on the polymerization conditions, and a slight molecular weight shift may be observed. Even in this case, the molecular weight variation range is about ± 50 or less.

  The high molecular weight compound contained in the composition of the present invention includes, for example, a dihydroxy compound represented by the general formula (5) and a dihalide represented by the general formula (6) in the presence of a base such as potassium carbonate or triethylamine. It is synthesized by reacting below.

(In the general formulas (5), (6) and (1), Ar ^{1 to} Ar ⁵ and X are as defined in the general formula (1), and X ′ represents a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom. .)
Generally, a structure in which the repeating unit represented by the general formula (1) is repeated by reacting the dihydroxy compound represented by the general formula (5) with the dihalide represented by the general formula (6). In addition to a high molecular weight compound having a low molecular weight component such as a cyclic dimer represented by the general formula (2) (a compound specified by a peak corresponding to the molecular weight of the compound represented by the general formula (2) Etc.).

  As described above, the product is identified by a peak corresponding to the molecular weight of the compound represented by the general formula (2) specified in the present invention, in addition to the high molecular weight compound represented by the general formula (1). In addition to low molecular weight components such as compounds (such as cyclic dimers), other low molecular weight components are also contained. However, in the present invention, the solubility and hole injection / transport properties can be improved by removing the compound specified by the peak corresponding to the molecular weight of the compound represented by the general formula (2). I understood. Further, the glass transition temperature was increased by the removal, and further improvement in heat resistance was observed.

The composition of the present invention is a low molecular weight component such as a compound (such as a cyclic dimer) identified by a peak corresponding to the molecular weight of the compound represented by the general formula (2) identified in the present invention. In addition, the low molecular weight component can be efficiently removed by purifying a solution containing a high molecular weight compound containing other low molecular weight components by a reprecipitation method. That is, the low molecular weight component is more soluble in the high molecular weight component having the repeating unit represented by the general formula (1) and the low molecular weight component such as the cyclic dimer represented by the general formula (2). Although the low molecular weight component has a lower precipitation rate, the low molecular weight component can be efficiently removed by separating the liquid layer within a certain time after re-precipitation. Is possible.

  That is, the reprecipitation method is a method in which a high-molecular-weight compound is mainly added by adding a solution to be purified, that is, a solution in which both a high-molecular-weight compound and a low-molecular-weight component are dissolved, to a solvent (bedding liquid) that serves as a precipitant. And the liquid layer is removed before the low molecular weight component is precipitated. As the solvent (rich solvent) for dissolving the high molecular weight compound and the low molecular weight component and the solvent (poor solvent) used as the precipitating agent (laying liquid), any solvent can be used, but the solubility and precipitation of the composition In view of operability such as the shape of the high molecular weight compound and filterability, the following solvents are preferred.

Examples of the rich solvent include halogen solvents such as chloroform, dichloromethane, 1,2-dichloroethane and chlorobenzene, ether solvents such as tetrahydrofuran, ethylene glycol dimethyl ether and anisole, N, N-dimethylformamide, N, N-dimethylacetamide, N An amide solvent such as methylpyrrolidone, an ester solvent such as γ-butrolactone and methyl benzoate, a ketone solvent such as cyclohexanone and acetophenone, and an aromatic solvent such as benzene, xylene and pyridine are preferable, and a halogen solvent. Chloroform, dichloromethane, 1,2-dichloroethane, ether solvents such as tetrahydrofuran and ethylene glycol dimethyl ether are more preferable in terms of operability because the composition of the present invention is dissolved in a small amount of solvent. Chloroform is halogenated solvent, more preferably dichloromethane.

  Examples of the poor solvent include alcohol solvents such as methanol, ethanol and isopropanol, ketone solvents such as acetone and methyl ethyl ketone, ether solvents such as diethyl ether and tert-butyl methyl ether, alkane solvents such as hexane and heptane, and ethyl acetate. Ester solvents such as butyl acetate are preferred, alcohol solvents such as methanol, ethanol, ketone solvents acetone, methyl ethyl ketone, and ester solvents ethyl acetate are moderate in terms of slow precipitation of low molecular weight components. Since it has a vapor pressure, it is more preferable in terms of operability, and acetone and methyl ethyl ketone which are ketone solvents are more preferable.

That is, in the present invention, it is preferable to use a halogen-based solvent and / or a ketone-based solvent from the viewpoint of the deposition rate of low molecular weight components and operability, and more preferably, as the rich solvent, the halogen-based solvent and the poor solvent. Using a ketone solvent.
In the method for producing the composition of the present invention, it is necessary to remove the liquid layer (supernatant liquid) after reprecipitation and before the low molecular weight component is precipitated. Specifically, from the point of time when the solution to be purified, which is a solution in which at least a high molecular weight compound and a low molecular weight component are dissolved, and a solvent that serves as a precipitant are mixed to form a mixture, that is, the solution is put into a bedding liquid. After the addition is complete, the liquid layer is preferably removed within 30 minutes, more preferably within 15 minutes, and even more preferably after 1 minute and within 7 minutes.

The glass transition temperature of the composition of the present invention is usually 90 ° C. or higher, preferably 110 ° C. or higher, more preferably 130 ° C. or higher in terms of driving stability including the heat resistance of the organic electroluminescent element. The potential to be oxidized is usually +0.2 to +1.2 V vs. SCE, preferably from +0.4 to +1.0 V vs. SCE in terms of charge transportability, and the ionization potential is usually 4 From the viewpoint of charge transportability, it is preferably 4.8 to 5.3 eV.

The composition of the present invention exhibits high solubility in various solvents mentioned as the aforementioned rich solvent.
Since the composition of the present invention has high solubility and excellent hole injection / transport properties, it can be used as a charge transporting material that can be used in a wet film-forming method as an electrophotographic photosensitive member, an organic electroluminescent device, a photoelectric conversion device, an organic material. It can be suitably used for solar cells, organic rectifying elements, and the like. Although the composition of the present invention itself can be used as a charge transport material, it can also be used as a charge transport material containing the composition of the present invention and other compounds.

In addition, since the composition of the present invention is difficult to crystallize, has a high glass transition temperature, and has excellent thin film forming properties, the organic electroluminescent device containing the composition of the present invention has excellent heat resistance and is stable for a long period of time. It is possible to provide an organic electroluminescent element that is driven (emitted).
Next, the organic electroluminescent element of the present invention will be described.
Here, when there is one layer between the anode and the light emitting layer in the organic electroluminescent element, this is referred to as a “hole injection layer”, and when there are two or more layers, the layer in contact with the anode is The “hole injection layer” and the other layers are collectively referred to as “hole transport layer”. In addition, layers provided between the anode and the light emitting layer may be collectively referred to as a “hole injection / transport layer”.

The organic electroluminescent element of the present invention is characterized by containing the composition of the present invention. The organic electroluminescent device of the present invention has an anode, a cathode, and a light emitting layer provided between the two electrodes, and the composition and electron accepting compound of the present invention are provided between the light emitting layer and the anode. A layer containing is provided. Of course, you may use the composition of this invention for a light emitting layer.
The layer containing the composition of the present invention between the light emitting layer and the anode is preferably a hole injection layer and / or a hole transport layer. In particular, when the composition of the present invention is used as a hole injection layer formed by a wet film formation method at a position in contact with the anode, the surface roughness of the anode is relaxed, and short circuit defects are prevented during device fabrication. It is preferable because the advantage of this layer is effective. The composition 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 electroluminescent devices.

A coating liquid for forming a layer containing the composition of the present invention (particularly, a hole injection layer) by a wet coating method is a composition for an organic electroluminescent device containing a solvent in addition to the composition of the present invention. It is preferable that it is a composition for organic electroluminescent elements containing an electron-accepting compound. Furthermore, you may contain hole transport materials other than the composition of this invention as needed.
First, the solvent that is a component of the coating solution will be described.

  Not only the formation of the hole injection layer of the organic electroluminescence device, but also the solvent used for forming the charge transport material using the composition of the present invention by a wet coating method, that is, the organic electroluminescence device composition. The solvent to be used is not particularly limited as long as it dissolves the composition of the present invention. Here, the solvent that dissolves the composition of the present invention is usually a solvent that dissolves 0.05% by weight or more, preferably 0.5% by weight or more, and more preferably 1% by weight or more. Since the composition of the present invention has high solubility, various solvents can be applied.

  Further, as described above, in order to improve the hole injection / transport property and lower the driving voltage of the organic electroluminescence device, it is preferable to form a hole injection layer containing an electron accepting compound. For this reason, the solvent used for forming the hole injection layer of the organic electroluminescence device by a wet coating method preferably dissolves 0.005% by weight or more of an electron-accepting compound, and dissolves 0.05% by weight or more. More preferably, it is more preferably 0.5% by weight or more.

Furthermore, as described above, the solvent used for forming the hole injection layer of the organic electroluminescence device by the wet coating method is a hole transporting material containing the composition of the present invention, an electron accepting compound, those The thing which does not contain the thing which generate | occur | produces the deactivated substance which deactivates the cation radical of the hole transportable material which arises from mixing, or a deactivated substance is preferable.
The cation radicals of the hole injecting / transporting material, the hole injecting / transporting material, the electron accepting compound, and the hole injecting / transporting material resulting from the mixture thereof may be altered. It is considered that the alteration is caused by an interaction such as charge transfer with another compound contained in the same layer formed in the organic electroluminescence device. When altered, there is a problem that the hole injection / transport property of a layer formed of these materials or the like is lowered. Many of these alterations are attributed to the solvent or impurities contained in the solvent. To form a layer with high hole injection / transport properties, an appropriate solvent that does not cause alteration is selected as the coating solvent. There is a need. Further, due to the above-mentioned alteration, there is a tendency that impurities are more likely to be generated in the coating solution prepared for the wet film forming method, and the storage stability of the coating solution is lowered.

  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 the ester solvent include aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl benzoate, benzoic acid And aromatic esters such as propyl and n-butyl benzoate.

  The concentration of these solvents in the coating solution is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more. 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. . Moreover, various additives, such as a leveling agent and an antifoamer, may be included.

Aromatic hydrocarbon solvents such as benzene, toluene, and xylene have the ability to dissolve cation radicals of electron-accepting compounds and hole-injecting / transporting materials resulting from the mixture of hole-transporting materials and electron-accepting compounds. Since it is low, it is preferable to use a mixture with an ether solvent and an ester solvent.
As a hole-transporting material, an electron-accepting compound containing the composition of the present invention, a deactivating substance for deactivating a cation radical of a hole-transporting material resulting from a mixture thereof, or a compound for generating such a deactivating substance Examples thereof include alcohol solvents such as ethyl alcohol; aldehyde solvents such as benzaldehyde; ketone solvents having a hydrogen atom at the α-position such as methyl ethyl ketone, cyclohexanone and acetophenone.

  Such alcohol solvents, aldehyde solvents and ketone solvents are particularly easy to react with electron accepting compounds. Specifically, alcohol is oxidized to aldehyde or carboxylic acid, aldehyde is oxidized to carboxylic acid, and ketone and aldehyde having a hydrogen atom at the α-position undergo a condensation reaction between solvent molecules. Or adhere to the cation radical of the hole injecting / transporting material to generate impurities.

Therefore, when a layer containing a hole transporting material and an electron accepting compound containing the composition of the present invention is formed by a wet film-forming method, the inclusion of these in the solution causes the above alcohol-based solvent, etc. A solvent susceptible to oxidation reacts with an electron-accepting compound. Solvents that are susceptible to oxidation are cation radicals of the hole-injecting / transporting material generated from the mixture of the hole-injecting / transporting material and the electron-accepting compound. May also react. From the reaction of these oxidizable solvents, the electron-accepting compounds or cation radicals in the coating solution are consumed and impurities are generated, so that the solution is gradually deactivated and the storage stability of the solution is reduced. Industrially unfavorable.

  Further, a hole transporting material containing the composition of the present invention, an electron-accepting compound, a deactivating substance that deactivates a cation radical of the hole-transporting material 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.

  When a layer is formed by a wet film-forming method using a solution containing a hole-transporting material and an electron-accepting compound containing the composition of the present invention, the solution contains an organic acid or a halogen-based solvent. For example, the organic acid reacts with the hole injecting / transporting site and transforms into an ammonium salt, so that the hole injecting / transporting property of the obtained layer is lowered. 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 forming method, moisture is mixed into the coating solution (composition) for forming the layer, so that moisture is mixed into the coating film and the uniformity of the film is impaired. Is preferably as small as possible.
Specifically, the amount of water contained in the coating solution for forming the layer containing the composition of the present invention by a wet coating method is 1% by weight or less, preferably 0.1% by weight or less, more preferably Is 0.05% by 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 is not preferable from the viewpoint of element degradation. Examples of the method for reducing the amount of water in the solution include nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, use of a solvent with low water solubility, and the like. In particular, it is preferable to use a solvent having low water solubility because the solution coating film can prevent whitening by absorbing moisture in the air during the coating process.

  From such a viewpoint, the coating liquid for forming the layer containing the composition of the present invention by a wet coating method has, for example, a water solubility at 25 ° C. of 1% by weight or less, preferably 0.1% by weight. % Or less of the solvent is preferably contained in the composition in an amount of 10% by weight or more. The solvent satisfying the solubility condition is more preferably 30% by weight or more, and particularly preferably 50% by weight or more.

  Next, the electron accepting compound will be described. The electron-accepting compound is contained in a coating solution for forming a layer containing the composition of the present invention by a wet coating method. Examples of the electron-accepting compound include one selected from the group consisting of triaryl boron compounds, metal halides, Lewis acids, organic acids, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Or 2 or more types of compounds etc. are mentioned. These electron-accepting compounds are used by mixing with a hole transporting material containing the compound of the present invention, and by oxidizing the composition of the present invention and / or other hole transporting materials, a hole injection layer. The electrical conductivity of can be improved.

Examples of the triarylboron compound as the electron-accepting compound include boron compounds represented by the following general formula (7). The boron compound represented by the general formula (7) is preferably a Lewis acid. Further, the electron affinity of the boron compound is usually 4 eV or more, preferably 5 eV or more.

In the general formula (7), preferably, Ar ^{7 to} Ar ⁹ are each independently a monocyclic 5- or 6-membered ring such as a phenyl group, a naphthyl group, an anthryl group, or a biphenyl group that may have a substituent, Or an aromatic hydrocarbon ring group formed by condensing and / or directly bonding 2 to 3 of these; or 5 or 6 such as a thienyl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, etc., which may have a substituent. It represents a single-membered ring or an aromatic heterocyclic group formed by condensing 2 or 3 of these and / or directly bonding them.

  Examples of such a substituent include a halogen atom such as a fluorine atom; a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; a methoxycarbonyl group and an ethoxy group. C1-C6 linear or branched alkoxycarbonyl group such as carbonyl group; C1-C6 linear or branched alkoxy group such as methoxy group and ethoxy group; Aryloxy such as phenoxy group and benzyloxy group Groups; dialkylamino groups such as dimethylamino group and diethylamino group; acyl groups such as acetyl group; haloalkyl groups such as trifluoromethyl group; and cyano groups.

As such a substituent, at least one of Ar ^{7 to} Ar ⁹ is preferably a compound having a substituent having a positive Hammett constant (σm and / or σp), Ar ⁷ to
It is particularly preferable that Ar ⁹ is a compound having a substituent whose Hammett constant (σm and / or σp) is a positive value. By having such an electron-withdrawing substituent, the electron acceptability of these compounds is improved. Further, it is more preferable that Ar ^{7 to} Ar ⁹ are all compounds representing an aromatic hydrocarbon group or an aromatic heterocyclic group substituted with a halogen atom.

  Preferred specific examples (1-29) of the boron compound represented by the general formula (7) are shown below, but are not limited thereto.

  Of these, the following compounds are particularly preferred.

  Further, as the electron-accepting compound, one or more compounds selected from the group consisting of metal halides, Lewis acids, organic acids, salts of arylamines and metal halides, salts of arylamines and Lewis acids Specific examples of these include the compounds shown below.

In addition, content with respect to the hole transportable material containing the composition of this invention of an electron-accepting compound is 0.1 weight% or more normally, Preferably it is 1 weight% or more. However, it is usually 100% by weight or less, preferably 40% by weight or less.
Next, a hole transporting material other than the composition of the present invention, which may be used as a mixture with the layer containing the composition of the present invention formed by a wet coating method, will be described.

As the hole transport material, a compound having an ionization potential of 4.5 eV to 5.5 eV is preferable from the viewpoint of charge transportability. For example, an aromatic amine compound, a phthalocyanine derivative or a porphyrin derivative, or a diarylamino group is used. -Metal complexes of hydroxyquinoline derivatives, oligothiophene derivatives and the like.
Moreover, since it uses for the layer formation by a wet film forming method, what is easy to melt | dissolve in a various solvent is preferable. As the aromatic amine compound, for example, a binaphthyl compound represented by the following general formula (8) is preferable. In addition, a compound that has been conventionally used as a hole injecting / transporting layer forming material in an organic electroluminescence device may be appropriately selected from compounds that are easily dissolved in various solvents.

(In the general formula (8), Ar ^{51 to} Ar ⁵⁸ are each independently a monocyclic group or a condensed 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring which may have a substituent. Represents a cyclic group, Ar ⁵¹ and Ar ⁵² , Ar ⁵⁵ and Ar ⁵⁶ may be bonded to each other to form a ring;
m and l each represents an integer from 0 to 4, and m + 1 satisfies 1. Particularly preferred are m = 1 and l = 1.
Q ¹ and Q ² each independently represents a direct bond or a divalent linking group.
In addition, the naphthalene ring in the general formula (8) is an arbitrary substituent in addition to — (Q ¹ NAr ⁵³ Ar ⁵⁷ (NAr ⁵¹ Ar ⁵² ) and — (Q ² NAr ⁵⁴ Ar ⁵⁸ (NAr ⁵⁵ Ar ⁵⁶ )). In addition, these substituents — (Q ¹ NAr ⁵³ Ar ⁵⁷ (NAr ⁵¹ Ar ⁵² ) and — (Q ² NAr ⁵⁴ Ar ⁵⁸ ) (NAr ⁵⁵ Ar ⁵⁶ ) may be substituted at any position of the naphthalene ring. Among them, binaphthyl compounds substituted in the 4-position and 4′-position of the naphthalene ring in the general formula (2), respectively, are more preferable.

The binaphthylene structure in the compound represented by the general formula (8) preferably has a substituent at the 2,2′-position. As the substituent bonded to the 2,2′-position, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an alkenyl group which may have a substituent, The alkoxycarbonyl group etc. which may have a substituent are mentioned.

In the compound represented by the general formula (8), the binaphthylene structure may have an arbitrary substituent other than the 2,2′-position. Examples of the substituent include 2,2′- Examples of the substituents at the position include the groups described above. The compound represented by the general formula (8) has a substituent at the 2-position and the 2′-position, so that two naphthalene rings are twisted, and thus the solubility is considered to be improved. The molecular weight of the binaphthyl compound represented by the general formula (8) is usually less than 2,000, preferably less than 1,200, but usually 500 or more, preferably 700 or more.

Examples of conventionally known compounds that have been used as hole injection / transport layer forming materials in organic electroluminescence devices include 3 such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane. Aromatic diamine compounds in which secondary aromatic amine units are linked (Japanese Patent Laid-Open No. 59-194393); two represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl Aromatic amines containing the above tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681); derivatives of triphenylbenzene and aromatic triamines having a starburst structure (USA) Patent No. 4,923,774); aromatic diamines 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-tolylaminophenyl) -p-xylene -2699084); a sterically asymmetric triphenylamine derivative as a whole molecule (JP-A-4-129271); a compound in which a plurality of aromatic diamino groups are substituted on a pyrenyl group (JP-A-4-175395) An aromatic diamine in which a tertiary aromatic amine unit is linked with an ethylene group (JP-A-4-264189); an aromatic diamine having a styryl structure (JP-A-4-290851); an aromatic tertiary with a thiophene group Concatenated amine units (JP-A-4-304466); starburst aromatic triamine (JP-A-4-308688); benzylphenyl compound (Japanese Patent Laid-Open No. 4-364153); a tertiary amine linked by a fluorene group (Japanese Patent Laid-Open No. 5-25473); a triamine compound (Japanese Patent Laid-Open No. 5-239455); N, N, N-triphenylamine derivative (JP-A-6-1972); aromatic diamine having a phenoxazine structure (JP-A-7-138562); diaminophenylphenanthridine derivative (JP-A-7-252474); hydrazone compound (JP-A-2-311591); silazane compound (US Pat. No. 4,950,950); silanamine derivative (JP-A-6-49079); phosphamine Derivatives (JP-A-6-25659); quinacridone compounds and the like Among these compounds, one kind or two or more kinds as necessary may be mixed with the compound of the present invention.

Next, preferred specific examples of the phthalocyanine derivative or porphyrin derivative that may be used in the composition of the present invention include the following compounds.
For example, 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 oxide magnesium phthalocyanine lead phthalocyanine copper ( II), 4, ', 4'',4''' - tetraaza-29H, 31H-phthalocyanine, and the like.

  Next, a metal complex of an 8-hydroxyquinoline derivative having a diarylamino group that may be used in the composition of the present invention will be described. In the above metal complex, the central metal is alkali metal, alkaline earth metal, Sc, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Al, Ga, In, Si, Ge, Sn. , Sm, Eu, Tb, and the ligand 8-hydroxyquinoline has at least one diarylamino group as a substituent, but may have any substituent other than the diarylamino group .

  In addition, examples of the oligothiophene derivative used as a hole injecting / transporting material that may be used by mixing with the composition of the present invention include α-sexithiophene. The molecular weight of these hole injection / transport materials is usually less than 2,000, preferably less than 1,800, more preferably less than 1,200, but usually 500 or more, preferably 700 or more. is there.

Next, the organic electroluminescent element of the present invention will be described. Fig.1 (a)-FIG.1 (c) are the figures for demonstrating the organic electroluminescent element of this invention. An organic electroluminescent element 100a shown in FIG. 1A includes a substrate 101, an anode 102, a hole injection layer 103, a light emitting layer 105, and a cathode 107, which are sequentially stacked on the substrate 101.
The substrate 101 is a support for the organic electroluminescent element 100a. Examples of the material forming the substrate 101 include a quartz plate, a glass plate, a metal plate, a metal foil, a plastic film, and a plastic sheet. Among these, a transparent plastic sheet such as a glass plate, polyester, polymethacrylate, polycarbonate, polysulfone is preferable. Note that in the case where plastic is used for the substrate 101, it is preferable to provide a dense silicon oxide film or the like on one or both surfaces of the substrate 101 to enhance gas barrier properties.

  The anode 102 is provided on the substrate 101 and plays a role of hole injection into the hole injection layer 103. Materials for the anode 102 include metals such as aluminum, gold, silver, nickel, palladium, and platinum; conductive metal oxides such as oxides of indium and / or tin; metal halides such as copper iodide; carbon black A conductive polymer such as poly (3-methylthiophene), polypyrrole, and polyaniline; The anode 102 is usually formed by sputtering on the substrate 101, vacuum deposition, etc .; fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine particles. A method in which powder or the like is dispersed in an appropriate binder resin solution and applied onto the substrate 101; a method in which a conductive polymer thin film is formed directly on the substrate 101 by electrolytic polymerization; a conductive polymer solution is applied onto the substrate 101 Methods and the like. The anode 102 usually has a visible light transmittance of 60% or more, particularly preferably 80% or more. The thickness of the anode 102 is usually 1000 nm or less, preferably 500 nm or less, and usually 5 nm or more, preferably 10 nm or more.

  The hole injection layer 103 is provided on the anode 102, and preferably contains the compound of the present invention and is formed by a wet film forming method. The hole injection layer 103 is preferably formed using the composition of the present invention and the electron accepting compound capable of oxidizing the composition of the present invention. The film thickness of the hole injection layer 103 formed in this way is usually 5 nm or more, preferably 10 nm or more. However, it is usually 1,000 nm or less, preferably 500 nm or less.

  The light emitting layer 105 is provided on the hole injection layer 103, and efficiently recombines electrons injected from the cathode 107 and holes transported from the hole injection layer 103 between electrodes to which an electric field is applied, and It is formed from a material that emits light efficiently by recombination. As a material for forming the light-emitting layer 105, a metal complex such as an aluminum complex of 8-hydroxyquinoline, a metal complex of 10-hydroxybenzo [h] quinoline, a bisstyrylbenzene derivative, a bisstyrylarylene derivative, (2-hydroxyphenyl) Low molecular light emitting materials such as metal complexes of benzothiazole and silole derivatives; poly (p-phenylene vinylene), poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene], poly (3- Examples thereof include a system in which a light emitting material and an electron transfer material are mixed with a polymer compound such as alkylthiophene and polyvinylcarbazole, and the composition of the present invention is also applicable.

Further, for example, using a metal complex such as an aluminum complex of 8-hydroxyquinoline as a host material, a condensed polycyclic aromatic ring such as a naphthacene derivative such as rubrene, a quinacridone derivative, and perylene is 0.1 to 0.1% relative to the host material. By doping 10% by weight, the light emission characteristics of the device, particularly the driving stability, can be greatly improved.
These materials are coated on the hole injection layer 103 by a vacuum vapor deposition method or a wet film formation method to form a thin film on the hole injection layer 103. The thickness of the light emitting layer 105 formed in this manner is usually 10 nm or more, preferably 30 nm or more. However, it is usually 200 nm or less, preferably 100 nm or less.

In the case where the light emitting layer 105 is a layer containing the composition of the present invention, the hole injection layer 103 is preferably a layer containing the compound of the present invention. In this case, the layer containing the composition of the present invention is substantially a single layer, and also serves as the hole injection layer 103 and the light emitting layer 105.
The cathode 107 serves to inject electrons into the light emitting layer 105. The material used for the cathode 107 is preferably a metal having a low work function. For example, a suitable metal such as tin, magnesium, indium, calcium, aluminum, 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 107 is usually the same as that of the anode 102. In order to protect the cathode 107 made of a low work function metal, it is effective to increase the stability of the device by further laminating a metal layer having a high work function and stable to the atmosphere. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used. Furthermore, by inserting an ultra-thin insulating film (film thickness of 0.1 to 5 nm) such as LiF, MgF ₂ , or Li ₂ O at the interface between the cathode 107 and the light emitting layer 105, the efficiency of the device can be improved. .

FIG. 1B is a diagram for explaining a function-separated light-emitting element. In the organic electroluminescent device 100b shown in FIG. 1B, a hole transport layer 104 is provided between the hole injection layer 103 and the light emitting layer 105 in order to improve the light emitting characteristics of the device. The layer has a configuration similar to that of the organic electroluminescent element 100a shown in FIG. The material of the hole transport layer 104 needs to be a material that has high hole injection efficiency from the hole injection layer 103 and can efficiently transport the injected holes. For this purpose, it is required to have an appropriate ionization potential, to have a high hole mobility, to be excellent in stability, and to prevent trapping impurities from being generated during manufacturing and use. In addition, since the layer is in direct contact with the light-emitting layer 105, it is preferable that a substance that quenches light emission is not included.

  Examples of the hole transporting material for forming the hole transporting layer 104 include, in addition to the composition of the present invention, the same compounds as those exemplified as the hole transporting material that may be mixed and used. In addition, polymer materials such as polyarylene ether sulfone containing polyvinyl carbazole, polyvinyl triphenylamine, and tetraphenylbenzidine can be given. The hole transport layer 104 is formed by laminating these hole injection / transport materials on the hole injection layer 103 by a wet film forming method or a vacuum deposition method. The thickness of the hole transport layer 104 formed in this way is usually 10 nm or more, preferably 30 nm. However, it is usually 300 nm or less, preferably 100 nm or less.

  FIG.1 (c) is a figure for demonstrating other embodiment of a function separation type light emitting element. In the organic electroluminescent device 100c shown in FIG. 1C, an electron transport layer 106 is provided between the light emitting layer 105 and the cathode 107, and the other layers are organic electroluminescent devices shown in FIG. The structure is similar to that of the element 100b. The compound used for the electron transport layer 106 is required to easily inject electrons from the cathode 107 and to have a larger electron transport capability. Examples of such electron transporting materials include 8-hydroxyquinoline aluminum complexes, oxadiazole derivatives or systems in which they are dispersed in a resin such as polymethyl methacrylate (PMMA), phenanthroline derivatives, 2-t-butyl. Examples include -9,10-N, N'-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide. The film thickness of the electron transport layer 106 is usually 5 nm or more, preferably 10 nm or more. However, it is usually 200 nm or less, preferably 100 nm or less.

In addition, the organic electroluminescent elements 100a to 100c shown in FIGS. 1A to 1C are not limited to the illustrated ones. For example, a structure reverse to that shown in FIGS. 1A to 1C, that is, a cathode 107, a light emitting layer 105, a hole injection layer 103, and an anode 102 may be stacked on the substrate 101 in this order. Is possible. It is also possible to provide an organic electroluminescent element between two substrates, at least one of which is highly transparent. Further, the layer containing the composition of the present invention does not need to be the hole injection layer 103 in contact with the anode 102 and may be any layer, but between the anode 102 and the light emitting layer 105 or in the light emitting layer 105. In particular, the hole injection layer 103 or the hole transport layer 104 is preferable, and the hole injection layer 103 is more preferable. Moreover, you may have arbitrary layers between each layer shown to Fig.1 (a)-FIG.1 (c).

  When at least one of the hole injection layer 103, the hole transport layer 104, and the light emitting layer 105 is formed by a wet film forming method, it is usually added to a predetermined amount of the composition of the present invention, if necessary. Add an electron-accepting compound that can oxidize the composition, a hole-transporting material other than the composition of the present invention, a binder resin that does not trap holes, or an additive such as a coating property improver, and dissolve and apply. A liquid, that is, a composition for an organic electroluminescent device is prepared, and after the preparation, usually within 24 hours, preferably within 12 hours, particularly preferably within 6 hours, a wet method such as spin coating or dip coating. It is applied onto the anode 102 by a film forming method and dried to form at least one of the hole injection layer 103, the hole transport layer 104, and the light emitting layer 105.

The content of the binder resin is usually preferably 50% by weight or less in these layers, more preferably 30% by weight or less, and most preferably no binder resin from the viewpoint of hole mobility. .
In addition, the layer containing the composition of the present invention has a thermally stable thin film structure that activates migration of molecules contained in the resulting film by further heating process after wet film forming and drying process. This is preferable because the surface flatness of the film is improved and the light emission efficiency of the device is improved.

  Specifically, a layer containing the composition of the present invention is formed by a wet film forming method, and then heated at a temperature not higher than the glass transition temperature Tg of the composition of the present invention used. The heating temperature is preferably 10 ° C. or more lower than the glass transition temperature Tg of the composition of the present invention. Moreover, in order to fully acquire the effect by heat processing, it is preferable to process at 60 degreeC or more. The heating time is usually about 1 minute to 8 hours. Thus, since the layer containing the compound of the present invention formed by the wet film-forming method has a smooth surface, there is a problem of short-circuiting at the time of device preparation due to the surface roughness of the anode 102 such as ITO. Can be resolved.

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.
Example 1
(Synthesis of Crude Composition Containing Example Repeating Unit (P-1-1))

N, N′-bis (4-hydroxyphenyl) -N, N′-diphenyl-p-phenylenediamine (1.00 parts by weight) and 4,4′-difluorobenzophenone (0.49 parts by weight) under a nitrogen stream Potassium carbonate (1.88 parts by weight) and NMP (23.4 parts by weight) were stirred at 148 ° C. for 15 hours. The obtained reaction mixture was filtered to remove insoluble matters, and then the filtrate was added to methanol. The resulting precipitate was collected by filtration, washed with a water-methanol mixture and methanol, and then dissolved in chloroform. After the chloroform solution was added to acetone, the mixture was stirred for 30 minutes, and the resulting precipitate was collected by filtration. Next, the obtained precipitate was washed with acetone, and then the solid obtained by drying was dissolved once again in chloroform. After the addition of this chloroform solution to acetone and stirring for 30 minutes, the resulting precipitate was collected by filtration and dried to give a crude composition (P-1- 1, 1.03 parts by weight, 74%). When the obtained crude composition (P-1-1) was subjected to differential thermal analysis measurement using DSC-20 manufactured by Seiko Electronics Co., Ltd., the glass transition temperature Tg was 171 ° C.
(Low molecular weight component reduction of crude composition (P-1-1) containing exemplary repeating unit)
The obtained crude composition (P-1-1, 1.00 parts by weight) was dissolved in chloroform, and after adding this solution to acetone, the liquid layer was removed in 10 minutes, and the resulting precipitate was obtained. Was recovered. The obtained precipitate was washed with a chloroform / acetone mixed solvent, and then once again dissolved in chloroform. After the addition of this solution to acetone was completed, the liquid layer was removed in 10 minutes, and the obtained precipitate was recovered. . The resulting precipitate was washed with a chloroform / acetone mixed solvent, dried, and then dissolved in chloroform. The chloroform solution was added to methanol, and the resulting precipitate was collected by filtration and then dried to collect the composition (P-1-2, 0.53 parts by weight). When the recovered composition (P-1-2) was subjected to differential thermal analysis measurement by DSC-20 manufactured by Seiko Electronics Co., Ltd., the glass transition temperature Tg was 177 ° C., and the above-mentioned crude composition (P-1-1) Since the high value was shown compared with this, it was shown that heat resistance improves by reducing a low molecular weight component.
(SEC measurement of composition (P-1-2) with reduced low molecular weight component)
The SEC (size exclusion chromatography) measurement of the composition (P-1-2) was performed under the following conditions, and the molecular weight distribution and the low molecular weight component area ratio were calculated. Here, the molecular weight corresponding to the general formula (2) is 1245.

SEC measurement conditions Equipment: HLC8020 manufactured by Tosoh Corporation
Column: Tosoh TSKgel GMH _XL (column size 30cm x 2)
Column temperature: 40 ° C
Moving bed: Tetrahydrofuran Flow rate: 1.0 ml / min Injection concentration: 0.1% by weight
Injection volume: 0.10ml
Detector: RI
Conversion method: Polystyrene conversion Approximation formula: Tertiary formula Low molecular weight component area ratio (%) = 2 × (area A) / (area B) × 100
(Area A): The common logarithm of molecular weight is the integral value on the low molecular weight side from the peak top near 3.
(That is, corresponding to the molecular weight of the compound represented by the general formula (2)
(Integrated value on the low molecular weight side from the peak top)
(Area B): Integrated value of the entire molecular weight distribution As a result, the molecular weight distribution obtained is shown in FIG. The weight average molecular weight Mw was 29,500, the number average molecular weight Mn was 16,000, and the low molecular weight component area ratio (%) was a very small value of 0.19%.
(Solubility measurement of composition (P-1-2) with reduced low molecular weight component)
The solubility of the composition (P-1-2) having a low molecular weight component area ratio of 0.19% in ethyl benzoate was examined. The results are shown in Table 1. As shown in Table 1, the composition (P-1-2) showed very high solubility.

(Example 2)
(Solubility Measurement of Composition (P-1-3) with Reduced Low Molecular Weight Components)
The crude composition (P-1-1) was dissolved in chloroform, and after adding this solution to acetone, the liquid layer was removed in 10 minutes, and the resulting precipitate was recovered. The resulting precipitate was washed with a chloroform / acetone mixed solvent, dried, and then dissolved in chloroform. The chloroform solution was added to methanol, and the resulting precipitate was collected by filtration and then dried to obtain a purified low molecular weight area ratio of 1.2% benzoic acid composition (P-1-3) The solubility in ethyl acid was examined. The results are shown in Table 1. As shown in Table 1, the composition (P-1-3) showed high solubility.

(Comparative Example 1)
(SEC measurement of crude composition (P-1-1) in which low molecular weight components are not reduced)
The SEC (size exclusion chromatography) measurement of the crude composition (P-1-1) was performed under the same conditions as in Example 1, and the molecular weight distribution and the low molecular weight component area ratio were calculated. The molecular weight distribution obtained as a result is shown in FIG. The weight average molecular weight Mw was 24,100, the number average molecular weight Mn was 8,400, and the low molecular weight component area ratio (%) was as large as 4.6%.
(Solubility measurement of crude composition (P-1-1) in which low molecular weight components are not reduced)
The solubility of the crude composition (P-1-1) having a low molecular weight area ratio of 4.6% in ethyl benzoate was examined. The results are shown in Table 1.

+: Dissolved.
−: Not dissolved but became a suspension.
As is clear from Table 1, the composition of the present invention was highly soluble in a solvent.

(Example 3)
An organic electroluminescent device having the same structure as that of the organic electroluminescent device 100c shown in FIG. 1C was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate with a thickness of 120 nm (manufactured by Geomat Corp .; electron beam film-formed product; sheet resistance 15 Ω) is 2 mm wide using ordinary photolithography technology and hydrochloric acid etching. The anode was formed by patterning into stripes. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

First, an organic electroluminescent device comprising the composition of the present invention (P-1-2, low molecular weight component area ratio 0.19%), PPB (tris (pentafluorophenyl) borane) as an electron-accepting compound, and a solvent. The composition for coating (coating solution) was spin-coated on the glass substrate under the following conditions to form a uniform thin film having a thickness of 30 nm. Spin coating was performed in air. The environmental conditions at this time are a temperature of 23 ° C. and a relative humidity of 60%.
Solvent Ethyl benzoate coating solution concentration Compound (P-1-2, low molecular weight component area ratio 0.19%) 2% by weight
Electron accepting compound (PPB) 0.2% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions After drying at 80 ° C for 1 minute on a hot plate,
Heat drying in an oven at 100 ° C for 60 minutes

Next, the substrate on which the hole injection layer is 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 2 × 10 ⁻⁶ Torr (about 2 Aromatic compounds shown in the following structural formula (H1), exhausted using an oil diffusion pump equipped with a liquid nitrogen trap until the pressure reaches 7 × 10 ⁻⁴ Pa) or less, and placed in a ceramic crucible arranged in the apparatus The amine compound, 4,4′-bis [N- (9-phenanthyl) -N-phenylamino] biphenyl was heated for vapor deposition. The degree of vacuum during deposition is 1.3 × 10 ⁻⁶ Torr (about 1.7 × 10 ⁻⁴ Pa), the deposition rate is 0.2 nm / second, and a 40 nm-thick film is laminated on the hole injection layer. Thus, a hole transport layer was formed.

Subsequently, as a material of the light emitting layer, an 8-hydroxyquinoline complex of aluminum represented by the following structural formula (E1), Al (C ₉ H ₆ NO) _3, and the following structural formula (D
The rubrenes shown in 1) were vapor-deposited by heating them simultaneously using separate crucibles.

The temperature of each crucible at this time was controlled in the range of 282 to 294 ° C. for the 8-hydroxyquinoline complex of aluminum and in the range of 200 to 210 ° C. for the compound (D1). The degree of vacuum during the deposition is 1.3 × 10 ⁻⁶ Torr (about 1.7 × 10 ⁻⁴ Pa), the deposition rate of the aluminum 8-hydroxyquinoline complex is 0.1 to 0.3 nm / second, and the deposition time is Was 2 minutes 24 seconds. As a result, a light emitting layer in which the compound (D1) was doped 2.3% by film thickness with respect to the complex (E1) at a film thickness of 30.7 nm was obtained. Furthermore, the heating of the compound (D1) was stopped, the temperature of only the aluminum 8-hydroxyquinoline complex was controlled in the range of 282 to 294 ° C., and an electron transport layer having a thickness of 30 nm was deposited. The degree of vacuum at this time was 1.3 × 10 ⁻⁶ Torr (about 1.7 × 10 ⁻⁴ Pa), the deposition rate was 0.1 to 0.4 nm / second, and the deposition time was 2 minutes and 43 seconds. . In addition, the substrate temperature at the time of vacuum-depositing a positive hole transport layer, a light emitting layer, and an electron carrying layer was kept at room temperature.

Here, the element that has been vapor-deposited up to the electron transport layer is once taken out from the vacuum vapor deposition apparatus to the atmosphere, and a 2 mm-wide stripe shadow mask is orthogonal to the ITO stripe of the anode as a mask for cathode vapor deposition. In close contact with the element, it is installed in another vacuum deposition apparatus, and the degree of vacuum in the apparatus is 2 × 10 ⁻⁶ Torr (about 2.7 × 10 ⁻⁴ Pa) or less in the same manner as in the organic layer deposition. It exhausted until it became. As a cathode, first, lithium fluoride (LiF) was deposited using a molybdenum boat at a deposition rate of 0.1 nm / second, a degree of vacuum of 7.0 × 10 ⁻⁶ Torr (about 9.3 × 10 ⁻⁴ Pa), and 0 A film having a thickness of 0.5 nm was formed on the light emitting layer. Next, aluminum is similarly heated by a molybdenum boat to form an aluminum layer having a thickness of 80 nm at a deposition rate of 0.5 nm / second and a degree of vacuum of 1 × 10 ⁻⁶ Torr (about 1.3 × 10 ⁻⁴ Pa). Thus, a cathode was formed. The substrate temperature at the time of vapor deposition of the above two-layer cathode was kept at room temperature. 2mm x 2m as above
An organic electroluminescent element having a light emitting area portion of size m was obtained. The light emission characteristics of this element are shown in Table 2.

Table 2 shows that, in a test in which a constant DC current with an initial light emission luminance of 1000 cd / m ² is continuously applied to an element installed in a thermostat kept at 85 ° C., the light emission luminance is 1/2 of the initial value. The result of measuring the time is shown. From the results in Table 2, it can be seen that, when a hole injecting / transporting polymer having a low proportion of low molecular weight components is used, a decrease in emission luminance is suppressed during continuous driving. That is, it is considered that hole injection / transport properties are improved without trapping charges.

(Comparative Example 2)
Using the crude composition (P-1-1, low molecular weight component area ratio 4.6%) obtained in Example 1 and PPB (tris (pentafluorophenyl) borane) as an electron-accepting compound and a solvent An attempt was made to prepare a composition for an organic electroluminescent element (coating solution), but the crude composition (P-1-1, low molecular weight component area ratio 4.6%) remained undissolved and became a suspension.
Solvent Ethyl benzoate coating solution concentration High molecular compound (P-1-1, low molecular weight component area ratio 4.6%) 2% by weight
Electron accepting compound (PPB) 0.2% by weight
An organic electroluminescent device was produced in the same manner as in Example 1 except that the solution obtained by removing the insoluble matter in the suspension by filtration was used for coating the hole injection layer.

  Table 2 shows the results obtained by measuring the time during which the light emission luminance was ½ of the initial value, measured under the same conditions as in Example 1. When a crude composition having a high proportion of low molecular weight components was used, the emission luminance decreased more rapidly than the device using the composition of the present invention during continuous driving. Furthermore, it is necessary to filter insoluble matter, which causes a problem in the process.

(Reference Example 1)
(Detection of low molecular weight component in crude composition (P-1-1) containing exemplary repeating unit)
Mass analysis of the crude composition (P-1-1) having a low molecular weight component area ratio (%) of 4.6% was performed under the following conditions, and the structure of the low molecular weight component was estimated.
Mass spectrometric measurement conditions Apparatus: Applied Biosystems Voyer Elite
Ionization method: MALDI (+)
Acceleration voltage: 20 kV
Matrix: DHB
Mode: Reflector mode

The resulting spectrum is shown in FIG. As shown in FIG. 4, the maximum peak intensity is shown at M / Z = 1245, and after M / Z = 1245, peaks are observed at approximately equal intervals at M / Z = 1868, 2492, 3114, 3737, 4359, The peak interval was almost equal to 622 which is the molecular weight of the repeating unit (P-1). Moreover, in the spectrum after M / Z = 1245, a peak corresponding to a chain-like low molecular weight component such as the following formulas (T-2) and (T-3) is not detected, and the following formula (T Peaks corresponding to m = 1 to 6 of -1) were observed. From these facts, in the composition used in this example, it is considered that the low molecular weight component is mainly a cyclic structure, and the peak of M / Z = 1245 is m = 1 in the following formula (T-1). It is thought to be derived from a cyclic dimer that is

Fig.1 (a)-FIG.1 (c) are the figures for demonstrating the organic electroluminescent element which has the thin layer formed by the wet film forming method. Example 1, molecular weight distribution Comparative Example 1, molecular weight distribution Reference example 1, mass spectrum

Explanation of symbols

100a, 100b, 100c Organic electroluminescent device 101 Substrate 102 Anode 103 Hole injection layer 104 Hole transport layer 105 Light emitting layer
106 Electron transport layer 107 Cathode

Claims (11)

A low molecular weight component having a weight average molecular weight of 3,000 to 1,000,000, a high molecular weight compound having a repeating unit represented by the following general formula (1), and a compound represented by the following general formula (2) A low molecular weight component comprising a compound represented by the following general formula (2) with respect to an integral value of the entire molecular weight distribution in a molecular weight distribution determined by SEC (size exclusion chromatography) measurement: A composition having a ratio of integrated values of peaks corresponding to 2 (hereinafter referred to as low molecular weight component area ratio) of 3% or less.

(In the formula, Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.
Ar ^{3 to} Ar ⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. .
X represents a linking group selected from the group of linkage groups X ¹ below. )
Linking group X ¹

(In the formula, Ar ^{11 to} Ar ²⁸ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. R ³¹ and R ³² each independently represent Represents a hydrogen atom or an arbitrary substituent.

(In the formula, Ar ¹ and Ar ² , Ar ^{3 to} Ar ⁵ , and X have the same meaning as in general formula (1).) The general formula (1) is the following general formula (1 ') is represented by, and the general formula (2) is the following general formula (2' you express in) A composition according to claim 1.

(In the formula, R ^{1 to} R ⁵ each independently represents an arbitrary substituent. P and q each independently represent an integer of 0 to ^5. r, s and t each independently represents 0 to 5) Represents an integer of 4. X has the same meaning as in formula (1).

(In the formula, R ^{1 to} R ⁵ , p, q, r, s, and t, and X have the same meaning as in general formula (1 ′).) The general formula (1) is represented by the following general formula (3), and the general formula (2) it expresses the following general formula (4) A composition according to claim 1 or 2.

(Wherein, Y represents a linking group selected from the group of linkage groups X ² below.)
Linking group X ²

^(Wherein, Ar 11 ^{to Ar 17} are the same as those in the consolidated Group ^{X 1.)}

(In the formula, Y has the same meaning as in general formula (3).)   The composition as described in any one of Claims 1-3 whose said low molecular weight component area ratio is 1.5% or less. Characterized by containing a composition according to any one of claims 1 to 4, the charge transport material. It has a layer containing the composition as described in any one of Claims 1-4, The organic electroluminescent element characterized by the above-mentioned.   In the organic electroluminescent element which has a light emitting layer which exists on a board | substrate, an anode, a cathode, and this both electrode, Between this light emitting layer and an anode, The composition as described in any one of Claims 1-4 An organic electroluminescence device comprising a layer containing an electron accepting compound. The composition for organic electroluminescent elements characterized by including the composition and solvent as described in any one of Claims 1-4.   Furthermore, the composition for organic electroluminescent elements of Claim 8 formed by containing an electron-accepting compound. Using the re-precipitation method, from the point of re-precipitation method mixture by mixing a solvent comprising an object to be purified and precipitating agent, purifying by removing the liquid layer portion of the mixture within 30 minutes The method for producing a composition according to any one of claims 1 to 4, wherein the method is characterized. In reprecipitation, Ru using a halogen-based solvent and / or ketone-based solvent, a manufacturing method of a composition according to claim 10.

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