JP3528370B2 - Organic electroluminescent device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device, and more specifically, an organic electroluminescence device having a specific hole-transporting polymer for facilitating device fabrication and further improving stability and for increasing the area. Regarding the device.

[0002]

2. Description of the Related Art An electroluminescent device (hereinafter referred to as an "EL device") is a self-luminous all-solid-state device, has high visibility, and is resistant to impact, and is therefore expected to be widely applied. At present, inorganic fluorescent materials are mainly used and widely used, but problems such as high manufacturing cost and insufficient brightness because an AC voltage of 200 V or more is required for driving. have. On the other hand, research on an EL device using an organic compound was first started by using a single crystal such as anthracene, but the film thickness was as thick as about 1 mm and a driving voltage of 100 V or higher was required. Therefore, thinning by vapor deposition has been attempted (Thin Solid Films, 9
4,171 (1982)). However, the thin film formed by the vapor deposition method still has a high driving voltage of 30 V, the carrier density of electrons and holes in the film is low, and the excitation probability due to carrier recombination is low, so that sufficient luminance cannot be obtained. .

In recent years, a functionally separated device in which a hole-transporting organic compound and an organic fluorescent substance having an electron-transporting ability are sequentially laminated by a vacuum deposition method to form a thin film has been actively studied, and about 10 V is being studied. It has been reported that a high luminance of 1000 cd / m ² or more can be obtained at a low voltage (Appl.
Phys. Lett. , 51, 913 (1987)).
However, in this EL element, since a thin film of 0.1 μm or less is formed by using the vacuum evaporation method, pinholes are easily generated, and in order to obtain sufficient performance, film formation is performed under strictly controlled conditions. Required, low productivity,
There is a problem that it is difficult to increase the area. Further, since this EL element is driven in a high current density state of several mA / cm ² , a large amount of heat is generated, and the tetraphenyldiamine derivative which is preferably used as a hole transport material is gradually crystallized, resulting in brightness There is a problem with respect to the stability of the EL device, such as a decrease in the EL.

In order to solve the problem of stability, a starburst amine which can obtain a stable amorphous state is used as a hole transport material (Proceedings of the 40th Joint Lecture on Applied Physics, 30a-SZK-14 (1993). )),
Using a polymer in which triphenylamine is introduced into the side chain of polyphosphazene (Proceedings of the 42nd Symposium on Polymers 2
0J21 (1993)), but the hole injection property to the layer is not satisfied by itself. Further, when a polymer is used, a high current density cannot be obtained and sufficient brightness cannot be obtained.

On the other hand, conductive polymers such as polyphenylene vinylene are used (Nature, Vol. 357, 4).
77 (1992)), an electron-transporting material and a fluorescent dye were mixed in a hole-transporting polyvinylcarbazole (Proceedings of the 38th Joint Lecture on Applied Physics, 31p-G-12 (19).
91)) A polymer single-layer structure EL element has been proposed, and it is expected that the productivity will be improved, but the brightness, the luminous efficiency, and the like are still lower than those of the laminated EL element.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and an object thereof is easy manufacture, sufficient brightness can be obtained, and durability is excellent. It is to provide an organic EL device.

[0007]

In order to achieve the above object, as a result of extensive studies on a hole transport material, a hole transport polymer represented by the following general formula (I) has favorable injection characteristics and positive characteristics suitable for EL devices. They have found that they have hole mobility and thin film forming ability, and have completed the present invention.

That is, the organic EL device of the present invention comprises a pair of electrodes, at least one of which is transparent or semitransparent, and one or a plurality of organic compound layers including a coloring layer sandwiched between the electrodes. One of the organic compound layers is characterized by containing a hole-transporting polymer represented by the following general formula (I).

[0009]

[Chemical 3] [In the formula, R ₁ and R ₂ each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a substituted amino group, a halogen atom, or a substituted or unsubstituted aryl group, and X is a substituted or unsubstituted 2 group. Represents a valent aromatic group, and the terminal group R is a hydrogen atom, an alkyl group, an acyl group or a group-
CONH-R '(R' represents an alkyl group or a substituted or unsubstituted aryl group), n represents an integer selected from 1 to 5, and y represents an integer selected from 0 and 1. , M means an integer selected from 0 and 1, and l means an integer selected from 5 to 5000. ]

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION First, regarding the organic EL device of the present invention, the hole transporting polymer represented by the above general formula (I) will be described. In the general formula (I), X represents a substituted or unsubstituted divalent aromatic group, and specific examples thereof include groups selected from the following formulas (1) to (7).

[Chemical 4] [R ₆ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted aralkyl group, and R _{7 to} R ₁₃ are each a hydrogen atom and 1 carbon atom. Represents an alkyl group having 4 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group or a halogen atom,
a means 0 or 1, and V is the following formula (8) to (1
Represents a group selected from 7).

[0011]

[Chemical 5] (B means an integer of 1 to 10 and c means an integer of 1 to 3)]

Specific examples of the hole transporting polymer represented by the above general formula (I) are shown in Tables 1 to 7.

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Table 5]

[0017]

[Table 6]

[0018]

[Table 7]

The hole transporting polymer represented by the above general formula (I) is synthesized by polymerizing a charge transporting compound having two hydroxyalkyl groups represented by the following general formula (III) by the following method. can do.

[Chemical 6] [In the formula, R ₁ and R ₂ each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a substituted amino group, a halogen atom, or a substituted or unsubstituted aryl group, and X is a substituted or unsubstituted 2 group. Represents a valent aromatic group, n
Means an integer selected from 1 to 5, y means an integer selected from 0 and 1, and m means an integer selected from 0 and 1. ]

1) The above hole transporting polymer can be synthesized by a method of heating dehydration condensation of the above charge transporting compound having two hydroxyalkyl groups (charge transporting monomer). In this case, it is desirable that the charge-transporting monomer is heated and melted without a solvent, and the reaction is performed under reduced pressure in order to promote the polymerization reaction by elimination of water. When a solvent is used, a solvent that is azeotropic with water, such as trichloroethane, toluene, chlorobenzene, dichlorobenzene, nitrobenzene, and 1-chloronaphthalene is effective for removing water, and the charge-transporting monomer 1 It is used in the range of 1 to 100 equivalents, preferably 2 to 50 equivalents, relative to the equivalents. The reaction temperature can be set arbitrarily, but it is preferable to carry out the reaction at the boiling point of the solvent in order to remove water generated during the polymerization. When the polymerization does not proceed, the solvent may be removed from the reaction system and the mixture may be heated and stirred in a viscous state.

2) The hole-transporting polymer is synthesized by a dehydration condensation method using a protonic acid such as p-toluenesulfonic acid, hydrochloric acid, sulfuric acid or trifluoroacetic acid, or a Lewis acid such as zinc chloride as an acid catalyst. You can also do it. In this case, the acid catalyst is used in an amount of 1 to 1/10000 to 1/10 equivalent, preferably 1/1000 to 1/50 equivalent, relative to 1 equivalent of the charge transporting monomer. In order to remove water generated during the polymerization, it is preferable to use a solvent which can be azeotropic with water. As the solvent, toluene, chlorobenzene, dichlorobenzene, nitrobenzene, 1-chloronaphthalene and the like are effective, and are used in the range of 1 to 100 equivalents, preferably 2 to 50 equivalents, relative to 1 equivalent of the charge transporting monomer. The reaction temperature can be set arbitrarily,
It is preferable to react at the boiling point of the solvent in order to remove water formed during the polymerization.

3) The hole-transporting polymer is an alkyl isocyanide such as cyclohexyl cyanide, a cyanate ester such as p-tolyl cyanate or 2,2-bis (4-cyanatophenyl) propane, or dichlorohexylcarbodiimide. It can also be synthesized by a method using a condensing agent such as (DCC) or trichloroacetonitrile. In this case, the condensing agent is used in the range of 1/2 to 10 equivalents, preferably 1 to 3 equivalents, relative to 1 equivalent of the charge transporting monomer. As the solvent, toluene, chlorobenzene, dichlorobenzene, 1-chloronaphthalene, etc. are effective, and 1 to 10 are used for 1 equivalent of the charge transporting monomer.
It is used in the range of 0 equivalent, preferably 2 to 50 equivalents.
The reaction temperature can be set arbitrarily, but it is preferable to carry out the reaction at room temperature to the boiling point of the solvent. 1), 2) and 3) above
Among these synthetic methods, the synthetic method 1) or 3) is preferable because isomerization and side reactions hardly occur. In particular, the synthesis method 3) is more preferable because the reaction conditions are milder.

After the reaction, if a solvent is not used, it is dissolved in a soluble solvent. When a solvent is used, as it is, alcohols such as methanol and ethanol,
After dropping the charge transporting polymer such as acetone into a poor solvent in which the charge transporting polymer is difficult to dissolve to precipitate the charge transporting polymer and separating the charge transporting polymer, it is thoroughly washed with water or an organic solvent and dried. Further, if necessary, the reprecipitation treatment of dissolving in a suitable organic solvent, dropping in a poor solvent and precipitating the charge transporting polymer may be repeated. The reprecipitation treatment is preferably carried out with a mechanical stirrer or the like while efficiently stirring. The solvent for dissolving the charge transporting polymer during the reprecipitation treatment is the charge transporting polymer 1
It is used in the range of 1 to 100 equivalents, preferably 2 to 50 equivalents, relative to the equivalents. The poor solvent is 1 to 1000 equivalents, preferably 1 equivalent to 1 equivalent of the charge transporting polymer.
It is used in the range of 0 to 500 equivalents. Furthermore, in the above reaction, the copolymerization polymer can be synthesized by using two or more types of charge transporting monomers, preferably 2 to 5 types, more preferably 2 to 3 types. By copolymerizing different types of charge-transporting monomers, it is possible to control the electrical characteristics, film-forming property, and solubility.

If the polymerization degree l of the charge transporting polymer is too low, the film-forming property is poor, and a strong film is difficult to obtain, and if it is too high, the solubility in a solvent is low and the processability is deteriorated. It is set in the range of 5 to 5000, preferably 10
˜3000, more preferably 15 to 1000 is set.

The terminal group of the hole-transporting polymer may be a hydroxyl group, that is, R may be a hydrogen atom, like the charge-transporting monomer, but it affects polymer properties such as solubility, film-forming property and mobility. In some cases, the terminal group R can be modified to control the physical properties. For example, the terminal hydroxyl group can be alkyl etherified with alkyl sulfate, alkyl iodide, or the like. The specific reagent can be arbitrarily selected from dimethyl sulfate, diethyl sulfate, methyl iodide, ethyl iodide and the like, and is used in the range of 1 to 3 equivalents, preferably 1 to 2 equivalents based on the terminal hydroxyl group. . At that time, a base catalyst can be used,
As a base catalyst, sodium hydroxide, potassium hydroxide,
It can be arbitrarily selected from sodium hydride, sodium metal and the like, and is used in a range of 0.9 to 3 equivalents, preferably 1 to 2 equivalents based on the terminal hydroxyl group. The reaction temperature may be 0 ° C. to the boiling point of the solvent used.
Further, as the solvent used at that time, benzene, toluene,
A single solvent selected from inert solvents such as methylene chloride, tetrahydrofuran, N, N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, or a mixed solvent of two or three kinds. Can be used. Depending on the reaction, a quaternary ammonium salt such as tetra-n-butylammonium iodide can be used as a phase transfer catalyst.

Further, the terminal hydroxyl group can be acylated with an acid halide to convert the group R into an acyl group. The acid halide is not particularly limited, but for example, acryloyl chloride, crotonoyl chloride, methacryloyl chloride, n-butyl chloride, 2
-Furoyl chloride, benzoyl chloride, cyclohexanecarbonyl chloride, enanthyl chloride, phenylacetyl chloride, o-toluoyl chloride, m-toluoyl chloride, p-toluoyl chloride, etc. It is used in the range of 3 equivalents, preferably 1 to 2 equivalents. At that time, a base catalyst can be used, but the base catalyst can be arbitrarily selected from pyridine, dimethylaminopyridine, trimethylamine, triethylamine, etc.
It is used in the range of 3 to 3 equivalents, preferably 1 to 2 equivalents. Examples of the solvent used at this time include benzene, toluene, methyl chloride, tetrahydrofuran, and methyl ethyl ketone. The reaction can be carried out at 0 ° C. to the boiling point of the solvent. Preferably, it is carried out in the range of 0 ° C to 30 ° C. Furthermore, the acylation can also be carried out using an acid anhydride such as acetic anhydride. When a solvent is used, specifically, an inert solvent such as benzene, toluene and chlorobenzene can be used. The reaction can be carried out at 0 ° C. to the boiling point of the solvent. Preferably, it may be carried out at 50 ° C. to the boiling point of the solvent.

In addition, monoisocyanate can be used to introduce a urethane residue (-CONH-R ') at the terminal. Specific monoisocyanates include benzyl isocyanate, isocyanic acid n-butyl ester, isocyanic acid t-butyl ester, isocyanic acid cyclohexyl ester, isocyanic acid 2,6-dimethyl ester, isocyanic acid ethyl ester, isocyanic acid isopropyl ester. , Isocyanic acid 2-methoxyphenyl ester, isocyanic acid 4-methoxyphenyl ester, isocyanic acid n-octadecyl ester, isocyanic acid phenyl ester, isocyanic acid iso-propyl ester, isocyanic acid m-tolyl ester, isocyanic acid p-tolyl ester, It can be arbitrarily selected from isocyanic acid 1-naphthyl ester and the like, and is used in the range of 1 to 3 equivalents, preferably 1 to 2 equivalents based on the terminal hydroxyl group. As the solvent used at that time, benzene, toluene, chlorobenzene, dichlorobenzene, methylene chloride, tetrahydrofuran, N, N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone,
1,3-dimethyl-2-imidazolidinone and the like can be mentioned. The reaction temperature can be 0 ° C. to the boiling point of the solvent used. If the reaction does not proceed easily, add a metal compound such as dibutyltin dilaurate (II), tin octylate (II), or lead naphthenate, or a tertiary amine such as triethylamine, trimethylamine, pyridine, or dimethylaminopyridine as a catalyst. You can also

Among the charge transporting monomers represented by the general formula (III), the tetraarylbenzidine monomer represented by the following general formula (IV) and having two hydroxyalkyl groups has various physical properties such as mobility and ionization potential. It is more preferable because of control, easiness of synthesis and the like.

[Chemical 7] (In the formula, R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a substituted amino group,
It represents a halogen atom or a substituted or unsubstituted aryl group, and n means an integer selected from 1 to 5. )

Therefore, the tetraarylbenzidine-based polyether represented by the following general formula (II) synthesized from the tetraarylbenzidine monomer represented by the general formula (IV) is preferable as the hole transporting polymer.

[Chemical 8] [In the formula, R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a substituted amino group, a halogen atom or a substituted or unsubstituted aryl group, and the terminal group R is a hydrogen atom. , An alkyl group, an acyl group, or a group -CONH-R '(R' is an alkyl group or a substituted or unsubstituted aryl group), and n is 1 to 5
Means an integer selected from, and l means an integer selected from 5 to 5000. ]

Next, the layer structure of the organic EL device of the present invention having a layer containing the above hole transporting polymer will be described in detail. The organic EL device of the present invention is composed of a pair of electrodes, at least one of which is transparent or semitransparent, and one or more organic compound layers including a light emitting layer sandwiched between the electrodes. In the present invention, when there is one organic compound layer, the organic compound layer means a light emitting layer. Further, when there are a plurality of organic compound layers, one of them is a light emitting layer, and the other organic compound layer means a hole transporting layer, an electron transporting layer, or a hole transporting layer and an electron transporting layer. .

1 and 2 are schematic sectional views for explaining the layer structure of the organic EL device of the present invention.
The case is an example of the case where there are a plurality of organic compound layers, and the case of FIG. 2 shows the case where there is one organic compound layer. In the figure, 1 is a transparent insulator substrate, 2 is a transparent electrode, 31 is a hole transporting layer, 32 is a light emitting layer, 4 is a light emitting layer having an electron transporting ability, 5
Is a back electrode.

The transparent insulator substrate 1 is preferably transparent in order to take out light emission, and glass, plastic film or the like is used. The transparent electrode 2 is preferably transparent so as to take out light emission similarly to the transparent insulator substrate and has a large work function for injecting holes, and indium tin oxide (ITO), tin oxide (NESA), An oxide film of indium oxide, zinc oxide or the like, and semitransparent vapor-deposited or sputtered gold, platinum, palladium or the like is used.

The organic compound layer composed of the hole-transporting polymer represented by the general formula (I) acts as the hole-transporting layer 31 in the layer structure of the organic EL device of FIG.
In the case of the layer structure of the organic EL element of FIG. 2, it functions as the light emitting layer 32.

In the case of the layer structure of the organic EL device shown in FIG. 1, the hole transport layer 31 may be formed of the hole transport polymer represented by the general formula (I) alone, but 1% by weight of tetraphenylenediamine derivative to adjust
It may be dispersed in the range of 50 to 50% by weight.

In FIG. 1, the light-emitting layer 4 having an electron transporting property exhibits fluorescence in a solid state, and a good thin film can be formed by a vacuum vapor deposition method, which is represented by the general formula (I) of the adjacent hole transporting layer. A compound that does not show strong electron interaction with the hole transporting polymer is used as a light emitting material. The following compounds (V-1) to (V-13) are preferably used, but the compounds are not limited thereto. Whether or not a compound exhibits electron interaction is distinguished by whether or not the fluorescent wavelength shifts to the long wavelength side by dispersing the compound in the hole transporting polymer represented by the general formula (I). be able to.

[0036]

[Chemical 9]

[0037]

[Chemical 10]

When a light-emitting material that can be vacuum-deposited but does not form a good thin film or that does not show a clear electron-transporting property is used, the durability of the organic EL element is improved or the luminous efficiency is improved. For the purpose of improvement, an electron transport layer may be inserted between the light emitting layer and the back electrode 5. As the electron transport material used in such an electron transport layer, an organic compound capable of forming a good thin film by a vacuum deposition method is used, and preferably an oxadiazole derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, or thiopyran. Dioxide derivatives, fluorenylidene methane derivatives and the like are used. As a preferred specific example, the following compound (VI-
1) to (VI-3), but the invention is not limited thereto.

[0039]

[Chemical 11]

In the case of the layer structure of the organic EL device of FIG. 2, the light emitting layer 32 is an organic compound layer in which the light emitting material is dispersed in the hole transporting polymer represented by the general formula (I) in an amount of 50% by weight or less. As the light emitting material, the exemplified compounds (V-1) to (V-13) are preferably used, and an electron transport material for adjusting the balance of holes and electrons injected into the organic EL device. May be dispersed in an amount of 10% by weight to 50% by weight, or an electron transport layer made of an electron transport material may be inserted between the light emitting layer 32 and the back electrode 5. As such an electron transporting material, an organic compound which does not show strong electron interaction with the hole transporting polymer represented by the general formula (I) is used, and preferably the following compound (VI
I) is used, but is not limited to this. Similarly, an appropriate amount of a tetraphenylenediamine derivative may be simultaneously dispersed and used in order to adjust the hole mobility.

[Chemical 12]

The back electrode 5 is made of a metal that has a low work function and can be vacuum-deposited so as to inject electrons, but magnesium, aluminum, silver, indium and alloys thereof are particularly preferable.

In these organic EL devices of the present invention, the hole-transporting layer 31 or the light-emitting layer 32 is composed of the hole-transporting polymer alone represented by the general formula (I) or the positive hole transporting polymer represented by the general formula (I). A hole-transporting polymer and a light-emitting material, and optionally an electron-transporting material and a hole-transporting material, are dissolved or dispersed in an organic solvent, and the obtained coating solution is used to spin-coat or dip the transparent electrode. And the like are used to form a film. The thickness of the hole transport layer or the light emitting layer is preferably about 0.03 to 0.2 μm. The dispersed state of the light emitting material may be a molecular dispersed state or a fine particle dispersed state. In order to obtain a molecular dispersion state, the dispersion solvent is a hole transporting polymer, a light emitting material, an electron transporting material,
It is necessary to use a common solvent for the hole-transporting material, and in order to obtain a fine particle dispersion state, the dispersion solvent has the dispersibility of the light-emitting material,
It is necessary to select in consideration of the solubility of the electron transport material, the hole transport material and the hole transport polymer. In order to disperse in fine particles, a ball mill, a sand mill, a paint shaker, an attritor ball mill, a homogenizer,
The ultrasonic method or the like can be used.

Then, a light emitting material, an electron transporting material, and a back electrode are vacuum-deposited on the layer containing the hole transporting polymer formed as described above, depending on the layer structure of each organic EL element. It is formed using the method. Thereby, an organic EL element can be easily manufactured. The thicknesses of the light-emitting layer and the electron-transporting layer having the electron-transporting ability to be laminated are each 0.1 μm or less, and particularly preferably in the range of 0.03 to 0.08 μm. The organic EL device of the present invention has a current density of 1 to 200 at a voltage of 4 to 20 V between a pair of electrodes.
Light can be emitted by applying a DC voltage of mA / cm ² .

[0044]

【Example】

Example 1 Hole transporting polymer (I-30) represented by the following structural formula
5 wt% dichloroethane solution of was prepared and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter. Using this solution, strip type ITO with a width of 2 mm
A hole transport layer having a film thickness of about 0.1 μm was formed on the glass substrate having the electrodes formed by etching, by the tip method. After being sufficiently dried, the exemplary compound (V-1) purified by sublimation as a light emitting material was put in a tungsten boat,
The film thickness is 0.0 on the hole transport layer by vacuum evaporation.
A 5 μm light emitting layer was formed. The vacuum degree at this time is 10 ^-5 T
The orr and boat temperatures were 300 ° C. Then Mg-
2mm width, 0.15
A back electrode having a thickness of μm was formed so as to intersect the ITO electrode. The effective area of the formed organic EL element is 0.04 cm.
^{Was 2} .

[Chemical 13]

Example 2 1 hole-transporting polymer (I-30) used in Example 1 was used.
1 part by weight of the above exemplified compound (V-1) as a light emitting material
Parts by weight were mixed to prepare a 10% by weight dichloroethane solution, which was filtered through a 0.1 μm PTFE filter. Using this solution, a 2 mm wide strip-shaped ITO electrode was applied on a glass substrate by etching by a dip method to form a hole transport layer having a thickness of about 0.15 μm.
After sufficiently drying, a Mg-Ag alloy was co-evaporated to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

Example 3 The hole-transporting polymer (I-30) used in Example 1 was used as 2
Parts by weight, 0.1 parts by weight of the compound (V-10) as a light emitting material, and 1 part of the exemplified compound (VII) as an electron transport material.
Parts by weight were mixed to prepare a 10% by weight dichloroethane solution, which was filtered through a 0.1 μm PTFE filter. Using this solution, a 2 mm wide strip-shaped ITO electrode was applied onto a glass substrate formed by etching by a dip method to form a hole transport layer having a thickness of about 0.15 μm. After sufficiently drying, a Mg-Ag alloy was co-evaporated to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

Example 4 Hole transporting polymer (I-29) represented by the following structural formula
An organic EL device was produced in the same manner as in Example 1 except that was used.

[Chemical 14]

Example 5 An organic EL device was produced in the same manner as in Example 2 except that the hole transporting polymer (I-29) was used. Example 6 An organic EL device was produced in the same manner as in Example 3 except that the hole transporting polymer (I-29) was used.

Example 7 Hole-transporting polymer (I-28) represented by the following structural formula
An organic EL device was produced in the same manner as in Example 1 except that was used.

[Chemical 15]

Example 8 An organic EL device was produced in the same manner as in Example 2 except that the hole transporting polymer (I-28) was used. Example 9 An organic EL device was produced in the same manner as in Example 3 except that the hole transporting polymer (I-28) was used.

Example 10 Hole-transporting polymer (I-12) represented by the following structural formula
An organic EL device was produced in the same manner as in Example 1 except that was used.

[Chemical 16]

Example 11 An organic EL device was produced in the same manner as in Example 2 except that the hole transporting polymer (I-12) was used. Example 12 An organic EL device was produced in the same manner as in Example 3 except that the hole transporting polymer (I-12) was used.

Example 13 An organic EL device was produced in the same manner as in Example 1 except that the hole transporting polymer (I-9) represented by the following structural formula was used.

[Chemical 17]

Example 14 An organic EL device was produced in the same manner as in Example 2 except that the hole transporting polymer (I-9) was used. Example 15 An organic EL device was produced in the same manner as in Example 3 except that the hole transporting polymer (I-9) was used.

Comparative Example 1 1 part by weight of a hole transporting material represented by the following structural formula (VIII), 1 part by weight of the exemplified compound (V-1) as a light emitting material, and polymethylmethacrylate (PMMA) as a binder resin. 1 part by weight was mixed to prepare a 10% by weight dichloroethane solution, which was filtered with a 0.1 μm PTFE filter. Using this solution, strip type ITO with a width of 2 mm
The electrode was applied by a dipping method on a glass substrate formed by etching to form a hole transport layer having a thickness of about 0.15 μm. After sufficiently drying, a Mg-Ag alloy was co-evaporated to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

[Chemical 18]

Comparative Example 2 Polyvinylcarbazole was used as a hole-transporting polymer.
Parts by weight, 0.1 parts by weight of the exemplified compound (V-10) as a light emitting material, and the exemplified compound (VI) as an electron transport material.
1 part by weight of -1) was mixed to prepare a 10% by weight dichloroethane solution, which was filtered through a 0.1 μm PTFE filter. Using this solution, a 2 mm wide strip-shaped ITO electrode was applied on a glass substrate by etching by a dip method to form a hole transport layer having a thickness of about 0.15 μm. After sufficiently drying, a Mg-Ag alloy was co-evaporated to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

The organic EL device manufactured as described above was subjected to a vacuum (10 ⁻³ Torr) with the ITO electrode side being positive and Mg
A direct current voltage was applied with the -Ag back electrode as a negative electrode, and light emission was measured to evaluate the maximum luminance and the emission color at this time. The results are shown in Table 8. In addition, the emission lifetime of the organic EL device was measured in dry nitrogen. The evaluation of the light emission lifetime was carried out by driving at low current with an initial light emission intensity of 50c
Measure the time from d / m ² until the emission intensity is halved,
The device life (hr) was used. The drive current density at this time is shown in Table 8 together with the element life.

[0058]

[Table 8]

[0059]

INDUSTRIAL APPLICABILITY The hole-transporting polymer represented by the above general formula (I) has an ionization potential and hole mobility suitable for organic EL devices, and is good by spin coating, dipping or the like. Since it is possible to form a thin film, the organic EL element of the present invention formed by using such a thin film shows sufficiently high brightness, and since the film thickness can be set to be relatively thick, pinholes and the like can be formed. There are few defects,
It is easy to increase the area and has improved durability.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an example of an organic EL element of the present invention.

FIG. 2 is a schematic cross-sectional view of another example of the organic EL element of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transparent insulator substrate, 2 ... Transparent electrode, 31 ... Hole transport layer, 32 ... Light emitting layer, 4 ... Light emitting layer having electron transporting ability, 5 ...
Back electrode.

Continuation of front page (56) References JP-A-6-200244 (JP, A) JP-A-2000-30867 (JP, A) JP-A-8-188773 (JP, A) JP-A-8-176293 (JP, A) JP 64-19049 (JP, A) JP 64-13061 (JP, A) JP 64-9964 (JP, A) JP 4-178487 (JP, A) (58) Survey Fields (Int.Cl. ⁷ , DB name) H05B 33/22 C09K 11/06 G03G 5/07

Claims (5)

(57) [Claims] 1. An organic electroluminescent device comprising a pair of electrodes, at least one of which is transparent or semitransparent, and one or more organic compound layers including a light emitting layer sandwiched between the electrodes, wherein An organic electroluminescent device comprising a hole transporting polymer represented by the following general formula (I) in one of the compound layers. [Chemical 1] [In the formula, R ₁ and R ₂ each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a substituted amino group, a halogen atom, or a substituted or unsubstituted aryl group, and X is a substituted or unsubstituted 2 group. Represents a valent aromatic group, and the terminal group R is a hydrogen atom, an alkyl group, an acyl group or a group-
CONH-R '(R' represents an alkyl group or a substituted or unsubstituted aryl group), n represents an integer selected from 1 to 5, and y represents an integer selected from 0 and 1. , M means an integer selected from 0 and 1, and l means an integer selected from 5 to 5000. ] 2. The organic electric field according to claim 1, wherein a hole transporting layer containing a hole transporting polymer represented by the general formula (I) and a light emitting layer are sequentially formed on a transparent electrode. Light emitting element. 3. The organic electroluminescent device according to claim 1, wherein a light emitting layer containing the hole transporting polymer represented by the general formula (I) and a light emitting material is formed on the transparent electrode. 4. The organic electroluminescent device according to claim 3, wherein the light emitting layer contains an electron transporting compound. 5. The hole transporting polymer has the following general formula (I
The organic electroluminescent device according to claim 1, which is a tetraarylbenzidine-based polyether represented by I). [Chemical 2] [In the formula, R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a substituted amino group, a halogen atom or a substituted or unsubstituted aryl group, and the terminal group R is a hydrogen atom. , An alkyl group, an acyl group, or a group -CONH-R '(R' is an alkyl group or a substituted or unsubstituted aryl group), and n is 1 to 5
Means an integer selected from, and l means an integer selected from 5 to 5000. ]