JP2000215987A - Polymer luminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer luminescent element having a characteristic of a polymer, i.e., easy forming, and having a high luminous efficiency, high heat resistance and a long service life. SOLUTION: This polymer luminescent element has at least one organic layer containing a siloxane-based hole-transporting polymer and a polymer phosphor between electrodes comprising a pair of an anode and a cathode at least one of which is transparent or semitransparent. The siloxane-based hole-transporting polymer includes an aromatic amine compound group in a polystyrene-reduced number average molecular weight of 103-107 in a side chain and/or a main chain, while an aromatic ring of the aromatic amine compound group and a silicon atom are directly bonded together. The polymer phosphor has a polystyrene-reduced number average molecular weight of 103-107 and generates fluorescence in a solid state. The polymer luminescent element contains the siloxane-based hole-transporting polymer and the polymer phosphor in a weight ratio of 99:1-60:40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer light emitting device (hereinafter, sometimes referred to as a polymer EL device) using a mixture of a siloxane-based hole transporting polymer and a polymer fluorescent material as a light emitting body. .

[0002]

2. Description of the Related Art As a backlight or a flat display, an element having a two-layer structure in which an organic fluorescent dye is used as a light emitting layer and an organic charge transport compound is laminated (Japanese Patent Laid-Open No. 59-194).
393) and an element using a polymer as a light emitting material (WO
JP-A-9013148, JP-A-3-244630
Publication). Electroluminescent elements using these organic materials are characterized in that they can easily emit multicolor light in addition to low-voltage DC drive and high luminance.

[0003] Among these devices, in a device having a laminated structure, when a low molecular compound is used as a light emitting material, the luminous efficiency of the device is degraded due to crystallization of the material, depending on the material used. In the material,
Problems such as low efficiency were pointed out. In order to improve these, Japanese Patent Application Laid-Open No. Hei 8-231951 proposes doping a low-molecular-weight hole transport material with a low-molecular-weight light-emitting material, and achieves high luminous efficiency. in this case,
Although the doping amount of the dye is about 5% by weight, a technique such as co-evaporation is necessary for controlling the doping amount, and it is difficult to dope uniformly when the area is increased.
Creation was not easy. Therefore, in order to achieve these high luminous efficiencies and to facilitate fabrication, mixing a luminescent material or a charge transporting material with a hole transporting polymer (Japanese Patent Application Laid-Open No. 4-212286), Adding a charge transport material (Japanese Patent Application Laid-Open No. 5-247460)
Has been proposed. Furthermore, in WO 9518771, a blend of a hole transporting polymer and a conjugated polymer light emitting material is known, and a polymer light emitting device using the same is also proposed. It is disclosed that the degree of polymerization of the conjugated polymer is 2 to 2000, and that the luminous efficiency is improved by mixing the hole transporting polymer and the conjugated polymer luminescent material at a mixing ratio of 1: 1 or more. Have been. Also,
A siloxane polymer having a carbazole group in a side chain is disclosed as a hole transporting polymer.

However, in the method of mixing a low-molecular light-emitting material or a charge-transport material with a hole-transport polymer, the low-molecular light-emitting material may separate and aggregate in the mixed film to cause concentration quenching. There was a problem. In addition, in the method of blending the hole transporting polymer and the conjugated polymer light emitting material, high heat resistance and long life characteristics have been required in addition to higher luminous efficiency. Accordingly, there has been a demand for a device having characteristics of a polymer that is easy to produce, having high luminous efficiency, high heat resistance, and long life.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polymer light-emitting device having characteristics of a polymer which is easy to produce, having high luminous efficiency, high heat resistance and a long life. .

[0006]

In view of such circumstances, the present inventors have conducted intensive studies to improve the heat resistance and the luminescence characteristics of the polymer light emitting device. A polymer fluorescent substance is added to a siloxane-based hole transporting polymer having a chain and / or a main chain in which an aromatic ring of the aromatic amine compound group is directly bonded to a silicon atom, with a specific mixing ratio. The present inventors have found that a polymer light-emitting device having excellent luminous efficiency, heat resistance, and life characteristics can be obtained by mixing them with each other.

That is, the present invention relates to the following [1] to [5]. [1] A polymer light-emitting device having at least one organic layer containing a siloxane-based hole-transport polymer and a polymer phosphor between electrodes composed of a pair of anodes and cathodes, at least one of which is transparent or translucent. Wherein the siloxane-based hole-transporting polymer has an aromatic amine compound group in a side chain and / or a main chain in a number average molecular weight in terms of polystyrene of 10 ³ to 10 ⁷ , and A siloxane-based hole-transporting polymer in which an aromatic ring of an amine compound group and a silicon atom are directly bonded, and the polymer fluorescent substance has a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁷ , and is a solid. A polymer light-emitting device, which is a polymer phosphor that shows fluorescence in a state, and wherein the weight ratio of the siloxane-based hole transporting polymer to the polymer phosphor is in the range of 99: 1 to 60:40. [2] The polymeric fluorescent substance is a conjugated polymer in which at least one kind of the repeating unit represented by the following formula (1) is contained, and the total of the repeating units is 50 mol% or more of all the repeating units. The polymer light-emitting device according to [1].

Embedded image -Ar ₁ -CR ₁ = CR _2- (1) [wherein, Ar ₁ comprises 4 to 20 carbon atoms contained in a conjugated bond of the main chain. It is an arylene group or a heterocyclic compound group. R ₁ and R ₂ each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, 6 to 2
And a group selected from the group consisting of an aryl group having 0 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. [3] a hole transport layer and / or a hole injection layer provided between the anode and the organic layer adjacent to the organic layer [1] or
The polymer light-emitting device according to [2]. [4] An electron transport layer and / or an electron injection layer is provided between the cathode and the organic layer adjacent to the organic layer [1] or
The polymer light-emitting device according to [2]. [5] A hole transport layer and / or a hole injection layer are provided between the anode and the organic layer, adjacent to the organic layer, and between the cathode and the organic layer, adjacent to the organic layer. The polymer light-emitting device according to [1] or [2], further comprising an electron transport layer and / or an electron injection layer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polymer light-emitting device of the present invention includes at least one organic layer containing a siloxane-based hole-transport polymer and a polymer fluorescent material between a pair of anodes and cathodes, at least one of which is transparent or translucent. In the polymer light emitting device having a layer, the siloxane-based hole-transporting polymer has an aromatic amine compound group in a side chain and / or a main chain in a number average molecular weight in terms of polystyrene of 10 ³ to 10 ^7. And a siloxane-based hole-transporting polymer in which an aromatic ring of the aromatic amine compound group is directly bonded to a silicon atom, wherein the polymer fluorescent material has a number average molecular weight in terms of polystyrene of 10 ³ to 10 ^7. Wherein the weight ratio of the siloxane-based hole-transporting polymer to the polymer fluorescent material is 99: 1 to 60: 4.
It is characterized by being in the range of 0.

The weight ratio of the siloxane-based hole transporting polymer to the fluorescent polymer is preferably in the range of 95: 5 to 70:30. When the weight ratio of the siloxane-based hole transporting polymer to the polymer fluorescent substance is more than 99: 1, sufficient luminescence characteristics may not be obtained. If the ratio is less than 60:40, the polymer fluorescent substance and the siloxane-based hole transporting polymer may undergo phase separation. Further, the total weight of the siloxane-based hole transporting polymer and the polymeric fluorescent substance in the organic layer is preferably in the range of 60% by weight to 100% by weight based on the weight of the organic layer. Further, in the organic layer containing the siloxane-based hole-transporting polymer and the polymer phosphor, the siloxane-based hole-transporting polymer and the polymer phosphor may be used alone. Two or more types may be used.

The siloxane-based hole transporting polymer used in the present invention has an aromatic amine compound group in a side chain and / or a main chain, and has an aromatic ring and a silicon atom in the aromatic amine compound group. It must be a siloxane-based hole transporting polymer directly bonded. Examples of the siloxane-based hole transporting polymer having an aromatic amine compound group in a side chain and having an aromatic ring of the aromatic amine compound group directly bonded to a silicon atom include (A) an aromatic amine Polymers in which the aromatic ring of the compound group is directly bonded to the silicon atom of the siloxane polymer forming the main chain. The siloxane-based hole transporting polymer having an aromatic amine compound group in the main chain and a silicon atom directly bonded to an aromatic ring of the aromatic amine compound group includes (B) aromatic Examples include those in which the aromatic ring of the amine compound group forms a main chain and those in which the nitrogen atom and the aromatic ring of the (C) aromatic amine compound group form a main chain. Among them, (A) the polymer in which the aromatic ring of the aromatic amine compound group is directly bonded to the silicon atom of the siloxane polymer forming the main chain, and (C) the nitrogen atom of the aromatic amine compound group and Those in which the aromatic ring forms the main chain are preferred. Among these, those represented by the following general formulas (2) (included in the above (A)) and (6) (included in the above (C)) are preferable, and more preferably those represented by the following general formula (6) The siloxane-based hole transporting polymer shown is exemplified.

Embedded image中 where R_ThreeIs an alkyl having 1 to 20 carbon atoms
Group, cycloalkyl having 3 to 20 carbon atoms
Group, aryl group having 6 to 30 carbon atoms or 7
Aralkyl groups having up to 32 carbon atoms. Ar
_TwoIs an arylene group having 6 to 30 carbon atoms, or
Or an aromatic ethenylene skeleton represented by the following general formula (3)
Is a group having_ThreeAnd Ar_FourAre independent
An aryl group having 6 to 30 carbon atoms,
A group having an aromatic amine skeleton represented by the general formula (4),
Or an aromatic ethenylene bone represented by the following general formula (5):
Shows a group having a case. Also, Ar_TwoAnd Ar_ThreeDuring or
Ar_TwoAnd Ar_FourOr Ar _ThreeAnd Ar_FourForms a ring between
It may be.

Embedded image (Wherein, Ar ₅ and Ar ₆ are each independently ₆ to 3
R ₄ and R ₅ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, , An aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 32 carbon atoms. )

Embedded image (Wherein, Ar ₇ represents an arylene group having 6 to 30 carbon atoms, and R ₆ and R ₇ each independently represent 1
An alkyl group having -20 carbon atoms, a cycloalkyl group having 3-20 carbon atoms, an aryl group having 6-30 carbon atoms, or an aralkyl group having 7-32 carbon atoms. Also, between Ar ₇ and R ₆ , A
A ring may be formed between r ₇ and R ₇ or between R ₆ and R ₇ . )

Embedded image (Wherein, Ar ₈ represents an arylene group having 6 to 30 carbon atoms, and R ₈ and R ₉ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, 3
Cycloalkyl groups having up to 20 carbon atoms, 6-3
Represents an aryl group having 0 carbon atoms or an aralkyl group having 7 to 32 carbon atoms, and Ar ₉ represents 6 to
Indicate an aryl group having 30 carbon atoms. )｝

Embedded image[Wherein, Ar_TenAnd Ar₁₂Are each independently 6 to
An arylene group having 30 carbon atoms, the following general formula
A group having an aromatic amine skeleton represented by (7), or
Having an aromatic ethenylene skeleton represented by the following general formula (8):
A group to be used. Also, Ar₁₁Is 6 to 30 carbon atoms
An aromatic group represented by the following general formula (9)
A group having an aromatic amine skeleton, or a group represented by the following general formula (10)
The group having the aromatic ethenylene skeleton represented is shown. Ma
Ar_TenAnd Ar₁₁During, Ar_TenAnd Ar ₁₂During or
Ar₁₁And Ar₁₂May form a ring therebetween. R_Ten,
R₁₁, R ₁₂And R₁₃Are each independently a hydroxyl group, 1
Alkyl or alkoxy having up to 20 carbon atoms
Xy group, cycloalkyl having 3 to 20 carbon atoms
Groups, aryl groups having 6 to 30 carbon atoms, 7 to 3
An aralkyl group having two carbon atoms, represented by the following general formula (1
1), the group represented by (13) or cross-linking in the molecule
May be bonded to a silicon atom in the molecule, or
Cross-links between the atoms and is bonded to silicon atoms of adjacent molecules.
Represents a divalent oxygen atom which may be present.

Embedded image (Wherein, Ar ₁₃ and Ar ₁₄ each independently represent 6 to
Represents an arylene group having 30 carbon atoms;
₁₄ is an alkyl group having 1 to 20 carbon atoms, 3 to
Cycloalkyl groups having 20 carbon atoms, 6-30
An aryl group having 7 carbon atoms or an aralkyl group having 7 to 32 carbon atoms. Further, a ring may be formed between Ar ₁₃ and Ar ₁₄ , between Ar ₁₃ and R ₁₄ , or between Ar ₁₄ and R ₁₄ . )

Embedded image (Wherein, Ar ₁₅ and Ar ₁₆ each independently represent 6 to
R ₁₅ and R ₁₆ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, , An aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 32 carbon atoms. )

Embedded image (Wherein, Ar ₁₇ represents an arylene group having 6 to 30 carbon atoms, and R ₁₇ and R ₁₈ each independently represent
An alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 32 carbon atoms. Show. Further, a ring may be formed between Ar ₁₇ and R ₁₇ , between Ar ₁₇ and R ₁₈ , or between R ₁₇ and R ₁₈ . )

Embedded image (In the formula, Ar ₁₈ represents an arylene group having 6 to 30 carbon atoms, and R ₁₉ and R ₂₀ each independently represent
A hydrogen atom, an alkyl group having 1 to 20 carbon atoms,
A cycloalkyl group having 3 to 20 carbon atoms, 6 to
Aryl groups having 30 carbon atoms, or 7-32
Represents an aralkyl group having carbon atoms, Ar ₁₉ is
An aryl group having 6 to 30 carbon atoms is shown. )

Embedded imageＡｒwhere Ar₂₀And Ar_{twenty two}Are each independently 6 to
An arylene group having 30 carbon atoms, the above general formula
A group having an aromatic amine skeleton represented by (7),
Is an aromatic ethenylene skeleton represented by the above general formula (8)
A group having the formula: In the formula, Ar_{twenty one}Is 6-30
An aryl group having a carbon atom of the general formula (9)
A group having an aromatic amine skeleton represented by the general formula
A group having an aromatic ethenylene skeleton represented by (10)
Show. Also, Ar₂₀And Ar_{twenty one}During, Ar ₂₀And Ar_{twenty two}of
Between or Ar_{twenty one}And Ar_{twenty two}May form a ring between
No. Also, R_{twenty one}And R_{twenty two}Is, independently, hydroxyl
A group, an alkyl group having 1 to 20 carbon atoms or
Alkoxy groups, cycloa having 3 to 20 carbon atoms
Alkyl groups, aryl groups having 6 to 30 carbon atoms,
An aralkyl group having 7 to 32 carbon atoms, or
It may be crosslinked in the molecule and bonded to the silicon atom in the molecule.
Or the silicon source of adjacent molecules
And represents a divalent oxygen atom which may be bonded to a child. Also,
Where R_{twenty three}Represents a hydrogen atom or the following general formula (12)
You.

Embedded image (Wherein R ₂₄ , R ₂₅ and R ₂₆ are each independently a hydroxyl group, an alkyl or alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, 6 to An aryl group having 30 carbon atoms or an aralkyl group having 7 to 32 carbon atoms is shown.)

Embedded image In the formula, R ₂₇ , R ₂₈ and R ₂₉ are each independently 1
An alkyl group having from 20 to 20 carbon atoms, a cycloalkyl group having from 3 to 20 carbon atoms, an aryl group having from 6 to 30 carbon atoms, an aralkyl group having from 7 to 32 carbon atoms, A group having an aromatic ethenylene skeleton represented by the formula (10) or the following general formula (14)
And a group having an aromatic amine skeleton represented by

Embedded image (In the formula, Ar ₂₃ is an arylene group having 6 to 30 carbon atoms, a group having an aromatic amine skeleton represented by the general formula (7), or an aromatic group represented by the general formula (8). Ar ₂₄ and Ar ₂₅ each independently represent an aryl group having 6 to 30 carbon atoms or an aromatic amine skeleton represented by the general formula (9). And a group having an aromatic ethenylene skeleton represented by the above general formula (10).

The siloxane-based high hole-transporting property used in the present invention.
Regarding the molecular weight of a molecule, the
Effect, the polystyrene equivalent number average molecular weight
10 ^Three-10⁷It is necessary to be within the range of, preferably
Is 10^Three-10⁶, More preferably 10^Three~ 5x10^Fiveof
Range. On the other hand, there is no restriction on the weight average molecular weight.
But 10^Three-10⁷Is exemplified, preferably 10
^Three-10⁶Range.

The polymer fluorescent substance used in the polymer light-emitting device of the present invention is not particularly limited as long as it is a polymer that exhibits fluorescence in a solid state, but a conjugated polymer soluble in an organic solvent. Is exemplified. Soluble conjugated polymers include polyphenylene and derivatives thereof, polymers of 5-membered heterocyclic compounds at 2,5-positions and derivatives thereof, polymers in which polycyclic aromatic compounds are bonded by carbon-carbon bonds, and derivatives thereof, or Polyarylene vinylene and its derivatives are preferable, and polyarylene vinylene and its derivatives are particularly preferable. In order for the conjugated polymer to be soluble, each derivative having a long-chain substituent on the side chain is preferable. Examples of the polyarylenevinylene and its derivative include a polymer containing at least one kind of the repeating unit represented by the formula (1), and a total of the repeating units being 50 mol% or more of all the repeating units. Although it depends on the structure of the repeating unit, the repeating unit represented by the formula (1) is preferably at least 70 mol% of all the repeating units. The conjugated polymer includes, as a repeating unit other than the repeating unit represented by the formula (1), a divalent aromatic compound group or a derivative thereof, a divalent heterocyclic compound group or a derivative thereof,
Alternatively, it may contain a group obtained by combining them. Further, the repeating unit represented by the formula (1) or another repeating unit may be linked by a non-conjugated unit having an ether group, an ester group, an amide group, an imide group, or the like, A non-conjugated moiety may be included.

The polymeric fluorescent substance has a repeating unit of the formula (1)
In the case of a conjugated polymer containing₁as,
Whether the number of carbon atoms involved in the conjugate bond is 4 or more and 20 or less
An arylene group or a heterocyclic compound group. Ma
And bound to a vinylene group in the repeating unit of the formula (1).
R₁, R_TwoAre independently hydrogen, 1 to 20 carbon atoms
Alkyl groups having 6 to 20 carbon atoms
Aryl groups, heterocyclic compounds having 4 to 20 carbon atoms
And a group selected from the group consisting of a compound group and a cyano group.
Specifically, an alkyl group having 1 to 20 carbon atoms
As methyl, ethyl, propyl, butyl
Group, pentyl group, hexyl group, heptyl group, octyl
Group, decyl group, dodecyl group and the like, methyl group,
Ethyl, pentyl, hexyl, heptyl, octyl
A tyl group is preferred. As the aryl group, a phenyl group,
4-C₁~ C₁₄An alkoxyphenyl group (where C₁~ C₁₄
Indicates that the number of carbon atoms is 1 to 14. The same applies to
Used in the same sense. ), 4-C₁~ C₁₄Alkylpheny
And a 1-naphthyl group and a 2-naphthyl group.
You. Examples of the heterocyclic compound group include a 2-pyridyl group and a 2-quino
An example is a ril group. Including the repeating unit of the formula (1)
For specific examples of conjugated polymers, see JP-A-3-244.
630, JP-A-5-202355, JP-A-5-202355
6-73374, JP-A-7-147190
Report, JP-A-7-278276, JP-A-7-300
580, JP 9-35870, JP 9
-45478, JP-A-9-111233,
JP-A-10-114891, JP-A-10-324
No. 870, WO 94229883, WO
Japanese Patent No. 9821262, WO9818996
Described in the opening specification and in the specification published in WO9827136
Polyarylene vinylenes and JP-A-10-364
No. 87 is preferably a fluorene-based polymer or the like.
Can be used. About the molecular weight of the polymeric fluorescent substance used in the present invention
Is mixed with a siloxane-based hole-transporting polymer.
Effect, the polystyrene equivalent number average molecular weight
10 ^Three-10⁷And preferably 10^Three-10⁶,
More preferably, 10^Three~ 5x10^FiveRange. one
On the other hand, there is no limitation on the weight average molecular weight.^Three~
10⁷Is exemplified, preferably 10^Three-10⁶Range of
It is an enclosure.

Next, the structure of the polymer EL device of the present invention has an aromatic amine compound group in a side chain and / or a main chain, and has an aromatic ring of the aromatic amine compound group and a silicon atom. It is only necessary to have at least one organic layer containing a siloxane-based hole-transport polymer directly bonded to a polymer and a polymeric fluorescent substance, and a known structure is employed. For example, as the structure of the polymer EL device of the present invention, an element structure having a pair of electrodes on both surfaces of a light-emitting layer, a hole transport layer and a light-emitting layer laminated, an anode on the surface of the hole transport layer, A device structure having a cathode on the surface, a light emitting layer and an electron transport layer laminated on each other, and an anode on the surface of the light emitting layer, a device structure having a cathode on the surface of the electron transport layer, or a hole transport layer, a light emitting layer, and electron transport Layers are laminated in this order, an anode is provided on the surface of the hole transport layer,
An element structure having a cathode on the surface of the electron transport layer is exemplified. Here, the organic layer of the present invention is used for the light emitting layer, but a plurality of organic layers may be used.

Here, in any of the device structures, the light emitting layer has an aromatic amine compound group in a side chain and / or a main chain, and an aromatic ring of the aromatic amine compound group and a silicon atom are present. It includes a siloxane-based hole-transporting polymer directly bonded and a polymer phosphor, the hole-transporting layer contains a hole-transporting material, and the electron-transporting layer contains an electron-transporting material. The shape, size, material, manufacturing method, and the like of the polymer EL device of the present invention having these structures are appropriately selected according to the use of the polymer EL device, and are not particularly limited. Further, the light emitting layer, the hole transport layer, the electron transport layer,
Two or more layers may be used independently, and a buffer layer may be inserted into any one of the interfaces in order to improve the efficiency of charge injection from the interface, improve the adhesion of the interface, prevent mixing, and the like. The order and number of layers to be laminated and the thickness of each layer are not particularly limited, but may be appropriately used in consideration of luminous efficiency and element life. The shape, size, material, manufacturing method, and the like of the polymer EL device of the present invention having such a structure are appropriately selected depending on the use of the polymer EL device, and there is no particular limitation.

The method of mixing the siloxane-based hole-transporting polymer and the polymer fluorescent substance is not particularly limited, but is generally performed from a solution. Examples of good solvents for both include chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene and the like. Although it depends on the structure and molecular weight of the polymeric fluorescent substance, it can be usually dissolved in these solvents in an amount of 0.1% by weight or more.

When a film is formed from a solution by using the organic solvent-soluble siloxane-based hole-transporting polymer and the polymer fluorescent material when preparing a polymer EL device, a mixed solution of the two is used. It is only necessary to remove the solvent by drying after coating, and the same method can be applied to the case where a charge transporting material or a luminescent material is further mixed, which is very advantageous in production. As a method of forming a film from a solution, spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, A coating method such as a flexographic printing method or an offset printing method can be used.

For example, a light emitting material other than the polymeric fluorescent substance may be mixed and used in the light emitting layer. As the light emitting material, known materials can be used. Examples of low molecular weight compounds include naphthalene derivatives, anthracene or derivatives thereof, perylene or derivatives thereof, polymethine-based, xanthene-based, coumarin-based, cyanine-based dyes, metal complexes of 8-hydroxyquinoline or derivatives thereof, and aromatic amines. , Tetraphenylcyclopentadiene or a derivative thereof, or tetraphenylbutadiene or a derivative thereof can be used. Specifically, known materials such as those described in JP-A-57-51781 and JP-A-59-194393 can be used.

When the polymer EL device of the present invention has a hole transporting layer, the hole transporting material used is not particularly limited, but may be polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, or a siloxane-based positive electrode. Hole transporting polymer, pyrazoline derivative, arylamine derivative, stilbene derivative, triphenyldiamine derivative, polyaniline or its derivative, polythiophene or its derivative, poly (p-phenylenevinylene)
Or a derivative thereof, or poly (2,5-thienylenevinylene) or a derivative thereof.

Specifically, examples of the hole transport material include JP-A-63-70257, JP-A-63-175860, JP-A-2-135359 and JP-A-2-13536.
No. 1, JP-A-2-209988, JP-A-3-3799
No. 2, JP-A-3-152184, etc. are exemplified. Among these, as a hole transporting material used for the hole transporting layer, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, the siloxane-based hole transporting polymer, polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly ( Polymeric hole transport materials such as p-phenylenevinylene) or a derivative thereof, or poly (2,5-thienylenevinylene) or a derivative thereof are preferable, and polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, and the siloxane are more preferable. It is a hole transporting polymer. In the case of a low-molecular-weight hole transport material, it is preferable to use the material by dispersing it in a polymer binder. In the present invention, when the polymer EL element has an electron transporting layer, known electron transporting materials can be used, and oxadiazole derivatives, anthraquinodimethane or its derivatives, benzoquinone or its derivatives, naphthoquinone Or a derivative thereof, anthraquinone or a derivative thereof, tetracyanoanthraquinodimethane or a derivative thereof, a fluorenone derivative, diphenyldicyanoethylene or a derivative thereof, a diphenoquinone derivative, or a metal complex of 8-hydroxyquinoline or a derivative thereof.

Specifically, JP-A-63-70257, JP-A-63-175860, and JP-A-2-1353
Nos. 59, 2-135361, 2-209
988, 3-37992, 3-152
No. 184 is exemplified. Of these, oxadiazole derivatives, benzoquinone or its derivatives, anthraquinone or its derivatives, or metal complexes of 8-hydroxyquinoline or its derivatives are preferred, and 2- (4-biphenylyl) -5 is preferred.
-(4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8
-Quinolinol) aluminum is more preferred.

The method of forming the charge transporting layer is not limited, but examples of the low molecular weight charge transporting material include a vacuum deposition method, a method of forming a film from a solution, and a method of forming a film from a mixed solution with a polymer binder. You. In the case of a polymer charge transporting material, a method of forming a film from a solution is exemplified. The solvent used for film formation from the solution is not particularly limited as long as the solvent can dissolve the charge transport material. As the solvent, chloroform, methylene chloride, chlorine solvents such as dichloroethane, ether solvents such as tetrahydrofuran, aromatic hydrocarbon solvents such as toluene and xylene, acetone, ketone solvents such as methyl ethyl ketone, ethyl acetate, butyl acetate,
Ester solvents such as ethylcellosolve acetate are exemplified.

As a method for forming a film from a solution, spin coating from a solution, casting, microgravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, etc. Method, screen printing method, flexographic printing method,
A coating method such as an offset printing method can be used.

As the polymer binder to be mixed, those which do not extremely inhibit charge transport are preferable, and those which do not strongly absorb visible light are suitably used. Examples of the polymer binder include poly (N-vinylcarbazole), polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly (p-phenylenevinylene) or a derivative thereof, poly (2,5-thienylenevinylene) or a derivative thereof, and polycarbonate. , Polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, polysiloxane and the like.

In the present invention, as a material of the transparent or translucent anode, a conductive metal oxide film, a translucent metal thin film or the like is used. Specifically, indium tin
A film (NESA or the like) formed using conductive glass made of oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), or the like, gold, platinum, silver, copper, or the like is used. ZnO and SnO ₂ are preferred. Examples of the manufacturing method include a vacuum evaporation method, a sputtering method, an ion plating method, and a plating method. Further, as the anode, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used.

Next, as the material of the cathode used in the present invention, a material having a small ionization energy work function is preferable. For example, aluminum, indium, magnesium, calcium, lithium, magnesium-silver alloy, magnesium-indium alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, calcium-aluminum alloy, graphite, or A graphite interlayer compound or the like is used.

As a method for producing the cathode, a vacuum deposition method, a sputtering method, a lamination method for thermocompression bonding of a metal thin film, and the like are used. After the cathode is formed, a protective layer for protecting the polymer EL device may be provided.

[0028]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it should not be construed that the present invention is limited thereto. <Measurement of Number Average Molecular Weight> The number average molecular weight was determined by gel permeation chromatography (GPC) in terms of polystyrene.

Reference Example 1 <Synthesis of polymeric fluorescent substance 1> 2,5-dioctyloxy-
The phosphonium salt (1) was synthesized by reacting p-xylylene dichloride with triphenylphosphine in N, N-dimethylformamide solvent. 47.75 parts by weight of the resulting phosphonium salt, and terephthalaldehyde.
5 parts by weight were dissolved in a mixed solvent of ethyl alcohol / chloroform. An ethyl alcohol solution containing 5.4 parts by weight of lithium ethoxide was added dropwise to a mixed solution of a phosphonium salt and dialdehyde in ethyl alcohol / chloroform to polymerize. Subsequently, a chloroform solution of 1-pyrenecarbaldehyde was added to the reaction solution, and then an ethyl alcohol solution containing lithium ethoxide was added dropwise to the reaction solution, and the mixture was polymerized with stirring at room temperature for 3 hours. After standing at room temperature overnight, the precipitate was separated by filtration, washed with ethyl alcohol, dissolved in chloroform, and ethanol was added thereto to reprecipitate. This was dried under reduced pressure to obtain 8.0 parts by weight of a polymer. This is called polymeric fluorescent substance 1. The repeating units of polymeric fluorescent substance 1 calculated from the charged ratio of the monomers and the molar ratios thereof are shown below. It was confirmed by ¹ H-NMR that a pyrenyl group was present at the molecular terminal.

Embedded image (In the above formula, the molar ratio of the two repeating units is 5
0:50, and the two repeating units are alternately linked. The polystyrene-equivalent number average molecular weight of the polymeric fluorescent substance 1 was 4.0 × 10 ³ . The structure of the polymeric fluorescent substance 1 was confirmed by an infrared absorption spectrum and NMR.

Reference Example 2 <Synthesis of polymeric fluorescent substance 2> 2,5-dioctyloxy-
p-Xylylene dichloride was reacted with triphenylphosphine in N, N-dimethylformamide solvent to synthesize a phosphonium salt. 3. The obtained phosphonium salt
78 parts by weight of 2-methoxy-5 obtained in the same manner.
4.28 parts by weight of a phosphonium salt of -octyloxy-p-xylylene dichloride and terephthalaldehyde 1.
01 parts by weight and 1-pyrenecarboxaldehyde 1.15
Was dissolved in a mixed solvent of 80 parts by weight of ethyl alcohol / 100 parts by weight of chloroform. 10% by weight of a 12% methanol solution of lithium methoxide and ethanol 40
The resulting mixture was added dropwise to a mixed solution of a phosphonium salt and an aldehyde in ethyl alcohol / chloroform, followed by a reaction at room temperature for 4 hours. After standing at room temperature overnight, the precipitate was collected, washed with ethyl alcohol, and then dissolved in toluene, to which ethanol was added for reprecipitation purification. After reprecipitation purification twice, this was dried under reduced pressure to obtain 2.0 parts by weight of a polymeric fluorescent substance. This is called polymeric fluorescent substance 2. The repeating units of the polymeric fluorescent substance 2 calculated from the charged ratios of the monomers and the molar ratios thereof are shown below.
It was confirmed by ¹ H-NMR that a pyrenyl group was present at the molecular terminal.

Embedded image The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 2 was 2.5 × 10 ³ . The structure of the polymeric fluorescent substance 2 was confirmed by infrared absorption spectrum and NMR.

Reference Example 3 <Synthesis of polymeric fluorescent substance 3> 2,5-dioctyloxy-
p-Xylylene dichloride was reacted with triphenylphosphine in N, N-dimethylformamide solvent to synthesize a phosphonium salt. 3. The obtained phosphonium salt
78 parts by weight of 2-methoxy-5 obtained in the same manner.
4.28 parts by weight of a phosphonium salt of -octyloxy-p-xylylenedichloride and 0.2% of terephthalaldehyde.
51 parts by weight, 0.51 part by weight of isofluraldehyde and 1
And 1.15 parts by weight of pyrenecarboxaldehyde were dissolved in a mixed solvent of 80 parts by weight of ethyl alcohol / 100 parts by weight of chloroform. A solution prepared by mixing 10 parts by weight of a 12% methanol solution of lithium methoxide and 40 parts by weight of ethanol was added dropwise to a mixed solution of a phosphonium salt and an aldehyde in ethyl alcohol / chloroform, followed by a reaction at room temperature for 4 hours. After standing at room temperature overnight, the precipitate was collected, washed with ethyl alcohol, and then dissolved in toluene, to which ethanol was added for reprecipitation purification. 2
After re-precipitation purification, this was dried under reduced pressure to obtain 2.0 parts by weight of a polymeric fluorescent substance. This is called polymeric fluorescent substance 3. The repeating units of the polymeric fluorescent substance 3 calculated from the charged ratio of the monomers and the molar ratios thereof are shown below. It was confirmed by ¹ H-NMR that a pyrenyl group was present at the molecular terminal.

Embedded image The polystyrene-equivalent number average molecular weight of the polymeric fluorescent substance 3 was 2 × 10 ³ . The structure of the polymeric fluorescent substance 3 was confirmed by an infrared absorption spectrum and NMR.

Reference Example 4 <Synthesis of silane compound 1>
A solution of 8.0 g of the dibromo derivative of N'-diphenyl-N, N'-bis (3 "-methylphenyl) -1,1'-biphenyl-4,4'-diamine in a dry tetrahydrofuran solution was added at -78.degree. 17 ml of a butyllithium / n-hexane solution was added for lithiation, and N, N′-diphenyl-N, N′-bis (3 ″ -methylphenyl) -1,1 ′ was added.
A dilithium derivative of -biphenyl-4,4'-diamine was produced.

In a dry argon atmosphere, a solution of 7.0 g of dimethoxymethylchlorosilane in dry tetrahydrofuran was added at -78 ° C to the N, N'-diphenyl-N, N '.
A solution of a dilithium derivative of -bis (3 "-methylphenyl) -1,1'-biphenyl-4,4'-diamine was added dropwise to the mixture, and the mixture was stirred at -78 ° C for 1 hour. After distilling off excess dimethoxymethylchlorosilane and the solvent, dry toluene was added thereto and the lithium salt was removed with a glass filter under a dry argon atmosphere, and the solvent was distilled off to obtain 7.1 g of a viscous solid. nuclear magnetic resonance spectra of the obtained reaction product from ^{(1 H-NMR), N} , N '
That a dimethoxymethylsilyl derivative and a bis (dimethoxymethylsilyl) derivative of -diphenyl-N, N'-bis (3 "-methylphenyl) -1,1'-biphenyl-4,4'-diamine are formed; confirmed.
Hereinafter, this is referred to as silane compound 1. ¹ H-NMR: 0.40 [s] (methyl group bonded to silicon atom), 2.28 [s] (methyl group), 2.40
[S] (methyl group), 3.60 [s] (methoxy group),
6.8 to 7.6 [m] (aromatic group)

<Synthesis of Hole-Transporting Polymer 1> 10 ml of a solution of silane compound 1 (6.5 g) in tetrahydrofuran
And 3.5 ml of triethylamine and 0.1 ml of water while stirring.
65 ml was added, and the mixture was stirred at 60 ° C. After evaporating the solvent, the residue was purified by reprecipitation with tetrahydrofuran / 2-propanol to obtain 3.17 g of a white solid. The nuclear magnetic resonance absorption spectrum ( ¹ H-NMR) of the obtained white solid shows 0.0
A signal of a methyl group bonded to a silicon atom at about 0.7 to 0.7 ppm, a broad signal of a methyl group on the phenyl ring at about 1.8 to 2.4 ppm, a signal of a methoxy group at about 3.4 to 3.7 ppm, and 6 A broad signal of the proton of the aromatic ring was observed around 0.2 to 7.6 ppm. In addition, the infrared absorption spectrum shows 1100 cm ^-1 ,
800 cm ^-1 broad signal of from siloxane bonds near, broad signal of from hydroxyl groups was observed around 3300 cm ^-1, N the obtained polymer, N'- diphenyl -
N, N'-bis (3 "-methylphenyl) -1,1'-
It was confirmed that the biphenyl-4,4'-diamine group was incorporated as a part of the repeating unit, and that a part of the hydroxyl group generated by hydrolysis remained unreacted. When the molecular weight was measured by gel permeation chromatography, the weight average molecular weight in terms of polystyrene was 2.2 × 10 ⁴ and the number average molecular weight was 6.2 × 10 ³ .

To 15 ml of a tetrahydrofuran solution of the white solid (1.0 g) obtained above, triethylamine 3
After addition of 1.7 ml of triphenylchlorosilane, the mixture was stirred at 55 ° C. Water was added to quench excess triphenylchlorosilane. After evaporating the solvent, dissolve in toluene and shake with water using a separating funnel,
The toluene layer was separated and the solvent was distilled off. The obtained solid was purified by reprecipitation with tetrahydrofuran / 2-propanol to obtain 0.85 g of a white solid. The integration ratio of the signal in the nuclear magnetic resonance absorption spectrum ( ¹ H-NMR) of this white solid confirmed that the triphenylsilyl group had been incorporated. In the infrared absorption spectrum, 33
Although the intensity was low around 00 cm ⁻¹ , a wide signal derived from a hydroxyl group was observed, and it was confirmed that the hydroxyl group still remained. When the molecular weight was measured by gel permeation chromatography, the weight average molecular weight in terms of polystyrene was 2.4 × 10 ⁴ , and the number average molecular weight was 7.9 × 1.
0 was ^3.

Further, 4 ml of triethylamine was added to 20 ml of a tetrahydrofuran solution of the above white solid (0.65 g) obtained by reacting with triphenylchlorosilane.
, 0.43 g of diphenylmethylchlorosilane
Was added and stirred at room temperature. The solid obtained by post-treatment of the reaction in the same manner as in the reaction with triphenylchlorosilane was purified by reprecipitation with tetrahydrofuran / ethanol to obtain 0.48 g of a white solid. Hereinafter, this is referred to as a hole transporting polymer 1.

The nuclear magnetic resonance absorption spectrum ( ¹ H-NMR) of the obtained hole transporting polymer 1 was 0.4 to 0.6.
A methyl signal of the diphenylmethylsilyl group was observed at around ppm, and it was confirmed that the diphenylmethylsilyl group was incorporated. Further, in the infrared absorption spectrum, no signal was observed around 3300 cm ⁻¹ , and it was confirmed that no hydroxyl group remained. When the molecular weight of the hole transporting polymer 1 was measured by gel permeation chromatography, the weight average molecular weight in terms of polystyrene was 2.9 × 10 ⁴ , and the number average molecular weight was 9.5 ×
It was 10 ^3.

Reference Example 5 <Synthesis of hole transporting polymer 2> A hole transporting polymer synthesized and synthesized in the same manner as hole transporting polymer 1 except that tetramethylammonium hydroxide was used instead of triethylamine. 2
I got

<Preparation and Evaluation of Device> Example 1 An ITO film having a thickness of 200 nm was formed by sputtering.
Polymer fluorescent substance 2 and hole transporting property
Using a toluene mixed solution of molecule 1 (1: 4 by weight)
Film with a thickness of 80 nm by spin coating
To form a light emitting layer. A homogeneous film was obtained. Then decompress it
After drying at 120 ° C. for 1 hour, an electron
Tris (8-quinolinol) aluminum as the transport layer
(Alq _Three) Was deposited to a thickness of 40 nm. Finally, on top of that,
Aluminum-lithium alloy (Al: Li =
99: 1 weight ratio) to a thickness of 100 nm.
A molecular light emitting device was manufactured. The degree of vacuum during evaporation is 8
× 10^-6Torr or less. A voltage of about 4 V is applied to this element.
When pressure is applied, EL emission of the polymeric fluorescent substance 2 is observed.
Was. The EL peak wavelength was 534 nm. Brightness 200
cd / m^TwoWas 5.0 cd / A.
This element is 25 mA / cm^TwoAt a current density of
After continuous driving, the luminance after aging for 5 hours was 7
04 cd / m^TwoAnd the luminance after 100 hours is 38
0 cd / m^TwoIt was about. At this time, the drive voltage
Only slightly increased from 10.3V to 13.1V
Met. Example 2 ITO film with a thickness of 200 nm by sputtering
21.2 weight of polymeric fluorescent substance 1 on a glass substrate with
% Of the hole transport polymer 2 and 78.8% by weight.
Using a spin coating solution (solids concentration 3% by weight).
An organic layer was formed by a filming method. Next, remove this under reduced pressure
The temperature was raised to 120 ° C., and the mixture was left in a vacuum overnight,
° C. Subsequently, as an electron transport layer on the organic layer,
Tris (8-quinolinol) aluminum 0.1 ~
50 nm was deposited at a rate of 0.2 nm / s. Finally,
Aluminum-lithium alloy (Al:
Li = 99: 1 by weight) is deposited to a thickness of 50 nm to form a two-layer structure.
Was produced. The degree of vacuum during evaporation is
8 × 10^-6Torr or less. 2.5 m
A / cm^TwoAt constant current density, driven under nitrogen atmosphere
When the light spectrum was measured, the peak wavelength was 538 nm.
And almost coincides with the fluorescence spectrum of the polymeric fluorescent substance 1.
Was. Further 25 mA / cm^TwoWith constant current drive
became. Brightness after aging for 5 hours is 732 cd / m^Two
And its half-life from brightness is about 118 hours.
Was. In addition, the drive during driving after aging for 5 hours
The rate of increase of the dynamic voltage was 0.032 V / hr.

Example 3 Polymeric fluorescent substance 3 was 20% by weight and hole transporting polymer 2 was 8%.
A film was formed by a spin coating method using a toluene solution containing 0% by weight (solid content concentration: 3% by weight) to form an organic layer. Next, the temperature was raised to 50 ° C. under reduced pressure, and left as it was in a vacuum overnight to 38 ° C. Subsequently, tris (8-quinolinol) aluminum was deposited as an electron transporting layer on the organic layer at a rate of 0.1 to 0.2 nm / s to a thickness of 50 nm. Finally, a 50 nm aluminum-lithium alloy (Al: Li = 99: 1 weight ratio) was deposited thereon as a cathode to produce a polymer light emitting device having a two-layer structure. The degree of vacuum at the time of deposition was 8 × 10 ⁻⁶ Torr or less. This device was driven under a nitrogen atmosphere at a constant current density of ^2.5 mA / cm ² , and the emission spectrum was measured. As a result, the peak wavelength was 536 nm, which almost coincided with the fluorescence spectrum of the polymeric fluorescent substance 3. Further, constant current driving was continuously performed at 25 mA / cm ² . The luminance after aging for 5 hours was 822 cd / m ² , and the half life from the luminance was about 47 hours. The rate of increase in the driving voltage during driving after aging for 5 hours was 0.044 V / hr.

[0041]

The polymer light emitting device of the present invention has the characteristics of a polymer that it is easy to fabricate, and has high luminous efficiency, high heat resistance, and long life. It can be preferably used as a device such as a display.

Claims (5)

[Claims] A polymer having at least one organic layer containing a siloxane-based hole-transporting polymer and a polymeric fluorescent substance between a pair of anodes and cathodes, at least one of which is transparent or translucent. In the light-emitting element, the siloxane-based hole-transporting polymer has an aromatic amine compound group in a side chain and / or a main chain in a number average molecular weight in terms of polystyrene of 10 ³ to 10 ⁷ , and A siloxane-based hole-transporting polymer in which an aromatic ring of an aromatic amine compound group and a silicon atom are directly bonded, and the polymer fluorescent material has a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁷ . A high molecular weight fluorescent material that exhibits fluorescence in a solid state, and a weight ratio of the siloxane-based hole transporting polymer to the high molecular weight fluorescent material ranges from 99: 1 to 60:40. Takaita Child light emitting element. 2. A conjugated polymer comprising at least one repeating unit represented by the following formula (1), wherein the total of the repeating units is 50 mol% or more of all repeating units. 2. The polymer light emitting device according to claim 1, wherein: Embedded image -Ar ₁ -CR ₁ = CR _2- (1) [wherein, Ar ₁ comprises 4 to 20 carbon atoms contained in a conjugated bond of the main chain. It is an arylene group or a heterocyclic compound group. R ₁ and R ₂ each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, 6 to 2
And a group selected from the group consisting of an aryl group having 0 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. ] 3. The polymer according to claim 1, wherein a hole transport layer and / or a hole injection layer are provided between the anode and the organic layer adjacent to the organic layer. Light emitting element. 4. The polymer light emitting device according to claim 1, wherein an electron transporting layer and / or an electron injecting layer are provided between the cathode and the organic layer adjacent to the organic layer. . 5. A method according to claim 1, wherein a hole transport layer and / or a hole injection layer are provided adjacent to the organic layer between the anode and the organic layer.
3. The polymer light emitting device according to claim 1, wherein an electron transporting layer and / or an electron injecting layer are provided between the cathode and the organic layer adjacent to the organic layer.