JPH10324870A - High-molecular phosphor and organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-molecular phosphor which is excellent in heat resistance since it has a specified number average mol.wt. and contains repeating units of which each comprises a mono- or polycyclic compd. group and a vinylene group bonded thereto and which account for a specified proportion of all the repeating units. SOLUTION: This phosphor contains, based on all the repeating units, 10-100 mol.% repeating units of the formula [wherein Ar1 is an arylene or heterocyclic compd. group which has 4-20 carbon atoms participating conjugated bonding and is selected from among a monocyclic compd. group (a) which has groups of formula II nuclearly bonded to carbon atoms at both sides next to at least one carbon atom bonded to the vinylene group, a polycyclic compd. group (b) which has groups of formula II nuclearly bonded to carbon atoms at both sides next to at least one carbon atom bonded to the vinylene group, and a polycyclic compd. group (c) in which one of carbon atoms at both sides next to at least one of carbon atoms bonded to the vinylene group is the condensation site and a group of formula II is bonded to the other carbon atom; Ar2 in formula II is a 1-20C hydrocarbon group, etc.; R1 and R2 are each H, 1-20C alkyl, etc.; R3 is a 1-20C hydrocarbon group; and X is O, S, etc.]. The phosphor has a number average mol.wt. of 10<3> -10<7> and, in the solid state, exhibits a visible fluorescence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer fluorescent material and an organic electroluminescent device (hereinafter, may be referred to as an organic EL device) formed using the polymer fluorescent material.

[0002]

2. Description of the Related Art Inorganic electroluminescent elements (hereinafter sometimes referred to as inorganic EL elements) using an inorganic phosphor as a light emitting material are used, for example, in a planar light source as a backlight or a display device such as a flat panel display. However, a high voltage alternating current was required to emit light. From the viewpoint of improving such an inorganic EL element,
A device 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. 59-19439)
No. 3) and an element using a polymer as a light emitting material (WO90)
No. 13148, JP-A-3-244630). Electroluminescent elements using these organic materials are characterized in that they can easily emit multicolor light in addition to low-voltage DC driving and high luminance, as compared with inorganic EL elements.

[0003] As a polymer light-emitting material that has been reported so far, WO 903148 discloses a polymer in which a soluble precursor is formed into a film on an electrode, and heat treatment is performed to convert the polymer into a conjugated polymer. An example of a p-phenylenevinylene thin film is disclosed in JP-A-3-244630, which discloses that poly-2,5-dialkoxy-p-phenylene has a feature that it is itself soluble in a solvent and does not require heat treatment. Conjugated polymers such as vinylene are exemplified. In addition, Japanese Patent Application Laid-Open No. 8-510483 discloses a highly soluble poly-p-type having a cholestanoxy group in a nucleus-substituted side chain.
A phenylene vinylene copolymer is exemplified.

[0004] In addition, attempts have been reported to reduce the emission wavelength of polythiophene by introducing a bulky substituent at the 3-position (Synthetic Metals (Synt.
Hetic Metals), vol. 71, p. 2121 (1
995)). In addition, as a polymer light emitting material, a polymer fluorescent substance containing a conjugated system and a non-conjugated system in a molecule and a poly-p-phenylenevinylene derivative in which a cyano group is introduced into a vinylene group have been reported [Nature (Nature)].
365, 628 (1993)]. As a polymeric fluorescent substance having a conjugated system and a non-conjugated system in a molecule, 2,5-
Random copolymer of dimethoxy-p-phenyleneethylene structure and p-phenylenevinylene [Nature (Nat
ure, Vol. 356, p. 47 (1992)] or a polymer in which a phenylene vinylene structure and an aliphatic hydrocarbon are linked by an ether bond [Macromocules (Macromo).
volumes 26, 1188 (1993)
Year)].

However, the organic E reported so far has
When the poly (arylene vinylene) -based polymer fluorescent substance used for the L element passes through a solvent-soluble intermediate, it is necessary to perform heat treatment, and there is a restriction that only a substrate having high heat resistance can be used. Was. In addition, in order to obtain a solvent-soluble polymer fluorescent substance, it is necessary to introduce a flexible repeating unit into the main chain or a flexible side chain having a high affinity for the solvent. There is a problem that the heat resistance of the device is lowered because the phosphor is easily softened.

Further, in order to obtain a polymeric fluorescent substance having a blue emission color, it is necessary to introduce a group having a non-conjugated bond such as an aliphatic hydrocarbon group into the main chain, which complicates the synthesis process. There was a problem. Attempts have been made to lengthen the wavelength by the electronic action of a nuclear substituent in a polymer in which aromatic compound groups are alternately bonded by vinylene groups, but a side chain with a specific structure is introduced at a specific position. As a result, there is no known compound capable of shortening the fluorescence wavelength, in particular, blue. As described above, a polyarylenevinylene-based blue light-emitting material that has high quantum efficiency of fluorescence and high luminous efficiency of an organic EL element, is thermally stable, and is easy to synthesize is demanded.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a solvent-soluble polymeric fluorescent substance having strong short-wavelength fluorescence, particularly strong blue fluorescence, and excellent heat resistance, and a coating method using the same. An object of the present invention is to provide an organic EL device having excellent characteristics which can be manufactured in a low temperature.

[0008]

In view of such circumstances, the present inventors have studied the luminous efficiency, heat resistance, and device life of an organic EL device using a polymeric fluorescent substance emitting blue light as a light emitting layer. As a result of diligent investigations to improve, the polymeric fluorescent substance having a specific structure side chain at a specific position in the molecular structural formula shows strong blue fluorescence, high quantum yield of fluorescence and high heat resistance. The present inventors have found that an organic EL device can be easily prepared by a coating method by using the polymer fluorescent substance, and that the organic EL device exhibits excellent characteristics.

That is, the present invention relates to [1] a polymer having visible fluorescence in a solid state and a number average molecular weight of 10
In the polymeric fluorescent substance is ³ to 10 ^7, the repeating unit represented by the following formula (1) wherein one or more, and the sum is 100 mol% or less than 10 mol% of all repeating units in their repeat unit It relates to a polymeric fluorescent substance.

Embedded image _{-Ar 1 -CR 1 = CR 2 -} ···· (1) [wherein, Ar ₁ represents an arylene group or a heterocyclic carbon atoms involved in conjugated bonds is composed of 20 or less 4 or more It is a ring compound group, and is a compound group represented by the following (a), (b) or (c). (A) a monocyclic compound in which at least one carbon atom adjacent to at least one carbon atom bonded to a vinylene group is nuclear-substituted with a substituent represented by the following formula (2). (B) a polycyclic compound group in which at least one carbon atom bonded to a vinylene group and both adjacent carbon atoms are substituted by a nucleus with a substituent represented by the following formula (2). (C) in the polycyclic compound group, one of the carbon atoms adjacent to at least one of the carbon atoms bonded to the vinylene group is a condensing position, and the other carbon atom has a substituent represented by the following formula (2): Nucleus substitution. R ₁ and R ₂ each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and 4 to 2 carbon atoms.
And a group selected from the group consisting of a heterocyclic compound group of 0 and a cyano group. ]

-(R ₃ ) _m- (X) _n -Ar ₂ (2) [where Ar ₂ is a hydrocarbon group having 1 to 20 carbon atoms, a carbon atom participating in a conjugate bond. And a group selected from the group consisting of an aryl group and a heterocyclic compound group having 4 to 20 carbon atoms, and an aliphatic cyclic hydrocarbon compound group having 6 to 20 carbon atoms constituting the ring. R ₃ is a hydrocarbon group having 1 to 20 carbon atoms. X represents -O-, -S-, -CO-, -CO-O
And a group selected from the group consisting of-and -O-CO-. m and n each independently represent an integer of 0 or 1. ]

Further, the present invention relates to [2] a compound having visible fluorescence in a solid state and having a number average molecular weight of 10 ^{3 in} terms of polystyrene.
In the polymeric fluorescent substance is 10 ^7, the repeating unit represented repeating units and repeating units represented by the following formula (3) represented by the above formula (1) each containing one or more, and in formula (1) Is 5 mol% of all repeating units
Not less than 95 mol%, and the total of the repeating unit represented by the formula (1) and the repeating unit represented by the formula (3) is 50 mol% to 100 mol% of all the repeating units; The present invention relates to a polymeric fluorescent substance in which the molar ratio of the total of the repeating units represented by the formula (1) to the total of the repeating units represented by the formula (3) is 20: 1 to 1:20.

-Ar ₃ -CR ₄ = CR _5- (3) [where Ar ₃ is an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms involved in a conjugate bond. Yes,
It is not the same as the Ar ₁ group shown in the above formula (1). R ₄ , R ₅
And each independently represents a group selected from the group consisting of hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. ]

The present invention further provides [3] an organic electroluminescent device having at least a light emitting layer between a pair of anodes and cathodes, at least one of which is transparent or translucent, wherein the light emitting layer is [1] Alternatively, the present invention relates to an organic electroluminescence device including the polymer fluorescent substance according to [2].

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polymeric fluorescent substance of the present invention has visible fluorescence in a solid state, and has a number average molecular weight of 10 ³ to 1 in terms of polystyrene.
0 In the polymeric fluorescent substance is a ^7, a repeating unit represented by the formula (1) wherein one or more, and the sum of their repeating units at least 10 mol% of all repeating units 1
It is characterized by being not more than 00 mol%. Although the polymer fluorescent substance of the present invention depends on the structure of the repeating unit, the formula (1)
The total of repeating units represented by is 30 of all repeating units.
More preferably, it is not less than 100 mol% and not more than 100 mol%.

Ar ₁ in the formula (1) is hydrogen or an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms participating in a conjugate bond, and at least one vinylene group has a bond. The substituents represented by the above formula (2) are provided as a nuclear substitution on the atoms adjacent to the above atom. That is, in the polymer chain composed of the repeating unit Ar ₁ and the vinylene group, there are Ar ₁ on both sides bonded to the vinylene group. Ar ₁ in the formula (1) has a substituent represented by the above formula (2) as a nucleus substitution on at least one of the atoms adjacent to the carbon atom of Ar ₁ . Alternatively, in the case of a polycyclic compound group, when one of the carbon atoms on both sides of at least one of the carbon atoms bonded to the vinylene group is a condensing position, it is not possible to attach a substituent to each of the carbon atoms on both sides. Therefore, the other carbon atom has a substituent represented by the above formula (2) as a nuclear substitution.

Specifically, examples of Ar ₁ include the following aromatic compound groups or derivative groups thereof, or repeating units formed by combining them.

Embedded image [Wherein R _{6 to} R ₆₁ each independently represent hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, and an alkylthio group; an aryl group and an aryloxy group having 6 to 18 carbon atoms; It is a group selected from the group consisting of 4 to 14 heterocyclic compound groups. However, the group adjacent to at least one carbon atom bonded to the vinylene group among these substituents is selected from the substituents represented by the formula (2). ]

Among these, 1,4-phenylene group,
2,6-naphthalenylene group, 4,4′-biphenyl group,
A 2,5-pyridinediyl group or a nuclear-substituted derivative thereof; a 1,3-phenylene group, a 1,3-naphthalenylene group, a 5,8-quinolinediyl group, or a derivative thereof is preferable. More preferably, a 1,4-phenylene group, a 2,5-pyridinediyl group, a 1,3-phenylene group, a 5,8-quinolinediyl group, or a derivative thereof is exemplified. One or more of these can be selected. R ₁ and R ₂ bonded to the vinylene group in the repeating unit of the formula (1) are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, 20 is a group selected from the group consisting of a heterocyclic compound group and a cyano group.

Specifically, examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group and a dodecyl group. And a methyl group,
Ethyl, pentyl, hexyl, heptyl and octyl groups are preferred. As the aryl group, a phenyl group,
4-C ₁ -C ₁₄ alkoxyphenyl group (C ₁ -C ₁₄ represents that it has 1-14 carbon atoms; the same applies to the following), 4-C ₁ -C ₁₄ alkylphenyl group, 1 -Naphthyl group, 2-naphthyl group and the like. Examples of the heterocyclic compound group include a 2-pyridyl group and a 2-quinolyl group.

Next, the substituent represented by the formula (2) will be described. R ₃ is a hydrocarbon group having 1 to 20 carbon atoms. Specifically, methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, decylene, dodecylene,
-Ethylhexylene group, 1,1-dimethylethylene group,
Phenylene group, naphthylene group and the like, methylene group, ethylene group, pentylene group, hexylene group, heptylene group, octylene group, 2-ethylhexylene group, 1,
A 1-dimethylethylene group and a phenylene group are preferred. m
Is an integer of 0 or 1.

X is -O-, -S-, -CO-, -CO
—O— or —O—CO—, preferably —O—
It is. n is an integer of 0 or 1;
It is.

Ar ₂ is a hydrocarbon group having 1 to 20 carbon atoms,
An aryl group and a heterocyclic compound group having 4 to 20 carbon atoms participating in a conjugate bond, and an aliphatic cyclic hydrocarbon compound group having 6 to 20 carbon atoms constituting a ring A group selected from the group consisting of: Specifically, the following aromatic compound groups or their derivative groups or aliphatic cyclic hydrocarbon compound groups are exemplified.

[0020]

Embedded image

Embedded image [Wherein R _{62 to} R ₁₄₁ each independently represent hydrogen, a cyano group, an alkyl group, an alkoxy group and an alkylthio group having 1 to 20 carbon atoms; an aryl group and an aryloxy group having 6 to 18 carbon atoms; It is a group selected from the group consisting of 4 to 14 heterocyclic compound groups. ]

Of these, phenyl, 1-naphthyl, 2-naphthyl, 9-anthryl, 4-biphenyl, pyrenyl, cyclohexyl, and their nuclear-substituted derivatives are preferred. More preferred are phenyl, 9-anthryl, 4-biphenyl and derivatives thereof. In the case of a phenyl group, the 2-position and 5
Those having a nuclear substituent at the 2-, 3-, or 2-, 3-, 5-, and 6-positions are preferred. One or more of these can be selected.

The second polymeric fluorescent substance of the present invention has visible fluorescence in a solid state, and has a polystyrene equivalent number average molecular weight of 10 ³ to 10 ^7. The repeating unit represented by the formula (1) and the repeating unit represented by the formula (3) each contain one or more kinds, and the total of the repeating units represented by the formula (1) is 5 mol% or more of all the repeating units. 95 mol% or less, and the total of the repeating unit represented by the formula (1) and the repeating unit represented by the formula (3) is 50 mol% or more and 100 mol% or less of all the repeating units; The molar ratio of the total of the repeating units represented by (1) to the total of the repeating units represented by the formula (3) is from 20: 1 to 1:20.

The total of the repeating units represented by the formula (1) is preferably from 30 mol% to 95 mol% of all the repeating units, although it depends on the structure of the repeating units.
The total of the repeating unit represented by the formula (1) and the repeating unit represented by the formula (3) is preferably from 70 mol% to 100 mol%, although it depends on the structure of the repeating unit. Further, the molar ratio of the total of the repeating units represented by the formula (1) to the total of the repeating units represented by the formula (3) is 9: 1 to 1: 1, depending on the structure of the repeating unit.
It is preferably 9 and more preferably 9: 1 to 1: 4. Ar _{3 in the} formula (3) is an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms participating in a conjugate bond. Specifically, the following aromatic compound groups or derivative groups thereof are exemplified.

[0024]

Embedded image

Embedded image

Embedded image [Wherein R _{142 to} R ₂₃₃ each independently represent hydrogen, a cyano group, an alkyl group, an alkoxy group, and an alkylthio group having 1 to 20 carbon atoms; an aryl group and an aryloxy group having 6 to 18 carbon atoms; It is a group selected from the group consisting of 4 to 14 heterocyclic compound groups. ]

Of these, 1,4-phenylene group,
2,6-naphthalenylene group, 9,10-anthrylene group, 2,5-pyridinediyl group, 2,5-thienylene group, or a nuclear-substituted derivative thereof, 1,3-phenylene group, 1,3-naphthalenylene group, A 2,6-pyridinediyl group, a 2,4-quinolinediyl group, or a derivative thereof is preferred. More preferably, a 1,4-phenylene group, a 2,5-pyridinediyl group, a 2,5-thienylene group, a 1,3-phenylene group, a 2,6-pyridinediyl group, a 2,4-quinolinediyl group, or a group thereof. Derivatives. One or more of these can be selected.

Further, R ₁ and R ₂ bonded to the vinylene group in the repeating unit of the formula (1) and R ₃ and R ₄ bonded to the vinylene group in the repeating unit of the formula (3) are each independently hydrogen. , An alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group.

Specifically, examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group and a dodecyl group. And a methyl group,
Ethyl, pentyl, hexyl, heptyl and octyl groups are preferred. As the aryl group, a phenyl group,
4-C ₁ ~C ₁₄ alkoxyphenyl group, 4- C ₁ ~C ₁₄
Examples thereof include an alkylphenyl group, a 1-naphthyl group, and a 2-naphthyl group. Examples of the heterocyclic compound group include a 2-pyridyl group and a 2-quinolyl group.

The terminal group of the polymer phosphor used in the present invention is
Although not particularly limited, if the polymerization active group remains as it is, there is a possibility that the light-emitting characteristics and lifetime of the device will be reduced, and therefore, it is preferable that the device is protected with a stable group. Those having a conjugated bond continuous with the conjugated structure of the main chain are more preferable, and examples thereof include a structure in which the conjugated structure is bonded to an aryl group or a heterocyclic compound group via a vinylene group. Specific examples include the following aromatic compound groups or derivative groups thereof, and groups in which these groups are bonded to a vinylene group.

[0029]

Embedded image

Embedded image

Embedded image

Embedded image (Wherein, R _{234 to} R ₃₉₈ each independently represent hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and an aryloxy group having 6 to 18 carbon atoms; It is a group selected from the group consisting of heterocyclic compound groups represented by Formulas 4 to 14.)

Of these, phenyl, 1-naphthyl, 9-anthryl, 2-pyridyl, 2-thienyl, oxadiazolyl, benzoxazolyl, 4
-(N, N-diphenylamino) phenyl group, 1-pyrenyl group, 2-fluorenyl group, 2-quinolyl group, 4-
(9-carbazolyl) phenyl group, 9-phenyl-3-
Carbazolyl groups or derivatives thereof are preferred. More preferably, 1-naphthyl group, 9-anthryl group,
An oxadiazolyl group, a 4- (N, N-diphenylamino) phenyl group, a 1-pyrenyl group, a 2-fluorenyl group, a 2-quinolyl group, a 4- (9-carbazolyl) phenyl group, a 9-phenyl-3-carbazolyl group or Derivatives thereof are mentioned, and particularly preferably, a 1-naphthyl group,
Examples thereof include a 9-anthryl group, a 1-pyrenyl group, and a 2-fluorenyl group.

The degree of polymerization of the polymeric fluorescent substance of the present invention is not particularly limited as long as the molecular weight is 10 ³ to 10 ⁷ in terms of polystyrene, and varies depending on the repeating structure and its ratio. In general, the total number of the repeating structures is preferably 4 to 10000, more preferably 5 to 3000, and particularly preferably 10 to 2000, from the viewpoint of film-forming properties. Here, the molecular weight is a number average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC) using chloroform as a solvent.

The polymer fluorescent substance of the present invention has the formula (1)
A polymer or copolymer consisting only of the repeating unit represented by the formula (1), a copolymer of the repeating units represented by the formulas (1) and (3), or a total of the repeating units represented by the formulas (1) and (3) Is 50% by mole or more of all repeating units, and in the case of a copolymer, it may be a random, block or graft copolymer, or a polymer having an intermediate structure between them. For example, a random copolymer having a block property may be used. From the viewpoint of obtaining a copolymer having a high quantum yield of fluorescence, a random copolymer or a block or graft copolymer having block properties is preferable to a complete random copolymer, and the main chain is branched and the terminal is terminated. The case where there are three or more is also included.

The polymer fluorescent substance of the present invention can be formed into a film by dissolving it in a solvent. Examples of good solvents for the polymeric fluorescent substance include chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, and xylene. Although it depends on the structure and molecular weight of the polymeric fluorescent substance,
Usually, 0.1 wt% or more can be dissolved in these solvents. When forming a film from a solution by using these organic solvent-soluble polymeric phosphors when preparing an organic EL device, it is only necessary to remove the solvent by drying after coating the solution, and to carry out charge transport described later. The same technique can be applied to the case where materials are mixed, which is very advantageous in manufacturing.

As a method for producing the polymeric fluorescent substance of the present invention, a polymer containing a repeating unit represented by the formula (1) or (3) is synthesized by a carbon-carbon double bond forming reaction. When the terminal group is converted to a specific stable group, it may be subsequently reacted with a monomer forming the terminal group. The reaction for forming a carbon-carbon double bond used in the present invention includes Wit
Examples include a tig reaction, a dehydrohalogenation method, a sulfonium salt decomposition method, and a Knoevenagel reaction.

In the Wittig reaction, for example, a dialdehyde compound represented by the formula (4) is reacted with a diphosphonium salt compound represented by the formula (5). Ar ₅ and Ar ₆ may be the same or different groups. When these are different, an alternating copolymer is obtained. Furthermore, when two or more kinds of dialdehyde compounds and / or two or more kinds of diphosphonium salt compounds are used, a copolymer of all of them can be obtained.

Embedded image OHC—Ar ₅ —CHO (4)

X ₁ (Ph) ₃ PH ₂ C—Ar ₆ —CH ₂ P (Ph) ₃ X ₁ (5) wherein Ar ₅ and Ar ₆ are each independently a group represented by the formula (1) ) selected from the groups represented by Ar ₁ or formula (3) Ar ₃ in in. However, it must be selected so that a predetermined amount of the group represented by Ar ₁ in the formula (1) is included after the polymerization. X
₁ is a counter ion such as a halide ion. Ph is a phenyl group. ]

In the dehydrohalogenation method, an aromatic compound having a methyl halide group bonded to both ends is polycondensed.

X ₂ R ₃₉₉ HC-Ar ₇ —CHR ₄₀₀ X ₂ (6) [where Ar ₇ is Ar ₁ in the formula (1) or the formula (3)
The group has the same meaning as the group represented by Ar ₃ in the formula (1), and must be selected so that a predetermined amount of the group represented by Ar ₁ in the formula (1) is contained after polymerization. X ₂ is a halogen atom;
₃₉₉ and R ₄₀₀ each independently represent hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 18 carbon atoms,
And a group selected from the group consisting of heterocyclic compound groups having 4 to 14 carbon atoms. ]

In the sulfonium salt decomposition method, an aromatic compound having a sulfonium salt bonded to both ends is polycondensed.

Embedded image ^{_{X 3 - R 401 R 402 S}} + R 403 HC-Ar 8 -CH
^{_{R 404 S + R 405 R 406}} -X 3 - ···· (7) [Ar ₈ is,
In group synonymous with a group represented by Ar ₁ in the formula (1), the group represented by Ar ₁ in the formula (1) after the polymerization should be chosen to include a predetermined amount. X ₃ is a halogen atom, and R ₄₀₃ and R ₄₀₄ each independently represent hydrogen, a cyano group,
A group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and an aryloxy group having 6 to 18 carbon atoms; and a heterocyclic compound group having 4 to 14 carbon atoms; R ₄₀₁ , R ₄₀₂ , R ₄₀₅
And R ₄₀₆ are each independently an alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 4 or more carbon atoms in which R ₄₀₁ and R ₄₀₂ and R ₄₀₅ and R ₄₀₆ each independently have a ring structure. ]

Further, in the Knoevenagel reaction, the Journal of Organic Chemistry (J.
Org. Chem. ) Vol. 25, p. 813 (1959)
Year), Macromolecular Chemie
l. Chem. The copolymer can be obtained by a method similar to that described in Vol. 74, p. 71 (1964).

That is, the dialdehyde compound represented by the formula (8) and the compound represented by the formula (9) are polycondensed.

OHC-Ar ₉ -CHO (8)

_{Embedded image} R ₄₀₇ H ₂ C—Ar ₁₀ —CH ₂ R ₄₀₈ (9) [Ar ₉ and Ar ₁₀ are each independently A in the formula (1)
In group synonymous with a group represented by r _1, A of formula (1) after the polymerization
It must be selected such that the group represented by r ₁ is contained in a predetermined amount. R ₄₀₇ and R ₄₀₈ each independently represent hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and an aryloxy group having 6 to 18 carbon atoms; Is a group selected from the group consisting of: ]

Specifically, a corresponding diacetonitrile compound, for example, m-phenylenediacetonitrile, and a corresponding dialdehyde compound, for example, 2,5-dioctyloxyterephthalaldehyde, are converted into ethyl alcohol /
Examples include polymerization using sodium methoxide in a chloroform mixed solvent. By reacting two or more diacetonitriles and / or two or more dialdehyde compounds, a copolymer of all of them can be obtained. Furthermore, Wittig reaction and Knoevenag
Since both of the el reactions can be performed using lithium ethoxide or the like, if a dialdehyde compound, a diphosphonium salt compound and a diacetonitrile compound are mixed and reacted in a considerable amount, all of these copolymers can be obtained. can get.

When a specific stable group is used as the terminal group, the terminal group may be subsequently reacted with a monofunctional compound forming the terminal group. The monofunctional compound is appropriately selected depending on the reaction to be used, or when two kinds of monomers having different functional groups are subjected to polycondensation, depending on the number of monomers used in the reaction. That is, Wi
Since the terminal is a phosphonium salt or an aldehyde in the tig reaction, an aldehyde group or a phosphonium salt is selected for each. In the dehydrohalogenation method, a methyl halide group is used, in the sulfonium salt decomposition method, a sulfonium base is used, and in the Knoevenagel reaction, an aldehyde group or an active methylene group, such as an acetonitrile group, is used. Let it. Among these, the method by the Wittig reaction is preferable in terms of control of the reaction and yield.

More specifically, a method for synthesizing an arylene vinylene copolymer, which is one example of the polymeric fluorescent substance of the present invention, will be described. As a case of obtaining an arylene vinylene copolymer by the Wittig reaction, specifically, first, a bis (methyl halide) compound, for example, 2,3,5,6
-Tetramethyl-p-xylylenedibromide is converted to N, N-
In a dimethylformamide solvent, a phosphonium salt is synthesized by reacting with triphenylphosphine, and a dialdehyde compound, for example, terephthalaldehyde, is condensed with lithium ethoxide in ethyl alcohol using a Wittig reaction to form an arylene vinylene-based compound. An example in which a copolymer is obtained is given. By reacting two or more diphosphonium salts and / or two or more dialdehyde compounds, a copolymer of all of them can be obtained.

Further, a methyl halide compound, for example, 9-chloromethylnaphthalene is reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt, and the previously obtained arylene having an aldehyde terminal is obtained. As in the case of the vinylene-based copolymer, an example in which a terminal-substituted copolymer is obtained by, for example, a Wittig reaction of condensing with lithium ethoxide in ethyl alcohol. Further, when these polymers are used as a light emitting material of an organic EL device, their purity affects the light emitting characteristics.
It is desirable to carry out purification treatment such as separation by chromatography.

Regarding the structure of an organic EL device produced using the polymeric fluorescent substance of the present invention, at least one of the light emitting layers provided between a pair of transparent or translucent electrodes has
There is no particular limitation as long as the light emitting material composed of the polymer fluorescent substance of the present invention is used, and a known structure is adopted. For example, a pair of electrodes are formed on both surfaces of a light emitting layer composed of the polymeric fluorescent substance, or a light emitting layer composed of a mixture of the polymeric fluorescent substance and a charge transporting material (which means a general term for an electron transporting material and a hole transporting material). And an electron transport layer containing an electron transport material between the cathode and the light emitting layer and / or a hole transport layer containing the hole transport material between the anode and the light emitting layer. You.

The present invention includes a single light emitting layer and a charge transporting layer, and a combination of a plurality of layers. Further, for example, a light emitting material other than the polymer fluorescent substance described below may be mixed and used in the light emitting layer. Further, a layer in which the polymeric fluorescent substance and / or the charge transporting material is dispersed in a polymeric compound may be used.

As the charge transporting material used with the polymeric fluorescent substance of the present invention, that is, an electron transporting material or a hole transporting material, known materials can be used, and without particular limitation, the pyrazoline derivative may be used as the hole transporting material. , An arylamine derivative, a stilbene derivative, a triphenyldiamine derivative, and the like. Examples of the electron transporting material include oxadiazole derivatives, anthraquinodimethane or its derivatives, benzoquinone or its derivatives, naphthoquinone or its derivatives, anthraquinone or its derivatives, Examples include 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, JP-A-2-135359
And JP-A-2-135361, JP-A-2-209988, JP-A-3-37992, and JP-A-3-152184. As a hole transport material,
As the triphenyldiamine derivative and the electron transporting material, an oxadiazole derivative, benzoquinone or a derivative thereof, anthraquinone or a derivative thereof, or a metal complex of 8-hydroxyquinoline or a derivative thereof is preferable. In particular, 4,4'-bis (N (3-methylphenyl) -N-phenylamino) biphenyl is used as the hole transport material, and 2- (4-biphenylyl) -5- (4-t is used as the electron transport material. -Butylphenyl) -1,3,4-
Oxadiazole, benzoquinone, anthraquinone, and tris (8-quinolinol) aluminum are preferred.

Of these, one or both of the electron transporting compound and the hole transporting compound may be used simultaneously. These may be used alone or as a mixture of two or more. In the case where a charge transport layer (which is a general term of a hole transport layer and an electron transport layer) is provided between the light emitting layer and the electrode, the charge transport layer may be formed using these charge transport materials.

When the charge transporting material is used in a mixture with the light emitting layer, the amount of the charge transporting material varies depending on the kind of the compound to be used. It may be determined appropriately in consideration of them. Usually, it is preferably from 1 to 40% by weight, more preferably from 2 to 30% by weight, based on the luminescent material.

Known light-emitting materials that can be used together with the polymeric fluorescent substance of the present invention are not particularly limited. Examples thereof include naphthalene derivatives, anthracene or its derivatives, perylene or its derivatives, polymethine-based, xanthene-based, coumarin-based, and cyanine-based And a metal complex of 8-hydroxyquinoline or a derivative thereof, an aromatic amine, tetraphenylcyclopentadiene or a derivative thereof, or tetraphenylbutadiene or a derivative thereof. Specifically, known materials such as those described in JP-A-57-51781 and JP-A-59-194393 can be used.

Next, a typical method for producing an organic EL device using the polymer fluorescent substance of the present invention will be described. As a pair of electrodes composed of an anode and a cathode, a transparent or translucent electrode formed by forming a transparent or translucent electrode on a transparent substrate such as glass or transparent plastic is used. As the material of the anode, a conductive metal oxide film, a translucent metal thin film, or the like is used. Specifically, indium
A film (such as NESA) made using conductive glass made of tin oxide (ITO), tin oxide, etc., A
u, Pt, Ag, Cu and the like are used. As a manufacturing method, a vacuum evaporation method, a sputtering method, a plating method, or the like is used.

Next, the above-mentioned polymer or a light-emitting layer containing the polymer and a charge transporting material is formed on the anode as a light-emitting material. As a forming method, a melt of these materials,
Coating methods such as spin coating, casting, dipping, bar coating, roll coating, gravure coating, flexographic printing, and spray coating using a solution or a mixed solution are exemplified. It is particularly preferable to form the solution or mixed solution by a coating method such as a spin coating method, a casting method, a dipping method, a bar coating method, a roll coating method, a gravure coating method, a flexographic printing method, and a spray coating method.

The thickness of the light emitting layer is preferably 1 nm.
１1 μm, more preferably 2 nm to 500 nm. In order to increase the current density and the luminous efficiency, it is necessary to use 5-2
A range of 00 nm is preferred. When the film is formed into a thin film by a coating method, it is preferable to heat and dry at a temperature of 30 to 300 ° C., more preferably 60 to 200 ° C., under reduced pressure or an inert atmosphere, in order to remove the solvent. In the case where the light-emitting layer and the charge transport layer are stacked, a hole-transport layer is formed on the anode before the light-emitting layer is formed by the above film forming method, and / or after the light-emitting layer is provided. It is preferable to form an electron transport layer thereon.

The method for forming the charge transport layer is not particularly limited, but is a vacuum deposition method from a powder state, or a spin coating method, a dipping method, a bar coating method, a bar coating method, a roll coating method after dissolving in a solution. Or a coating method such as spin coating, casting, dipping, bar coating, roll coating, etc. after mixing and dispersing a polymer compound and a charge transport material in a solution state or a molten state. Can be used. The polymer compound to be mixed is not particularly limited, but those which do not extremely inhibit charge transport are preferable, and those which do not strongly absorb visible light are suitably used. As long as it is a charge transporting polymer compound, it can be used for the charge transporting layer without being mixed with a low molecular weight charge transporting material.

As the polymer compound, for example, poly (N
-Vinylcarbazole), polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly (p-
Phenylene vinylene) or a derivative thereof, poly (2,
5-thienylenevinylene) or a derivative thereof, polycarbonate, polyacrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, or polysiloxane. It is preferable to use a coating method in that the film can be easily formed.

The thickness of the charge transport layer is required to be at least such that pinholes do not occur. However, if the thickness is too large, the resistance of the device increases and a high drive voltage is required, which is not preferable. Therefore, the thickness of the charge transport layer is preferably 1 nm to 1 μm, more preferably 2n.
m to 500 nm, particularly preferably 5 nm to 200 nm.

Next, an electrode is provided on the light emitting layer or the electron transport layer. This electrode becomes an electron injection cathode. The material is not particularly limited, but a material having a small ionization energy is preferable. For example, Al, In, Mg, C
a, Li, Mg-Ag alloy, In-Ag alloy, Mg-I
n alloy, Mg-Al alloy, Mg-Li alloy, Al-Li
An alloy, an Al-Ca alloy, a graphite thin film or the like is used. As a method for manufacturing the cathode, a vacuum evaporation method, a sputtering method, or the like is used.

[0058]

In the present invention, the polymeric fluorescent substance is excellent as a luminescent material because it has a nuclear substituent at a specific position.
It is considered that strong fluorescence, especially strong blue fluorescence is obtained because of having a side chain having a specific structure. Further, since a light-emitting layer having excellent uniformity can be easily formed by a coating method, an organic EL device having high luminous efficiency, high heat resistance, and long life can be manufactured very easily.

[0059]

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. Here, regarding the number average molecular weight, the number average molecular weight in terms of polystyrene was determined by gel permeation chromatography (GPC) using chloroform as a solvent.

Example 1 <Synthesis of polymeric fluorescent substance 1> 2,3,5,6-tetramethyl-p-xylylenedibromide was reacted with triphenylphosphine in a N, N-dimethylformamide solvent to form a phosphonium salt. Was synthesized. 4,22 parts by weight of the obtained phosphonium salt, 0.335 parts by weight of terephthalaldehyde, and 0,335 parts by weight of isophthalaldehyde were dissolved in an ethanol solvent. An ethyl alcohol solution containing 0.81 part by weight of sodium methoxide was added dropwise to an ethanol solution of the phosphonium salt and dialdehyde, followed by a reaction at room temperature for 4 hours.

After standing at room temperature overnight, the formed precipitate was recovered. Next, the precipitate was washed with ethanol, subsequently with an ethanol-water mixed solvent, and further washed with ethanol. This was dried under reduced pressure to obtain 0.7 parts by weight of a polymer. The obtained polymer is called polymer fluorescent substance 1. The repeating units of the polymeric fluorescent substance 1 are represented by the following (10), (11), (1)
See 2). Depending on the charge ratio of the monomers and the type of polymerization reaction, those in which the following (10) and (11) and (10) and (12) are alternately bonded are copolymerized at random.

[0062]

Embedded image

Embedded image

Embedded image The polystyrene-equivalent number average molecular weight of the polymeric fluorescent substance 1 was 1.5 × 10 ³ . The structure of the polymeric fluorescent substance 1 was confirmed by ¹ H-NMR and IR spectrum.

Example 2 <Synthesis of polymeric fluorescent substance 2> 2,3,5,6-tetramethyl-p-xylylenedibromide was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to form a phosphonium salt. Was synthesized. 4.22 parts by weight of the obtained phosphonium salt, 5.66 parts by weight of 4,4′-diphenylpropyloxy-3,3′-biphenylenebis (methylenetriphenylphosphonium bromide) and 1.34 parts by weight of terephthalaldehyde It was dissolved in a toluene-ethanol mixed solvent. An ethyl alcohol solution containing 1.62 parts by weight of sodium methoxide was dropped into a toluene-ethanol solution of the phosphonium salt and dialdehyde, and the mixture was reacted at room temperature for 4 hours.

After standing at room temperature overnight, the formed precipitate was recovered. Next, the precipitate was washed with ethanol, subsequently with an ethanol-water mixed solvent, and further washed with ethanol. This precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. This was dried under reduced pressure to obtain 1.0 part by weight of a polymer. The obtained polymer was used as polymer fluorescent substance 2
Call. The repeating unit of the polymeric fluorescent substance 2 is represented by the following (1)
3), (14) and (15). Based on the monomer charging ratio and the type of polymerization reaction, the following (13) and (14),
Those obtained by alternately bonding (13) and (15) are copolymerized at random.

[0065]

Embedded image

Embedded image

Embedded image The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 2 was 2.0 × 10 ³ . The structure of the polymeric fluorescent substance 2 was confirmed by ¹ H-NMR and IR spectrum.

Comparative Example 1 <Synthesis of polymeric fluorescent substance 3> 2,3,5,6-tetramethyl-p-xylylenedibromide was obtained by reaction with triphenylphosphine in an N, N-dimethylformamide solvent. Instead of the phosphonium salt 4.7, the phosphonium salt of 2,5-dioctyloxy-p-xylylene dichloride
Except using 8 parts by weight, polymerization was carried out in the same manner as in Example 1,
Purification and drying were performed to obtain 1.0 part by weight of a polymer. The obtained polymer is called polymer fluorescent substance 3. The repeating units of the polymeric fluorescent substance 3 are shown in (16) and (17) below. Depending on the charging ratio of the monomers and the type of polymerization reaction, the following (16) and (17) are alternately bonded to form an alternating copolymer.

Embedded image

Embedded image The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 7 was 9.0 × 10 ³ . The structure of the polymeric fluorescent substance 3 was confirmed by ¹ H-NMR and IR spectrum.

Example 3 <Measurement of Absorption Spectrum and Fluorescence Spectrum> The polymeric fluorescent substances 1 to 3 could be easily dissolved in chloroform. The 0.4% chloroform solution was spin-coated on a quartz plate to form a polymer thin film. The ultraviolet-visible absorption spectrum and the fluorescence spectrum of this thin film were measured using a self-recording spectrophotometer UV365 manufactured by Shimadzu Corporation and a fluorescence spectrophotometer 850 manufactured by Hitachi, Ltd., respectively. The fluorescent peak wavelengths of polymeric fluorescent substances 1 and 2 were 476 nm and 496 nm, which were shorter than 532 nm of polymeric fluorescent substance 3.

Example 4 <Evaluation of Heat Resistance by Differential Scanning Calorimetry (DSC)> Thermal analysis of polymeric fluorescent substances 1 to 3 was performed using a differential scanning calorimeter DSC200 manufactured by Seiko Denshi. In each case, an endothermic peak which seems to correspond to the softening of the polymer was observed. Polymeric fluorescent substances 1 and 2 had an endothermic peak at 157 ° C. and 75 ° C., respectively, at a temperature higher than 2.6 ° C. of polymeric fluorescent substance 3.

Example 5 <Preparation and evaluation of device>
Using a chloroform solution of polymeric fluorescent substance 1 obtained in Example 1 on a glass substrate having an ITO film with a thickness of 0 nm,
A film having a thickness of 100 nm is formed by dipping. A 100 nm aluminum layer is vapor-deposited thereon at a degree of vacuum of 8 × 10 ⁻⁶ Torr or less to form a cathode, thereby manufacturing an organic EL device. When a voltage of about 10 V is applied to this element, EL light emission having the same spectrum as the fluorescence of the polymer fluorescent substance 1 is observed. Polymer fluorescent substance 2 obtained in Example 2 in the same manner
When EL is used, EL light emission from the polymeric fluorescent substance 2 is observed.

[0070]

The polymer phosphor of the present invention has short wavelength fluorescence, especially blue fluorescence, and thermal stability, and is excellent as a material for an organic EL device. Further, an organic EL device using the polymer fluorescent substance is easy to make,
Further, since it shows excellent light-emitting characteristics and heat resistance, it can be preferably used as a planar light source as a backlight, a device such as a flat panel display, or the like.

Claims (6)

[Claims] 1. A polymeric fluorescent substance which has visible fluorescence in a solid state and has a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁷ , wherein the repeating unit represented by the following formula (1) is 1
A polymeric fluorescent substance comprising at least one kind, and the total of the repeating units is 10 mol% or more and 100 mol% or less of all repeating units. Embedded image -Ar ₁ -CR ₁ = CR _2- (1) wherein Ar ₁ is an arylene group or a complex having 4 to 20 carbon atoms involved in a conjugated bond. It is a ring compound group, and is a compound group represented by the following (a), (b) or (c). (A) a monocyclic compound in which at least one carbon atom adjacent to at least one carbon atom bonded to a vinylene group is nuclear-substituted with a substituent represented by the following formula (2). (B) a polycyclic compound group in which at least one carbon atom bonded to a vinylene group and both adjacent carbon atoms are substituted by a nucleus with a substituent represented by the following formula (2). (C) in the polycyclic compound group, one of the carbon atoms adjacent to at least one of the carbon atoms bonded to the vinylene group is a condensing position, and the other carbon atom has a substituent represented by the following formula (2): Nucleus substitution. R ₁ and R ₂ each independently represent hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and 4 to 2 carbon atoms.
And a group selected from the group consisting of a heterocyclic compound group of 0 and a cyano group. -(R ₃ ) _m- (X) _n -Ar ₂ (2) wherein Ar ₂ is a hydrocarbon group having 1 to 20 carbon atoms, And a group selected from the group consisting of an aryl group and a heterocyclic compound group having 4 to 20 atoms, and an aliphatic cyclic hydrocarbon compound group having 6 to 20 carbon atoms constituting a ring. R ₃ is a hydrocarbon group having 1 to 20 carbon atoms. X represents -O-, -S-, -CO-, -CO-
It represents a group selected from the group consisting of O- and -O-CO-. m and n each independently represent an integer of 0 or 1. ] 2. A polymeric fluorescent substance which has visible fluorescence in a solid state and has a number average molecular weight in terms of polystyrene of 10 ³ to 10 ⁷ , wherein the repeating unit represented by the above formula (1) and the following formula (3) ), The total of the repeating units represented by the formula (1) is 5 mol% to 95 mol% of all the repeating units, and the repeating unit represented by the formula (1) The total of the repeating unit represented by the formula (3) is at least 50 mol% and not more than 100 mol% of all the repeating units, and the total of the repeating unit represented by the formula (1) is represented by the formula (3) ) Is 20: 1 to 1:
20. A polymeric fluorescent substance, which is 20. ## STR3 ## _{-Ar 3 -CR 4 = CR 5 -} ···· (3) [wherein, Ar ₃ has a number of carbon atoms involved in a conjugated bond an arylene group or a heterocyclic compound group having 4 to 20 Yes,
It is not the same as the Ar ₁ group shown in the above formula (1). R ₄ , R ₅
And each independently represents a group selected from the group consisting of hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. ] 3. An organic electroluminescent device having at least a light emitting layer between a pair of anodes and cathodes, at least one of which is transparent or translucent, wherein the light emitting layer is a polymer fluorescent material according to claim 1 or 2. An organic electroluminescent device comprising a body. 4. The organic electroluminescent device according to claim 3, wherein a layer made of an electron transporting compound is provided between the cathode and the light emitting layer, adjacent to the light emitting layer. 5. The organic electroluminescent device according to claim 3, wherein a layer made of a hole transporting compound is provided between the anode and the light emitting layer, adjacent to the light emitting layer. 6. A layer comprising an electron transporting compound between the cathode and the light emitting layer, adjacent to the light emitting layer, and a hole transporting layer between the anode and the light emitting layer, adjacent to the light emitting layer. The organic electroluminescent device according to claim 3, wherein a layer made of a compound is provided.