Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2001-03-30
2004-02-24
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S917000, C349S069000, C252S301350, C313S506000
Reexamination Certificate
active
06696180
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to a polymeric fluorescent substance, a method for producing the same, a polymer light-emitting device (hereinafter, sometimes referred to as polymer LED) using the same.
Inorganic electroluminescence devices (hereinafter, sometimes referred to as inorganic EL device) using an inorganic luminescent material as a light emitting material are used for example for flat light sources as back-lights and displays such as a flat panel display and the like, however, an alternating current of high voltage has been required for light emission.
Recently, Tang et al. fabricated an organic electroluminescence device (hereinafter, sometimes referred to as organic EL device) having a double-layer structure in which an organic fluorescent dye as a light emitting layer is laminated with an organic charge transport compound used in photosensitive layer for electrophotography and the like (Japanese Patent Application Laid-Open (JP-A) No. 59-194393). Since organic EL devices have characteristics that light emissions of a lot of colors are obtained easily in addition to low voltage driving and high luminance as compared with inorganic EL devices, there have been reported a lot of trials regarding device structures, organic fluorescent dyes and organic charge transport compounds of organic EL devices [Jpn. J. Appl. Phys., 27, L269 (1988), J. Appl. Phys., 65, 3610 (1989)].
Further, apart from organic EL devices using mainly organic compounds having a lower molecular weight, polymer light emitting devices (hereinafter, sometimes referred to as polymer LEDs) using light emitting materials having a higher molecular weight have been proposed in such as WO 9013148 published specification, JP-A No. 3-244630, Appl. Phys. Lett., 58, 1982 (1991). WO9013148 discloses in the Examples an EL device using a thin film of poly(p-phenylene vinylene) obtained by forming a film of a soluble precursor on the electrode and subjecting it to a heat treatment to convert the precursor into a conjugated polymer.
Further, JP-A 3-244630 has exemplified a conjugated polymers having a feature that they are themselves soluble in a solvent and needs no heat treatment. Also in Appl. Phys. Lett., 58, 1982 (1991), a polymeric light emitting materials soluble in a solvent and a polymer LED fabricated using the same are described.
As the polymeric fluorescent substance used in these polymer LEDs, polyfluorenes (Japanese Journal of Applied Physics, 30, L1941 (1991)), poly(p-phenylene) derivatives (Advanced Materials, 4, 36 (1992)) and the like are also disclosed, in addition to the above-mentioned poly(p-phenylene vinylene).
(0005)
As described above, in a polymer LED, a light-emitting layer can be easily formed by application using a polymeric fluorescent substance soluble in a solvent, therefore, the LED has a feature that it is advantageous for large area and low cost as compared with vapor deposition of a fluorescent substance having lower molecular weight. For utilizing this feature, there are requirements for a polymeric fluorescent substance further having excellent light-emitting efficiency when used in a light-emitting layer of a polymer LED, while maintaining excellent solubility and film-forming ability, a method for producing the same, and a polymer LED having high light-emitting efficiency using the same.
The object of the present invention is to provide a polymeric fluorescent substance further having excellent light-emitting efficiency when used in a light-emitting layer of a polymer LED, while maintaining excellent solubility and film-forming ability, a method for producing the polymeric fluorescent substance, and a polymer LED having high light-emitting efficiency using the polymeric fluorescent substance.
SUMMARY OF THE INVENTION
The present inventors have intensively investigated in view of such circumstances, and resultantly found that a polymeric fluorescent substance containing specific repeating units at a specific ratio in the main chain and having a branching polymeric chain satisfies also excellent film-forming ability simultaneously without losing solubility in a solvent, that this polymeric fluorescent substance can be produced by reacting specific compounds at a specific ratio, and that a polymer LED having high light-emitting efficiency can be obtained by using this polymeric fluorescent substance, leading to completion of the present invention.
Namely, the present invention related to:
[1] A polymeric fluorescent substance which emits fluorescence in solid state, has a polystyrene-reduced number-average molecular weight of 10
3
to 10
8
and contains one or more repeating units represented by the following formula (1) in main chain, wherein 0.05 to 10 mol % repeating units of all repeating units contained in the polymeric fluorescent substance have branching polymeric chains:
In the formula, Ar
1
is a group selected from the group consisting of an arylene group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms and a group containing a metal complex having, as a ligand, one or more organic compounds containing 4 to 60 carbon atoms; Ar
1
may have one or more substituents; each of R
1
and R
2
independently represents a group selected from the group consisting of a hydrogen atom, alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 60 carbon atoms, heterocyclic compound groups having 4 to 60 carbon atoms and a cyano group; and n is 0 or 1.
[2] The polymeric fluorescent substance according to [1], wherein the substances contains each one or more of repeating units represented by the formula (1) and the following formula (2) in main chain, and the total amount of these repeating units is 50 mol % or more based on the amount of all repeating units, the amount of repeating units of the formula (2) is 0.1 to 10 mol % based on the total amount of repeating units of the formulae (1) and (2), and the substance has a polymeric chain which is branched at a repeating unit of the formula (2) as a branching point:
In the formula, Ar
2
is an arylene group having 6 to 60 carbon atoms or a heterocyclic compound group having 4 to 60 carbon atoms; X
1
is a group of the following formula (3), and constitutes apart of the main chain; the symbol “1” is an integer of 1 to 4. Ar
2
may further have one or more substituents; when Ar
2
has a plurality of substituents, they may be the same or different; each of R
3
and R
4
independently represents a group selected from the group consisting of a hydrogen atom, alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 60 carbon atoms, heterocyclic compound groups having 4 to 60 carbon atoms and a cyano group; and m is 0 or 1:
In the formula, Ar
3
is an arylene group having 6 to 60 carbon atoms or a heterocyclic compound group having 4 to 60 carbon atoms; Ar
3
may have one or more substituents; each of R
5
, R
6
, R
7
and R
8
independently represents a group selected from the group consisting of a hydrogen atom, alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 60 carbon atoms, heterocyclic compound groups having 4 to 60 carbon atoms and a cyano group; and each of j and k is independently 0 or 1.
[3] The polymeric fluorescent substance according to [1], wherein the substance contains each one or more of repeating units of said formula (1) and the following formula (4) in main chain, and the total amount of these repeating units is 50 mol % or more based on the amount of all repeating units, the amount of repeating units of the formula (4) is 0.1 to 10 mol % based on the total amount of repeating units of the formulae (1) and (4), and the substance has a polymeric chain which is branched at a repeating unit of the formula (4) as a branching point.
In the formula, Ar
4
and Ar
5
are an arylene group having 6 to 60 carbon atoms or a heterocyclic compound group having 4 to 60 carbon atoms; Ar
4
and Ar
5
may have one or more substituents. R
9
represents a group s
Doi Shuji
Tsubata Yoshiaki
Garrett Dawn
Kelly Cynthia H.
Sumitomo Chemical Company Limited
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