Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1999-06-08
2002-06-11
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S704000, C428S917000, C313S504000, C313S506000, C257S040000, C257S103000, C252S301160, C528S244000, C528S232000, C528S316000, C528S398000
Reexamination Certificate
active
06403237
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polymeric fluorescent substance and an organic electroluminescence device (hereinafter, sometimes referred to as an organic EL device) fabricated by using the polymeric fluorescent substance.
2. Description of the Related Art
An inorganic electroluminescence device (hereinafter, sometimes referred to as an inorganic EL device) obtained by using as a luminescent material an inorganic fluorescent substance has been used for a flat light source as back light, a display apparatuses, such as a flat panel display and the like, however, this device requires high-voltage alternating current for driving the device.
From the standpoint of improvement in such an inorganic EL device, there have been reported a device having two-layer structure comprising a laminate of a light emitting layer composed of an organic fluorescent dye and a layer of an organic charge transporting,compound (Japanese Patent Application Laid-Open (JP-A) No. 59-194393) and a device using a polymeric fluorescent substance as a luminescent material (WO 9013148, JP-A-3-244630). These electroluminescence devices using organic materials have feature that they can provide multi-color luminescence easily in addition to low voltage direct current activation and high luminance as compared with inorganic EL devices.
As polymeric fluorescent substance heretofore reported, WO 9013148 exemplifies a poly-p-phenylenevinylene film obtained by forming a film of a soluble precursor on an electrode and conducting heat treatment, and JP-A-3-244630 exemplifies conjugated polymers such as poly-2,5-dialkoxy-p-phenylenevinylene and the like which are themselves soluble in a solvent and required no heat treatment. WO 9610617 exemplifies as a conjugated polymer having a condensed polycyclic aromatic group in the main chain, a polyarylenevinylene-based polymeric fluorescent substance having a 2,7-pyrenediyl group in the main chain.
As polymeric fluorescent substances showing luminescent color having a long wave length from orange to red, there have been heretofore reported a polythiophene-based polymeric fluorescent substance (J. J. Appl. Phys., 30, L1938, (1991)) and a poly(arylenevinylene)-based polymeric fluorescent substance in which an electron withdrawing cyano group has been introduced into a vinylene group (WO 9429883), however, there has been reported no polymeric fluorescent substance containing a condensed polycyclic aromatic ring having a bonding part at specific position in the main chain of a poly(arylenevinylene)-based polymeric fluorescent substance and revealing luminescent color having a long wave length from orange to red.
The poly(arylenevinylene)-based polymeric fluorescent substances used in organic EL devices heretofore reported have had restriction that when they are obtained via intermediates soluble in solvents, heat treatment is necessary and only substrates having high heat-resistance can be used. Further, there has been a problem that, for obtaining a polymeric fluorescent substance soluble in a solvent, introduction of a flexible repeating unit into the main chain or introduction of a flexible side chain having high affinity with a solvent is required and heat-resistance of the device decreases when temperature is raised since then the polymeric fluorescent substance is easily softened.
An object of the present invention is to provide a polymeric fluorescent substance which shows fluorescence at a long wave length from orange to red, has excellent heat-resistance and is soluble in a solvent, and an organic EL device having excellent properties which can be easily fabricated by a coating method using the same.
The present inventors, in view of such conditions, have intensively studied to improve heat-resistance and luminescent property of an organic EL device using as a light emitting layer a polymeric fluorescent substance showing luminescent color from orange to red. As a result, the present inventors have found that a polymeric fluorescent substance having a divalent condensed polycyclic aromatic group of specific size having a bonding part at specific position shows fluorescence at a long wave length from orange to red and has high heat-resistance, and an organic EL device can be easily fabricated by a coating method using the above-described polymeric fluorescent substance and, further, this organic EL device exhibits excellent property, and completed the present invention.
SUMMARY OF THE INVENTION
Namely, the present invention relates to (1) a polymeric fluorescent substance showing visible fluorescence in solid state and having a polystyrene-reduced number-average molecular weight of 10
3
to 10
7
, wherein the polymeric fluorescent substance comprises one or more repeating units represented by the following formula (1) and the amount of these repeating units is from 0.5% by mole to 100% by mole based on the total amount of repeating units:
—Ar
1
—CR
1
═CR
2
— (1)
(wherein,
Ar
1
represents a condensed polycyclic aromatic group which may be substituted with a substituent selected from the group consisting of a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and alkylthio group having 1 to 20 carbon atoms, an alkylsilyl group having 3 to 60 carbon atoms, an alkylamino group having 1 to 40 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an arylalkenyl group having 8 to 20 carbon atoms, an arylalkynyl group having 8 to 20 carbon atoms, an aralkyl group having 7 to 14 carbon atoms and a heterocyclic compound group having 4 to 14 carbon atoms, and which satisfies the following condition (a) to (c):
(a) the condensed polycyclic aromatic group has two bonding parts which are not adjacent each other, and the number of carbon atoms forming conjugated bonds excepting carbon atoms of said substituent is from 16 to 30;
(b) a condensed polycyclic aromatic compound obtained by substituting all substituent on Ar
1
by hydrogen atoms and by allowing the two bonding parts to be bonded to hydrogen atoms has a plane of symmetry or a twofold axis or threefold axis vertical to the plane including the condensed polycyclic aromatic compound and contains only 6-membered-ring structures;
(c) two carbon atoms selected according to the following method have a bonding part:
any one of the highest occupied molecular orbitals of the condensed polycyclic aromatic compound of (b) determined by a semi-empirical molecular orbital method, AM1 method is selected, the sum of squares of atomic orbital coefficients of only carbon atoms to which a hydrogen atom is bonded among carbon atoms in the condensed polycyclic aromatic compound of (b), and two carbon atoms are selected from the group consisting of carbon atoms having the largest and second-largest sum value as the carbon atoms having a bonding part; and
R
1
and R
2
each independently represents a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound having 4 to 20 carbon atoms and a cyano group.).
Further, the present invention relates to (2) a polymeric fluorescent substance showing visible fluorescence in solid state and having a polystyrene-reduced number-average molecular weight of 10
3
to 10
7
, wherein the polymeric fluorescent substance comprises one or more repeating units represented by said formula (1) and one or more repeating units represented by the following formula (2), the sum of the repeating units represented by the formula (1) is from 0.5% by mole to 95% by mole based on the total amount of repeating units, the sum of the repeating units represented by the formula (1) and the repeating units represented by the formula (2) is from 50% by mole to 100% by mole based on the total amount of repeating units, and the molar ratio of the sum of the repeating units represented by the formula (1) to the sum of the repeating units represented by the formula (2) is from 20:1 to 1:1
Ishitobi Masamitsu
Kitano Makoto
Noguchi Takanobu
Kelly Cynthia H.
Sumitomo Chemical Co,. Ltd.
Xu Ling
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