U.S. patent application number 09/986551 was filed with the patent office on 2002-05-16 for polymeric fluorescent substance and polymer light-emitting device using the same.
This patent application is currently assigned to SUMITOMO CHEMICAL COMPANY, LIMITED. Invention is credited to Doi, Shuji, Tsubata, Yoshiaki, Ueoka, Takahiro.
Application Number | 20020058157 09/986551 |
Document ID | / |
Family ID | 26603740 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020058157 |
Kind Code |
A1 |
Doi, Shuji ; et al. |
May 16, 2002 |
Polymeric fluorescent substance and polymer light-emitting device
using the same
Abstract
A polymeric fluorescent substance exhibiting fluorescence in
solid state and having a polystyrene-reduced number-average
molecular weight of 10.sup.3 to 10.sup.8 wherein the polymeric
fluorescent substance contains one or more of segments represented
by the following formula (1) and one or more of repeating units
represented by the following formula (2): 1 The polymeric
fluorescent substance exhibits particularly strong fluorescence,
and a high performance polymer LED which can be driven at low
voltage and high efficiency is obtained.
Inventors: |
Doi, Shuji; (Tsukuba-shi,
JP) ; Tsubata, Yoshiaki; (Tsukuba-shi, JP) ;
Ueoka, Takahiro; (Tsukuba-shi, JP) |
Correspondence
Address: |
SUGHRUE, MION, PLLC
2100 Pennsylvania Avenue, NW
Washington
DC
20037-3213
US
|
Assignee: |
SUMITOMO CHEMICAL COMPANY,
LIMITED
|
Family ID: |
26603740 |
Appl. No.: |
09/986551 |
Filed: |
November 9, 2001 |
Current U.S.
Class: |
428/690 ;
428/917; 525/242; 525/289 |
Current CPC
Class: |
C09K 11/06 20130101 |
Class at
Publication: |
428/690 ;
428/917; 525/242; 525/289 |
International
Class: |
B32B 009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2000 |
JP |
2000-343301 |
Apr 26, 2001 |
JP |
2001-129289 |
Claims
1. A polymeric fluorescent substance manifesting fluorescence in
solid state and having a polystyrene-reduced number-average
molecular weight of 10.sup.3 to 10.sup.8 wherein the polymeric
fluorescent substance contains one or more of segments represented
by the following formula (1) and one or more of repeating units
represented by the following formula (2): 22in the formula,
Ar.sub.1 and Ar.sub.2 each independently represent an arylene group
or a divalent heterocyclic compound group; R.sub.2 and R.sub.3 each
independently represent a group selected from the group consisting
of a hydrogen atom, alkyl groups, aryl groups, heterocyclic
compound groups and cyano group; R.sub.1 and R.sub.4 each
independently represent a group selected from the group consisting
of alkyl groups, alkoxy groups, alkylthio groups, alkylsilyl
groups, alkylamino groups, aryl groups, aryloxy groups, arylsilyl
groups, arylamino groups, arylalkyl groups, arylalkoxy groups,
arylalkylsilyl groups, arylalkylamino groups, arylalkenyl groups,
arylalkinyl groups, monovalent heterocyclic compound groups and
cyano group; a and c each independently represent an integer of 0
to 4, and b represents an integer of 1 or more; when b is 1, a and
c do not represent 0 simultaneously; when b is 2, at least one of
groups R.sub.2 and R.sub.3 represents a group other than a hydrogen
atom and cyano group; when b is 3 or more, a and c do not represent
0 simultaneously if both of R.sub.2 and R.sub.3 are a hydrogen
atom; when a is 2 or more, a plurality of R.sub.1s may be the same
or different; when c is 2 or more, a plurality of R.sub.4s may be
the same or different; R.sub.1 to R.sub.4 may be connected to form
a ring; and when R.sub.1 to R.sub.4 are a group containing an alkyl
chain, one or more of a methyl group, methylene group and methine
group constituting this alkyl chain may be substituted with a group
containing a hetero atom, 23in the formula, R.sub.5 and R.sub.6
each independently represent a group selected from the group
consisting of a hydrogen atom, alkyl groups, aryl groups and
monovalent heterocyclic compound groups; R.sub.7 and R.sub.8 each
independently represent a group selected from the group consisting
of alkyl groups, alkoxy groups, alkylthio groups, alkylsilyl
groups, alkylamino groups, aryl groups, aryloxy groups, arylsilyl
groups, arylamino groups, arylalkyl groups, arylalkoxy groups,
arylalkylsilyl groups, arylalkylamino groups, monovalent
heterocyclic compound groups and cyano group; k and leach
independently represent an integer of 0 to 3; when k is 2 or more,
a plurality of R.sub.7s may be the same or different; when 1 is 2
or more, a plurality of R.sub.8s may be the same or different; two
or more of R.sub.5 to R.sub.8 may be mutually connected to form a
ring; and when R.sub.5 to R.sub.8 are a group containing an alkyl
chain, this alkyl chain may be interrupted with a group containing
a hetero atom.
2. A polymeric fluorescent substance manifesting fluorescence in
solid state and having a polystyrene-reduced number-average
molecular weight of 103 to 108 wherein the polymeric fluorescent
substance contains one or more of repeating units represented by
the formula (2) and one or more of repeating units represented by
the following formula (3): 24in the formula, Ar.sub.3 and Ar.sub.4
each independently represent an arylene group or a divalent
heterocyclic compound group; R.sub.10 and R.sub.11 each
independently represent a group selected from the group consisting
of a hydrogen atom, alkyl groups, aryl groups, monovalent
heterocyclic compound groups and cyano group; R.sub.9 and R.sub.12
each independently represent a group selected from the group
consisting of alkyl groups, alkoxy groups, alkylthio groups,
alkylsilyl groups, alkylamino groups, aryl groups, aryloxy groups,
arylsilyl groups, arylamino groups, arylalkyl groups, arylalkoxy
groups, arylalkylsilyl groups, arylalkylamino groups, arylalkenyl
groups, arylalkinyl groups, heterocyclic compound groups and cyano
group; m and n each independently represent an integer of 0 to 4; m
and n do not represent 0 simultaneously; when m is 2 or more, a
plurality of R.sub.9s may be the same or different; when n is 2 or
more, a plurality of R.sub.12s may be the same or different;
R.sub.9 to R.sub.12 may be connected to form a ring; and when
R.sub.9 to R.sub.12 are a group containing an alkyl chain, one or
more of a methyl group, methylene group and methine group
constituting this alkyl chain may be substituted with a group
containing a hetero atom.
3. The polymeric fluorescent substance according to claim 2 wherein
the total amount of repeating units represented by the formulae (2)
and (3) is 50 mol % or more based on the total amount of all
repeating units, and the total amount of repeating units
represented by the formula (3) is 0.1 mol % or more and 50 mol % or
less based on the total amount of the repeating units represented
by the formulae (2) and (3).
4. The polymeric fluorescent substance according to claim 3 wherein
the group represented by the formula (3) is a group represented by
the following formula (4) 25in the formula, R.sub.14 and R.sub.15
each independently represent a group selected from the group
consisting of a hydrogen atom, alkyl groups, aryl groups,
heterocyclic compound groups and cyano group; R.sub.13 and R.sub.16
each independently represent a group selected from the group
consisting of alkyl groups, alkoxy groups, alkylthio groups,
alkylsilyl groups, alkylamino groups, aryl groups, aryloxy groups,
arylsilyl groups, arylamino groups, arylalkyl groups, arylalkoxy
groups, arylalkylsilyl groups, arylalkylamino groups, monovalent
heterocyclic compound groups and cyano group; i and j each
independently represent an integer of 0 to 4; i and j do not
represent 0 simultaneously; when i is 2 or more, a plurality of
R.sub.13S may be the same or different; when j is 2 or more, a
plurality of R.sub.16s may be the same or different; and R.sub.13
to R.sub.16 may be connected to form a ring.
5. A polymeric fluorescent substance manifesting fluorescence in
solid state and having a polystyrene-reduced number-average
molecular weight of 10.sup.3 to 10.sup.8 wherein the polymeric
fluorescent substance contains one or more of repeating units
represented by the formula (2) and one or more of repeating units
represented by the following formula (5): 26in the formula,
Ar.sub.5, Ar.sub.6 and Ar.sub.7 each independently represent an
arylene group or a divalent heterocyclic compound group; R.sub.17
and R.sub.20 each independently represent a group selected from the
group consisting of a hydrogen atom, alkyl groups, aryl groups,
monovalent heterocyclic compound groups and cyano group. One or
more of R.sub.17 and R.sub.20 represent a group other than a
hydrogen atom and cyano group; two or more of R.sub.17 and R.sub.20
may be mutually connected to form a ring; and when R.sub.17 to
R.sub.20 are a group containing an alkyl chain, this alkyl chain
may be interrupted with a group containing a hetero atom.
6. The polymeric fluorescent substance according to claim wherein
the total amount of repeating units represented by the formulae (2)
and (5) is 50 mol % or more based on the total amount of all
repeating units, and the total amount of repeating units
represented by the formula (5) is 0.1 mol % or more and 50 mol % or
less based on the total amount of the repeating units represented
by the formulae (2) and (5).
7. The polymeric fluorescent substance according to claim 6 wherein
the group represented by the formula (5) is a group represented by
the following formula (6) 27in the formula, Ar.sub.8 represents an
arylene group or a divalent heterocyclic compound group; R.sub.23
and R.sub.24 each independently represent a group selected from the
group consisting of a hydrogen atom, alkyl groups, aryl groups,
monovalent heterocyclic compound groups and cyano group; R.sub.21,
R.sub.22, R.sub.25 and R.sub.26 each independently represent a
group selected from the group consisting of alkyl groups, alkoxy
groups, alkylthio groups, alkylsilyl groups, alkylamino groups,
aryl groups, aryloxy groups, arylsilyl groups, arylamino groups,
arylalkyl groups, arylalkoxy groups, arylalkylsilyl groups,
arylalkylamino groups, monovalent heterocyclic compound groups and
cyano group. o and r each independently represent an integer of 0
to 4, and p and q each independently represent an integer of 0 to
5; when o is 2 or more, a plurality of R.sub.21s may be the same or
different; when p is 2 or more, a plurality of R.sub.32s may be the
same or different; when q is 2 or more, a plurality of R.sub.25S
may be the same or different; when r is 2 o rmore, a plurality of
R.sub.26s may be the same or different; two or more of R.sub.21 and
R.sub.26 may be mutually connected to form a ring; and when
R.sub.21 to R.sub.26 are a group containing an alkyl chain, this
alkyl group may be interrupted with a group containing a hetero
atom.
8. A polymer light emitting device comprising at least a light
emitting layer between a pair of electrodes composed of an anode
and a cathode at least one of which is transparent or
semi-transparent wherein the light emitting layer contains a
polymeric fluorescent substance according to any of claims 1 to
7.
9. The polymer light emitting device according to claim 8, further
comprising a layer containing an conducting polymer disposed
between one electrode and the light emitting layer so that the
layer containing an conducting polymer is adjacent to said
electrode.
10. The polymer light emitting device according to claim 8, further
comprising an insulation layer having a thickness of 2 nm or less
disposed between one electrode and the light emitting layer so that
the insulation layer is adjacent to said electrode.
11. The polymer light emitting device according to any of claims 8
to 10, further comprising a layer comprising an electron
transporting compound disposed between the cathode and the light
emitting layer so that the layer comprising an electron
transporting compound is adjacent to said light emitting layer.
12. The polymer light emitting device according to any of claims 8
to 10, further comprising a layer comprising a hole transporting
compound disposed between the anode and the light emitting layer so
that the layer comprising a hole transporting compound is adjacent
to said light emitting layer.
13. The polymer light emitting device according to any of claims 8
to 10, further comprising a layer comprising an electron
transporting compound and a layer comprising ahole transporting
compound disposed between the cathode and the light emitting layer
so that the layer comprising an electron transporting compound is
adjacent to said light emitting layer, and the layer comprising a
hole transporting compound is adjacent to said light emitting
layer.
14. A flat light source obtained by using the polymer light
emitting device of any of claims 8 to 13.
15. A segment display obtained by using the polymer light emitting
device of any of claims 8 to 13.
16. A dot matrix display obtained by using the polymer light
emitting device of any of claims 8 to 13.
17. A liquid crystal display obtained by using the polymer light
emitting device of any of claims 8 to 13 as a back-light.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a polymeric fluorescent
substance and more specifically a polymer light-emitting device
using the same.
[0003] 2. Description of Related Art
[0004] An organic electroluminescence device is an device using
mainly an organic compound of lower molecular weight as a light
emitting material, and there are a lot of trials reported regarding
device structures, organic fluorescent dyes and organic charge
transporting materials since the electroluminescence device has
characteristics that it is driven at lower voltage, has higher
luminance and can easily give light emission of many colors as
compared with conventional inorganic electroluminescence devices
[Jpn. J. Appl. Phys., 27, p. L269 (1988), J. Appl. Phys., 65, p.
3610 (1989)].
[0005] Apart from organic electroluminescence devices using mainly
an organic compound having lower molecular weight, there is a
polymer light emitting device (hereinafter, referred sometimes to
as polymer LED) using a light emitting material having higher
molecular weight (hereinafter, referred sometimes to as polymeric
fluorescent substance). WO9013148, JP-A No. 3-244630, Appl. Phys.
Lett., 58, p. 1982 (1991) and the like disclose polymer LEDs using
a polymeric fluorescent substance, poly(p-phenylenevinylene)
(hereinafter, referred to as PPV), or a derivative thereof in a
light emitting layer.
[0006] Polymeric fluorescent substances and derivatives thereof
have a merit that they can be dissolved in a solvent, and can form
a light emitting layer by an wet film-forming method.
[0007] As the polymeric fluorescent substance used in these polymer
LEDs, polyfluorene (Jpn. J. Appl. Phys., 30, p. L1941 (1991)),
poly-p-phenylene derivatives (Adv. Mater., 4, p. 36 (1992)), and
the like are also reported, in addition to the above-mentioned
poly(p-phenylenevinylene) and derivatives thereof.
[0008] Regarding the poly fluorene derivative, J. Mater. Sci.
Mater. Ele., 11, p. 111 (2000) describes copolymers composed of a
fluorene repeating unit and a repeating unit of stilbene,
phenylene, 1,4-naphthalene, aromatic amines and the like in which a
cyano group is substituted on vinylene, and polymer LEDs using
these copolymers.
[0009] An object of the present invention is to provide a polymeric
fluorescent substance containing an arylene vinylene structure and
a fluorene structure and manifesting strong fluorescence, and a
polymer LED of high performance which can be driven at lower
voltage with high efficiency, using this polymeric fluorescent
substance.
SUMMARY OF THE INVENTION
[0010] The present inventors have intensively studied in view of
such conditions, and resultantly found that a polymeric fluorescent
substance manifesting fluorescence in solid state and having a
polystyrene-reduced number-average molecular weight of 10.sup.3 to
10.sup.8 wherein the polymeric fluorescent substance contains one
or more of segments represented by the following formula (1) and
one or more of repeating units represented by the following formula
(2) shows strong fluorescence and a polymer LED of high performance
which can be driven at lower voltage with high efficiency is
obtained using the above-mentioned polymeric fluorescent substance,
leading to completion of the invention.
[0011] Namely, in accordance with the present invention there is
provided [1] A polymeric fluorescent substance manifesting
fluorescence in solid state and having a polystyrene-reduced
number-average molecular weight of 10.sup.3 to 10.sup.8 wherein the
polymeric fluorescent substance contains one or more of segments
represented by the following formula (1) and one or more of
repeating units represented by the following formula (2): 2
[0012] [wherein, Ar.sub.1 and Ar.sub.2 each independently represent
an arylene group or a divalent heterocyclic compound group. R.sub.2
and R.sub.3 each independently represent a group selected from the
group consisting of a hydrogen atom, alkyl groups, aryl groups,
heterocyclic compound groups and cyano group. R.sub.1 and R.sub.4
each independently represent a group selected from the group
consisting of alkyl groups, alkoxy groups, alkylthio groups,
alkylsilyl groups, alkylamino groups, aryl groups, aryloxy groups,
arylsilyl groups, arylamino groups, arylalkyl groups, arylalkoxy
groups, arylalkylsilyl groups, arylalkylamino groups, arylalkenyl
groups, arylalkinyl groups, monovalent heterocyclic compound groups
and cyano group. The symbols a and c each independently represent
an integer of 0 to 4, and b represents an integer of 1 or more.
When b is 1, a and c do not represent 0 simultaneously. When b is
2, at least one of groups R.sub.2 and R.sub.3 represents a group
other than a hydrogen atom and cyano group. When b is 3 or more, a
and c do not represent 0 simultaneously if both of R.sub.2 and
R.sub.3 are a hydrogen atom. When a is 2 or more, a plurality of
R.sub.1s may be the same or different. When c is 2 or more, a
plurality of R.sub.4s may be the same or different. R.sub.1 to
R.sub.4 may be connected to form a ring. Further, when R.sub.1 to
R.sub.4 are a group containing an alkyl chain, one or more of a
methyl group, methylene group and methine group constituting this
alkyl chain may be substituted with a group containing a hetero
atom], 3
[0013] [wherein, R.sub.5 and R.sub.6 each independently represent a
group selected from the group consisting of a hydrogen atom, alkyl
groups, aryl groups and monovalent heterocyclic compound groups.
R.sub.7 and R.sub.8 each independently represent a group selected
from the group consisting of alkyl groups, alkoxy groups, alkylthio
groups, alkylsilyl groups, alkylamino groups, aryl groups, aryloxy
groups, arylsilyl groups, arylamino groups, arylalkyl groups,
arylalkoxy groups, arylalkylsilyl groups, arylalkylamino groups,
monovalent heterocyclic compound groups and cyano group. The
symbols k and 1 each independently represent an integer of 0 to 3.
When k is 2 or more, a plurality of R.sub.7s may be the same or
different. When 1 is 2 or more, a plurality of R.sub.8s may be the
same or different. Two or more of R.sub.5 to R.sub.8 may be
mutually connected to form a ring. Further, when R.sub.5 to R.sub.8
are a group containing an alkyl chain, this alkyl chain may be
interrupted with a group containing a hetero atom.] The present
invention also provides [2] A polymer light emitting device
comprising at least a light emitting layer between a pair of
electrodes composed of an anode and a cathode at least one of which
is transparent or semi-transparent wherein the light emitting layer
contains a polymeric fluorescent substance according to [1].
[0014] The present invention provides a flat light source, a
segment display, and a dot matrix display all obtained by using the
polymer light emitting device. The present invention also provides
a liquid crystal display obtained by using the polymer light
emitting device as a back-light.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] The polymeric fluorescent substance of the present invention
is a polymeric fluorescent substance manifesting fluorescence in
solid state and having a polystyrene-reduced number-average
molecular weight of 10.sup.3 to wherein the polymeric fluorescent
substance contains one or more of segments represented by the
formula (1) and one or more of repeating units represented by the
formula (2).
[0016] When a segment represented by the formula (1) comprises a
repeating unit represented by the formula (3) or the formula (5),
it is preferable that the total amount of repeating units
represented by the formula (2) and the formula (3) or the formula
(5) is 50 mol % or more based on the total amount of all repeating
units and the total amount of repeating units represented by the
formula (3) or the formula (5) is 0.1 mol % or more and 50 mol % or
less based on the total amount of repeating units represented by
the formula (2) and the formula (3) or the formula (5).
[0017] The repeating unit represented by the formula (1) is a
segment comprising an arylenevinylene derivative group containing a
substituent, and there are exemplified segments of the
above-mentioned formula (3) or (5) and segments formed by
connecting two or more of them. More specifically, there are
exemplified stilbene groups having a substituent represented by the
formula (4), distilbene groups having a substituent represented by
the formula (6), and the like.
[0018] The repeating unit represented by the formula (2) is a
fluorene group optionally having a substituent.
[0019] R.sub.2 and R.sub.3 in the formula (1) each independently
represent a group selected from the group consisting of a hydrogen
atom, alkyl groups, aryl groups, monovalent heterocyclic compound
groups and cyano group.
[0020] Those in which R.sub.2 and R.sub.3 represent a substituent
other than a hydrogen atom or cyano group are described below.
[0021] The alkyl group may be any of linear, branched or cyclic,
and usually has about 1 to 20 carbon atoms, and specific examples
thereof include a methyl group, ethyl group, propyl group, i-propyl
group, butyl group, 1-butyl group, t-butyl group, pentyl group,
isoamyl group, hexyl group, cyclohexyl group, heptyl group, octyl
group, 2-ethylhexyl group, nonyl group, decyl group,
3,7-dimethyloctyl group, lauryl group and the like, and preferable
are a pentyl group, isoamyl group, hexyl group, octyl group,
2-ethylhexyl group, decyl group and 3,7-dimethyloctyl group.
[0022] The aryl group usually has about 6 to 60 carbon atoms, and
specific examples thereof include a phenyl group, C.sub.1 to
C.sub.12 alkoxyphenyl groups, C.sub.1 to C.sub.12 alkylphenyl
groups, 1-naphthyl group, 2-naphthyl group and the like, and
preferable are C.sub.1 to C.sub.12 alkoxyphenyl groups and C.sub.1
to C.sub.12 alkylphenyl groups.
[0023] The monovalent heterocyclic compound group usually has about
4 to 60 carbon atoms, and specific examples thereof include a
thienyl group, C.sub.1 to C.sub.12 alkylthienyl groups, pyrrolyl
group, furyl group, pyridyl group, C.sub.1 to C.sub.12 alkylpyridyl
groups and the like, and preferable are a thienyl group, C.sub.1 to
C.sub.12 alkylthienyl groups, pyridyl group and C.sub.1 to C.sub.12
alkylpyridyl groups.
[0024] R.sub.2 and R.sub.3 in the formula (1) may be in the
relation of cis or trans.
[0025] Ar.sub.1 and Ar.sub.2 in the repeating unit represented by
the formula (1) each independently represent an arylene group or a
divalent heterocyclic group.
[0026] The arylene group is an atomic group obtained by removing
two hydrogen atoms from an aromatic hydrocarbon. The aromatic
hydrocarbon referred to here is a hydrocarbon used as a mother body
of an aromatic compound and containing a benzene ring, and includes
those having a condensed ring and those containing a dependent
benzene ring or condensed ring connected directly or via a group
such as vinylene and the like.
[0027] The arylene group usually has 6 to 60 carbon atoms, and
specific examples thereof include a phenylene group, biphenylene
group, terphenylene group, naphthalenediyl group, anthracenediyl
group and the like. The carbon number of the arylene group does not
include the carbon number of a substituent.
[0028] The divalent heterocyclic compound group indicates a
residual atomic group obtained by removing two hydrogen atoms from
a heterocyclic compound. The carbon number is usually from 4 to 60,
and a furandlyl group, thienylene group, fluorenediyl group,
pyridinediyl group, quinolinediyl group, quinoxalinediyl group and
the like are exemplified. The carbon number of the divalent
heterocyclic compound group does not include the carbon number of a
substituent.
[0029] Here, examples of the heterocyclic compound includes those
organic compounds having a cyclic structure in which elements
constituting the ring include not only a carbon atom but also a
hetero atom such as oxygen, sulfur, nitrogen, phosphorus, boron and
the like.
[0030] In the formula, a and c each independently represent an
integer of 0 to 4, and b represents an integer of 1 or more. When b
is 1, a and c do not represent 0 simultaneously. When b is 2, at
least one of groups R.sub.2 and R.sub.3 represents a group other
than a hydrogen atom and cyano group. When b is 3 or more, a and c
do not represent 0 simultaneously if both of R.sub.2 and R.sub.3
are a hydrogen atom. When a is 2 or more, a plurality of R.sub.1s
may be the same or different. When c is 2 or more, a plurality of
R.sub.4S may be the same or different. R.sub.1 to R.sub.4 may be
connected to form a ring. Further, when R.sub.1 to R.sub.4 are a
group containing an alkyl chain, one or more of a methyl group,
methylene group and methine group constituting this alkyl chain may
be substituted with a group containing a hetero atom.
[0031] The repeating unit represented by the formula (2) is a
fluorene group optionally having a substituent.
[0032] R.sub.5 and R.sub.6 in the formula (2) each independently
represent a group selected from the group consisting of a hydrogen
atom, alkyl groups, aryl groups and monovalent heterocyclic
compound groups. When R.sub.5 and R.sub.6 represent a substituent
other than a hydrogen atom, examples thereof are the same as
exemplified for R.sub.1.
[0033] In the repeating unit represented by the formula (2), k and
1 each independently represent an integer of 0 to 3. When k is 2 or
more, a plurality of R.sub.7s may be the same or different. When 1
is 2 or more, a plurality of R.sub.8 s may be the same or
different. Two or more of R.sub.5 to R.sub.8 may be mutually
connected to form a ring. Further, when R.sub.5 to R.sub.8 are a
group containing an alkyl chain, this alkyl chain may be
interrupted with a group containing a hetero atom.
[0034] R.sub.1 and R.sub.4 in the formula (1) and R.sub.7 and
R.sub.8 in repeating units represented by the formula (2) each
independently represent a group selected from the group consisting
of alkyl groups, alkoxy groups, alkylthio groups, alkylsilyl
groups, alkylamino groups, aryl groups, aryloxy groups, arylsilyl
groups, arylamino groups, arylalkyl groups, arylalkoxy groups,
arylalkylsilyl groups, arylalkylamino groups, arylalkenyl groups,
arylalkinyl groups, monovalent heterocyclic compound groups and
cyano group.
[0035] Those in which R.sub.7 and R.sub.8 represent a substituent
other than cyano group are described below.
[0036] The alkyl group may be any of linear, branched or cyclic,
and usually has about 1 to 20 carbon atoms, and specific examples
thereof include a methyl group, ethyl group, propyl group, i-propyl
group, butyl group, 1-butyl group, t-butyl group, pentyl group,
isoamyl group, hexyl group, cyclohexyl group, heptyl group, octyl
group, 2-ethylhexyl group, nonyl group, decyl group,
3,7-dimethyloctyl group, lauryl group and the like, and preferable
are a pentyl group, isoamyl group, hexyl group, octyl group,
2-ethylhexyl group, decyl group and 3,7-dimethyloctyl group.
[0037] The alkoxy group may be any of linear, branched or cyclic,
and usually has about 1 to 20 carbon atoms, and specific examples
thereof include a methoxy group, ethoxy group, propyloxy group,
i-propyloxy group, butoxy group, 1-butoxy group, t-butoxy group,
pentyloxy group, isoamyloxy group, hexyloxy group, cyclohexyloxy
group, heptyloxy group, octyloxy group, 2-ethylhexyloxy group,
nonyloxy group, decyloxy group, 3,7-dimethyloctyloxy group,
lauryloxy group and the like, and preferable are a pentyloxy group,
isoamyloxy group, hexyloxy group, octyloxy group, 2-ethylhexyloxy
group, decyloxy group and 3,7-dimethyloctyloxy group.
[0038] The alkylthio group may be any of linear, branched or
cyclic, and usually has about 1 to 20 carbon atoms, and specific
examples thereof include amethylthio group, ethylthio group,
propylthio group, 1-propylthio group, butylthio group, 1-butylthio
group, t-butylthio group, pentylthio group, isoamylthio group,
hexylthio group, cyclohexylthio group, heptylthio group, octylthio
group, 2-ethylhexylthio group, nonylthio group, decylthio group, 3,
7-dimethyloctylthio group, laurylthio group and the like, and
preferable are a pentylthio group, isoamylthio group, hexylthio
group, octylthio group, 2-ethylhexylthio group, decylthio group and
3,7-dimethyloctylthio group.
[0039] The alkylsilyl group may be any of linear, branched or
cyclic, and usually has about 1 to 60 carbon atoms, and specific
examples thereof include a methylsilyl group, ethylsilyl group,
propylsilyl group, 1-propylsilyl group, butylsilyl group,
i-butylsilyl group, t-butylsilyl group, pentylsilyl group,
isoamylsilyl group, hexylsilyl group, cyclohexylsilyl group,
heptylsilyl group, octylsilyl group, 2-ethylhexylsilyl group,
nonylsilyl group, decylsilyl group, 3,7-dimethyloctylsilyl group,
laurylsilyl group, trimethylsilyl group, ethyldimethylsilyl group,
propyldimethylsilyl group, i-propyldimethylsilyl group,
butyldimethylsilyl group, t-butyldimethylsilyl group,
pentyldimethylsilyl group, isoamyldimethylsilyl group,
hexyldimethylsilyl group, heptyldimethylsilyl group,
octyldimethylsilyl group, 2-ethylhexyl-dimethylsilyl group,
nonyldimethylsilyl group, decyldimethylsilyl group,
3,7-dimethyloctyl-dimethylsilyl group, lauryldimethylsilyl group
and the like, and preferable are a pentylsilyl group, isoamylsilyl
group, hexylsilyl group, octylsilyl group, 2-ethylhexylsilyl group,
decylsilyl group, 3,7-dimethyloctylsilyl group, pentyldimethylsilyl
group, isoamyldimethylsilyl group, hexyldimethylsilyl group,
octyldimethylsilyl group, 2-ethylhexyl-dimethylsilyl group,
decyldimethylsilyl group and 3,7-dimethyloctyl-dimethylsilyl
group.
[0040] The alkylamino group may be any of linear, branched or
cyclic, may be a monoalkyl group or a dialkylamino group, and
usually has about 1 to 40 carbon atoms, and specific examples
thereof include a methylamino group, dimethylamino group,
ethylamino group, diethylamino group, propylamino group,
1-propylamino group, butylamino group, 1-butylamino group,
t-butylamino group, pentylamino group, isoamylamino group,
hexylamino group, cyclohexylamino group, heptylamino group,
octylamino group, 2-ethylhexylamino group, nonylamino group,
decylamino group, 3,7-dimethyloctylamino group, laurylamino group
and the like, and preferable are a pentylamino group, isoamylamino
group, hexylamino group, octylamino group, 2-ethylhexylamino group,
decylamino group and 3,7-dimethyloctylamino group.
[0041] The aryl group usually has about 6 to 60 carbon atoms, and
specific examples thereof include a phenyl group, C.sub.1 to
C.sub.12 alkoxyphenyl groups (C.sub.1 to C.sub.12 indicates 1 to 12
carbon atoms, the same in the following), C.sub.1 to C.sub.12
alkylphenyl groups, 1-naphthyl group, 2-naphthyl group and the
like, and preferable are C.sub.1 to C.sub.12 alkoxyphenyl groups
and C.sub.1 to C.sub.12 alkylphenyl groups. The aryl group is an
atomic group obtained by removing one hydrogen atom from an
aromatic hydrocarbon.
[0042] The aryloxy group usually has about 6 to 60 carbon atoms,
and specific examples thereof include a phenoxy group, C.sub.1 to
C.sub.12 alkoxyphenoxy groups, C.sub.1 to C.sub.12 alkylphenoxy
groups, 1-naphthyloxy group, 2-naphthyloxy group and the like, and
preferable are C.sub.1 to C.sub.12 alkoxyphenoxy groups and C.sub.1
to C.sub.12 alkylphenoxy groups.
[0043] The arylsilyl group usually has about 6 to 60 carbon atoms,
and specific examples thereof include a phenylsilyl group, C.sub.1
to C.sub.12 alkoxyphenylsilyl groups, C.sub.1 to C.sub.12
alkylphenylsilyl groups, 1-naphthylsilyl group, 2-naphthylsilyl
group, dimethylphenylsilyl group and the like, and preferable are
C.sub.1 to C.sub.12 alkoxyphenylsilyl groups and C.sub.1 to
C.sub.12 alkylphenylsilyl groups.
[0044] The arylamino group usually has about 6 to 60 carbon atoms,
and specific examples thereof include a phenylamino group,
diphenylamino group, C.sub.1 to C.sub.12 alkoxyphenylamino groups,
di(C.sub.1 to C.sub.12 alkoxyphenyl) amino groups, di(C.sub.1 to
C.sub.12 alkylphenyl)amino groups, 1-naphthylamino group,
2-naphthylamino group, and the like, and preferable are C.sub.1 to
C.sub.12 alkylphenylamino groups and di(C.sub.1 to C.sub.12
alkylphenyl)amino groups.
[0045] The arylalkyl group usually has about 7 to 60 carbon atoms,
and specific examples thereof include phenyl-C.sub.1 to C.sub.12
alkyl groups, C.sub.1 to C.sub.12 alkoxyphenyl-C.sub.1 to C.sub.12
alkyl groups, C.sub.1 to C.sub.12 alkylphenyl-C.sub.1 to C.sub.12
alkyl groups, 1-naphtyl-C.sub.1 to C.sub.12 alkyl groups,
2-naphtyl-C.sub.1 to C.sub.12 alkyl groups and the like, and
preferable are C.sub.1 to C.sub.12 alkoxyphenyl-C.sub.1 to C.sub.12
alkyl groups and C.sub.1 to C.sub.12 alkylphenyl-C.sub.1 to
C.sub.12 alkyl groups.
[0046] The arylalkoxy group usually has about 7 to 60 carbon atoms,
and specific examples thereof include phenyl-C.sub.1 to C.sub.12
alkoxy groups, C.sub.1 to C.sub.12 alkoxyphenyl-C.sub.1 to C.sub.12
alkoxy groups, C.sub.1 to C.sub.12 alkylphenyl-C.sub.1 to C.sub.12
alkoxy groups, 1-naphtyl-C.sub.1 to C.sub.12 alkoxy groups,
2-naphtyl-C.sub.1 to C.sub.12 alkoxy groups and the like, and
preferable are C.sub.1 to C.sub.12 alkoxyphenyl-C.sub.1 to C.sub.12
alkoxy groups and C.sub.1 to C.sub.12 alkylphenyl-C.sub.1 to
Cl.sub.2 alkoxy groups.
[0047] The arylalkylsilyl group usually has about 7 to 60 carbon
atoms, and specific examples thereof include phenyl-C.sub.1 to
C.sub.12 alkylsilyl groups, C.sub.1 to C.sub.12
alkoxyphenyl-C.sub.1 to C.sub.12 alkylsilyl groups, C.sub.1 to
C.sub.12 alkylphenyl-C.sub.1 to C.sub.12 alkylsilyl groups,
1-naphtyl-C.sub.1 to C.sub.12 alkylsilyl groups, 2-naphtyl-C.sub.1
to C.sub.12 alkylsilyl groups, phenyl-C.sub.1 to C.sub.12
alkyldimethylsilyl groups and the like, and preferable are C.sub.1
to C.sub.12 alkoxyphenyl-C.sub.1 to C.sub.12 alkylsilyl groups and
C.sub.1 to C.sub.12 alkylphenyl-C.sub.1 to C.sub.12 alkylsilyl
groups.
[0048] The arylalkylamino group usually has about 7 to 60 carbon
atoms, and specific examples thereof include phenyl-C.sub.1 to
C.sub.12 alkylamino groups, C.sub.1 to C.sub.12
alkoxyphenyl-C.sub.1 to C.sub.12 alkylamino groups, C.sub.1 to
C.sub.12 alkylphenyl-C.sub.1 to C.sub.12 alkylamino groups,
di(C.sub.1 to C.sub.12 alkoxyphenyl-C.sub.1 to C.sub.12 alkyl)amino
groups, di(C.sub.1 to C.sub.12 alkylphenyl-C.sub.1 to C.sub.12
alkyl)amino groups, 1-naphtyl-C.sub.1 to C.sub.12 alkylamino
groups, 2-naphtyl-C.sub.1 to C.sub.12 alkylamino groups and the
like, and preferable are C.sub.1 to C.sub.12 alkylphenyl-C.sub.1 to
C.sub.12 alkylamino groups and di(C.sub.1 to C.sub.12
alkylphenyl-C.sub.1 to C.sub.12 alkyl)amino groups.
[0049] The monovalent heterocyclic compound group usually has about
4 to 60 carbon atoms, and specific examples thereof include a
thienyl group, C.sub.1 to C.sub.12 alkylthienyl groups, pyrrolyl
group, furyl group, pyridyl group, C.sub.1 to C.sub.12 alkylpyridyl
groups and the like, and preferable are a thienyl group, C.sub.1 to
C12 alkylthienyl groups, pyridyl group and C.sub.1 to C.sub.12
alkylpyridyl groups. The monovalent heterocyclic compound group
means a residual atomic group obtained by removing one hydrogen
atom from a heterocyclic compound.
[0050] In the formula (1), when b is 1, a repeating unit
represented by the following formula (3) is formed. 4
[0051] Ar.sub.3 and Ar.sub.4 in the repeating unit represented by
the formula (3) represent the same group as exemplified for
Ar.sub.1. R.sub.9 and R.sub.12 in the formula (3) represent the
same group as exemplified for R.sub.1. R.sub.10 and R.sub.11 in the
formula (3) represent the same group as exemplified for R.sub.2.
The symbols m and n do not represent 0 simultaneously. Groups
R.sub.10 and R.sub.11 in the formula (3) may be in the relation of
cis or trans.
[0052] Specifically, stilbene groups represented by the following
formula (4) are exemplified. 5
[0053] R.sub.13 and R.sub.16 in the formula (4) represent the same
group as exemplified for R.sub.1. R.sub.14 and R.sub.15 in the
formula (4) represent the same group as exemplified for R.sub.2. i
and j each independently represent an integer of 0 to 4. i and j do
not represent 0 simultaneously. Groups R.sub.14 and R.sub.15 in the
formula (4) may be in the relation of cis or trans.
[0054] In the formula (1), when b is 2, a repeating unit
represented by the following formula (5) is formed. 6
[0055] Ar.sub.5, Ar.sub.6 and Ar.sub.7 in the repeating unit
represented by the formula (5) represent the same group as
exemplified for Arl. R.sub.17, R.sub.18, R.sub.19 and R.sub.20 in
the formula (5) represent the same group as exemplified for
R.sub.2. One ormore of R.sub.17, R.sub.18, R.sub.19 and R.sub.20
represent a group other than a hydrogen atom and cyano group. Two
or more of R.sub.17 to R.sub.20 may be mutually connected to form a
ring. Further, when R.sub.17 to R.sub.20 are a group containing an
alkyl chain, this alkyl chain may be interrupted with a group
containing a hetero atom. Groups R.sub.17 and R.sub.18 in the
formula (5) may be in the relation of cis or trans, and groups
R.sub.19 and R.sub.20 may also be in the relation of cis or
trans.
[0056] Specifically, distilbene groups having a substituent on a
vinylene group represented by the following formula (6) are
exemplified. 7
[0057] Ar.sub.8 in the repeating unit represented by the formula
(6) represents the same group as exemplified for Ar.sub.1.
R.sub.21, R.sub.22, R.sub.25 and R.sub.26 in the formula (6)
represent the same group as exemplified for R.sub.1. R.sub.23 and
R.sub.24 in the formula (6) represent the same group as exemplified
for R.sub.2. The symbols o and r each independently represent an
integer of 0 to 4, and p and q each independently represent an
integer of 0 to 5. When o is 2 or more, a plurality of R.sub.21s
may be the same or different. When p is 2 or more, a plurality of
R.sub.32s may be the same or different. When q is 2 or more, a
plurality of R.sub.25S may be the same or different. When r i s 2
or more, a plurality of R.sub.26S may be the same or different. Two
or more of R.sub.21 to R.sub.26 may be connected to form a ring.
Further, when R.sub.21 to R.sub.26 are a group containing an alkyl
chain, this alkyl chain may be interrupted with a group containing
a hetero atom.
[0058] R.sub.23 in the formula (6) anda group represented by the
following formula: 8
[0059] may be in the relation of cis or trans, and R.sub.24 and a
group represented by the following formula: 9
[0060] may also be in the relation of cis or trans.
[0061] In the repeating unit represented by the formula (2), k and
1 each independently represent an integer of 0 to 3. When k is 2 or
more, a plurality of R.sub.7s may be the same or different. When 1
is 2 or more, a plurality of R.sub.8s may be the same or different.
Two or more of R.sub.5 to R.sub.8 may be connected to form a ring.
Further, when R.sub.5 to R.sub.8 are a group containing an alkyl
chain, this alkyl chain may be interrupted with a group containing
a hetero atom.
[0062] In the repeating unit represented by the formula (3), i and
1 each independently represent an integer of 0 to 4, and j and k
each independently represent an integer of 0 to 5. When i is 2 or
more, a plurality of Rgs may be the same or different. When j is 2
or more, a plurality of R.sub.12s may be the same or different.
When k is 2 or more, a plurality of R.sub.13S may be the same or
different. When 1 is 2 or more, a plurality of R.sub.16s may be the
same or different. Two or more of R.sub.9 to R.sub.14 may be
connected to form a ring. Further, when R.sub.9 to R.sub.14 are a
group containing an alkyl chain, this alkyl chain may be
interrupted with a group containing a hetero atom.
[0063] Here, as the hetero atom, an oxygen atom, sulfur atom,
nitrogen atom and the like are exemplified.
[0064] As the group containing a hetero atom, the following groups
are exemplified. 10
[0065] Here, as R', a hydrogen atom, alkyl groups having 1 to 20
carbon atoms, aryl groups having 6 to 60 carbon atoms, and
monovalent heterocyclic compound groups having 4 to 60 carbon atoms
are exemplified.
[0066] Substituents containing an alkyl group may be linear,
branched or cyclic, or a combination thereof, and when not linear,
there are exemplified an isoamyl group, 2-ethylhexyl group,
3,7-dimethyloctyl group, cyclohexyl group, 4-C.sub.1 to C.sub.12
alkylcyclohexyl group and the like. It is preferable that one or
more of substituents of the formula (1) contain a cyclic or
branched alkyl chain, for enhancing solubility of a polymeric
fluorescent substance into a solvent.
[0067] It is preferable that the form of a repeating unit including
a substituent has little symmetric property, for obtaining a
material showing strong fluorescence.
[0068] Further, when R.sub.1 and R.sub.2 contain an aryl group
and/or a heterocyclic compound group as a part of their structure,
the aryl group and/or heterocyclic compound group may further have
one or more substituents.
[0069] Furthermore, the end group of a polymeric fluorescent
substance may also be protected with a stable group since if a
polymerization active group remains intact, there is a possibility
of reduction in light emitting property and life when the
fluorescent substance is made into an device. Those having a
conjugated bond continuing to a conjugated structure of the main
chain are preferable, and there are exemplified structures
connected to an aryl group or heterocyclic compound group via a
carbon-carbon bond. Specifically, substituents of the chemical
formula 10 in JP-A No. 9-45478 and the like are exemplified.
[0070] As the method of synthesizing the polymeric fluorescent
substance, there are exemplified a method in which polymerization
is effected according to a Suzuki coupling reaction from the
corresponding monomer, a method in which polymerization is effected
according to a Grignard reaction, a method in which polymerization
is effected using a Ni(O) catalyst, a method in which
polymerization is effected using an oxidizing agent such as
FeCl.sub.3 and the like, a method of effecting oxidation
polymerization electrochemically, a method according to
decomposition of an intermediate polymer having a suitable
releasing group, and the like. Of them, the method of effecting
polymerization according to a Suzuki coupling reaction, the method
of effecting polymerization according to a Grignard reaction, the
method of effecting polymerization using a Ni(O) catalyst are
preferable since reaction control is easy.
[0071] The polymeric fluorescent substance may contain a repeating
unit other than repeating units represented by the formula (1) or
(2), in an amount which does not deteriorate fluorescent property
and charge carrying property. Further, repeating units represented
by the formula (1) or (2) and other repeating units may be
connected with a non-conjugation unit, or such a non-conjugation
part may be contained in the repeating unit. As the bonding
structure, there are exemplified those illustrated below, those
obtained by combining those illustrated below with a vinylene
group, those obtained by combining two or more of those illustrated
below, and the like. Here, R represents a group selected from the
group consisting of a hydrogen atom, alkyl groups having 1 to 20
carbon atom, aryl groups having 6 to 60 carbon atoms and
heterocyclic compound groups having 4 to 60 carbon atoms, and Ar
represents a hydrocarbon group having 6 to 60 carbon atoms. 11
[0072] This polymeric fluorescent substance may also be a random,
block or graft copolymer, or a polymer having an intermediate
structure thereof, for example, a random copolymer having blocking
property. From the view point for obtaining a polymeric fluorescent
substance having high fluorescent quantum yield, random copolymers
having blocking property and block or graft copolymers are more
preferable than complete random copolymers. Further, copolymers'
may have branched main chain and more than three terminals.
[0073] Further, as the polymeric fluorescent substance, those
emitting fluorescence in a solid state are suitably used, since the
material utilizes light emission from a thin film.
[0074] As good solvents for the polymeric fluorescent substance,
there are exemplified chloroform, methylene chloride,
dichloroethane, tetrahydrofuran, toluene, xylene, mesitylene,
tetralin, decalin, n-butylbenzene and the like. The polymeric
fluorescent substance can be usually dissolved in these solvents in
an amount of 0.1 wt % or more, though the amount differs depending
on the structure and molecular weight of the polymeric fluorescent
substance. The polymeric fluorescent substance has a
polystyrene-reduced number-average molecular weight of
5.times.10.sup.4 to 1.times.10.sup.8, and the degree of
polymerization thereof also changes depending on repeating
structures and proportion thereof. From the standpoint of film
forming property, generally the total amount of repeating
structures is preferably from 20 to 10000, more preferably from 30
to 10000, particularly preferably from 50 to 5000.
[0075] When these polymeric fluorescent substances are used as a
light emitting material of a polymer LED, the purity thereof exerts
an influence on light emitting property, therefore, it is
preferable that a monomer before polymerization is purified by a
method such as distillation, sublimation purification,
re-crystallization and the like before being polymerized and
further, it is preferable to conduct a purification treatment such
as re-precipitation purification, chromatographic separation and
the like after the synthesis.
[0076] The polymeric fluorescent substance of the present invention
can be used not only as a light emitting material, but also as an
organic semiconductor material, optical material, or as conductive
material by doping.
[0077] Next, the polymer LED of the present invention will be
illustrated. The polymer LED of the present invention is a polymer
LED comprising at least a light emitting layer between a pair of
electrodes composed of an anode and a cathode at least one of which
is transparent or semi-transparent wherein the light emitting layer
contains a polymeric fluorescent substance of the present
invention.
[0078] As the polymer LED of the present invention, there are
listed polymer LEDs having an electron transporting layer disposed
between a cathode and a light emitting layer, polymer LEDs having a
hole transporting layer disposed between an anode and a light
emitting layer, polymer LEDs having an electron transporting layer
disposed between a cathode and a light emitting layer and having a
hole transporting layer disposed between an anode and a light
emitting layer.
[0079] For example, the following structures a) to d) are
specifically exemplified.
[0080] a) anode/light emitting layer/cathode
[0081] b) anode/hole transporting layer/light emitting
layer/cathode
[0082] c) anode/light emitting layer/electron transporting
layer//cathode
[0083] d) anode/hole transporting layer/light emitting
layer/electron transporting layer/cathode
[0084] (wherein, / indicates adjacent lamination of layers.
Hereinafter, the same)
[0085] Herein, the light emitting layer is a layer having function
to emit a light, the hole transporting layer is a layer having
function to transport a hole, and the electron transporting layer
is a layer having function to transport an electron. Herein, the
electron transporting layer and the hole transporting layer are
generically called a charge transporting layer.
[0086] The light emitting layer, hole transporting layer and
electron transporting layer may also each independently used in two
or more layers.
[0087] Of charge transporting layers disposed adjacent to an
electrode, that having function to improve charge injecting
efficiency from the electrode and having effect to decrease driving
voltage of an device are particularly called sometimes a charge
injecting layer (hole injecting layer, electron injecting layer) in
general.
[0088] For enhancing adherence with an electrode and improving
charge injection from an electrode, the above-described charge
injecting layer or insulation layer having a thickness of 2 nm or
less may also be provided adjacent to an electrode, and further,
for enhancing adherence of the interface, preventing mixing and the
like, a thin buffer layer may also be inserted into the interface
of a charge transporting layer and light emitting layer.
[0089] The order and number of layers laminated and the thickness
of each layer can be appropriately applied while considering light
emitting efficiency and life of the device.
[0090] In the present invention, as the polymer LED having a charge
injecting layer (electron injecting layer, hole injecting layer)
provided, there are listed a polymer LED having a charge injecting
layer provided adjacent to a cathode and a polymer LED having a
charge injecting layer provided adjacent to an anode.
[0091] For example, the following structures e) to p) are
specifically exemplified.
[0092] e) anode/charge injecting layer/light emitting
layer/cathode
[0093] f) anode/light emitting layer/charge injecting
layer/cathode
[0094] g) anode/charge injecting layer/light emitting layer/charge
injecting layer/cathode
[0095] h) anode/charge injecting layer/hole transporting
layer/light emitting layer/cathode
[0096] i) anode/hole transporting layer/light emitting layer/charge
injecting layer/cathode
[0097] j) anode/charge injecting layer/hole transporting
layer/light emitting layer/charge injecting layer/cathode
[0098] k) anode/charge injecting layer/light emitting
layer/electron transporting layer/cathode
[0099] l) anode/light emitting layer/electron transporting
layer/charge injecting layer/cathode
[0100] m) anode/charge injecting layer/light emitting
layer/electron transporting layer/charge injecting
layer/cathode
[0101] n) anode/charge injecting layer/hole transporting
layer/light emitting layer/electron transporting layer/cathode
[0102] o) anode/hole transporting layer/light emitting
layer/electron transporting layer/charge injecting
layer/cathode
[0103] p) anode/charge injecting layer/hole transporting
layer/light emitting layer/electron transporting layer/charge
injecting layer/cathode
[0104] As the specific examples of the charge injecting layer,
there are exemplified layers containing an conducting polymer,
layers which are disposed between an anode and a hole transporting
layer and contain a material having an ionization potential between
the ionization potential of an anode material and the ionization
potential of a hole transporting material contained in the hole
transporting layer, layers which are disposed between a cathode and
an electron transporting layer and contain a material having an
electron affinity between the electron affinity of a cathode
material and the electron affinity of an electron transporting
material contained in the electron transporting layer, and the
like.
[0105] When the above-described charge injecting layer is a layer
containing an conducting polymer, the electric conductivity of the
conducting polymer is preferably 10.sup.-5 S/cm or more and
10.sup.3 S/cm or less, and for decreasing the leak current between
light emitting pixels, more preferably 10.sup.-5 S/cm or more and
10.sup.2 S/cm or less, further preferably 10.sup.-5 S/cm or more
and 10.sup.1 S/cm or less.
[0106] Usually, to provide an electric conductivity of the
conducting polymer of 10.sup.-5 S/cm or more and 10.sup.3 S/cm or
less, a suitable amount of ions are doped into the conducting
polymer.
[0107] Regarding the kind of an ion doped, an anion is used in a
hole injecting layer and a cation is used in an electron injecting
layer. As examples of the anion, a polystyrene sulfonate ion,
alkylbenzene sulfonate ion, camphor sulfonate ion and the like are
exemplified, and as examples of the cation, a lithium ion, sodium
ion, potassium ion, tetrabutyl ammonium ion and the like are
exemplified.
[0108] The thickness of the charge injecting layer is for example,
from 1 nm to 100 nm, preferably from 2 nm to 50 nm.
[0109] Materials used in the charge injecting layer may properly be
selected in view of relation with the materials of electrode and
adjacent layers, and there are exemplified conducting polymers such
as polyaniline and derivatives thereof, polythiophene and
derivatives thereof, polypyrrole and derivatives thereof,
poly(phenylenevinylene) and derivatives thereof, poly(thienylene
vinylene) and derivatives thereof, polyquinoline and derivatives
thereof, polyquinoxaline and derivatives thereof, polymers
containing aromatic amine structures in the main chain or the side
chain, and the like, and metal phthalocyanine (copper
phthalocyanine and the like), carbon and the like.
[0110] The insulation layer having a thickness of 2 nm or less has
function to make charge injection easy. As the material of the
above-described insulation layer, metal fluoride, metal oxide,
organic insulation materials and the like are listed. As the
polymer LED having an insulation layer having a thickness of 2 nm
or less, there are listed polymer LEDs having an insulation layer
having a thickness of 2 nm or less provided adjacent to a cathode,
and polymer LEDs having an insulation layer having a thickness of 2
nm or less provided adjacent to an anode.
[0111] Specifically, there are listed the following structures
[0112] q) to ab) for example.
[0113] q) anode/insulation layer having a thickness of 2 nm or
less/light emitting layer/cathode
[0114] r) anode/light emitting layer/insulation layer having a
thickness of 2 nm or less/cathode
[0115] s) anode/insulation layer having a thickness of 2 nm or
less/light emitting layer/insulation layer having a thickness of 2
nm or less/cathode
[0116] t) anode/insulation layer having a thickness of 2 nm or
less/hole transporting layer/light emitting layer/cathode
[0117] u) anode/hole transporting layer/light emitting
layer/insulation layer having a thickness of 2 nm or
less/cathode
[0118] v) anode/insulation layer having a thickness of 2 nm or
less/hole transporting layer/light emitting layer/insulation layer
having a thickness of 2 nm or less/cathode
[0119] w) anode/insulation layer having a thickness of 2 nm or
less/light emitting layer/electron transporting layer/cathode
[0120] x) anode/light emitting layer/electron transporting
layer/insulation layer having a thickness of 2 nm or
less/cathode
[0121] y) anode/insulation layer having a thickness of 2 nm or
less/light emitting layer/electron transporting layer/insulation
layer having a thickness of 2 nm or less/cathode
[0122] z) anode/insulation layer having a thickness of 2 nm or
less/hole transporting layer/light emitting layer/electron
transporting layer/cathode
[0123] aa) anode/hole transporting layer/light emitting
layer/electron transporting layer/insulation layer having a
thickness of 2 nm or less/cathode
[0124] ab) anode/insulation layer having a thickness of 2 nm or
less/hole transporting layer/light emitting layer/electron
transporting layer/insulation layer having a thickness of 2 nm or
less/cathode
[0125] In producing a polymer LED, when a film is formed from a
solution by using such polymeric fluorescent substance soluble in
an organic solvent, only required is removal of the solvent by
drying after coating of this solution, and even in the case of
mixing of a charge transporting material and a light emitting
material, the same method can be applied, causing an extreme
advantage in production. As the film forming method from a
solution, there can be used coatingmethods such as a spin coating
method, casting method, micro gravure coating method, gravure
coating method, bar coating method, roll coating method, wire bar
coating method, dip coating method, spray coating method, screen
printing method, flexo printing method, offset printing method,
inkjet printing method and the like.
[0126] Regarding the thickness of the light emitting layer, the
optimum value differs depending on material used, and may properly
be selected so that the driving voltage and the light emitting
efficiency become optimum values, and for example, it is from 1 nm
to 1 am, preferably from 2 nm to 500 nm, further preferably from 5
nm to 200 nm.
[0127] In the polymer LED of the present invention, a light
emitting material other than the above-mentioned polymeric
fluorescent substances may be mixed in a light emitting layer.
Further, in the polymer LED according to the instant application, a
light emitting layer containing a light emitting material other
than the above-mentioned polymeric fluorescent substance may be
laminated with a light emitting layer containing the
above-mentioned polymeric fluorescent substance.
[0128] As the light emitting material, known materials can be used.
In a compound having lower molecular weight, there can be used, for
example, naphthalene derivatives, anthracene or derivatives
thereof, perylene or derivatives thereof; dyes such as polymethine
dyes, xanthene dyes, coumarine dyes, cyanine dyes; metal complexes
of 8-hydroxyquinoline or derivatives thereof, aromatic amine,
tetraphenylcyclopentane or derivatives thereof, or
tetraphenylbutadiene or derivatives thereof, and the like.
[0129] Specifically, there can be used known compounds such as
those described in JP-A Nos. 57-51781, 59-195393 and the like, for
example.
[0130] When the polymer LED of the present invention has a hole
transporting layer, as the hole transporting materials used, there
are exemplified polyvinylcarbazole or derivatives thereof,
polysilane or derivatives thereof, polysiloxane derivatives having
an aromatic amine in the side chain or the main chain, pyrazoline
derivatives, arylamine derivatives, stilbene derivatives,
triphenyldiamine derivatives, polyaniline or derivatives thereof,
polythiophene or derivatives thereof, polypyrrole or derivatives
thereof, poly(p-phenylenevinylene) or derivatives thereof,
poly(2,5-thienylenevinylene) or derivatives thereof, or the
like.
[0131] Specific examples of the hole transporting material include
those described in JP-A Nos. 63-70257, 63-175860, 2-135359,
2-135361,2-209988, 3-37992 and 3-152184.
[0132] Among them, as the hole transporting materials used in the
hole transporting layer, preferable are polymer hole transporting
materials such as polyvinylcarbazole or derivatives thereof,
polysilane or derivatives thereof, polysiloxane derivatives having
an aromatic amine compound group in the side chain or the main
chain, polyaniline or derivatives thereof, polythiophene or
derivatives thereof, poly(p-phenylenevinylene) or derivatives
thereof, poly(2,5-thienyleneviny- lene) or derivatives thereof, or
the like, and further preferable are polyvinylcarbazole or
derivatives thereof, polysilane or derivatives thereof and
polysiloxane derivatives having an aromatic amine compound group in
the side chain or the main chain. In the case of a hole
transporting material having lower molecular weight, it is
preferably dispersed in a polymer binder for use.
[0133] Polyvinylcarbazole or derivatives thereof are obtained, for
example, by cation polymerization or radical polymerization from a
vinyl monomer.
[0134] As the polysilane or derivatives thereof, there are
exemplified compounds described in Chem. Rev., 89, 1359 (1989) and
GB 2300196 published specification, and the like. For synthesis,
methods described in them can be used, and a Kipping method can be
suitably used particularly.
[0135] As the polysiloxane or derivatives thereof, those having the
structure of the above-described hole transporting material having
lower molecular weight in the side chain or main chain, since the
siloxane skeleton structure has poor hole transporting property.
Particularly, there are exemplified those having an aromatic amine
having hole transporting property in the side chain or main
chain.
[0136] The method for forming a hole transporting layer is not
restricted, and in the case of a hole transporting layer having
lower molecular weight, a method in which the layer is formed from
a mixed solution with a polymer binder is exemplified. In the case
of a polymer hole transporting material, a method in which the
layer is formed from a solution is exemplified.
[0137] The solvent used for the film forming from a solution is not
particularly restricted providing it can dissolve a hole
transporting material. As the solvent, there are exemplified
chlorine solvents such as chloroform, methylene chloride,
dichloroethane and the like, ether solvents such as tetrahydrofuran
and the like, aromatic hydrocarbon solvents such as toluene, xylene
and the like, ketone solvents such as acetone, methyl ethyl ketone
and the like, and ester solvents such as ethyl acetate, butyl
acetate, ethylcellosolve acetate and the like.
[0138] As the film forming method from a solution, there can be
used coating methods such as a spin coating method, casting method,
micro gravure coating method, gravure coating method, bar coating
method, roll coating method, wire bar coating method, dip coating
method, spray coating method, screen printing method, flexo
printing method, offset printing method, inkjet printing method and
the like, from a solution.
[0139] The polymer binder mixed is preferably that does not disturb
charge transport extremely, and that does not have strong
absorption of a visible light is suitably used. As such polymer
binder, polycarbonate, polyacrylate, poly(methyl acrylate),
poly(methyl methacrylate), polystyrene, poly(vinyl chloride),
polysiloxane and the like are exemplified.
[0140] Regarding the thickness of the hole transporting layer, the
optimum value differs depending on material used, and may properly
be selected so that the driving voltage and the light emitting
efficiency become optimum values, and at least a thickness at which
no pin hole is produced is necessary, and too large thickness is
not preferable since the driving voltage of the device increases.
Therefore, the thickness of the hole transporting layer is, for
example, from 1 nm to 1 1 m, preferably from 2 nm to 500 nm,
further preferably from 5 nm to 200 nm.
[0141] When the polymer LED of the present invention has an
electron transporting layer, known compounds are used as the
electron transporting materials, and there are exemplified
oxadiazole derivatives, anthraquinonedimethane or derivatives
thereof, benzoquinone or derivatives thereof, naphthoquinone or
derivatives thereof, anthraquinone or derivatives thereof,
tetracyanoanthraquinodimethane or derivatives thereof, fluorenone
derivatives, diphenyldicyanoethylene or derivatives thereof,
diphenoquinone derivatives, or metal complexes of
8-hydroxyquinoline or derivatives thereof, polyquinoline and
derivatives thereof, polyquinoxaline and derivatives thereof,
polyfluorene or derivatives thereof, and the like.
[0142] Specifically, there are exemplified those described in JP-A
Nos. 63-70257, 63-175860, 2-135359, 2-135361,2-209988, 3-37992 and
3-152184.
[0143] Among them, oxadiazole derivatives, benzoquinone or
derivatives thereof, anthraquinone or derivatives thereof, or metal
complexes of 8-hydroxyquinoline or derivatives thereof,
polyquinoline and derivatives thereof, polyquinoxaline and
derivatives thereof, polyfluorene or derivatives thereof are
preferable, and 2-(4-biphenyl)-5-(4-t-butylphenyl-
)-1,3,4-oxadiazole, benzoquinone, anthraquinone,
tris(8-quinolinol)aluminu- m and polyquinoline are further
preferable.
[0144] The method for forming the electron transporting layer is
not particularly restricted, and in the case of an electron
transporting material having lower molecular weight, a vapor
deposition method from a powder, or a method of film-forming from a
solution or melted state is exemplified, and in the case of a
polymer electron transporting material, a method of film-forming
from a solution or melted state is exemplified, respectively.
[0145] The solvent used in the film-forming from a solution is not
particularly restricted provided it can dissolve electron
transporting materials and/or polymer binders. As the solvent,
there are exemplified chlorine solvents such as chloroform,
methylene chloride, dichloroethane and the like, ether solvents
such as tetrahydrofuran and the like, aromatic hydrocarbon solvents
such as toluene, xylene and the like, ketone solvents such as
acetone, methyl ethyl ketone and the like, and ester solvents such
as ethyl acetate, butyl acetate, ethylcellosolve acetate and the
like.
[0146] As the film-forming method from a solution or melted state,
there can be used coating methods such as a spin coating method,
casting method, micro gravure coating method, gravure coating
method, bar coating method, roll coating method, wire bar coating
method, dip coating method, spray coating method, screen printing
method, flexo printing method, offset printing method, inkjet
printing method and the like.
[0147] The polymer binder to be mixed is preferably that which does
not extremely disturb a charge transport property, and that does
not have strong absorption of a visible light is suitably used. As
such polymer binder, poly(N-vinylcarbazole), polyaniline or
derivatives thereof, polythiophene or derivatives thereof,
poly(p-phenylene vinylene) or derivatives thereof,
poly(2,5-thienylene vinylene) or derivatives thereof,
polycarbonate, polyacrylate, poly(methyl acrylate), poly(methyl
methacrylate), polystyrene, poly(vinyl chloride), polysiloxane and
the like are exemplified.
[0148] Regarding the thickness of the electron transporting layer,
the optimum value differs depending on material used, and may
properly be selected so that the driving voltage and the light
emitting efficiency become optimum values, and at least a thickness
at which no pin hole is produced is necessary, and too large
thickness is not preferable since the driving voltage of the device
increases. Therefore, the thickness of the electron transporting
layer is, for example, from 1 nm to 1 .mu.m, preferably from 2 nm
to 500 nm, further preferably from 5 nm to 200 nm.
[0149] The substrate forming the polymer LED of the present
invention may preferably be that does not change in forming an
electrode and layers of organic materials, and there are
exemplified glass, plastics, polymer film, silicon substrates and
the like. In the case of a opaque substrate, it is preferable that
the opposite electrode is transparent or semitransparent.
[0150] In the present invention, it is preferable that an anode is
transparent or semitransparent, and as the material of this anode,
electron conductive metal oxide films, semitransparent metal thin
films and the like are used. Specifically, there are used indium
oxide, zinc oxide, tin oxide, and films (NESA and the like)
fabricated by using an electron conductive glass composed of
indium.tin.oxide (ITO), indium.zinc.oxide and the like, which are
metal oxide complexes, and gold, platinum, silver, copper and the
like are used, and among them, ITO, indium.zinc.oxide, tin oxide
are preferable. As the fabricating method, a vacuum vapor
deposition method, sputtering method, ion plating method, plating
method and the like are used. As the anode, there may also be used
organic transparent conducting films such as polyaniline or
derivatives thereof, polythiophene or derivatives thereof and the
like.
[0151] The thickness of the anode can be appropriately selected
while considering transmission of a light and electric
conductivity, and for example, from 10 nm to 10 .mu.m, preferably
from 20 nm to 1 .mu.m, further preferably from 50 nm to 500 nm.
[0152] Further, for easy charge injection, there may be provided on
the anode a layer comprising a phthalocyanine derivative conducting
polymers, carbon and the like, or a layer having an average film
thickness of 2 nm or less comprising a metal oxide, metal fluoride,
organic insulating material and the like.
[0153] As the material of a cathode used in the polymer LED of the
present invention, that having lower work function is preferable.
For example, there are used metals such as lithium, sodium,
potassium, rubidium, cesium, beryllium, magnesium, calcium,
strontium, barium, aluminum, scandium, vanadium, zinc, yttrium,
indium, cerium, samarium, europium, terbium, ytterbium and the
like, or alloys comprising two of more of them, or alloys
comprising one or more of them with one or more of gold, silver,
platinum, copper, manganese, titanium, cobalt, nickel, tungsten and
tin, graphite or graphite intercalation compounds and the like.
Examples of alloys include a magnesium-silver alloy,
magnesium-indium alloy, magnesium-aluminum alloy, indium-silver
alloy, lithium-aluminum alloy, lithium-magnesium alloy,
lithium-indium alloy, calcium-aluminum alloy and the like. The
cathode may be formed into a laminated structure of two or more
layers.
[0154] The film thickness of a cathode can be appropriately
selected in view of electric conductivity and durability, and for
example, it is from 10 nm to 10 .mu.m, preferably from 20 nm to 1
.mu.m, further preferably from 50 nm to 500 nm.
[0155] As the method for fabricating a cathode, there are used a
vacuum vapor deposition method, sputtering method, lamination
method in which a metal thin film is adhered under heat and
pressure, and the like. Further, there may also be provided,
between a cathode and an organic layer, a layer comprising an
conducting polymer, or a layer having an average film thickness of
2 nm or less comprising a metal oxide, metal fluoride, organic
insulation material and the like, and after fabrication of the
cathode, a protective layer may also be provided which protects the
polymer LED. For stable use of the polymer LED for a long period of
time, it is preferable to provide a protective layer and/or
protective cover for protection of the device in order to prevent
it from outside damage.
[0156] As the protective layer, there can be used a polymer
compound, metal oxide, metal fluoride, metal borate and the like.
As the protective cover, there can be used a glass plate, a plastic
plate the surface of which has been subjected to
lower-water-permeation treatment, and the like, and there is
suitably used a method in which the cover is pasted with an device
substrate by a thermosetting resin or light-curing resin for
sealing. If space is maintained using a spacer, it is easy to
prevent an device from being injured. If an inner gas such as
nitrogen and argon is sealed in this space, it is possible to
prevent oxidation of a cathode, and further, by placing a desiccant
such as barium oxide and the like in the above-described space, it
is easy to suppress the damage of an device by moisture adhered in
the production process. Among them, any one means or more are
preferably adopted.
[0157] For obtaining light emission in plane form using the polymer
LED of the present invention, an anode and a cathode in the plane
form may properly be placed so that they are laminated each other.
Further, for obtaining light emission in pattern form, there are a
method in which a mask with a window in pattern form is placed on
the above-described plane light emitting device, a method in which
an organic layer in non-light emission part is formed to obtain
extremely large thickness providing substantial non-light emission,
and a method in which any one of an anode or a cathode, or both of
them are formed in the pattern. By forming a pattern by any of
these methods and by placing some electrodes so that independent
on/off is possible, there is obtained a display device of segment
type which can display digits, letters, simple marks and the like.
Further, for forming a dot matrix device, it may be advantageous
that anodes and cathodes are made in the form of stripes and placed
so that they cross at right angles. By a method in which a
plurality of kinds of polymeric fluorescent substances emitting
different colors of lights are placed separately or a method in
which a color filter or luminescence converting filter is used,
area color displays and multi color displays are obtained. A dot
matrix display can be driven by passive driving, or by active
driving combined with TFT and the like. These display devices can
be used as a display of a computer, television, portable terminal,
portable telephone, car navigation, view finder of a video camera,
and the like.
[0158] Further, the above-described light emitting device in plane
form is a thin self-light-emitting one, and can be suitably used as
a flat light source for back-light of a liquid crystal display, or
as a flat light source for illumination. Further, if a flexible
plate is used, it can also be used as a curved light source or a
display.
EXAMPLES
[0159] The following examples further illustrate the present
invention in detail but do not limit the scope thereof.
[0160] Herein, regarding the number average molecular weight, a
polystyrene reduced number-average molecular weight was measured by
gel permeation chromatography (GPC) using chloroform as a
solvent.
Example 1
[0161] <Synthesis of Polymeric fluorescent substance 1>
[0162] Under an inert atmosphere,
9,9-dioctylfluorene-2,7-bis(ethyleneboro- nate) (317mg, 0.598
mmol), 2,7-dibromo-9,9-dioctylfluorene (250 mg, 0.456 mmol),
4,4'-dibromo-2,2',5,5'-tetrakis(2,7-dimethyloctyloxy)stilb ene (110
mg, 0.114 mmol) and aliquat.RTM. 336 (tricaprylylmethylammonium
chloride, manufactured byAldrich, 220 mg, 0.547 mmol) were
dissolved in toluene (10 ml) and to this was added 10 ml of an
aqueous solution of potassium carbonate (295 mg, 2.14 mmol).
Further, tetrakis(triphenylphosp- hine)palladium (20 mg, 0.018
mmol) was added, and the mixture was heated under ref lux for 20
hours. After cooling, the solution was separated, and the organic
layer was washed with water.
[0163] This organic layer was dropped into methanol, and the
deposited precipitate was filtrated off. The precipitate was
purified by silica gel chromatography (toluene), to obtain
poly(9,9-dioctylfluorene-2,7-diyl-co-- 2,2',5,5'-tetrakis(3,
7-dimethyloctyloxy)stilbene-4,4'-diyl) (Polymeric fluorescent
substance 1). The yield was 350 mg. The ratio of repeating units
represented by the formulae (7) and (8) in Polymeric fluorescent
substance 1 was 9:1 depending on monomer charging ratio. 12
[0164] Polymeric fluorescent substance 1 had a polystyrene-reduced
number-average molecular weight of 1.3.times.10.sup.4. Polymeric
fluorescent substance 1 could be dissolved in a solvent such as
toluene, chloroform and the like.
[0165] <Evaluation of Fluorescent Property>
[0166] A 0.4 wt % chloroform solution of Polymeric fluorescent
substance 1 was spin-coated on quartz, to form a thin film of
Polymeric fluorescent substance 1. The ultraviolet visible
absorption spectrum and fluorescent spectrum of this thin film were
measured by using a ultraviolet visible absorption
spectrophotometer (UV3500 manufactured by Hitachi, Ltd.) and a
fluorescent spectrophotometer (850 manufactured by Hitachi, Ltd.),
respectively. For calculation of fluorescent strength, a
fluorescent spectrum excited at 350 nm was used. The area of
fluorescent spectra plotted against wave-number on the abscissa was
divided by the absorption at 350 nm, to obtain a relative value of
the fluorescent strength.
[0167] Polymeric fluorescent substance 1 has a fluorescent peak
wave-length of 470 nm, and revealed a relative value of the
fluorescent strength of 2.2.
[0168] <Production and Evaluation of the Device>
[0169] On a glass substrate on which an ITO film had been made at a
thickness of 150 nm according to a sputtering method, a film having
a thickness of 50 nm was formed using a solution (Baytron,
manufactured by Bayer) of
poly(ethylenedioxythiophene)/polystyrenesulfonic acid by spin
coating, and the film was dried at 120.degree. C. for 10 minutes on
a hot plate. Then, a film having a thickness of about 70 nm was
formed using a 1.5 wt % toluene solution of Polymeric fluorescent
substance 1 by spin coating. Further, this film was dried at
80.degree. C. for 1 hour under reduced pressure, then, lithium
fluoride was vapor-deposited at 0.4 nm as a cathode buffer layer,
calcium was vapor-deposited at 25 nm and aluminum was
vapor-deposited at 40 nm as a cathode, to produce a polymer LED. In
any vapor deposition, the degree of vacuum was 1 to
8.times.10.sup.-6 Torr. Voltage was applied on the resulted device,
to give EL light emission from Polymeric fluorescent substance 1.
The strength of EL light emission was approximately in proportion
to the current density.
Example 2
[0170] Poly(9,9-dioctylfluorene-2,7-diyl-co-2,2',5,5'-tetraki
s(3,7-dimethyloctyloxy)stilbene-4,4'-diyl) (Polymeric fluorescent
substance 2) was obtained in the same manner as in Example 1 except
that 2,7-dibromo-9,9-dioctylf luorene and
4,4'-dibromo-2,2',5,5'-tetrakis(2,7-- dimethyloctyloxy)stilb ene
were used at a molar ratio of 2:3. Polymeric fluorescent substance
2 contained repeating units represented by the formulae (7) and (8)
copolymerized at a molar ratio of 7:3.
[0171] <Evaluation of Fluorescent Property>
[0172] The relative value of the fluorescent strength of Polymeric
fluorescent substance 2 was obtained in the same manner as in
Example 1.
[0173] Polymeric fluorescent substance 2 had a fluorescent peak
wave-length of 470 nm and showed a relative value of the
fluorescent strength of 1.9.
Example 3
[0174] <Synthesis of
4,4'-bis(2-(4-bromophenyl)-2-phenyl-ethenyl)-biphe- nyl>
[0175] Under an inert atmosphere, 4-bromobenzophenone (0.783 g, 3
mmol) and 4,4'-bis-(diethylmethyl phosphonate)-biphenyl (0.559 g,
1.23 mmol) were added to and dissolved in tetrahydrofuran (10 g).
At room temperature, a solution of tert-butoxypotassium (0.414 g,
3.69 mmol) in tetrahydrofuran (3.28 g) was added dropwise over 5
minutes. The mixture was stirred under this condition for 3.5
hours. The reaction mixture was added into water (100 ml) and the
mixture was neutralized with 5% sulfuric acid. After
neutralization, toluene (250 ml) was added to separate an organic
layer. The organic layer was washed with water, and dried with
anhydrous sodium sulfate. The solvent was distilled off under
reduced pressure, and the resulted crude product was purified by
silica gel chromatography, to obtain the intended substance. The
yielded amount was 0.34 g and the yield was 41%.
[0176] <Synthesis of Polymeric fluorescent substance 3>
[0177] Under an inert atmosphere, 2,7-dibromo-9,9-dioctylfluorene
(560 mg, 1.0 mmol),
4,4'-bis(2-(4-bromophenyl)-2-phenyl-ethenyl)-biphenyl (76 mg, 0.11
mmol) were dissolved in tetrahydrofuran (10 ml), and to this was
added magnesium (55 mg, 2.3 mmol), nickel chloride (NiCl.sub.2) (10
mg, 0.079 mmol) and bipyridyl (12 mg, 0.079 mmol), and the mixture
was heated under reflux for 5 hours. After cooling, the reaction
solution was added dropwise into methanol (100 ml), and the
deposited precipitate was filtrated off. The resulted precipitate
was dissolved in toluene, washed with dilute hydrochloric acid,
then, washed with water until pH of the washing solution reached 7,
then, the organic layer was distilled off under reduced pressure.
The residue was dissolved in 20 ml of toluene, and re-precipitated
from 100 ml of methanol, to give Polymeric fluorescent substance 3.
The yielded amount was 238 mg. Polymeric fluorescent substance 3
contained repeating units represented by the following formulae (7)
and (9) at a molar ratio of about 9:1, depending on the charging
ratio of monomers. 13
[0178] Polymeric fluorescent substance 3had a polystyrene-reduced
average molecular weight of Mw=26,400, Mn=8,800. Polymeric
fluorescent substance 3 could be dissolved in a solvent such as
toluene, chloroform and the like.
[0179] <Evaluation of Fluorescent Property>
[0180] The relative value of the fluorescent strength of Polymeric
fluorescent substance 3 was obtained in the same manner as in
Example 1.
[0181] Polymeric fluorescent substance 3 had a fluorescent peak
wave-length of 476 nm and showed a relative value of the
fluorescent strength of 4.2.
[0182] <Production and Evaluation of the Device>
[0183] Polymer LED was fabricated in the same manner as in Example
1 except for using polymeric fluorescent substance 3 in place of
polymeric fluorescent substance 1. Voltage was applied on the
resulted device, to give EL light emission from Polymeric
fluorescent substance 3. The strength of EL light emission was
approximately in proportion to the current density.
Example 4
[0184] <Synthesis of Polymeric Fluorescent Substance 4>
[0185] Polymeric fluorescent substance 4 was obtained in the same
manner as in Example 3 except that
1,4-bis(2-(4-bromophenyl)-2-phenyl-ethenyl-2-- (2-ethylhexyl
oxy)-5-methoxybenzene was used instead of
4,4'-bis(2-(4-bromophenyl)-2-phenyl-ethenyl)-biphenyl. The yielded
amount was 201 mg. Polymeric fluorescent substance 4 contained
repeating units represented by the following formulae (7) and (10)
at a molar ratio of about 9:1, depending on the charging ratio of
monomers. 14 15
[0186] Polymeric fluorescent substance 4 had a polystyrene-reduced
average molecular weight of Mw=25,600, Mn=8,400. Polymeric
fluorescent substance 3 could be dissolved in a solvent such as
toluene, chloroform and the like.
[0187] <Evaluation of Fluorescent Property>
[0188] The relative value of the fluorescent strength of Polymeric
fluorescent substance 4 was obtained in the same manner as in
Example 1.
[0189] Polymeric fluorescent substance 4 had a fluorescent peak
wave-length of 504 nm and showed a relative value of the
fluorescent strength of 2.9.
[0190] <Production and Evaluation of the Device>
[0191] Polymer LED was fabricated in the same manner as in Example
1 except for using polymeric fluorescent substance 4 in place of
polymeric fluorescent substance 1. Voltage was applied on the
resulted device, to give EL light emission from Polymeric
fluorescent substance 4. The strength of EL light emission was
approximately in proportion to the current density.
Example 5
[0192] Under an inert atmosphere, 2,7-dibromo-9,9-dioctylfluorene
(560 mg, 1.0 mmol),
2,5-bis(2-(4-bromophenyl)-2-phenyl-ethenyl)-2-octyldimethy
lsilylbenzene (83 mg, 0.11 mmol) were dissolved in tetrahydrofuran
(10 ml), and to this was added magnesium (53 mg, 2.2 mmol), nickel
chloride (NiCl.sub.2) (10 mg, 0.077 mmol) and bipyridyl (12 mg,
0.077 mmol), and the mixture was heated under reflux for 5 hours.
After cooling, the reaction solution was added dropwise into
methanol (100 ml), and the deposited precipitate was filtrated off.
The resulted precipitate was dissolved in toluene, washed with
dilute hydrochloric acid, then, washed with water, and dried under
reduced pressure, to give Polymeric fluorescent substance 5. The
yielded amount was 200 mg. Polymeric fluorescent substance 5
contained repeating units represented by the following formulae (7)
and (11) at a molar ratio of about 9:1, depending on the charging
ratio of monomers. 16 17
[0193] Polymeric fluorescent substance 5 had a polystyrene-reduced
average molecular weight of Mw=13,600, Mn=5,900. Polymeric
fluorescent substance 5 could be dissolved in a solvent such as
toluene, chloroform and the like.
[0194] <Evaluation of Fluorescent Property>
[0195] The relative value of the fluorescent strength of Polymeric
fluorescent substance 5 was obtained in the same manner as in
Example 1.
[0196] Polymeric fluorescent substance 5 had a fluorescent peak
wave-length of 486 nm and showed a relative value of the
fluorescent strength of 3.5.
[0197] <Production and Evaluation of the Device>
[0198] Polymer LED was fabricated in the same manner as in Example
1 except for using polymeric fluorescent substance 5 in place of
polymeric fluorescent substance 1. Voltage was applied on the
resulted device, to give EL light emission from Polymeric
fluorescent substance 5. The strength of EL light emission was
approximately in proportion to the current density.
Example 6
[0199] <Synthesis of Polymeric Fluorescent Substance 6>
[0200] Under an inert atmosphere,
9,9-dioctylfluorene-2,7-bis(ethylene boronate) (314 mg, 0.59 mmol),
9,10-bis(2-(4-bromophenyl)-2-phenyl-etheny- l)-anthracene (390 mg,
0.56 mmol) and aliquat.RTM. 336 (manufactured by Aldrich, 220 mg,
0.55 mmol) were dissolved in toluene (10 ml) and to this was added
10 ml of an aqueous solution of potassium carbonate (290 mg, 2.1
mmol). Further, tetrakis(triphenylphosphine)palladium (21 mg, 0.018
mmol) was added, and the mixture was heated under reflux for 20
hours. After cooling, the organic layer was added dropwise into
methanol, and the deposited precipitate was filtrated off. This was
dissolved in toluene (100 ml), and washed with 3% oxalic acid
water, then, water, and the organic layer was distilled off under
reduced pressure. The residue was dissolved in toluene (20 ml) and
added dropwise into methanol, and the deposited precipitate was
filtrated off, to obtain Polymeric fluorescent substance 6. The
yielded amount was 280 mg. Polymeric fluorescent substance 6
contained repeating units represented by the following formulae (7)
and (12), bonded alternately, at a molar ratio of about 1:1,
depending on the charging ratio of monomers. 18
[0201] Polymeric fluorescent substance 6 had apolystyrene-reduced
average molecular weight of Mw=22,000, Mn=8,800. Polymeric
fluorescent substance 6 could be dissolved in a solvent such as
toluene, chloroform and the like.
[0202] <Evaluation of Fluorescent Property>
[0203] The relative value of the fluorescent strength of Polymeric
fluorescent substance 6 was obtained in the same manner as in
Example 1.
[0204] Polymeric fluorescent substance 6 had a fluorescent peak
wave-length of 548 nm and showed a relative value of the
fluorescent strength of 0.41.
Example 7
[0205] <Synthesis of Polymeric Fluorescent Substance 7>
[0206] Polymeric fluorescent substance 7 was obtained in the same
manner as in Example 4 except that
1,4-bis(2-(4-bromophenyl)-2-phenyl-ethenyl-2--
methyl-5-(3,7-dimethyloctyl)benzene was used instead of
9,10-bis(2-(4-bromophenyl)-2-phenyl-ethenyl)-anthracene. The
yielded amount was 220 mg. Polymeric fluorescent substance 7
contained repeating units represented by the following formulae (7)
and (13), bonded alternately, at a molar ratio of about 1:1,
depending on the charging ratio of monomers. 19
[0207] Polymeric fluorescent substance 7had a polystyrene-reduced
average molecular weight of Mw=26,100, Mn=10,700. Polymeric f
luorescent substance 7 could be dissolved in a solvent such as
toluene, chloroform and the like.
[0208] <Evaluation of Fluorescent Property>
[0209] The relative value of the f luorescent strength of Polymeric
fluorescent substance 7 was obtained in the same manner as in
Example 1.
[0210] Polymeric fluorescent substance 7 had a fluorescent peak
wave-length of 496 nm and showed a relative value of the
fluorescent strength of 2.2.
Example 8
[0211] <Synthesis of Polymeric Fluorescent Substance 8>
[0212] Under an inert atmosphere,
9,9-dioctylfluorene-2,7-bis(ethylene boronate) (305 mg, 0.57 mmol),
1,4-bis(2-(4-bromophenyl)-2-phenyl-ethenyl- )-2-(4-(3,7-dime
thyloctyloxy)-phenyl)benzene (451 mg, 0.547 mmol) and aliquate 336
(manufacturedbyAldrich, 220 mg, 0.547 mmol) were dissolved in
toluene (10 ml) and to this was added 10 ml of an aqueous solution
of potassium carbonate (226 mg, 1.64 mmol). Further,
tetrakis(triphenylphosp- hine)palladium (1.3 mg, 0.001 mmol) was
added, and the mixture was heated under reflux for 10 hours. After
cooling, the organic layerwas added dropwise into methanol, and the
deposited precipitate was filtrated off, to obtain Polymeric
fluorescent substance 8. The yielded amount was 280 mg. Polymeric
fluorescent substance 8 contained repeating units represented by
the following formulae (7) and (14), bonded alternately, at a molar
ratio of about 1:1, depending on the charging ratio of monomers.
20
[0213] <Evaluation of Fluorescent Property>
[0214] The relative value of the fluorescent strength of Polymeric
fluorescent substance 8 was obtained in the same manner as in
Example 1.
[0215] Polymeric fluorescent substance 8 had a fluorescent peak
wave-length of 473 nm and showed a relative value of the
fluorescent strength of 2.2.
Comparative Example 1
[0216] <Synthesis of
1,4-bis(2-(4-bromophenyl)ethenyl)-4'-(3,7-dimethyl- octyloxy
)biphenyl>
[0217] Under an inert atmosphere, 4-bromobenzaldehyde (2.18 g, 11.8
mmol), 2,5'-bis-(diethylmethyl
phosphonate)-4'-(3,7-dimethyloctyloxy)biphenyl (3.0 g, 5.0 mmol)
and tert-butoxypotassium (2.0 g, 1.76 mmol) were added to and
dissolved in tetrahydrofuran (30 g), and the solution was stirred
for 3 hours. The solvent was distilled off, and the residue was
dissolved in toluene (200 ml), and hydrochloric acid water (200 ml)
was added. After liquid separation, the aqueous layer was extracted
with toluene(100 ml). Theorganic layer was combined with this and
was with water twice, then, filtrated through Celite.RTM.
(manufactured by Aldrich). The organic layer was dried over
molecular sieves, then, the solvent was distilled off. The resulted
crude product was purified by silica gel column chromatography
(hexane/toluene), to obtain the intended substance. The yielded
amount was 1.36 g, and the yield was 41%.
[0218] <Synthesis of Polymeric Fluorescent Substance 8>
[0219] Under an inert atmosphere,
9,9-dioctylfluorene-2,7-bis(ethylene boronate) (185 mg, 0.35 mmol),
1,4-bis(2-(4-bromophenyl)ethenyl-4'-(3,7-d- imethyloctyloxy)
biphenyl (223 mg, 0.33 mmol) and aliquat.RTM. 336 (manufactured by
Aldrich, 17 mg, 0.042 mmol) were dissolved in toluene (2.7 g) and
to this was added 8 ml of an aqueous solution of potassium
carbonate (1.13 g, 8.1 mmol). Further,
tetrakis(triphenylphosphine)pallad- ium (2 mg, 0.0017 mmol) was
added, and the mixture was heated under reflux for 10 hours. After
cooling, the organic layer was added dropwise into methanol/water
(1/1). The supernatant was discarded, and methanol was added to the
residue and suspended. The precipitate was filtrated off, to obtain
Polymeric fluorescent substance 9. The yielded amount was 290 mg.
Polymeric fluorescent substance 9 contained repeating units
represented by the following formulae (7) and (15), bonded
alternately, at a molar ratio of about 1:1, depending on the
charging ratio of monomers. 21
[0220] <Evaluation of Fluorescent Property>
[0221] The relative value of the fluorescent strength of Polymeric
fluorescent substance 9 was obtained in the same manner as in
Example 1.
[0222] Polymeric fluorescent substance 9 had a fluorescent peak
wave-length of 468 nm and showed a relative value of the
fluorescent strength of 0.27.
[0223] The polymeric fluorescent substance of the present invention
contains an arylenevinylene structure and a fluorene structure,
shows strong fluorescence, and can be suitably used as a polymer
LED or a pigment for laser. The polyfluorene-based polymeric
fluorescent substance of the present invention can also be used as
an organic solar battery material, organic semiconductor for
organic transistor, and conductive thin film material. Further, a
polymer LED using this polymeric fluorescent substance is a polymer
LED of high performance which can be driven at lower voltage with
high efficiency. Therefore, this polymer LED can be preferably used
as a back light of a liquid crystal display, a light source in the
form of curved surface or flat surface for illumination, or a
display device of segment type, and in apparatuses such as a flat
panel display of dot matrix, and the like.
* * * * *