U.S. patent application number 09/345253 was filed with the patent office on 2002-01-17 for electroluminescent assemblies using boron chelates of 8-aminoquinoline derivatives.
Invention is credited to ELSCHNER, ANDREAS, HEUER, HELMUT-WERNER, WEHRMANN, ROLF.
Application Number | 20020006528 09/345253 |
Document ID | / |
Family ID | 7872991 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020006528 |
Kind Code |
A1 |
HEUER, HELMUT-WERNER ; et
al. |
January 17, 2002 |
ELECTROLUMINESCENT ASSEMBLIES USING BORON CHELATES OF
8-AMINOQUINOLINE DERIVATIVES
Abstract
Electroluminescent assembly comprising a substrate, an anode, an
electroluminescent element and a cathode, where at least one of the
two electrodes is transparent in the visible spectral region and
the electroluminescent element contains one or more zones selected
from the group consisting of hole injection zone, hole transport
zone, electroluminescent zone, electron transport zone and electron
injection zone in the order specified, where each of the zones
present may also assume functions of the other zones mentioned,
characterized in that the electroluminescent element contains a
boron complex of an 8-aminoquinoline derivative.
Inventors: |
HEUER, HELMUT-WERNER;
(KREFELD, DE) ; WEHRMANN, ROLF; (KREFELD, DE)
; ELSCHNER, ANDREAS; (MULHEIM, DE) |
Correspondence
Address: |
BAYER CORPORATION
PATENT DEPARTMENT
100 BAYER ROAD
PITTSBURG
PA
152059741
|
Family ID: |
7872991 |
Appl. No.: |
09/345253 |
Filed: |
June 30, 1999 |
Current U.S.
Class: |
428/690 ;
313/504; 313/506; 428/704; 428/917 |
Current CPC
Class: |
C08G 61/126 20130101;
Y10S 428/917 20130101; C07F 5/02 20130101; H01L 51/5012
20130101 |
Class at
Publication: |
428/690 ;
428/704; 428/917; 313/504; 313/506 |
International
Class: |
H05B 033/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 4, 1998 |
DE |
19829949.4 |
Claims
1. Electroluminescent assembly comprising a substrate, an anode, an
electroluminescent element and a cathode, where at least one of the
two electrodes is transparent in the visible spectral region and
the electroluminescent element contains one or more zones selected
from the group consisting of hole injection zone, hole transport
zone, electroluminescent zone, electron transport zone and electron
injection zone in the order specified, where each of the zones
present may also assume functions of the other zones mentioned,
characterized in that the electroluminescent element contains a
boron complex of an 8-aminoquinoline derivative.
2. Electroluminescent assembly according to claim 1, characterized
in that the hole injection zone contains an uncharged or cationic
polythiophene of the formula (I) 14where Q.sup.1 and Q.sup.2
represent, independently of one another, hydrogen, substituted or
unsubstituted (C.sub.1-C.sub.20)-alkyl, CH.sub.2OH or
(C.sub.6-C.sub.14)-aryl or Q.sup.1 and Q.sup.2 together represent
--(CH.sub.2).sub.m--CH.sub.2-- where m=0 to 12, preferably 1 to 5,
(C.sub.6-C.sub.14)-arylene, and n represents an integer from 2 to
10,000, preferably from 5 to 5000.
3. Electroluminescent assemblies according to claim 1,
characterized in that the hole injection zone contains an uncharged
or cationic polythiophene of the formula (Ia) or (Ib) or a mixture
thereof, 15where Q.sup.3 and Q.sup.4 represent, independently of
one another, hydrogen or substituted or unsubstituted
(C.sub.1-C.sub.18)-alkyl, (C.sub.2-C.sub.12)-alkenyl,
(C.sub.3-C.sub.7)-cycloalkyl, (C.sub.7-C.sub.15)-aralkyl,
(C.sub.6-C.sub.10)-aryl, (C.sub.1-C.sub.18)-alkoxy or
(C.sub.2-C.sub.18)-alkyl-oxy ester and Q.sup.5 and Q.sup.6
represent, independently of one another, hydrogen or
(C.sub.1-C.sub.18)-alkyl, (C.sub.2-C.sub.12)-alkenyl,
(C.sub.3-C.sub.7)-cycloalkyl, (C.sub.7-C.sub.15)-aralkyl,
(C.sub.6-C.sub.10)-aryl, (C.sub.1-C.sub.18)-alkoxy or
(C.sub.2-C.sub.18)-alkyloxy ester which are each substituted by at
least one sulphonate group, where if Q.sup.5 represents hydrogen,
Q.sup.6 is not hydrogen and vice versa, and n represents an integer
from 2 to 10,000.
4. Electroluminescent assemblies according to claim 3,
characterized in that the cationic or uncharged polythiophenes have
the formulae (Ia-1) and (Ib-1), 16where Q.sup.5 and n are as
defined in claim 3.
5. Electroluminescent assemblies according to any of claims 1 to 4,
characterized in that the anions of polymeric carboxylic acids
and/or polymeric sulphonic acids are present as polyanions.
6. Electroluminescent assemblies according to any of claims 1 to 5,
characterized in that polystyrenesulphonic acid and/or an alkaline
earth metal salt thereof are/is present is as counterion.
7. Electroluminescent assembly according to claim 1, characterized
in that the hole injection and/or hole transport zone contains an
aromatic tertiary amino compound of the general formula (II)
17where R.sup.2 represents hydrogen, substituted or unsubstituted
alkyl or halogen, R.sup.3 and R.sup.4 represent, independently of
one another, substituted or unsubstituted (C.sub.1-C.sub.10)-alkyl,
alkoxycarbonyl-substituted (C.sub.1-C.sub.10)-alkyl, or substituted
or unsubstituted aryl, aralkyl or cycloalkyl.
8. Electroluminescent assembly according to claim 2, characterized
in that, in formula (II), R.sup.2 represents hydrogen or
(C.sub.1-C.sub.6)-alkyl, p1 R.sup.3 and R.sup.4 represent,
independently of one another, (C.sub.1-C.sub.6)-alkyl,
(C.sub.1-C.sub.4)-alkoxycarbonyl- -(C.sub.1-C.sub.6)-alkyl, or
unsubstituted or (C.sub.1-C.sub.4)-alkyl- and/or
(C.sub.1-C.sub.4)-alkoxy-substituted phenyl, naphthyl,
phenyl-(C.sub.1-C.sub.4)-alkyl, naphthyl-(C.sub.1-C.sub.4)-alkyl,
cyclopentyl or cyclohexyl.
9. Electroluminescent assembly according to claim 7, characterized
in that the tertiary amino compound is selected from among the
following compounds: 18
10. Electroluminescent assembly according to claim 1, characterized
in that the boron complex is a compound selected from among
compounds of the general formulae (IIIa) to (IIIg) 19where R.sub.1
represents a substituted or unsubstituted aryl radical or fluorine
and R.sub.2 represents a substituted or unsubstituted acyl or
acyloxy radical or hydrogen and z represents atoms which complete a
structure comprising at least 2 fused rings, 20where R.sub.3
represents substituted or unsubstituted (C.sub.6-C.sub.10)-aryl or
halogen, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9
represent, independently of one another, hydrogen, substituted or
unsubstituted (C.sub.1-C.sub.16)-alkyl or halogen or sulphonamide
or cyano or a substituted or unsubstituted amino group, R.sub.10
represents a substituted or unsubstituted acyl or acyloxy radical,
21where R.sub.4, R.sub.5, R.sub.6 and R.sub.7, R.sub.8 and R.sub.9
represent, independently of one another, hydrogen, branched or
unbranched (C.sub.1-C.sub.12)-alkyl or chlorine or a sulphonamide
radical or cyano or a substituted amino group, R.sub.11 represents
branched or unbranched alkyl which may be substituted or
unsubstituted, x represents an O atom or a group --CH.sub.2-- or
--NH--.
11. Electroluminescent assembly according to claim 1, characterized
in that the transparent binder is selected from the group
consisting of polycarbonates, polyester carbonates, copolymers of
styrene, polysulphones, polymers based on vinyl-containing
monomers, polyolefins, cyclic olefin copolymers and phenoxy
resins.
12. Electroluminescent assembly according to claim 1, characterized
in that the boron complex is selected from among compounds of the
group 22
Description
[0001] An electroluminescent (EL) assembly is characterized in that
it emits light and an electric current flows when an electric
potential is applied. Such assemblies have long been known in
industry under the name "light emitting diodes" (LEDs). The
emission of light results from recombination of positive charges
(holes) and negative charges (electrons) with emission of
light.
[0002] In the development of light-emitting components for
electronics or photoelectronics, use is at present made mainly of
inorganic semiconductors such as gallium arsenide. Dot-shaped
display elements can be produced on the basis of such substances.
Large-area assemblies are not possible.
[0003] Apart from light emitting semiconductor diodes,
electroluminescent assemblies based on vapour-deposited low
molecular weight organic compounds are known (U.S. Pat. Nos.
4,539,507, 4,769,262, 5,077,142, EP-A 0 406 762, EP-A 0 278 758,
EP-A 0 278 757).
[0004] Furthermore, polymers such as poly-(p-phenylenes) and
poly-(p-phenylene-vinylenes) (PPVs) have been described as
electroluminescent polymers: G. Leising et al., Adv. Mater. 4
(1992) No. 1; Friend et al., J. Chem. Soc., Chem. Commun. 32
(1992); Saito et al., Polymer, 1990, Vol. 31, 1137; Friend et al.,
Physical Review B, Vol. 42, No. 18, 11670 or WO 90/13148. Further
examples of PPV in electroluminescent displays are described in
EP-A 0 443 861, WO-A 92/03490 and 92/03491.
[0005] EP-A 0 294 061 discloses an optical modulator based on
polyacetylene.
[0006] To produce flexible polymer LEDs, Heeger et al. have
proposed soluble, conjugated PPV derivatives (WO-A 92/16023).
[0007] Polymer blends of different compositions are likewise known:
M. Stolka et al., Pure & Appt. Chem., Vol. 67, No. 1, pp
175-182, 1995; H. Bssler et al., Adv. Mater. 1995, 7, No. 6, 551;
K. Nagai et al., Appl. Phys. Lett. 67 (16), 1995, 2281; EP-A 0 532
798.
[0008] The organic EL assemblies generally contain one or more
layers comprising organic charge transport compounds. The
in-principle structure in the order of the layers is as
follows:
[0009] 1 Support, substrate
[0010] 2 Base electrode
[0011] 3 Hole injection layer
[0012] 4 Hole transport layer
[0013] 5 Light-emitting layer
[0014] 6 Electron transport layer
[0015] 7 Electron injection layer
[0016] 8 Top electrode
[0017] 9 Contacts
[0018] 10 Covering, encapsulation.
[0019] Layers 3 to 7 represent the electroluminescent element.
[0020] This structure represents the most general case and can be
simplified by leaving out individual layers so that one layer
assumes a plurality of functions. In the simplest case, the EL
assembly comprises two electrodes between which there is located
one organic layer which fulfils all functions, including the
emission of light. Such systems are described, for example, in the
Application WO-A 90/13148 on the basis of
poly(p-phenylene-vinylene).
[0021] Multilayer systems can be built up by means of vapour
deposition processes in which the layers are applied successively
from the gas phase or by means of casting processes. Owing to the
higher process speeds, casting processes are preferred. However,
partial dissolution of a layer which has already been applied when
the next layer is applied on top of it can in certain cases be a
difficulty.
[0022] It is an object of the present invention to provide
electroluminescent assemblies having a high light flux, in which
novel boron complexes or chelates having improved solubility in
customary solvents are to be used as emitters and/or electron
conductors. These novel boron complexes should also be able to be
applied from the gas phase by means of vapour deposition
processes.
[0023] It has been found that electroluminescent assemblies
containing the boron complexes mentioned below meet these
requirements. In the following, the term "zone" is equivalent to
the term "layer".
[0024] The present invention accordingly provides
electroluminescent assemblies comprising a substrate, an anode, an
electroluminescent element and a cathode, where at least one of the
two electrodes is transparent in the visible spectral region and
the electroluminescent element contains one or more zones selected
from the group consisting of hole injection zone, hole transport
zone, electroluminescent zone, electron transport zone and electron
injection zone in the order specified, where each of the zones
present may also assume functions of the other zones mentioned,
characterized in that the electroluminescent element contains a
boron complex of 8-aminoquinoline derivatives.
[0025] The hole injection zone preferably contains an uncharged or
cationic polythiophene of the formula (I) 1
[0026] where
[0027] Q.sup.1 and Q.sup.2 represent, independently of one another,
hydrogen, substituted or unsubstituted (C.sub.1-C.sub.20)-alkyl,
CH.sub.2OH or (C.sub.6-C.sub.14)-aryl or
[0028] Q.sup.1 and Q.sup.2 together represent
--(CH.sub.2).sub.m--CH.sub.2- -- where m=0 to 12, preferably 1 to
5, (C.sub.6-C.sub.14)-arylene, and
[0029] n represents an integer from 2 to 10,000, preferably from 5
to 5000.
[0030] The hole conduction zone adjoining the hole injection zone
preferably contains one or more aromatic tertiary amino compounds,
preferably substituted or unsubstituted triphenylamine compounds,
particularly preferably 1,3,5-tris(aminophenyl)benzene compounds of
the formula (II).
[0031] The zone or zones located between the hole injection zone
and the cathode can also assume a plurality of functions, i.e. one
zone can contain, for example, hole-injecting, hole-transporting,
electroluminescent, electron-transporting and/or electron-injecting
substances.
[0032] The electroluminescent element can additionally contain one
or more transparent polymeric binders.
[0033] The substituted or unsubstituted
1,3,5-tris(aminophenyl)benzene compound preferably represents an
aromatic tertiary amino compound of the general formula (II) 2
[0034] where
[0035] R.sup.2 represents hydrogen, substituted or unsubstituted
alkyl or halogen,
[0036] R.sup.3 and R.sup.4 represent, independently of one another,
substituted or unsubstituted (C.sub.1-C.sub.10)-alkyl,
alkoxycarbonyl-substituted (C.sub.1-C.sub.10)-alkyl, or substituted
or unsubstituted aryl, aralkyl or cycloalkyl,
[0037] R.sup.3 and R.sup.4 preferably represent, independently of
one another, (C.sub.1-C.sub.6)-alkyl, in particular methyl, ethyl,
n- or iso-propyl, n-, iso-, sec- or tert-butyl,
(C.sub.1-C.sub.4)-alkoxycarbony- l-(C.sub.1-C.sub.6)-alkyl, for
example methoxycarbonyl-, ethoxycarbonyl-, propoxycarbonyl- or
butoxycarbonyl-(C.sub.1-C.sub.4)-alkyl or unsubstituted or
(C.sub.1-C.sub.4)-alkyl- and/or (C.sub.1-C.sub.4)-alkoxy-
-substituted phenyl-(C.sub.1-C.sub.4)-alkyl,
naphthyl-(C.sub.1-C.sub.4)alk- yl, cyclopentyl, cyclohexyl, phenyl
or naphthyl.
[0038] Particularly preferably, R.sup.3 and R.sup.4 represent,
independently of one another, unsubstituted phenyl or naphthyl or
else phenyl or naphthyl substituted by from one to three methyl,
ethyl, n-, iso-propyl, methoxy, ethoxy, n- and/or iso-propoxy
radicals.
[0039] R.sup.2 preferably represents hydrogen,
(C.sub.1-C.sub.6)-alkyl, for example methyl, ethyl, n- or
iso-propyl, n-, iso-, sec- or tert-butyl, or chlorine.
[0040] Such compounds and their preparation are described in U.S.
Pat. No. 4,923,774 for use in electrophotography; this patent is
hereby expressly incorporated by reference into the present
description. The tris-nitrophenyl compound can, for example, be
converted into the tris-aminophenyl compound by generally known
catalytic hydrogenation, for example in the presence of Raney
nickel (Houben-Weyl 4/1C, 14-102. Ullmann (4) 13, 135-148). The
amino compound is reacted with substituted halogenobenzenes in a
generally known manner.
[0041] The following compounds may be mentioned by way of example:
3
[0042] Apart from the tertiary amino compound, further hole
conductors, e.g. in the form of a mixture with the tertiary amino
compound, may also be used for building up the electroluminescent
element. The further hole conductor or conductors can be, on the
one hand, one or more compounds of the formula (II), including
mixtures of isomers, or, on the other hand, mixtures of hole
transport compounds with compounds of tertiary amino compounds
having the general formula (II) and having various structures.
[0043] A listing of possible hole injection and hole conductor
materials is given in EP-A 0 532 798.
[0044] In the case of mixtures of the aromatic amines, the
compounds can be used in any ratio.
[0045] Examples which may be mentioned are:
[0046] Materials which have hole-conducting properties and can be
used in pure form or as mixing partners for the tertiary amino
compounds are, for example, the following compounds, where X.sup.1
to X.sup.6 represent, independently of one another H, halogen,
alkyl, aryl, alkoxy, aryloxy. 4
[0047] These and further examples are described in J. Phys. Chem.
1993, 97, 6240-6248 and Appl. Phys. Lett., Vol. 66, No. 20,
2679-2681.
[0048] In general, various amines having different basic structures
and/or different substitution patterns can be mixed.
[0049] X.sup.1 to X.sup.6 preferably represent, independently of
one another, hydrogen, fluorine, chlorine, bromine,
(C.sub.1-C.sub.10)-, in particular (C.sub.1-C.sub.4)-alkyl or
-alkoxy, phenyl, naphthyl, phenoxy and/or naphthyloxy. The aromatic
rings may be substituted by one, two, three or four, identical or
different radicals X.sup.1 to X.sup.6.
[0050] The polythiophenes having the structural repeating unit of
the formula (I) are known (cf. EP-A 0 440 958 and 0 339 340). The
preparation of the dispersions or solutions used according to the
invention is described in EP-A 0 440 957 and DE-A 42 11 459.
[0051] The polythiophenes in the dispersion or solution are
preferably used in cationic form as are obtained, for example, by
treatment of the neutral thiophenes with oxidizing agents.
Customary oxidizing agents such as potassium peroxodisulphate are
used for the oxidation. The oxidation gives the polythiophenes
positive charges which are not in the formulae since their number
and position cannot be determined unambiguously. They can be
prepared directly on supports using the methods described in EP-A 0
339 340.
[0052] Q.sup.1 and Q.sup.2 in formula (I) are preferably
--(CH.sub.2).sub.m--CH.sub.2-- where m=1 to 4, very particularly
preferably ethylene.
[0053] Preferred cationic or neutral polydioxythiophenes comprise
structural units of the formula (Ia) or (Ib) 5
[0054] where
[0055] Q.sup.3 and Q.sup.4 represent, independently of one another,
hydrogen, substituted or unsubstituted (C.sub.1-C.sub.18)-alkyl,
preferably (C.sub.1-C.sub.10)-, in particular
(C.sub.1-C.sub.6)-alkyl, (C.sub.2-C.sub.12)-alkenyl, preferably
(C.sub.2-C.sub.8)-alkenyl, (C.sub.3-C.sub.7)-cycloalkyl, preferably
cyclopentyl or cyclohexyl, (C.sub.7-C.sub.15)-aralkyl, preferably
phenyl-(C.sub.1-C.sub.4)-alkyl, (C.sub.6-C.sub.10)-aryl, preferably
phenyl or naphthyl, (C.sub.1-C.sub.18)-alkoxy, preferably
(C.sub.1-C.sub.10)-alkoxy, preferably methoxy, ethoxy, n- or
iso-propoxy, or (C.sub.2-C.sub.18)-alky- loxy ester and
[0056] Q.sup.5 and Q.sup.6 represent, independently of one another,
hydrogen or (C.sub.1-C.sub.18)-alkyl, preferably
(C.sub.1-C.sub.10)-, in particular (C.sub.1-C.sub.6)-alkyl,
(C.sub.2-C.sub.12)-alkenyl, preferably (C.sub.2-C.sub.8)-alkenyl,
(C.sub.3-C.sub.7)-cycloalkyl, preferably cyclopentyl or cyclohexyl,
(C.sub.7-C.sub.15)-aralkyl, preferably
phenyl-(C.sub.1-C.sub.4)-alkyl, (C.sub.6-C.sub.10)-aryl, preferably
phenyl or naphthyl, (C.sub.1-C.sub.18)-alkoxy, preferably
(C.sub.1-C.sub.10)-alkoxy, for example methoxy, ethoxy, n- or
iso-propoxy, or (C.sub.2-C.sub.18)-alkyloxy ester which are each
substituted by at least one sulphonate group, where if Q.sup.5
represents hydrogen, Q.sup.6 is not hydrogen and vice versa,
and
[0057] n represents an integer from 2 to 10,000, preferably from 5
to 5000.
[0058] Particular preference is given to cationic or uncharged
polythiophenes of the formulae (Ia-1) and (Ib-1) 6
[0059] where
[0060] Q.sup.5 and n are as defined above.
[0061] To balance the positive charge, the cationic form of the
polythiophenes contains anions, preferably polyanions.
[0062] Polyanions present are preferably the anions of polymeric
carboxylic acids such as polyacrylic acids, polymethacrylic acid or
polymaleic acids and polymeric sulphonic acids such as
polystyrenesulphonic acids and polyvinylsulphonic acids. These
polycarboxylic and polysulphonic acids can also be copolymers of
vinylcarboxylic and vinylsulphonic acids with other polymerizable
monomers such as acrylates and styrene.
[0063] The anion of polystyrenesulphonic acid is particularly
preferred as counterion.
[0064] The molecular weight of the polyacids forming the polyanions
is preferably from 1000 to 2,000,000, particularly preferably from
2000 to 500,000. The polyacids or their alkali metal salts are
commercially available, e.g. polystyrenesulphonic acids and
polyacrylic acids, or else can be prepared by known methods (see,
for example, Houben-Weyl, Methoden der organischen Chemie, Volume E
20 Makromolekulare Stoffe, Part 2 (1987), p. 1141 ff.).
[0065] In place of the free polyacids required for the formation of
the dispersions of polydioxythiophenes and polyanions, it is also
possible to use mixtures of alkali metal salts of the polyacids and
corresponding amounts of monoacids.
[0066] In the case of the formulae (Ib) and (Ib-1), the
polydioxythiophenes bear positive and negative charges in the
monomer unit itself.
[0067] The assemblies of the invention may, if desired, contain
polymers and/or copolymers as binder, for example polycarbonates,
polyester carbonates, copolymers of styrene such as SAN or
styrene-acrylates, polysulphones, polymers based on
vinyl-containing monomers such as poly(meth)acrylates,
polyvinylpyrrolidone, polyvinylcarbazol, vinyl acetate and vinyl
alcohol polymers and copolymers, polyolefins, cyclic olefin
copolymers, phenoxy resins, etc. It is also possible to use
mixtures of various polymers. The polymeric binders have molecular
weights of from 10,000 to 2,000,000 g/mol, are soluble and
film-forming and are transparent in the visible spectral region.
They are described, for example, in Encyclopedia of Polymer Science
and Engineering, 2nd ed., A. Wiley-Interscience publication. They
are usually used in an amount of up to 95% by weight, preferably up
to 80% by weight, based on the total weight of the
electroluminescent elements.
[0068] The boron complex (boron chelate) is preferably a compound
of the general formula (III)a or (III)b 7
[0069] where
[0070] R.sub.1 represents a substituted or unsubstituted aryl
radical or fluorine
[0071] and
[0072] R.sub.2 represents a substituted or unsubstituted acyl or
acyloxy radical or hydrogen
[0073] and
[0074] z represents, independently in the two forms, atoms which
complete a structure comprising at least 2 fused rings.
[0075] Particular preference is given to a compound of the general
formula (IIIc) or (IIId) 8
[0076] where
[0077] R.sub.3 represents substituted or unsubstituted
(C.sub.6-C.sub.10)-aryl or halogen,
[0078] R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9
represent, independently of one another, hydrogen, substituted or
unsubstituted (C.sub.1-C.sub.16)-alkyl or halogen or sulphonamido
or cyano or a substituted or unsubstituted amino group,
[0079] R.sub.10 represents a substituted or unsubstituted acyl or
acyloxy radical.
[0080] Very particular preference is given to a compound of the
general formula (IIIe), (IIIf) or (IIIg) 9
[0081] where
[0082] R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9
represent, independently of one another, in particular hydrogen,
branched or unbranched (C.sub.1-C.sub.12)-alkyl, for example
methyl, ethyl or 4-ethyl-1-methyloctyl, or chlorine or a
sulphonamido radical or cyano or a substituted amino group,
[0083] R.sub.11 represents branched or unbranched alkyl which may
be unsubstituted or substituted, for example by an amino group,
[0084] X represents an 0 atom or a group --CH.sub.2-- or
--NH--.
[0085] Such compounds and their preparation are known as
fluorescent compounds in chemical analysis and are described, for
example, in E. Hohaus, F. Umland; Chem. Ber. 102. 4025-4031
(1969).
[0086] A general synthesis scheme which differs only in the choice
of solvent is: 10
[0087] Examples are the following compounds: 11
[0088] It is possible to use one or more compounds of the formulae
B1 to B21.
[0089] The 8-aminoquinoline ligands can be prepared by known
methods of organic chemistry.
[0090] To produce the electroluminescent element, the boron complex
and, if desired, the tertiary amino compound and the binder are
dissolved in a suitable solvent and applied to a suitable substrate
by casting, doctor blade coating or spin coating. However, if
desired, the boron complex can also be applied separately as a
layer by a vapour deposition process. The substrate can be, for
example, glass or a polymer material which is provided with a
transparent electrode. As polymer material, it is possible to use,
for example, a film of polycarbonate, polyester such as
polyethylene terephthalate or polyethylene naphthalate,
polysulphone or polyimide.
[0091] Suitable transparent electrodes are
[0092] a) metal oxides, e.g. indium-tin oxide (ITO), tin oxide
(NESA), zinc oxide, doped tin oxide, doped zinc oxide, etc.,
[0093] b) semi-transparent metal films, e.g. Au, Pt, Ag, Cu
etc.,
[0094] c) conductive polymer films such as polyanilines,
polythiophenes, etc.
[0095] The metal oxide electrodes and the semitransparent metal
film electrodes are applied in a thin layer by techniques such as
vapour deposition, sputtering, platination, etc. The conductive
polymer films are applied from the solution by techniques such as
spin coating, casting, doctor blade coating, etc.
[0096] The thickness of the transparent electrode is from 3 nm to
several .mu.m, preferably from 10 nm to 500 nm.
[0097] The electroluminescent layer is applied as a thin film
directly to the transparent electrode or to a charge transport
layer which may be present. The thickness of the film is from 10 to
500 nm, preferably from 20 to 400 nm, particularly preferably from
50 to 250 nm.
[0098] A further charge transport layer may be inserted on the
electroluminescent layer before application of a
counterelectrode.
[0099] A listing of suitable intermediate charge transport layers,
which may be hole conductor or electron conductor materials and may
be present in polymeric or low molecular weight form, if desired as
a blend, is given in EP-A 0 532 798. Particularly suitable charge
transport materials are specifically substituted polythiophenes
which have hole transport properties. They are described, for
example, in EP-A 0 686 662.
[0100] The content of a low molecular weight hole conductor in a
polymeric binder can be varied within the range from 2 to 97% by
weight; the content is preferably from 5 to 95% by weight,
particularly preferably from 10 to 90% by weight, in particular
from 10 to 85% by weight. The hole injection or hole conduction
zones can be deposited by various methods.
[0101] Film-forming hole conductors can also be used in pure form
(100% hole conductor). If desired, the hole injection or hole
conduction zone can also contain amounts of an electroluminescent
substance.
[0102] Blends consisting entirely of low molecular weight compounds
can be vapour-deposited; soluble and film-forming blends, which may
contain a binder in addition to low molecular weight compounds, can
be deposited from solution, e.g. by means of spin coating, casting
or doctor blade coating.
[0103] It is also possible to apply emitting and/or
electron-conducting substances in a separate layer on the hole
conduction layer. Here, an emitting substance can also be added as
dopant to the layer containing the compound (II) and, in addition,
an electron-conducting substance can be applied. An
electroluminescent substance can also be added to the electron
injection or electron conduction layer.
[0104] The content of low molecular weight electron conductors in
the polymeric binder can be varied within the range from 2 to 95%
by weight; the content is preferably from 5 to 90% by weight,
particularly preferably from 10 to 85% by weight. Film-forming
electron conductors can also be used in pure form (100% electron
conductor).
[0105] The counterelectrode comprises a conductive substance which
may be transparent. Preference is given to metals, e.g. Al, Au, Ag,
Mg, In, etc., or alloys and oxides of these, which can be applied
by techniques such as vapour deposition, sputtering or
platination.
[0106] The assembly of the invention is connected to a power source
by means of two electric leads (e.g. metal wires) connected to the
two electrodes.
[0107] On application of a DC potential in the range from 0.1 to
100 volt, the assemblies emit light having a wavelength of from 200
to 2000 nm. They display photoluminescence in the range from 200 to
2000 nm.
[0108] The assemblies of the invention are suitable for producing
lighting units and units for the display of information.
EXAMPLES
Example 1
[0109] 12
[0110] 5.0 g (34.67 mmol) of 8-aminoquinoline together with 50 ml
of dry pyridine are placed in the reaction vessel. While cooling in
an ice bath, 5.15 g (34.67 mmol) of heptanoyl chloride are added
dropwise. The mixture is subsequently stirred for 6 hours at room
temperature. The reaction mixture is then poured into 500 ml of ice
water. The aqueous solution is shaken with portions of chloroform,
using a total of 600 ml of chloroform. The organic phase is dried
over sodium sulphate. Removal of the solvent and distillation under
a high vacuum gave 6.69 g ( 75.3% of theory) of the desired
ligand.
Example 2
Complexation
[0111] 13
[0112] 4.0 g (15.6 mmol) of the ligand from Example 1 and 5.4 g
(15.6 mmol) of diphenylboric anhydride are refluxed in 250 ml of a
dry mixture of ethanol/tetrahydrofuran (3:1) with TLC monitoring.
Removal of the solvent gives a crude product which can be purified
by chromatography.
[0113] This gives 2.1 g ( 32% of theory) of an orange solid which
displays a green solid-state fluorescence. The compound is
completely soluble in cold methanol.
Examples, Physical Part
Example 1
[0114] The substance B4 according to the invention is used for
making an organic light emitting diode (OLED). The following
procedure was used for producing the OLED:
[0115] 1. Cleaning the ITO substrate
[0116] ITO-coated glass (Merck Balzers AG, FL, Part. No. 253 674
XO) is cut into 50 mm.times.50 mm pieces (substrates). The
substrates are subsequently cleaned in a 3% strength aqueous
Mukasol solution in an ultrasonic bath for 15 min. The substrates
are then rinsed with distilled water and spun dry in a centrifuge.
This rinsing and drying procedure is repeated 10 times.
[0117] 2. Application of the .RTM.Baytron P layer to the ITO
[0118] About 10 ml of the 1.3% strength
polyethylenedioxythiophene/polysty- renesulphonic acid solution
(Bayer AG, Baytron P) are filtered (Millipore HV, 0.45 .mu.m). The
substrate is subsequently placed on a spin coater and the filtered
solution is spread over the ITO-coated side of the substrate. The
excess solution on the substrate is subsequently spun off by
rotation of the plate at 500 rpm for 3 minutes. The substrate which
has been coated in this way is then dried at 110.degree. C. for 5
minutes on a hotplate. The thickness of the layer is 60 nm (Tencor,
Alphastep 200).
[0119] 3. Application of the hole conduction layer
[0120] 5 ml of a 1.5% strength dichloroethane solution of 1 part by
weight of polyvinylcarbazole (BASF, Luvican), 1 part by weight of
phenylamine (Agfa-Gevaert, Compound A1) and 1 part by weight of
phenylamine (Agfa-Gevaert, A2) are filtered (Millipore HV, 0.45
.mu.m) and spread on the dried Baytron P layer. The excess solution
on the substrate is subsequently spun off by rotation of the plate
at 800 rpm for 30 seconds. The substrate which has been coated in
this way is then dried at 110.degree. C. for 5 minutes on a
hotplate. The total thickness of the layers is 150 nm.
[0121] 4. Application of the light-emitting/electron-injecting
layer by vapour deposition
[0122] A third organic layer, namely the substance B4 according to
the invention, is applied to the above two organic layers by
thermal vapour deposition. This is carried out in a vapour
deposition unit (Leybold, Univex 350). The pressure in the vapour
deposition unit during the deposition procedure is 10.sup.-3 Pa and
the deposition rate is 2 .ANG./sec. The total thickness of the 3
organic layers is 200 nm.
[0123] 5. Application of the metal cathode by vapour deposition
[0124] A metal electrode is applied to the organic layer system by
vapour deposition. For this purpose, the substrate is placed with
the organic layer system facing downwards on a perforated mask
(hole diameter: 5 mm). At a pressure of 10.sup.-3 Pa, the elements
Mg and Ag are vaporized in parallel from two vaporization boats.
The deposition rate for Mg is 28 .ANG./sec. The thickness of the
vapour-deposited metal contacts is 500 nm.
[0125] The two electrodes of the organic LED are connected to a
voltage source by means of electric leads. The positive pole is
connected to the ITO electrode and the negative pole is connected
to the MgAg electrode.
[0126] From a voltage of only 3 volt, electroluminescence can be
detected by means of a photodiode (EG&G C30809E). At a voltage
of 10 volt, the current per unit area is 1.5 mA/cm.sup.2 and the
electroluminescence is readily visible. The color of the
electroluminescence is greenish blue.
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