U.S. patent application number 10/038218 was filed with the patent office on 2002-07-11 for electroluminescent arrangement using doped blend systems.
Invention is credited to Deussen, Martin, Elschner, Andreas, Heuer, Helmut-Werner, Huppauff, Martin, Wehrmann, Rolf.
Application Number | 20020090532 10/038218 |
Document ID | / |
Family ID | 7856318 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020090532 |
Kind Code |
A1 |
Heuer, Helmut-Werner ; et
al. |
July 11, 2002 |
Electroluminescent arrangement using doped blend systems
Abstract
Electroluminescent arrangements, composed of a substrate, an
anode, an electroluminescent element and a cathode, at least one of
the two electrodes being transparent in the spectral range and it
being possible for the electroluminescent element to contain the
following zones: a hole-injecting zone, hole-transporting zone,
electroluminescent zone, electron-transporting zone and/or an
electron-injecting zone, characterized in that the hole-injecting
and/or hole-transporting zone contains an optionally substituted
tris-1,3,5-(aminophenyl)benzene compound A) or a mixture thereof
and the electroluminescent element optionally contains a further
functionalized compound from the group consisting of the optionally
hole-transporting materials, a luminescent material B) or a
quinacridone derivative C), it being possible for the
hole-injecting and hole-transporting zone to contain one or more
further hole-transporting compounds in addition to the component A,
at least one zone being present, it being possible for individual
zones to be omitted and it being possible for the zone(s) present
to perform several functions.
Inventors: |
Heuer, Helmut-Werner;
(Krefeld, DE) ; Wehrmann, Rolf; (Krefeld, DE)
; Deussen, Martin; (Marburg, DE) ; Elschner,
Andreas; (Mulheim, DE) ; Huppauff, Martin;
(Stuttgart, DE) |
Correspondence
Address: |
CONNOLLY, BOVE, LODGE & HUTZ, LLP
1220 Market Street
P.O. Box 2207
Wilmington
DE
19899
US
|
Family ID: |
7856318 |
Appl. No.: |
10/038218 |
Filed: |
January 4, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10038218 |
Jan 4, 2002 |
|
|
|
09236937 |
Jan 25, 1999 |
|
|
|
Current U.S.
Class: |
428/690 ;
313/504; 313/506; 427/66; 428/917 |
Current CPC
Class: |
C09K 11/00 20130101;
H01L 51/0072 20130101; Y10S 428/917 20130101; H01L 51/0037
20130101; H01L 2251/308 20130101; H01L 51/0042 20130101; H01L
51/0059 20130101; H01L 51/5012 20130101 |
Class at
Publication: |
428/690 ;
428/917; 313/504; 313/506; 427/66 |
International
Class: |
H05B 033/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 1998 |
DE |
198 03 889.5 |
Claims
1. An electroluminescent arrangement which comprises a substrate,
an anode, an electroluminescent element, cathode and said anode or
said cathode is transparent in the visible spectral range and the
electroluminescent element contains at least one zone selected from
the group consisting of: (1) a hole-injecting zone, (2)
hole-transporting zone, (3) electroluminescent zone, (4)
electron-transporting zone and (5) electron-injecting zone, and at
least one quinacridone is present in at least one of said zones and
with the proviso that if more than one zone is present then the
zones would be in the following order of (1) to (5) providing that
the zone is present.
2. The electroluminescent arrangement as claimed in claim 1,
wherein the quinacridone is a compound of the formula (IIIa) 17in
which R.sub.11, R.sub.12, R.sub.13 and R.sub.14, independently of
one another, represent hydrogen, halogen, a substituted
C.sub.1-C.sub.15-alkyl, unsubstituted C.sub.1-C.sub.15-alkyl,
C.sub.1-C.sub.16-alkoxy, C.sub.1-C.sub.16-alkylth- io,
C.sub.4-C.sub.8-cycloalkyl, a substituted aryl, an unsubstituted
aryl or arylalkyl, wherein the substituents are selected from the
group consisting of C.sub.1-C.sub.15 alkyl,
C.sub.1-C.sub.15-alkoxy, halogen, OH and C.sub.6-C.sub.15-aryl, and
with the proviso that at least 2 radicals per outer phenyl ring are
not simultaneously representing hydrogen and in addition it being
possible for an alkylation to be present at the nitrogen atom, or
at least one adjacent R.sub.11, R.sub.12, R.sub.13 and R.sub.14,
with the atoms between them are joined together to form a ring
R.sub.15 is hydrogen, unsubstituted C.sub.1-C.sub.16-alkyl,
substituted C.sub.1-C.sub.16-alkyl, unsubstituted
C.sub.4-C.sub.8-cycloalkyl or substituted
C.sub.4-C.sub.8-cycloalkyl, and wherein the substituents are
selected from the group consisting of C.sub.1-C.sub.15 alkyl,
C.sub.1-C.sub.15-alkoxy, halogen, OH and C.sub.6-C.sub.15-aryl.
3. The electroluminescent arrangement as claimed in claim 2,
wherein the quinacridone is a compound of the formula (IIIb) 18in
which Z, independently in the two rings, is the atoms which
complete a ring and R.sup.1 is hydrogen, C.sub.1-C.sub.16-alkyl or
C.sub.4-C.sub.8-cycloalkyl- .
4. The electroluminescent arrangements according to claim 1,
wherein the electroluminescent element further contains a
transparent polymeric binder.
5. The electroluminescent arrangements according to claim 1,
wherein electroluminescent element further contains an aromatic
tertiary amino compound of the formula (I) 19in which R.sup.2 is
hydrogen, halogen, unsubstituted alkyl, or an alkyl substituted
with an alkoxy, hydroxy or halogen, R.sup.3 and R.sup.4,
independently of one another, are optionally substituted
C.sub.1-C.sub.10-alkyl, alkoxycarbonyl-substituted
C.sub.1-C.sub.10-alkyl, optionally substituted aryl, optionally
substituted aralkyl or optionally substituted cycloalkyl, wherein
the substitutent are alkyl, alkoxy, hydroxy, aryl or halogen.
6. The electroluminescent arrangement according to claim 5, wherein
R.sup.2 is hydrogen or C.sub.1-C.sub.6-alkyl, R.sup.3 and R.sup.4,
independently of one another, are C.sub.1-C.sub.6-alkyl,
C.sub.1-C.sub.4-alkoxycarbonyl-C.sub.1-C.sub.6-alkyl, phenyl,
naphthy, phenyl-C.sub.1-C.sub.4-alkyl,
naphthyl-C.sub.1-C.sub.4-alkyl, cyclopentyl or cyclohexyl, each of
which is optionally substituted by at least one
C.sub.1-C.sub.4-alkyl or C.sub.1-C.sub.4-alkoxy.
7. The electroluminescent arrangement according to claim 1, which
further comprises a tertiary amine selected from the group
consisting of 20
8. The electroluminescent arrangement according to claim 1, which
further comprises a luminescent compound of the formula (II) 21in
which Me represents a metal, m is a number from 1 to 3 n is a
number from 1 to 3 and Z independently in the two forms, represents
atoms which complete a nucleus which consists of at least of 2
fused rings.
9. The electroluminescent arrangement according to claim 7, which
further comprises a luminescent compound of the formula (II) 22in
which Me represents a metal, m is a number from 1 to 3 n is a
number from 1 to 3 and Z independently in the two forms, represents
atoms which complete a nucleus which consists of at least of 2
fused rings and wherein the electroluminescent element further
contains a transparent polymeric binder.
10. The electroluminescent arrangement according to claim 1,
wherein the quinacridone compound is selected from the group
consisting of 23
11. The electroluminescent arrangement according to claim 9,
wherein Me is a monovalent, divalent or trivalent metal which forms
chelates.
12. The electroluminescent arrangement according to claim 9,
wherein said luminescent compound is oxine complexes
(8-hydroxyquinoline complexes) of Al.sup.3+, Mg.sup.2+, In.sup.3+,
Ca.sup.2+, Na.sup.+ or aluminiumtris(5-methyloxine) or
gallium-tris(5-chloroquinoline) or rare earth metal complexes.
13. The electroluminescent arrangement according to claim 3,
wherein the transparent binder is selected from the group
consisting of polycarbonates, polyester carbonates, copolymers of
styrene, polysulphones, polymers based on monomers containing vinyl
groups, polyolefins, cyclic olefin copolymers and phenoxy
resins.
14. The electroluminescent arrangement according to claim 3,
wherein the transparent binder is styrene-acrylonitrile copolymer
or styrene acrylates.
15. The electroluminescent arrangement according to claim 1,
wherein the sum of the amounts by weight trisaminophenyl benzene
compound and luminscent material in the polymeric binder is in the
range from about 0.2 to about 98% by weight (based on 100% by
weight of trisaminophenyl benzene compound, quinacridone and
luminscent material) and the weight ratio weight of trisaminophenyl
benzene compound: luminscent material is between about 0.05 and
about 20.
16. The electroluminescent arrangement according to claim 1,
wherein the electroluminescent element contains a further
charge-transporting substance selected from the group consisting of
the hole-conducting material and electron-conducting material.
17. The electroluminescent arrangement according to claim 1,
wherein the electroluminescent element consists of a one layer
system.
18. The electroluminescent arrangement according to claim 1,
wherein the electroluminescent element consists essentially of a
zone which contains an optionally substituted
tris-1,3,5-(aminophenyl)benzene compound, aluminum salt of
8-hydroxquinoline (aluminum oxinate) and polyvinylcarbazole.
19. An article which comprises the electroluminescent as claimed in
claim 1.
20. The article as claimed in claim 19, wherein said article is
selected from the group consisting of illumination/backlighting
display, information display, segment display and matrix display.
Description
[0001] This application claims priority to German Patent
Application 198 03 889.5 filed Jan. 31, 1998 which is incorporated
by reference in its entirety for all purposes.
[0002] An electroluminescent (EL) arrangement is characterized in
that, with application of an electric voltage, it emits light with
a flow of current. Such arrangement has long been known in industry
by the name "light emitting diodes" (LEDs). The emission of light
occurs as result of positive charges (holes) and negative charges
(electrons) recombining with emission of light.
[0003] In the development of light-emitting components for
electronics or photonics, mainly inorganic semiconductors, such as
gallium arsenide, are used today. Point-like display elements can
be produced on the basis of such substances. Extensive arrangements
are not possible.
[0004] In addition to the semiconductor light emitting diodes,
electroluminescent arrangements based on low molecular weight
organic compounds applied by vapour deposition are known (U.S. Pat.
No. 4,539,507, U.S. Pat. No. 4,769,262, U.S. Pat. No. 5,077,142,
EP-A 406,762, EP-A 278,758, EP-A 278,757).
[0005] Furthermore, polymers such as poly-(p-phenylene) and
poly-(p-phenylenevinylene) (PPV) are 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 443 861, WO-A-9203490 and 92003491.
[0006] EP-A 0 294 061 presents an optical modulator based on
polyacetylene.
[0007] For the production of flexible polymer LEDs, Heeger et al.,
have proposed soluble conjugated PPV derivatives (WO 92/16023).
[0008] Polymer blends of different compositions are likewise known:
M. Stolka et al., Pure and Appl. 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 532 798.
[0009] The organic EL arrangements contain, as a rule, one or more
layers of organic charge-transporting compounds. The basic
structure in the sequence of the layers is as follows:
1 1 Carrier, substrate 2 Base electrode 3 Hole-injecting layer 4
Hole-transporting layer 5 Light-emitting layer 6
Electron-transporting layer 7 Electron-injecting layer 8 Top
electrode 9 Contacts 10 Envelope, encapsulation.
[0010] The layers 3 to 7 constitute the electroluminescent
element.
[0011] This structure represents the most general case and can be
simplified by omitting individual layers so that one layer performs
several functions. In the simplest case, an EL arrangement consists
of two electrodes between which is located an organic layer which
performs all functions--including the function of light emission.
Such systems are described, for example, in the application WO
90/13148, on the basis of poly-(p-phenylenevinylene).
[0012] Tang et al. state that the efficiency of electroluminescent
arrangements can be improved by using an emitter layer which
consists of organic matrix material with which a small amount of a
dopant has been mixed (U.S. Pat. No. 4,769,292). Preferred material
is aluminium 8-hydroxyquinoline (Alq.sub.3). The dopants can be
chosen from a number of different classes of intensely fluorescent
substances. Preferred examples of these are coumarins and
rhodamines.
[0013] Murayama et al. describe insoluble quinacridone pigments as
dopants (U.S. Pat. No. 5,227,252) which is incorporated by
reference in its entirety for all purposes. Further, substituted
but insoluble quinacridone pigments are described, all of which are
applied by vapour deposition methods, together with the
electroluminescent component (generally Alq.sub.3) (covaporization)
(EP 0 766 498 A2 and Tang, Information Display 10/96, C. W. Tang,
Information Display 10/96, 16 (1996), T. Wakimoto, S. Kawami, K.
Nagayama, Y. Yonemoto, R. Murayama, J. Funaki, H. Sato, H. Nakada,
K. Imai, International Symposium of Inorganic and Organic
Electroluminescence 1994, Hamamatsu, Japan 1994, Conference Volume
S. 77, J/.Shi, C. W. Tang, Appl. Phys. Lett. 70 (13), 1665 (1997),
U.S. Pat. No. 5,616,427 A). It was found that EL arrangements
having a dopant in the organic emitter layer also had improved
long-term behaviour during operation in addition to an increased
efficiency.
[0014] Multilayer systems can be built up by vapour deposition
methods, in which the layers are applied successively from the gas
phase, or by casting methods. Owing to the higher process speeds,
casting methods are preferred. However, the surface dissolution
process of an already applied layer during overcoating with the
next layer may present a difficulty in certain cases.
[0015] The object of the present invention is the provision of
electroluminescent arrangements having high luminous density and
improved stability, it being possible to use a casting method to
apply the doped mixture to be applied.
[0016] For this purpose, it was necessary to synthesize specially
substituted quinacridone derivatives which have sufficient
solubility for the casting process in the solvents used. Cast,
doped systems are said to have improved long-term behaviour
compared with undoped systems.
[0017] It was found that electroluminescent arrangements which
contain the blend system stated below meet these requirements.
Below, the term zone is also equivalent to layer.
[0018] The present invention therefore relates to
electroluminescent arrangements containing a substrate, an anode,
an electroluminescent element and a cathode, at least one of the
two electrodes being transparent in the visible spectral range and
it being possible for the electroluminescent element to contain in
sequence:
[0019] A hole-injecting zone, hole--transporting zone,
electroluminescent zone, electron-transporting zone and/or an
electron-injecting zone, characterized in that the hole-injecting
and/or hole-transporting zone is an optionally substituted
tris-1,3,5-(aminophenyl)benzene compound A or a mixture thereof and
the electroluminescent element optionally contains a further
functionalized compound from the group consisting of the
hole-transporting materials, a luminescent material B and
optionally electron-transporting materials, it being possible for
the hole-injecting and hole-transporting zone to contain one or
more further hole-transporting compounds in addition to the
component A, at least one zone being present, it being possible to
omit individual zones and it being possible for the zone(s) present
to perform several functions, the electroluminescent element
containing a substituted quinacridone compound C as a dopant in at
least one zone.
[0020] A zone may perform several functions, that is to say that a
zone may contain, for example, hole-injecting, hole-transporting,
electroluminescent, electron-injecting and/or electron-transporting
substances and dopant.
[0021] The electroluminescent element may furthermore contain one
or more transparent polymeric binders D.
[0022] The optionally substituted tris-1,3,5-(aminophenyl)benzene
compound A represents an aromatic tertiary amino compound of the
general formula (I) 1
[0023] in which
[0024] R.sup.2 represents hydrogen, optionally substituted alkyl or
halogen, wherein the substituent is alkoxy, aryl, OH or
halogen,
[0025] R.sup.3 and R.sup.4, independently of one another, represent
hydrogen, optionally substituted C.sub.1-C.sub.10-alkyl,
alkoxycarbonyl-substituted C.sub.1-C.sub.10-alkyl, or aryl, aralkyl
or cycloalkyl, each of which is optionally substituted with a
hydrocarbon, halogen heteroatom, hydroxy or alkoxy.
[0026] R.sup.3 and R.sup.4, independently of one another,
preferably represent 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-alkoxycarbonyl-- C.sub.1-C.sub.6-alkyl, such as,
for example, methoxy-, ethoxy-, propoxy- or
butoxycarbonyl-C.sub.1-C.sub.4-alkyl, or
phenyl-C.sub.1-C.sub.4-alkyl, naphthyl-C.sub.1-C.sub.4-alkyl,
cyclopentyl, cyclohexyl, phenyl or naphthyl, each of which is
optionally substituted by C.sub.1-C.sub.4-alkyl and/or
C.sub.1-C.sub.4-alkoxy.
[0027] R.sup.3 and R.sup.4, independently of one another,
particularly preferably represent unsubstituted phenyl or naphthyl
or phenyl or naphthyl, each of which is monosubstituted to
trisubstituted by methyl, ethyl, n- or iso-propyl, methoxy, ethoxy,
n- and/or iso-propoxy.
[0028] R.sup.2 preferably represents hydrogen,
C.sub.1-C.sub.6-alkyl, such as, for example, methyl, ethyl, n- or
iso-propyl, n-, iso-, sec- or tert-butyl, or chlorine.
[0029] Such compounds and their preparation are described in U.S.
Pat. No. 4,923,774 for use in electrophotography, which is hereby
expressly incorporated by reference as part of the description. The
tris-nitrophenyl compound can be converted into the trisaminophenyl
compound, for example 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 in
a generally known manner with substituted halogenobenzenes.
[0030] The following compounds may be mentioned by way of example,
it being possible for the substitution on the phenyl ring to take
place ortho, meta and/or para to the amine nitrogen: 2
[0031] In addition to the component A, further hole conductors, for
example in the form of a mixture with the component A, may
optionally be used for producing the electroluminescent elements.
These may be, on the one hand, one or more compounds of the formula
(I), mixtures of isomers also being included, and, on the other
hand, also mixtures of hole-transporting compounds with compounds
of A--of the general formula (I)--having different structures.
[0032] A list of possible hole-injecting and hole-conducting
materials is given in EP-A 532 798 which corresponds to U.S. Pat.
No. 5,281,489 which is incorporated by reference in its entirety
for all purposes.
[0033] In the case of mixtures of the component A), the compound
can be used in any desired ratio between 0 and 100% by weight
(based on the mixture A)). In a preferred embodiment, 1 to 99% by
weight and 99 to 1% by weight, particularly preferably about 5 to
about 95% by weight and about 95 to about 5% by weight, are used.
In a further preferred embodiment, about 30 to about 70% by weight
and about 70 to about 30% by weight are used.
[0034] The following may be mentioned by way of example:
[0035] Anthracene compounds, e.g.
2,6,9,10-tetraisopropoxyanthracene; oxadiazole compounds, e.g.
2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole- , triphenylamine
compounds, e.g. N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1-
'-biphenyl-4,4'-diamine; aromatic tertiary amines, e.g.
N-phenylcarbazole, N-isopropyl-carbazole and compounds which can be
used in hole-transporting layers, as described in Japanese Patent
Application Publication No. 62-264 692; furthermore pyrazoline
compounds, e.g.
1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)-2-pyrazoline;
styryl compounds, e.g. 9-(p-diethylaminostyryl)-anthracene;
hydrazone compounds, e.g.
bis-(4-dimethylamino-2-methylphenyl)-phenyl-methane; stilbene
compounds, e.g. -(4-methoxyphenyl)-4-N,N-diphenylamino-(4'-metho-
xy)stilbene, enamine compounds, pounds, e.g.
1,1-(4,4'-diethoxyphenyl)-N,N- -(4,4'-dimethoxyphenyl)enamine;
metal- or nonmetal-phthalocyanines and porphyrin compounds.
[0036] Triphenylamine compounds and/or aromatic tertiary amines are
preferred, the compounds mentioned by way of example being
particularly preferred.
[0037] Materials which have hole-conducting properties and can be
used for mixing with component A are, for example 3
[0038] These and further examples are described in J. Phys. Chem.
1993, 97, 6240-6248 and Appl. Phys. Lett., Vol. 66, No. 20,
2679-2681.
[0039] The component B) represents a compound of the general
formula (II) 4
[0040] in which
[0041] Me represents a metal,
[0042] m is a number from 1 to 3 and
[0043] Z independently in the two forms, represents atoms which
complete a nucleus which consists at least of 2 fused rings.
[0044] In general, monovalent, divalent or trivalent metals which
are known to form chelates may be used.
[0045] The metal may be a monovalent, divalent or trivalent metal,
preferably of the 1st, 2nd and 3rd main group and 2nd subgroup of
the Periodic Table, for example lithium, sodium, potassium,
magnesium, calcium, boron, aluminium, indium, gallium, zinc and
beryllium.
[0046] Z completes the heterocyclic molecular moiety which consists
at least of two fused rings, one of which is an azole or azine
ring, it being possible for further additional aliphatic or
aromatic ring to be bonded to the two fused rings.
[0047] Suitable examples for the component B) are the oxine
complexes (8-hydroxyquinoline complexes) of Al.sup.3+, Mg.sup.2+,
In.sup.3+, Ga.sup.3+, Zn.sup.2+, Be.sup.2+, Li.sup.+, Ca.sup.2+,
Na.sup.+ or aluminiumtris(5-methyloxine) and
galliumtris(5-chloro-quinoline). Complexes with rare earth metals
may also be used.
[0048] Examples of component B are 5
[0049] Inq.sub.3, Gaq.sub.3, Znq.sub.2, Beq.sub.2, Mgq.sub.2,
[0050] or Al(qa).sub.3, Ga(qa).sub.3, In(qa).sub.3, Zn(qa).sub.2,
Be(qa).sub.2, Mg(qa).sub.2 in which (qa) represents 6
[0051] One or more compounds of the component B) may be used. The
compounds or oxine complexes according to B) are generally known or
can be prepared by known processes (cf. for example U.S. Pat. No.
4,769,292) which is incorporated by references in its entirety for
all purposes.
[0052] The substituted quinacridone compounds C) have the following
general formulae (IIIa) and (IIIb) 7
[0053] in which
[0054] R.sub.11, R.sub.12, R.sub.13 and R.sub.14, independently of
one another, represent hydrogen, halogen and optionally
halogen-substituted C.sub.1-C.sub.15-alkyl,
C.sub.1-C.sub.16-alkoxy, C.sub.1-C.sub.20-alkylth- io, cycloalkyl,
optionally substituted aryl or arylalkyl, at least 2 radicals per
outer phenyl ring not simultaneously representing hydrogen and it
being possible additionally for alkylation to be present at both
nitrogen atoms, wherein the substituents are alkoxy, halogen or
alkyl,
[0055] R.sub.15 represents hydrogen or optionally substituted
C.sub.1-C.sub.18-alkyl or optionally substituted cycloalkyl,
[0056] R.sub.11, R.sub.12, R.sub.13 and R.sub.14, independently of
one another, preferably represent C.sub.1-C.sub.6-alkyl, in
particular methyl, tert-butyl, C.sub.1-C.sub.12-alkoxy, in
particular methoxy, dodecyloxy, and C.sub.4-C.sub.10-alkylthio, in
particular octylthio, halogeno-C.sub.1-C.sub.4-alkyl, in particular
trifluoromethyl,
[0057] R.sub.15 preferably represents hydrogen,
C.sub.1-C.sub.8-alkyl, in particular methyl, octyl, tert-butyl or
cyclohexyl.
[0058] Halogen preferably represents fluorine, chlorine,
bromine.
[0059] The following may be mentioned as examples of such
compounds: 8
[0060] The substituted quincridone compound C) may also have the
following general formulae (IIIb) (stereoisomers): 9
[0061] in which
[0062] Z, independently in the two rings, represents atoms which
complete a ring, preferably an aliphatic ring having 3 to 12 carbon
atoms which may be interrupted by one or more, hetero atoms, such
as but not limited to, O, S, P or N in particular 2 to 5, oxygen
atoms,
[0063] R.sub.1 represents hydrogen, C.sub.1-C.sub.16-alkyl,
preferably C.sub.1-C.sub.10-alkyl, in particular methyl, octyl,
tert-butyl, or cyclohexyl.
[0064] The following may be mentioned as examples of such
compounds: 10
[0065] Component C may also be mixtures of possible stereoisomers
of the general forms (IIIa) and (IIIb).
[0066] The quinacridone derivatives of the formula (III) are known
or can be prepared by known methods, cf., for example, the
following reaction scheme: 11
[0067] R and R' represent one or more radicals R.sub.11, R.sub.12,
R.sub.13, R.sub.14 and have the abovementioned meaning.
[0068] The starting materials are known or commercially available
or can be prepared by generally known methods of organic
chemistry.
[0069] The binder D) represents polymers and/or copolymers, such
as, for example, polycarbonates, polyester carbonates, copolymers
of styrene, such as styrene-acrylonitrile ("SAN") or styrene
acrylates, polysulphones, polymers based on monomers containing
vinyl groups, such as, for example, poly(meth)acrylates,
polyvinyl-pyrrolidone, polyvinylcarbazole, vinyl acetate and vinyl
alcohol polymers and copolymers, polyolefins, cyclic olefin
copolymers, phenoxy resins, etc. Mixtures of different polymers may
also be used. The polymeric binders C) have molecular weights of
10,000 to 200,000 g/mol, are soluble and film-forming and are
transparent in the visible spectral range. 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 up to about 95, preferably up to about 80,% by weight, based
on the total weight of A) and B).
[0070] The electroluminescent arrangements according to the
invention are characterized in that they have a light-emitting
layer which contains a mixture of the components A), B) and C) in,
optionally, a transparent binder D). The weight ratio of A), B) and
C) to one another can be varied.
[0071] The sum of the amounts by weight of A) and B) in polymeric
binder is in the range from about 0.2 to about 98% by weight,
preferably from about 2 to about 95% by weight, particularly
preferably from about 10 to about 90% by weight, very particularly
preferably from about 10 to about 85% by weight.
[0072] The weight ratio A:B of the components A and B is between
about 0.05 and about 20, preferably about 0.2 and about 10 and
particularly preferably between about 0.3 and about 8, in
particular about 0.3 to about 7. The components A) and B) may
consist of either one component or a mixture of components having
any desired composition.
[0073] The quinacridone compound C) is present in the
electroluminescent element, it being possible for it to be
contained as a dopant in low concentration in any desired layer. It
is also possible that it is contained simultaneously in several
layers of the EL element, in each case in a different
concentration.
[0074] Preferably, the dopant is added to the hole-transporting
layer and/or light-emitting layer and/or electron-transporting
layer, very particularly preferably to the light-emitting or
light-transporting layer.
[0075] The concentration of C) in the respective guest matrix is,
independently of one another, between about 0.01 and about 40% by
weight, preferably between about 0.4 and about 10% by weight (based
on 100% by weight of components A) and B)).
[0076] For the production of the layer, the components A), B), C)
and optionally D) are dissolved in a suitable solvent and are
applied to a suitable substrate by casting, knife-coating or
spin-coating. Said substrate may be, for example, glass or a
plastics material which is provided with a transparent electrode.
For example, a film of polycarbonate, polyester, such as
polyethylene terephthalate, polybutyl terphthalate, or polyethylene
naphthalate, polysulphone or polyimide may be used as plastics
material.
[0077] Suitable as transparent electrodes are
[0078] a) metal oxides, e.g. indium tin oxide (ITO), tin oxide
(NESA), zinc oxide, doped tin oxide, doped zinc oxide, etc.,
[0079] b) semi-transparent metal films, e.g. Au, Pt, Ag, Cu,
etc.,
[0080] c) conductive polymer films, such as polyanilines,
polythiophenes, etc.
[0081] The metal oxide electrodes and the semitransparent metal
film electrodes are applied in a thin layer by techniques such as
vapour deposition, sputtering, platinization, etc. The conductive
polymers films are applied from the solution by techniques such as
spin coating, casting, knife coating, etc.
[0082] The thickness of the transparent electrode is 3 nm to about
several .mu.m or preferably about 10 nm to about 500 nm.
[0083] The electroluminescent layer is applied as a thin film,
directly to the transparent electrode or to an optionally present
charge-transporting layer. The thickness of the film is about 10 to
about 500 nm, preferably about 20 to about 400 nm, particularly
preferably about 50 to about 250 nm.
[0084] A further charge-transporting layer may be added to the
electroluminescent layer before a counter-electrode is applied.
[0085] A list of suitable charge-transporting intermediate layers
which may comprise hole- and/or electron-conducting materials,
which may be present in polymeric or low molecular weight form,
optionally as a blend, is given in EP-A 532 798 which corresponds
to U.S. Pat. No. 5,281,489 which is incorporated by reference in
its entirety. Particularly suitable are specially substituted
polythiophenes which have hole-transporting properties. They are
described, for example, in EP-A 686 662 which corresponds to U.S.
Pat. No. 5,766,515 which is incorporated by reference in its
entirety for all useful purposes. The stated references are
expressly incorporated by reference in the description.
[0086] The content of low molecular weight hole-conductor in a
polymeric binder can be varied in the range from about 2 to about
97% by weight; the content is preferably about 5 to about 95% by
weight, particularly preferably about 10 to about 90% by weight.
The hole-injecting or hole-conducting zones can be deposited by
various methods.
[0087] Film-forming hole conductors may also be used in pure form
(100% strength). Optionally, the hole-injecting or hole-conducting
zone may also contain proportions of an electroluminescent
material.
[0088] Blends which consist exclusively of low molecular weight
compounds can be applied by vapour deposition; soluble and
film-forming blends which may (not necessarily) also contain a
binder D) in addition to low molecular weight compounds and dopant
can be deposited from a solution, for example by means of spin
coating, casting or knife coating.
[0089] It is also possible to apply emitting and/or
electron-conducting substances in a separate layer onto the
hole-conducting layer with the component A. An emitting substance
according to component C) can also be added as the dopant to the
layer containing the compound A, and in addition an
electron-conducting substance can be applied. The
electroluminescent substance may also be added to the
electron-injecting or electron-conducting layer.
[0090] The content of low molecular weight electron conductors in
the polymeric binder can be varied in the range from about 2 to
about 95% by weight; the content is preferably about 5 to about 90%
by weight, particularly preferably about 10 to about 85% by weight.
Film-forming electron conductors can also be used in pure form
(100% strength).
[0091] The counter-electrode consists of a conductive substance
which may be transparent. Suitable metals are preferably, for
example, Al, Au, Ag, Mg, In, etc. or alloys and oxides thereof,
which can be applied by techniques such as vapour deposition,
sputtering or platinization.
[0092] The arrangement according to the invention is brought into
contact with the two electrodes by two electric leads (e.g. metal
wires). On application of a DC voltage in the range from about 0.1
to about 100 volt, the arrangements emit light of a wavelength from
about 200 to about 2000 .mu.m. They exhibit photoluminescence in
the range from about 200 to about 2000 nm.
[0093] The arrangements according to the invention are suitable for
the production of units for illumination and for information
display.
EXAMPLES
[0094] A) Synthesis I:
[0095] The synthesis of substituted quinacridones is carried out in
a 3-stage synthesis from diethyl
2,5-dihydroxy-1,4-cyclohexadiene-1,4-dicar- boxylate (diester of
succinylosuccinic acid) and the corresponding aniline compound
according to the following reaction scheme 12
[0096] The individual synthesis steps are described in more detail,
for example, in:
[0097] R. H. Altiparmakian, H. Bohler, B. L. Kaul, F. Kehrer,
Helvetica Chimica Acta Vol. 55, 85-100 (1972)
[0098] K. Kitahara, H. Yanagimoto, N. Nakajima, H. Nishi, J.
Heterocyclic Chem. 29, 167-169 (1992)
[0099] V. Keller, K. Muller, S. De Feyter, F. C. De Schryver, Adv.
Mater. 8, No. 6, 490-493 (1996).
Example 1
Synthesis of Compound (C.sub.1)
[0100] 13
[0101] a) 1 st Stage
[0102] 4.85 g (40 mmol) of 2,4-dimethylaniline and 5.13 g (20 mmol)
of diethyl 2,5-di-hydroxy-1,4-cyclohexadiene-1,4-di-carboxylate are
refluxed for 7 h in a mixture of 1000 ml of ethanol and 400 ml of
acetic acid under argon. After cooling to room temperature, the
pale red precipitate which has separated out is separated off and
is washed with warm ethanol. After drying, 2.54 g (27.5% of theory)
of a pink solid is obtained, which could be used without further
purification for the 2nd reaction stage.
[0103] b) 2nd Stage
[0104] 70 ml of 1-chloronaphthalene are added to 2.5 g (5.5 mmol)
of Example 1a) and thoroughly freed from oxygen in a vacuum from an
oil pump, by repeated evacuation and flushing with argon. The
mixture is refluxed on the metal bath at 260.degree. C. for 1
h.
[0105] After cooling, the solvent is separated off under reduced
pressure. The solid residue obtained is boiled several times in
acetone and filtered hot in order to remove by-products. After
drying, 1.57 g (78% of theory) of a pink solid are obtained.
[0106] c) 3rd Stage
[0107] 1.5 g (4.1 mmol) of Example 1b) and 1.25 g of KOH are
dissolved in 75 ml of diethylene glycol monomethyl ether at about
80.degree. C. 2.5 ml of nitrobenzene are added in one portion to
the solution obtained and boiling is then carried out for 4.5 hours
at 75.degree. C. while stirring. Thereafter, 10 ml of acetic acid
are added to the reaction batch and stirring is continued for 10
minutes at room temperature. After dilution with 60 ml of ethanol,
the deep red solid obtained is separated off and is washed several
times with warm ethanol and ethanol. Further purification is
effected with hot tetrahydrofuran (THF). Final purification is
effected by sublimation.
Example 2
Synthesis of Compound (C.sub.6)
[0108] 14
[0109] a) 1 st Stage
[0110] 30 g (146.1 mmol) of 2,5-di-tert-butylaniline and 18.7 g
(73.05 mmol) of diethyl
2,5-di-hydroxy-1,4-cyclohexadiene-1,4-di-carboxylate are refluxed
for 26 h in a mixture of 1000 ml of ethanol and 400 ml of acetic
acid under argon. After cooling to room temperature, the pale red
precipitate which has separated out is separated off and is washed
with warm ethanol. After drying, 33.2 g (72% of theory) of a pale
red solid are obtained, which can be used without further
purification for the 2nd reaction stage.
[0111] b) 2nd Stage
[0112] 280 ml of 1-chloronaphthaline are added to 15 g (23.8 mmol)
of Example 2a) and thoroughly freed from oxygen in a vacuum from an
oil pump, by repeated evacuation and flushing with argon. The
mixture is refluxed on the metal bath at 260.degree. C. for 3 h.
After cooling, the solvent is separated off under reduced pressure.
The solid residue obtained is boiled several times in acetone and
filtered hot in order to remove by-products. After drying, 5 g (39%
of theory) of a pink solid are obtained.
[0113] c) 3rd Stage
[0114] 5 g (9.3 mmol) of Example 2b) and 3.7 g of KOH are dissolved
in 200 ml of diethylene glycol monomethyl ether at about 80.degree.
C. 7.5 ml of nitrobenzene are added in one portion to the solution
obtained and boiling is then carried out for about 4 hours at
75.degree. C. while stirring. Thereafter, 10 ml of acetic acid are
added to the reaction batch and stirring is continued for 10
minutes at room temperature. After dilution with 100 ml of ethanol,
the deep red solid obtained is separated off and is washed several
times with warm ethanol and methanol. Further purification is
effected in hot THF. After drying, 0.66 g (13.2% of theory) of a
red solid is obtained. Final purification is effected by
sublimation.
Example 3
Synthesis of Compound (C.sub.28)
[0115] 15
[0116] a) 1 st Stage
[0117] 14.3 g (78.04 mmol) of 3,4,5-trimethoxyaniline and 10 g
(39.02 mmol) of diethyl
2,5-di-hydroxy-1,4-cyclohexadiene-1,4-dicarboxylate are refluxed in
a mixture of 500 ml of ethanol and 200 ml of acetic acid for 26 h
under argon. After cooling to room temperature, the pale red
precipitate which has separated out is separated off and is washed
with warm ethanol. After drying, 18.25 g (79.7% of theory) of a
pale red solid are obtained, which could be used without further
purification for the 2nd reaction stage.
[0118] b) 2nd Stage
[0119] 85 ml of 1-chloronaphthaline are added to 5 g (8.52 mmol) of
Example 3a) and thoroughly freed from oxygen in a vacuum from an
oil pump, by repeated evacuation and flushing with argon. The
mixture is refluxed on the metal bath at 260.degree. C. for 3 h.
After cooling, the solvent is separated off under reduced pressure.
The solid residue obtained is boiled several times in acetone and
filtered hot in order to remove by-products. After drying, 32.6 g
(77.3% of theory) of a pink solid are obtained.
[0120] c) 3rd Stage
[0121] 3 g (6.06 mmol) of Example 2b) and 3.5 g of KOH are
dissolved in 200 ml of diethylene glycol monomethyl ether at about
80.degree. C. 7.0 ml of nitrobenzene are added in one portion to
the solution obtained and boiling is then carried out for about 4
hours at 75.degree. C. while stirring. Thereafter, 10 ml of acetic
acid are added to the reaction batch and stirring is continued for
10 minutes at room temperature. After dilution with 100 ml of
ethanol, the deep red solid obtained is separated off and is washed
several times with warm ethanol and methanol. Further purification
is effected with hot THF. After drying, 1.57 g (52.5% of theory) of
a red solid are obtained. Final purification is effected by
sublimation.
[0122] Depending on the parent aniline component, all parent
quinacridone structures can be synthesized by processes analogous
to Examples 1 to 3 and are further reacted in a subsequent
N-alkylation step:
[0123] Synthesis II: 16
[0124] N,N-Dialkylquinacridone derivative
[0125] B) EL Arrangements:
[0126] The following 2 examples illustrate EL arrangements.
Example 1
[0127] The substance C.sub.6 was dissolved in methanol so that the
extinction at 500 nm in a 10 nm quartz cell is E=0.04. A
fluorescence spectrum and an excitation spectrum of this solution
were recorded on a fluorescence spectrometer (Edinburgh, FS 900),
FIG. 1. The maximum of the excitation spectrum is at 505 nm and the
maximum of the emission at 540 nm. The quantum efficiency of the
substance in methanol on excitation at ex 505 nm is 0=0.33.
Example 2
[0128] The substance C.sub.6 according to the invention is used for
producing an organic light-emitting diode (OLED). In the production
of the OLED, the following procedure is adopted:
[0129] 1. Cleaning of the ITO substrate
[0130] ITOa-coated glass (Merck Balzers AG, Germany, Flor., Part
No. 253 674 XO) is cut into 50 mm.times.50 mm pieces (substrates).
The substrates are then cleaned in 3% strength aqueous Mukasol
solutions in an Ultrasound bath for 15 min. Thereafter, the
substrates are rinsed with distilled water and spun dry in a
centrifuge. This washing and drying process is repeated 10
times.
[0131] 2. Application of the Baytron P layer to the ITO
[0132] About 10 ml of the 1.3% strength
polyethylenedioxythiophene/polysul- phonic acid solution (Bayer AG,
Leverkusen, Germany, Baytron P) are filtered (millipore HV, 0.45
.mu.m). The substrate is then placed on a spin coater and the
filtered solution is distributed over the ITO-coated side of the
substrate. The supernatant solution is then spun off by rotating
the table at 500 rpm over a period of 3 min. The substrate coated
in this manner is then dried for 5 min at 110.degree. C. on a hot
plate. The layer thickness is 60 nm (Tencor, Alphastep 200).
[0133] 3. Application of the light-emitting layer
[0134] 5 ml of 0.5% strength dichloroethane solution comprising 1
part by weight of polyvinylcarbazole (BASF AG, Ludwigshafen,
Germany, Luvican), 1 part by weight of phenylamine and 0.2 part by
weight of C.sub.6 are filtered (Millipore HV, 0.45 .mu.m) and
distributed over the dried Baytron-P layer. The supernatant
solution is then spun off by rotating the table at 100 rpm for 30
sec. The substrate coated in this manner is then dried for 5 min at
110.degree. C. on a hot plate. The total layer thickness is 150
nm.
[0135] 4. Application of the metal cathode by vapour deposition
[0136] 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). The elements Mg and Ag are vapourized
simultaneously from two vapour deposition boats at a pressure of
10.sup.-3 Pa. The vapour deposition rates are 28 .ANG./sec for Mg
and 2 .ANG./sec for Ag. The thickness of the metal contacts applied
by vapour deposition is 500 nm.
[0137] The two electrodes of the organic LED are connected to a
voltage source via electric leads. The positive pole is connected
to the ITO electrode and the negative pole is connected to the
Mg/Ag electrode.
[0138] From a voltage of only 2.5 volt, it is possible to detect
electroluminescence with a photodiode (EG&G C30809E). At a
voltage of 3 volt, a current per unit area of 1 mA/cm.sup.2 flows
and the electroluminescence is clearly visible. The colour of the
electroluminescence is green-yellow.
* * * * *