Electroluminescent arrangements using blend systems

Details Electroluminescent arrangements using blend systems Electroluminescent arrangements using blend systems

1999-02-09

2003-04-01

Yamnitzky, Marie (Department: 1774)

Stock material or miscellaneous articles

Composite

Of inorganic material

C428S917000, C313S504000

Reexamination Certificate

active

06541128

ABSTRACT:

An electroluminescent (EL) arrangement is characterised in that it emits light with current flow on the application of an electrical voltage. In technology such arrangements have for a long time been known by the term “light diodes” (LEDs =light-emitting diodes). The emission of light takes place owing to the fact that positive charges (holes) and negative charges (electrons) recombine with the emission of light.
Nowadays mainly inorganic semiconductors, such as gallium arsenide, are used in the development of light-emitting components for electronics or photonics. Display elements in the form of dots can be produced from such substances. Large-surface arrangements are not possible.
Besides the semiconductor light diodes, electroluminescent arrangements based on vapour-deposited low-molecular organic compounds 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).
Polymers, such as poly(p-phenylenes) and poly(p-phenylenevinylenes) (PPV) are also reported as being 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.
EP-A 0 294 061 introduces an optical modulator based on polyacetylene.
For the production of flexible polymer LEDs, Heeger et al. have proposed soluble conjugated PPV-derivatives (WO 92/16023).
Polymer blends of varying composition are also known: M Stolka et. al., Pure 7 Appt. Chem., Vol. 67, No. 1, pp 175-182, 1995; H. Bässler et al., Adv. Mater. 1995, 7, No. 6, 551; K. Nagaietal., Appl. Phys. Lett. 67 (16) 1995, 2281; EP-A 532 798.
The organic EL arrangements generally contain one or more layers of organic charge-transport compounds. The fundamental structure, in order of layers, is as follows:
1. carrier, substrate
2. basis electrode
3. hole-injecting layer
4. hole-transporting layer
5. light-emitting layer
6. electron-transporting layer
7. electron-injecting layer
8. top electrodes
9. contacts
10. case, encapsulation.
Layers 3 to 7 constitute the electroluminescent element.
This structure represents the most universal case and can be simplified by omitting individual layers, so that one layer assumes several functions. In the simplest case, an EL arrangement consists of two electrodes, between which there is an organic layer which fulfils all the functions, including that of light emission. Such systems are described, for example, in the Application WO 90/13148, based on poly(p-phenylenevinyls).
Multilayered systems can be built up by vapour-deposition processes, during which the layers are successively applied from the vapour phase, or by casting processes. Casting processes are preferred, because of the higher processing speeds. Admittedly, the partial solution of an already applied layer in the course of covering it with the next layer can be a difficulty in certain cases.
The object of the present invention is to provide electroluminescent arrangements which have high luminance and in which the mixture to be applied can be applied by casting.
It has been found that these requirements are met by electroluminescent arrangements containing the blend system specified below. In the following, the term “zone” is to be regarded as equivalent to “layer”. The present invention accordingly provides electroluminescent arrangements containing a substrate, an anode, an electroluminescent element and a cathode, wherein at least one of the two electrodes is transparent in the visible spectral range and the electroluminescent element can contain, in order:
a hole-injecting zone, hole-transporting zone, electroluminescent zone, electron-transporting zone and/or an electron-injecting zone, characterised 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 contains optionally a further functionalised compound selected from among the hole-transporting materials, a luminescent material B) and optionally electron-transporting materials, and the hole-injecting and hole-transporting zone can contain one or more further hole-transporting compounds in addition to component A), at least one zone being present, individual zones can be omitted and the zone(s) present can assume one or more functions.
A zone can assume several functions; that is to say, a zone can contain, for example, hole-injecting, hole-transporting, electroluminescent, electron-injecting and/or electron-transporting substances.
The electroluminescent element can also contain one or more transparent polymeric binders C.
The optionally substituted tris-1,3,5-(aminophenyl)benzene compound A) represents an aromatic tertiary amino compound corresponding to the general formula (I)
wherein
R
2
represents hydrogen, optionally substituted alkyl or halogen,
R
3
and R
4
, independently of one another, represent optionally substituted C
1
-C
10
-alkyl, alkoxycarbonyl-substituted C
1
-C
10
-alkyl, optionally substituted aryl, optionally substituted aralkyl or optionally substituted cycloalkyl.
R
3
and R
4
, independently of one another, represent preferably C
1
-C
6
-alkyl, in particular methyl, ethyl, n- or isopropyl, n-, iso-, sec.- or tert.-butyl, C
1
-C
4
-alkoxycarbonyl-C
1
-C
6
-alkyl, such as, for example, methoxy-, ethoxy-, propoxy-, butoxycarbonyl-C
1
-C
4
-alkyl; also phenyl-C
1
-C
4
-alkyl, naphthyl-C
1
-C
4
-alkyl, cyclopentyl, cyclohexyl, phenyl or naphthyl, in each case optionally substituted by C
1
-C
4
-alkyl and/or C
1
-C
4
-alkoxy.
Particularly preferably R
3
and R
4
, independently of one another, represent unsubstituted phenyl or naphthyl, or phenyl or naphthyl each singly to triply substituted by methyl, ethyl, n-, isopropyl, methoxy, ethoxy, n- and/or isopropoxy.
R
2
represents preferably hydrogen, C
1
-C
6
-alkyl, such as, for example, methyl, ethyl, n- or isopropyl, n-, iso-, sec.- or tert.-butyl or chlorine.
Compounds such as these and their preparation are described in U.S. Pat. No. 4,923,774 for use in electrophotography, and the patent just cited is herewith expressly incorporated as part of the present description (“incorporated by reference”). The tris(nitrophenyl) compound can be converted into the tris(aminophenyl) compound, for example, by generally known catalytic hydrogenation, for instance, in the presence of Raney nickel (Houben-Weyl 4/1 C, 14-102, Ullmann (4) 13, 135-148). The amino compound is reacted with substituted halobenzenes in the generally known way.
The following compounds, wherein the substitution on the phenyl ring can be ortho, meta and/or para to the amine nitrogen, are given by way of example.
In addition to component A), further hole conductors, for example, in the form of a mixture with component A), may optionally be used for the construction of the electroluminescent element. These may on the one hand be one or more compounds corresponding to formula (I), also including mixtures of isomers; on the other hand they may also be mixtures of hole-transporting compounds with compounds of A)—corresponding to the general formula (I)—of different structure.
A list of possible hole-injecting and hole-conducting materials is given in EP-A 532 798.
In the case of mixtures of component A), the compounds may be used in any proportion between 0 and 100 wt. % (based on the mixture A)). In a preferred embodiment, 1 to 99 wt. % and 99 to 1 wt. %, particularly preferably 5 to 95 wt. % and 95 to 5 wt. %, are used. In another preferred embodiment, 30 to 70 wt. % and 70 to 30 wt. % are used.
Examples which may be given are:
anthracene compounds, for example, 2,6,9, 10-tetraisopropoxyanthracene; oxadiazole compounds, for example, 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; triphenylamine compounds, for example, N,N′-diphenyl-N,N′-di(3-methylphenyl)-1,1′

Affiliated with

Also associated with

Rating

Electroluminescent arrangements using blend systems does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electroluminescent arrangements using blend systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electroluminescent arrangements using blend systems will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3067940