Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Patent
1997-04-17
1998-04-21
Gerstl, Robert
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
25229962, 528 13, 528 32, C09K 1106, C08G 6100
Patent
active
057419213
DESCRIPTION:
BRIEF SUMMARY
RELATED APPLICATION
This application claims priority to German Application No. P 44 42 08, filed Nov. 25, 1994, incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the use in electrochemiluminescence materials, of conjugated polymers comprising at least one repeating unit based on a heterospiro framework. Such compounds surprisingly have excellent thermal stability, improved solubility in organic solvents, improved film-forming properties and particularly good electroluminescence with high color purity.
2. Description of the Related Art
Several publications are referenced in this application. These references describe the state of the art to which this invention pertains, and are incorporated herein by reference.
There is a great industrial need for large-area solid-state light sources for a series of applications, predominantly in the field of display elements, VDU technology and lighting engineering. The demands made on these light sources cannot at present be completely satisfactorily achieved by any of the existing technologies.
As an alternative to conventional display and lighting elements, such as incandescent lamps, gas-discharge lamps and non-self-illuminating liquid crystal display elements, use has been made for some time of electroluminescence (EL) materials and devices, such as light-emitting diodes (LEDs).
Apart from inorganic materials, low molecular weight organic electroluminescence materials and devices have also been known for about 30 years (see, for example, U.S. Pat. No. 3,172,862). Until recently, however, such devices had a very limited practical usability.
WO 90/13148 and EP-A 0 443 861 describe electroluminescence devices containing a film of a conjugated polymer as light-emitting layer (semiconductor layer). Such devices offer numerous advantages such as the opportunity of producing large-area, flexible displays simply and inexpensively. In contrast to liquid crystal displays, electroluminescence displays are self-illuminating and therefore require no additional backward lighting source.
A typical device according to WO 90/13148 comprises a light-emitting layer in the form of a thin, dense polymer film (semiconductor layer) which contains at least one conjugated polymer. A first contact layer is in contact with a first surface, a second contact layer with a further surface of the semiconductor layer. The polymer film of the semiconductor layer has a sufficiently low concentration of extrinsic charge carriers so that, on application of an electric field between the two contact layers, charge carriers are introduced into the semiconductor layer, which makes the one contact layer positively charged compared with the other and the semiconductor layer emits radiation. The polymers used in such devices are conjugated. For the purposes of the present invention, a conjugated polymer is a polymer possessing a delocalized electron system along the main chain. The delocalized electron system gives the polymer semiconducting properties and enables it to transport positive and/or negative charge carriers with high mobility.
In WO 90/13148, the polymeric material used for the light-emitting layer is poly(p-phenylenevinylene), and it is proposed that the phenyl group in such a material be replaced by a heterocyclic or a condensed carbocyclic ring system. In addition, poly(p-phenylene), PPP, is also used as electroluminescencing material.
Although good results have been obtained with these materials, the color purity, for example, is still unsatisfactory. Furthermore, with the polymers known hitherto it is hardly possible to generate a blue or white emission.
Since, in addition, the development of electroluminescence materials, particularly on the basis of polymers, can in no way be regarded as being concluded, the manufacturers of lighting and display devices are interested in a great variety of electroluminescence materials for such devices.
This is, inter alia, because only the combined action of the electroluminescence materia
REFERENCES:
patent: 5026894 (1991-06-01), Tour et al.
J.M. Tour et al., J. Am. Chem. Soc., vol. 113, 1991, p. 7064 ff.
J. M. Tour et al., Polym. Prepr., 1990, p. 408 ff.
J.M. Tour et al., J. Am. Chem. Soc., vol. 112, 1990, p. 5662 ff.
H. Nishihara et al., J. Chem. Soc. Faraday Trans., vol. 90, No. 2, 1994, p. 321 ff.
Kreuder Willi
Lupo Donald
Salbeck Josef
Schenk Hermann
Stehlin Thomas
Gerstl Robert
Hoechst Aktiengesellschaft
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