Stock material or miscellaneous articles – Composite – Of inorganic material
Patent
1997-03-10
1999-02-16
Nold, Charles
Stock material or miscellaneous articles
Composite
Of inorganic material
428691, 428917, 313504, H05B 3300
Patent
active
058718540
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention relates to an emission device by utilizing electroluminescence of an emitting element which emits light by injection of an electric current wherein the emission device is provided with an emission layer wherein the emitting element is formed into a layer. More specifically, it relates to an organic electroluminescent device (hereinafter referred to as "organic EL device") in which the emission layer is composed of an organic compound as an emitting element.
Hithertofore, organic EL devices having various structures have been proposed. For example, a two-layer type structure wherein a thin film of a fluorescent material 2 as an emission layer and a hole transport layer 3, each comprising an organic compound and being layered on each other, are arranged between a metal cathode 1 and a transparent anode 4, as shown in FIG. 1; and a three-layer type structure wherein an electron transport layer 6 comprising an organic compound, an emission layer 2 and a hole transport layer 3 are layered between a metal cathode 1 and a transparent anode 4 are known. In the above devices, the hole transport layer 3 has the function of easily injecting positive holes from the anode and the function of blocking electrons; and the electron transport layer 6 has the function of easily injecting the electrons from the cathode and the function of blocking holes.
In these organic electroluminescent devices, ITO is mainly used for the transparent electrode 4, and a film thereof is formed on a glass substrate 5. By recombination of an electron injected from the metal cathode 1 and a hole injected into the emission layer from the anode 4, light radiated in the process of radiative decay of the produced exciton is emitted through the transparent anode and the transparent glass substrate.
Detailed explanation of organic electroluminescent devices are described, for example, in the following literature references: Display Device Research Association, Science Forum (published 1992) SPIE Proceedings Vol. 1910 (1993), E. M. Conwell and M. R. Miller.
However, in the conventional organic EL devices, the stability of light emission is not necessarily considered sufficiently satisfactory, and organic EL devices which emit light more stably are desired. Under such circumstances, the present inventors extensively studied the development of organic EL devices having excellent characteristics, and, as a result, found that an organic EL device having an improved stability can be obtained by using specific benzoxazinone derivatives, and, based on this finding, completed the present invention. An object of the present invention is to provide an organic EL device which stably emits at high luminance.
The organic EL device according to the present invention is characterized in that, in the organic EL device comprising an organic compound, the emission layer comprises a benzoxazinone derivative represented by the formula (1): ##STR1## wherein R represents an electron withdrawing group, which is preferably either an acyl group represented by formula (2): or an aryl group, preferably having from 4 to 10 carbon atoms, which may have a substituent, or an aryl group, preferably having from 4 to 10 carbon atoms, which may have a substitutent; or ester group, each having from 1 to 16 carbon atoms, an aryl- or aryloxy group, having from 4 to 10 carbon atoms, which may have one or more substituents, --CN, --CF.sub.3, --F or --NR.sup.5 R.sup.6, wherein R.sup.5, R.sup.6 independently of each other represent an alkyl group, having from 1 to 16 carbon atoms, or an aryl group, having from 4 to 10 carbon atoms, which may have one or more substituents.
m, n are 0, 1, 2 or 3, preferably 0, 1 or 2, especially preferably 0.
In the above-described formulae (1), (2) and (3), when R is an alkyl group having from 1 to 16 carbon atoms, the alkyl group may have a straight chain or a branched chain and is preferably a methyl group, an ethyl group or a t-butyl group. When R.sup.1 is an aryl group which may have a substituent, preferred groups include the p
REFERENCES:
patent: 4839219 (1989-06-01), Uekita et al.
patent: 5482921 (1996-01-01), Seckinger et al.
patent: 5693693 (1997-12-01), Auslander et al.
Indian Journal of Pure and Applied Physics, Jun. 1991, vol. 29, No. 6, ISSN 0019-5596.
Chemical Physics Letters, 13 Apr. 1984, vol. 106, No. 1-2, ISSN 0009-2614, pp. 124-127.
Solar Energy Materials, Feb. 1987, vol. 15, No. 2, ISSN 0165-1633, pp. 65-75.
Kang Wen-Bing
Potrawa Thomas
Tokida Akihiko
Winterfeldt Andreas
Yu Nu
Hoechst Aktiengesellschaft
Nold Charles
LandOfFree
Organic electroluminescent device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Organic electroluminescent device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Organic electroluminescent device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2060482