Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1999-07-06
2001-12-25
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S917000, C313S504000, C313S506000
Reexamination Certificate
active
06333122
ABSTRACT:
This application is a 371 application of PCT/JP97/02206 filed Jun. 26, 1997.
1. Technical Field
The present invention relates to a red light emitting material and an organic electroluminescence (hereinafter called “organic EL”) element. More particularly, the present invention r elates to a red light emitting material using fluorescent light of porphyrin and an organic EL made by using the material.
2. Background Art
An organic EL element has c characteristics of self-luminescence and thin thickness, and the element can be driven with a low voltage. The principle of the organic EL element had already been known in the 60's; at that time, however, the luminescent efficiency was still low so that the emission could only be seen in a dark place.
However, since C. W. Tang et al. published an improved element, which could be seen even in a bright place with a high luminescent efficiency, in the Applied Physics Letter, 51, 913 (1987), the research and development of organic EL has rapidly proceeded.
At the beginning of the development of organic EL, a blue light emitting element was placed emphasis on also several sorts of chemical compound therefor were suggested, because a blue emitting element having a high brightness had not existed at that time. While, many green emitting materials existed, so there was no problem concerning the green emitting material.
On the other hand, nevertheless a red light emitting material is an elemental requirement to realize a full color display; the number of sorts thereof, which have been developed until now, is smaller in comparison to the other colors, so that it is now required rapidly to develop the red light emitting material.
Conventionally, elements are known, for instance, which are disclosed in the Journal of the Applied Physics, 65, 3610 (1989), in Japanese Patent Preliminarily Publication No. Hei6-9953, in the Preliminarily Prepared Paper for the 41th Spring Lecture Meeting of Applied Physics Society, p28-N-1. However, these elements have a low color purity in order to use them as the red component of a multiple color display or a full color display, because the light emission thereof contains a low wave length component. Therefore, these elements are not sufficient for practical use.
By the way, the fact that the porphyrin derivative is useful for an electronic material, particularly, for a hole transporting material can be predicted from the property of phthalocyanine, which is called as “azaporphyrin” and has a similar construction to that of porphyrin. The electric characteristic of phthalocyanine has been well studied; many trials for an organic functional material have been taken for phthalocyanine.
Further, it is also well known that phthalocyanine is useful as a hole transporting layer of the organic EL element, from which it can be guessed that porphyrin could be used as a hole transporting layer of the organic EL element.
However, the conventionally known usage of porphyrin as an organic electronic material is limited to the hole transporting function. For instance, an application of porphyrin for a hole transporting material is mentioned in Japanese Patent Publication No. Hei01-7635, Japanese Patent Preliminarily Publication Nos. Sho63-295695, Hei-04-233194, Hei04-233195, Hei05-17765 and Hei06-215874, an application for an electrochromic material is disclosed in Japanese Patent Publication Nos. Hei01-33808 and Hei01-33809; an application for an optical memory or an optical conductive material is recited in Japanese Patent Preliminarily Publication No. Hei07-278445. All of these techniques use the hole transporting function of porphyrin; there is no study however as to the use of porphyrin as a light emitting material using its fluorescent characteristic.
In this manner, the usage of porphyrin for an organic electronic material has been widely known, but the application of porphrin for a light emitting element using its fluorescent characteristic has never been considered, much less it has not been known at all that porphyrin functions as a material for the organic EL element to realize a red light emission with a high purity.
Disclosure of Invention
The present invention has been made to solve the task of the prior art mentioned above and has its purpose to provide a red light emitting material which realizes a red light emission with a high purity and to provide an organic EL element using the material.
The present inventors studied several sorts of material to realize a red emitting organic element having a high purity; then they paid attention to a characteristic in that the porphyrin derivative has a strong absorption called a “soret band” in the vicinity of 400 nm and shows a fluorescence in the vicinity of 600 nm. As a request of studying to use the fluorescent characteristic of porphyrin, which had not been considered at all at that time, the inventors found that a red light emitting EL element with a high purity can be produced by the porphyrin and completed the present invention.
That is to say, the red light emitting material according to the present invention has a characteristic in that the material is for use in an organic electroluminescent element and consists of porphyrin.
Further, the organic electroluminescent element according to the invention comprises a light emitting layer which contains porphyrin.
Furthermore, the other organic electroluminescent element according to the invention comprises a hole transporting material, an electron transporting material and a layer which contains porphyrin of 1.0% by weight or above.
The detail of the present invention will be explained below.
It should be noted that the “porphyrin” used in the present invention is a generic term for a chemical compound having its basic structure of porphyrin where four pyrrole rings are combined by a methine group and it is obtained by substitution of hydrogen atoms existing around the basic structure.
Sometimes such a definition is used that phthalocyanine is a sort of porphyrin, however, phthalocyanine is excluded from the present invention. Since phthalocyanine, which is possessed in porphyrin, does not have the intended fluorescent characteristic, therefore it cannot be preferably used.
The porphyrin according to the invention can be expressed, for instance, by the following generic formula (1):
(wherein, R1 to R12 in the formula represent, independently, hydrogen, halogen, substituted or non-substituted alkyl group, alkoxy group, aryloxy group, perfluoroalkyl group, perfluoroalkoxy group, amino group, alkylcarbonyl group, arylcarbonyl group, alkoxycarbonyl group, aryloxycarbonyl group, azo group, alkylcarbonyloxy group, arylcarbonyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, sulfinyl group, sulfonyl group, silyl group, carbamoyl group, aryl group, heterocyclic group, alkenyl group, alkynyl group, nitro group, formyl group, nitroso group, formyloxy group, isocyano group, cyanate group, isocyanate group, thiocyanate group, isothiocyanate group, cyano group, or condensate of substituted or non-substituted cycles in case of adjacent substituent groups thereof.
Further, the porphyrin for use in a light emitting material of organic EL element, particularly, a red light emitting material of organic EL element in the present invention, is not limited to the porphyrin expressed by the above-mentioned generic, formula (1) but may be provided with natural porphyrin, a high polymer molecule derived from the above-mentioned porphyrin, or a metalloporphyrin that is a metal complex of these porphyrins.
More concretely, ethioporphyrin-I, deuteroporphyrin-IX, meso-porphyrin-IX, hematoporphyrin-IX, protoporphyrin-IX, coproporphyrin-I, coproporphyrin-III, uroporphyrin-I, uroporphyrin-III, chlorofluoroporphyrin, hematoporphyrin, deuteroporphyrin-IX 2,4-di-acrylic acid, 2,4-diformyldeuteroporphyrin-IX, 2,4-diacetyldeuteroporphyrin-IX, deuteroporphyrin-IX 2,4-disulfonic acid, phylloporphyrin-XV, pyroporphyrin-XV, rhodoporphyrin-XV, phylloerythrin, phaeoporphyrin-a5, tetoraphenylporphyrin, protoheme, etc. can be cited.
Furthermor
Furukawa Kenji
Izumizawa Takenori
Uchida Manabu
Chisso Corporation
Wenderoth , Lind & Ponack, L.L.P.
Yamnitzky Marie
LandOfFree
Red-emitting material and 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 Red-emitting material and organic electroluminescent device..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Red-emitting material and organic electroluminescent device... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2588039