Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2002-10-25
2004-09-14
Garrett, Dawn (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S917000, C313S504000, C313S506000, C252S301160
Reexamination Certificate
active
06790540
ABSTRACT:
FIELD OF TECHNOLOGY
This invention relates to a luminescent material and an organic electroluminescent element and, more particularly, to an organic electroluminescent element material (EL material) which is used as a luminescent body in a variety of displays and to an organic electroluminescent element (EL element) prepared from said EL material.
BACKGROUND TECHNOLOGY
An EL element utilizing electroluminescence is characterized by its high visibility because of self-luminescence and by its high impact resistance because of its being a completely solid element and is used in a thin display element, back light of a liquid crystal display and planar light source.
Some of known EL elements use a diamine derivative in the hole transporting layer and a complex of aluminum and 8-hydroxyquinoline (hereinafter referred to as Alq3) in the luminescent layer and emit green light at low direct-current voltage [Appl. Phys. Lett., 51, 913 (1987)]. Moreover, it is disclosed that the color of electroluminescence can be changed from green to yellow or red by the use of Alq3 alone [J. Appl. Phys. 65 (9), May (1989)].
The luminescent layer of EL elements which are currently in practical use is prepared as film from materials of low molecular weight by the technique of vacuum deposition while using Alq3 and the like as a luminescent material. In 1990, Burroughes et al. at the Cambridge University succeeded in observing an occurrence of electroluminescence from poly(p-phenylvinylene); induced with this success, the subject of high-molecular-weight EL materials is now receiving vigorous investigation. It is the film-making technique that will gain the greatest advantage from replacement of a low-molecular-weight material in the organic layer with a high-molecular-weight material: that is, a high-molecular-weight material in solution can be made into film by such coating technique as spin coating, dip coating and ink jet printing. Advantages of coating over vacuum deposition are, for example, ease of film making over a large-area substrate, low cost of a film-making apparatus and a short film-making time. However, high-molecular-weight materials generally have difficult problems in control of molecular weight and in purification. Metal complexes containing a ligand of an 8-aminoquinoline skeleton (JP2-255790 A) and compounds containing a ligand of oxazole ring or phenylpyridine ring (Toyota Central R & D Labs, Inc., R & D Review, Vol. 33, No. 2, pp. 3-21, June, 1998) have been reported, but they have not yielded high-performance elements emitting blue light.
DISCLOSURE OF THE INVENTION
Accordingly, an object of this invention is to provide a low-molecular-weight EL material which shows fluorescent quality comparable to that of the aforementioned Alq3 in the solid state and is soluble in an organic solvent such as chloroform and toluene. Another object of this invention is to provide an EL element prepared from the aforementioned EL material. A further object of this invention is to provide an EL material which emits blue fluorescent light with its principal wavelength located in the vicinity of 450 nm.
This invention relates to an organic electroluminescent element material represented by general formula (1).
wherein Ar
1
is a group represented by the following formula (2) and Ar
2
is a group represented by the following formula (3) or (4) and, in case Ar
2
is represented by formula (3), Ar
1
and Ar
2
may condense to form a 10-membered ring.
In formulas (2), (3) and (4), R
1
-R
4
are independently hydrogen, halogen, an alkyl group with 1-6 carbon atoms, an alkoxy group with 1-6 carbon atoms, an aryloxy group with 6-18 carbon atoms, phenyl group, a substituted phenyl group with up to 18 carbon atoms, amino group, a substituted amino group or hydroxyl group and R
1
and R
2
or R
3
and R
4
in adjacent position may link together to form a saturated or unsaturated 5- or 6-membered ring. The group R
5
is hydrogen, an alkyl group with 1-16 carbon atoms, an alkoxy group with 1-6 carbon atoms, an aryloxy group with 6-18 carbon atoms, an alkyl group with 1-16 carbon atoms optionally containing a substituent selected from phenyl, amino, cyano, nitro, hydroxyl and halogen, an aryl group with 6-20 carbon atoms or an aralkyl group with 7-20 carbon atoms; in case Ar
1
and Ar
2
condense to form a 10-membered ring, R5 is an alkyl group with 6-16 carbon atoms optionally containing 1 or more of the aforementioned substituents, an aryl group with 6-20 carbon atoms or an aralkyl group with 7-20 carbon atoms. The group X is O or S, Z is a metal linked to N in formula (1) and to N constituting the hetero ring of Ar
2
and is a divalent or trivalent metal selected from zinc, aluminum, copper, beryllium, ruthenium, cobalt, rhodium, iridium and platinum and n is 2 or 3.
El materials represented by the aforementioned formula (1) include compounds represented by the following general formulas (5), (6) and (7).
Moreover, this invention relates to an EL element which contains the aforementioned EL material between two electrodes at least one of which is transparent. Still more, this invention relates to an EL element which contains at least one kind of the aforementioned EL material in its luminescent or electron transporting layer.
The EL materials of this invention are represented by the aforementioned general formula (1) and comprise the compounds represented by the aforementioned general formulas (5), (6) and (7).
The symbols in the aforementioned general formulas (5), (6) and (7) are the same as those in the aforementioned general formulas (1) to (4). However, R
5
is preferably a group with 6 or more carbon atoms from the viewpoint of solvent solubility; for example, an alkyl group with 6-16 carbon atoms optionally containing one or more of the aforementioned substituents, an aryl group with 6-20 carbon atoms and an aryl group with 7-20 carbon atoms. In particular, R
5
is preferably an alkyl group with 6-16 carbon atoms in a compound represented by formula (7).
The compounds represented by the aforementioned general formula (1) can be prepared by a variety of known methods; the following method is cited as an example.
An amine is treated with a sulfonyl chloride in pyridine and the reaction product is treated with a metal sulfate in alcohol.
The compounds represented by the aforementioned general formula (5) can also be prepared by a variety of known methods. 2-Tributylstannylpyridine or its derivative is coupled with 2-iodonitrobenzene or its derivative and the nitro group is reduced to amino group. Thereafter, the resulting amine is treated with a variety of sulfonyl chlorides in pyridine and the reaction product is treated with a metal sulfate in alcohol. An example is shown below.
Likewise, the compounds represented by the aforementioned general formula (6) can be prepared by a variety of known methods. Anthranilic acid or its derivative is coupled with ortho-aminophenol or its derivative and the coupled product is treated with a variety of sulfonyl chlorides in pyridine and the reaction product is treated with a metal sulfate in alcohol to give a product represented by formula (6). An example is shown below.
The compounds represented by the aforementioned general formula (7) can be prepared by a variety of known methods. 8-Aminoquinoline or its derivative is treated with a variety of sulfonyl chlorides in pyridine and the reaction product is treated with a metal sulfate in alcohol to give a product represented by general formula (7).
In the aforementioned general formulas (1) to (7), R
1
-R
4
, R
5
, X, Z and n are as defined above. Preferable as R
1
-R
4
are hydrogen, halogen or a lower alkyl group (with 5 or less carbon atoms). Moreover, two of R
1
-R
4
are preferably hydrogen. In case at least two of R
1
-R
4
in adjacent position link together to form a ring, preferably a benzene ring, the new benzene ring condenses with the existing benzene ring bearing the two in question to form a naphthalene ring. Suitable for R5 are hydrogen, an alkyl group with 1-16 carbon atoms, an
Miyazaki Hiroshi
Mizutani Teruyoshi
Mori Tatsuo
Takeda Toru
Yamashita Koichi
Garrett Dawn
Nippon Steel Chemical Co. Ltd.
Rader & Fishman & Grauer, PLLC
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