Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2001-03-29
2004-03-30
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S917000, C313S504000, C313S506000
Reexamination Certificate
active
06713192
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an organic electroluminescence (electroluminescence will be referred to as EL, hereinafter) device and an organic light emitting medium and, more particularly, to an organic EL device which exhibits excellent heat resistance, has a long life time and provides efficient light emission and an organic light emitting medium which is advantageously used for the organic EL device.
BACKGROUND ART
EL devices which utilize EL show high self-distinguishability because of the self-emission and are excellent in impact resistance because they are completely solid devices. Therefore, EL devices have been attracting attention for application as light emitting devices in various types of display apparatus.
The EL devices include inorganic EL devices in which an inorganic compound is used as the light emitting material and organic EL devices in which an organic compound is used as the light emitting material. Organic EL devices have been extensively studied for practical application as a light emitting device of the next generation because the applied voltage can be decreased to a great extent, the size of the device can be reduced easily, consumption of electric power is small, planar light emission is possible and three primary colors are easily emitted.
As for the construction of the organic EL device, the basic construction comprises an anode/an organic light emitting layer/a cathode. Constructions having a hole injecting and transporting layer or an electron injecting layer suitably added to the basic construction are known. Examples of such construction include the construction of an anode/a hole injecting and transporting layer/an organic light emitting layer/a cathode and the construction of an anode/a hole injecting and transporting layer/an organic light emitting layer/an electron injecting layer/a cathode.
In practical application of organic EL devices, driving stability and storage stability in environments at high temperatures such as outdoors and in automobiles are required. When an EL device is used outdoors or for an instrument used in an automobile, in general, storage stability at a high temperature of 75° C. is required. However, when a conventional organic EL device is stored at a high temperature of about 75° C., problems arise in that color of emitted light changes and the efficiency of light emission decreases. These problems inevitably restrict application of the organic EL devices.
Various attempts have been made to obtain a device which exhibits excellent heat resistance, has a long life time, achieves a high efficiency and emits bluish light. However, it is the actual present situation that no devices having satisfactory properties are obtained.
For example, a technology in which a single monoanthracene compound is used as the organic light emitting material has been disclosed in Japanese Patent Application Laid-Open No. Heisei 11(1999)-3782. However, in accordance with this technology, for example, the luminance obtained under a current density of 165 mA/cm
2
is as small as 1650 cd/m
2
and the efficiency is as small as 1 cd/A. Therefore, the technology is not practically useful. Another technology in which a single bisanthracene compound is used as the organic light emitting material has been disclosed in Japanese Patent Application Laid-Open No. Heisei 8(1996)-12600. However, in accordance with this technology, the efficiency is as small as 1 to 3 cd/A and further improvement is desired for practical use. An organic EL device having a long life time in which a distyryl compound is used as the organic light emitting material and styrylamine is additionally used has been disclosed in International Patent Application Laid-Open No. 94-6157. However, this device has a half-life time of about 1000 hours and further improvement is desired.
DISCLOSURE OF THE INVENTION
Under the above circumstances, the present invention has an object of providing an organic EL device which exhibits excellent heat resistance, has a long life time and provides efficient light emission and an organic light emitting medium advantageously used for the organic EL device.
As the result of extensive studies by the present inventors to achieve the above object, it was found that an organic EL device in which the organic light emitting medium comprises a combination of an electron transporting material and a specific anthracene derivative and a layer comprising the organic light emitting medium is disposed between a pair of electrodes exhibited excellent heat resistance, had a long life time and provided efficient blue light emission. The present invention has been completed based on the knowledge.
The present invention can be summarized as follows.
[1] An organic electroluminescence device which comprises a pair of electrodes and a layer of an organic light emitting medium disposed between the pair of electrodes, wherein the layer of an organic light emitting medium comprises (A) at least one electron transporting compound and (B) at least one compound selected from anthracene derivatives represented by general formula (1):
A
1
—L—A
2
(I)
wherein A
1
and A
2
each represent a substituted or unsubstituted monophenylanthryl group or a substituted or unsubstituted diphenylanthryl group and may represent a same group or different groups and L represents a single bond or a divalent connecting group; and anthracene derivatives represented by general formula (II):
A
3
—An—A
4
(II)
wherein An represents a substituted or unsubstituted divalent anthracene residue group and A
3
and A
4
each represent a substituted or unsubstituted monovalent condensed aromatic ring group having 10 or more carbon atoms or a substituted or unsubstituted non-condensed ring aryl group having 12 or more carbon atoms and may represent a same group or different groups.
[2] An organic electroluminescence device described in [1], wherein the anthracene derivative represented by general formula (I) is an anthracene derivative represented by general formula (I-a):
wherein R
1
to R
6
each independently represent an alkyl group, a cycloalkyl group, an alkenyl group, a substituted or unsubstituted aryl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group or a substituted or unsubstituted heterocyclic group; a and b each represent an integer of 0 to 5; c, d, e and f each represent an integer of 0 to 4; when any of a to f represents an integer of 2 or greater, a plurality of groups represented by corresponding R
1
, R
2
, R
3
, R
4
, R
5
or R
6
may be the same with or different from each other and may form a ring by forming a bond between each other; and L
1
represents a single bond, —O—, —S—, —N(R)— or an arylene group, R representing an alkyl group or a substituted or unsubstituted aryl group; or an anthracene derivative represented by general formula (I-b):
wherein R
7
to R
14
each independently represent an alkyl group, a cycloalkyl group, an alkenyl group, a substituted or unsubstituted aryl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group or a substituted or unsubstituted heterocyclic group; g and h each represent an integer of 0 to 4; i, j, k and 1 each represent an integer of 0 to 5; m and n each represent an integer of 0 to 3; when any of g to 1 represents an integer of 2 or greater, a plurality of groups represented by corresponding R
7
, R
8
, R
9
, R
10
, R
11
or R
12
may be the same with or different from each other and may form a ring by forming a bond between each other; and L
2
represents a single bond, —O—, —S—, —N(R)— or an arylene group, R representing an alkyl group or a substituted or unsubstituted aryl group.
[3] An organic electroluminescence device described in any of [1] and [2], wherein the anthracene derivative represented by general formula (II) of component (B) is an anthracene derivative represented by general formula (II-a):
Ar
1
—An—Ar
2
(II-a)
wherein An represents a substituted or uns
Fukuoka Kenichi
Hosokawa Chishio
Garrett Dawn
Idemitsu Kosan Co. Ltd.
Kelly Cynthia H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Organic electroluminescence device and organic light... 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 electroluminescence device and organic light..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Organic electroluminescence device and organic light... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3248095