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AssigneeIdemitsu Kosan Co., Ltd.
InventorsToshio Sakai, Hisahiro Higashi, Hiroaki Nakamura, Hisayuki Kawamura, Chishio Hosokawa
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Disclosed is a practical, organic, blue-emitting EL device having a long life and having high luminous efficiency and good thermal stability. The device comprises organic compound layers, of which at least one is an organic blue-emitting layer, as sandwiched between a pair of electrodes, and is characterized in that the organic blue-emitting layer comprises an organic host compound having a fluorescence quantum efficiency of not smaller than 0.3 in a solid state and a fluorescent substance, and the organic host compound and the fluorescent substance are selected such that the device retains a monomeric blue-emitting ability, and that all the organic compound layers have a glass transition temperature of not lower than 75° C., while the organic compound layers adjacent to the organic blue-emitting layer have a glass transition temperature of not lower than 105° C.
An organic electroluminescent device comprising organic compound layers, of which at least one is an organic blue-emitting layer, as sandwiched between a pair of electrodes, said device being characterized in that (1) the organic blue-emitting layer comprises an organic host compound having a fluorescence quantum efficiency of not smaller than 0.3 in a solid state and a fluorescent substance, and the organic host compound and the fluorescent substance are selected such that the device retains a monomeric blue-emitting ability, and (2) all the organic compound layers have a glass transition temperature of not lower than 75° C., while the organic compound layers adjacent to the organic blue-emitting layer have a glass transition temperature of not lower than 105° C.
Dependencies are inferred from the claim text.