Nippon Steel Chemical Co., Ltd.

Osamu Yoshitake

Yu Yamada

Hiroshi Miyazaki

Daisuke Suzaki

Toshihiro Yamamoto

Sadao Kamimura

Provided is an organic electroluminescent device which is suitable for use in full-color and multicolor panels and shows higher luminous efficiency and better driving stability than organic electroluminescent devices utilizing luminescence from the singlet state. The organic electroluminescent device comprises a substrateand an anode, organic layers, and a cathodepiled one upon another on the substrate, at least one of the organic layers comprises a light-emitting layercontaining a host material and a dopant material, and a compound having 2 to 4 pyrazole structures represented by the following formula I (wherein Arto Arare independently hydrogen or substituted or unsubstituted aromatic hydrocarbon groups or aromatic heterocyclic groups) is used as said host material.

Organic electroluminescent device

This invention provides an organic electroluminescent element (organic EL element) utilizing phosphorescence which emits light efficiently with high luminance at low current density, shows good driving stability and is applicable to display devices such as flat panel displays and illuminating devices. The element comprises an anode, organic layers and a cathode piled one upon another on a substrate, at least one of the organic layers is a light-emitting layer containing a host material and a dopant material and a pyrazole-derived compound having 2-4 pyrazole structures represented by the following formula I in the same molecule is used as said host material; wherein, Ar-Arare independently hydrogen or substituted or unsubstituted aromatic hydrocarbon groups and at least one of Ar-Aris a group other than hydrogen.

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Fukuoka, Japan

Osamu Yoshitake