Nippon Steel & Sumikin Chemical Co., Ltd.

Takayuki Shimizu

Hiroyuki Hayashida

Kazuaki Yoshimura

Tohru Asari

Kazuto Shiraishi

Yasushi Koishikawa

Disclosed is a highly reliable organic electroluminescent device, in particular, a phosphorescent organic electroluminescent device using a low-molecular-weight host material, wherein a good balance between electron and hole injection and an efficient mechanism of phosphorescence are maintained. The organic electroluminescent device contains a light-emitting layer between an anode layer and a cathode layer and the light-emitting layer comprises a phosphorescent dopant material and a host material with a molecular weight of not more than 10,000. The host material is composed of a first host material and a second host material that is different from the first host material and the first host material differs from the second host material by not more than 0.1 eV in the ionization potential (IP), by not more than 0.1 eV in the electron affinity (EA), and by not more than 0.1 eV in the triplet energy (T1).

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Kitakyushu, Japan

Takayuki Shimizu