High Efficiency White Electrophosphorescence Mechanism with Two Phosphorescent Dopants

Yoshiro Sato, Kenichi Goushi, Hiroyuki Sasabe, Chihaya Adachi, Kenichi Goushi, Hiroyuki Sasabe, Masami Saito, Chihaya Adachi, Julie J. Brown

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1 Citation (Scopus)


High efficiency white organic light emitting diodes (WOLED) have been expected for applications of lighting, illumination and back-light sources for LCD. Recently, since organic phosphors demonstrated very high electroluminescence (EL) quantum efficiency of ∼100%, high efficiency WOLED with the organic phosphors has been anticipated. In this study, we employed an emitter layer which is doped with blue and red phosphorescence molecules. In our optimized device structure, we obtained maximum EL quantum efficiency of 4%. However, the shapes of the EL spectrum were strongly dependent on current density. With analysis of exciton decay process under optical and electrical excitations, we conclude that triplet-triplet annihilation occurs in blue and red phosphors independently, resulted in a significant change of the EL spectrum. Thus, the coincidence of the lifetimes of the blue and red phosphors is indispensable to escape change of EL spectrum with current density.

Original languageEnglish
Pages (from-to)414-420
Number of pages7
JournalThe transactions of the Institute of Electrical Engineers of Japan.A
Issue number5
Publication statusPublished - 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


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