TY - JOUR
T1 - High Efficiency White Electrophosphorescence Mechanism with Two Phosphorescent Dopants
AU - Sato, Yoshiro
AU - Goushi, Kenichi
AU - Sasabe, Hiroyuki
AU - Adachi, Chihaya
AU - Goushi, Kenichi
AU - Sasabe, Hiroyuki
AU - Saito, Masami
AU - Adachi, Chihaya
AU - Brown, Julie J.
PY - 2004
Y1 - 2004
N2 - 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.
AB - 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.
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U2 - 10.1541/ieejfms.124.414
DO - 10.1541/ieejfms.124.414
M3 - Article
AN - SCOPUS:85009607678
VL - 124
SP - 414
EP - 420
JO - IEEJ Transactions on Fundamentals and Materials
JF - IEEJ Transactions on Fundamentals and Materials
SN - 0385-4205
IS - 5
ER -