High efficiency blue phosphorescent organic light-emitting diode with partially mixed host

In this report, we demonstrated a series of blue phosphorescent organic light-emitting diodes (OLED) using the mixed host as the partial emitting layer to achieve ultrahigh external quantum efficiency over 30%. The blue phosphorescent emitter was FIrpic and these host materials was developed by Professor Leung in Department of Chemistry, National Taiwan University. By well optimizing the doping ratio among hosts and FIrpic, and designing the device structure to balance carrier in the emitting layer, a ultrahigh efficiency blue OLED could be obtained with external quantum efficiency over 30%.