Host-free, yellow phosphorescent material in white organic light-emitting diodes

A white organic light-emitting diode (WOLED) with a high power efficiency has been demonstrated by dispersing a host-free, yellow phosphorescent material in between double blue phosphorescent emitters. The device performance achieved a comparable value to that of using a complicated host–guest doping system to form the yellow emitter in WOLEDs. Based on this device concept as well as the molecular engineering of blue phosphorescent host material and light-extraction film, a WOLED with a power efficiency of 65 lm W −1 at a practical brightness of 1000 cd m −2 with Commission Internationale d'Echariage coordinates (CIE x , y ) of (0.37, 0.47) was achieved.