Some critical properties of all displays used in mobile applications are mechanical robustness, reliability, full color, light weight, and high efficiency to extend battery life. Recently, however, it has been shown that increasing the conductivity of organic semiconductor layers by doping with either donors (for electron conducting materials) or acceptors (for hole-transport materials) can significantly reduce the voltage drop across organic thin films, and in particular, fluorescent OLEDs. In this work, the authors extend this approach to small molecular weight electrophosphorescent light-emitting devices, thereby achieving very high efficiency OLEDs that perform in a manner similar to LEDs employing conventional semiconductor materials. The authors plot the power efficiency versus current density for sample B, along with those previously reported for optimized, conventional ultrahigh efficiency green-emitting PHOLEDs.