Electrophosphorescence has attracted much interest, with the potential of 100% internal quantum efficiency, generated from both singlet and triplet excitons. Phosphorescent organic light-emitting diodes (PHOLEDs) based on electrophosphorescent materials can be applied to highly energyefficient, flat-panel displays and are also promising candidates for the next generation of solid-state lighting.[1] However, the longer lifetime of triplet excitons ...