High-power-efficiency hybrid white organic light-emitting diodes with a single emitting layer doped with blue delayed fluorescent and yellow phosphorescent emitters

High-efficiency hybrid white organic light-emitting diodes (HWOLEDs) with a blue thermally activated delayed fluorescent (TADF) emitter and a yellow phosphorescent emitter doped in a single emitting layer were developed. Exciton harvesting by the blue TADF and yellow phosphorescent emitters rendered both singlet and triplet excitons to contribute to the white emission, which leads to a high quantum efficiency of 22.4% and a power efficiency of 60.3 lm W-1 in the HWOLEDs. In addition, the electroluminescence spectra of the HWOLEDs were kept stable from 100 cd m(-2) to 5, 000 cd m(-2).