Influence of Doping Concentrations in White Organic Light-emitting Diodes based on Phosphorescent Iridium Complexes

Phosphorescent white organic light-emitting diodes (PhWOLEDs) based on blue (Firpic) and yellow [(t-bt)2Ir(acac)] phosphorescent emitters with various doping concentration were reported. A PhWOLED with high performance characteristics has been obtained when the doping concentration for Firpic and (t-bt) 2Ir (acac) is 8 wt% and at 6 wt%, respectively. The Commission Internationale del’Eclairage (CIE) coordinates of the optimal PhWOLED is (0.333, 0.416) at 10 V. The high performance of the optimized PhWOLED is attributed to effective host-guest energy transfer and efficient exciton recombination combining with suppressed exciton-quenching process in the emitting layers.