Improvement in carrier transport and recombination of white phosphorescent organic light-emitting devices using a composite blue emitter

We demonstrate high-efficiency white phosphorescent organic light-emitting devices (PHOLEDs) based on a yellow and composite blue emitters. The composite blue emitter is constructed from a wide-band-gap host, organometallic iridium dopant, and a carrier-transporting material. Under the same driving current density and emissive color, the current efficiency of the white PHOLEDs can be enhanced by a factor of 1.4 comparing to that of using typical blue emitter composed of host and dopant only. Attaching an outcoupling enhancement film onto glass substrate, the white PHOLEDs with a current efficiency of 47 cd/A, a power efficiency of 32 lm/W, and a CIEx,y (CIE: Commission Internationale d'Eclairage) of (0.40,0.44) at a practical brightness of 1000 cd/m(2) can be achieved. (C) 2008 American Institute of Physics.