Performance enhancement of white-electrophosphorescent devices incorporating a mixed-transition layer

The performance of white organic light-emitting devices has been improved significantly by incorporating a mixed-transition layer, consisting of the hole-transporting (or electron-transporting) layer doped with the emissive dye. These devices exhibit maximum current and power efficiencies of 13.3cd∕A and 11.3lm∕W, respectively (1.6 and 2 times higher than the corresponding values of devices without the mixed-transition layer), with slightly modified Commission Internationale De L’Eclairage coordinates, from (0.300, 0.371) to (0.312, 0.366). This is attributed to the enhancement of carrier transport by doping, thereby improving both the exciton formation probability and the charge transport balance.