Charge trapping host structure for high efficiency in phosphorescent organic light‐emitting diodes

Abstract A charge trapping host structure was developed to improve the light‐emitting efficiency of green phosphorescent organic light‐emitting diodes. N, N'‐dicarbazolyl‐3,5‐benzene(mCP) and a spirobifluorene based triplet host(PH1) were co‐deposited as hosts in the emitting layer and the device performance was examined according to the composition mCP and PH1. The results showed that the quantum efficiency could be improved by 30 % using a mixed host of mCP and PH1.