Efficient solution-processed blue phosphorescent organic light-emitting diodes with halogen-free solvent to optimize the emissive layer morphology

Efficient solution-processed blue phosphorescent organic light-emitting diodes featuring with environmental-friendly solvent processing are fabricated in this study. The morphology of the TPCz:FIrpic emissive layers prepared with different polar solvents including chlorobenzene, n-butanol and isopropanol and the effect on its electroluminescent performance is investigated in detail. It is found that the phase separation morphology in the film spin-cast from chlorobenzene can be effectively restrained by using the more polar halogen-free solvents n-butanol and isopropanol, which results in the increased electroluminescent performance. When using isopropanol to replace chlorobenzene, the power efficiency is enhanced from 3.3 lm/W to 15.6 lm/W.