Iridium complexes having phosphrous ligands of large steric hindrance: Photophysical comparison between solution state, solid state and electrospun fibers

•Phosphorous ligands with large steric hindrance were used in phosphorescent ir complexes to allow enough time for the transformation of highly phosphorescent 3MLLCT excited state.•Aggregation-caused quenching was limited, showing high emission yield (Φ=0.27) and long emission lifetime (0.43 µs) in solid state.•The potential surface crossing and energy transfer were revealed by density functional theory calculation and temperature-dependent emission.