Efficient Red-Emitting Cyclometalated Iridium(III) Complexes Containing\nLepidine-Based Ligands

Abstract

Heteroleptic cyclometalated iridium(III) complexes featuring lepidine-based ligands and acetyl acetone auxiliary\nligand are synthesized. Multiple lowest energy absorption bands are observed for these complexes indicating\nsubstantial mixing of the singlet and triplet levels. All the complexes emit orange or red color in dichloromethane\nsolutions with lifetimes in the range 1.6−3.7 μs. The emission in the complexes probably originates from the\n³MLCT state. The complexes are applied as emitting guests in LED devices of the structure ITO/HTL(BPAPF or\nNPB)/6% Ir in CBP/BCP/Alq₃/LiF/Al. They exhibit excellent device characteristics with an orange to red EL profile.