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

Heteroleptic cyclometalated iridium(III) complexes featuring lepidine-based ligands and acetyl acetone auxiliary
ligand are synthesized. Multiple lowest energy absorption bands are observed for these complexes indicating
substantial mixing of the singlet and triplet levels. All the complexes emit orange or red color in dichloromethane
solutions with lifetimes in the range 1.6−3.7 μs. The emission in the complexes probably originates from the
3MLCT state. The complexes are applied as emitting guests in LED devices of the structure ITO/HTL(BPAPF or
NPB)/6% Ir in CBP/BCP/Alq3/LiF/Al. They exhibit excellent device characteristics with an orange to red EL profile.