Theoretical studies on the electronic structures and spectral properties of two iridium(III) complexes with tetraphenylimidodiphosphinate ligand

The geometrical structures, electronic structures, and spectral properties of two Ir(III) complexes with tetraphenylimidodiphosphinate ligand were investigated theoretically. The ground and the lowest lying triplet excited states were fully optimized at the B3LYP/LANL2DZ. TDDFT/PCM calculations have been employed to predict the absorption and emission spectra starting from the ground and excited state geometries, respectively. The lowest lying absorptions were calculated to be at 436 and 405 nm for the two Ir(III) complexes, respectively, and they have the transition configuration of HOMO → LUMO. The lowest lying transitions can be assigned as metal/ligand-to-ligand charge transfer (MLCT/LLCT) character for the two Ir(III) complexes. Ionization potentials (IP) and electron affinities (EA) were calculated to evaluate the injection abilities of holes and electrons. The theoretical results can be expected to provide valuable information to design new OLED materials.