DFT and TD-DFT study a series of blue and green iridium complexes with mesityl-phenyl-imidazole ligand

A series of blue and green-emitting phosphorescent heteroleptic cyclometalated Ir(III) complexes with mesityl-phenyl-imidazole Ligand for organic light-emitting devices are investigated theoretically to explore their electronic structures, spectroscopic properties and the application value for organic light emitting devices. The geometries, electronic structures, lowest-lying singlet absorptions, and triplet emissions of Ir(mpim)3, and the theoretically designed models Ir(F-mpim)3, Ir(F2-mpim)3, (mpim)2Ir(acac), (F-mpim)2Ir(acac), (F2-mpim)2Ir(acac), (mpim)2Ir(tpip), (F-mpim)2Ir(tpip), (F2-mpim)2Ir(tpip), are investigated with Density Functional Theory (DFT) approaches, where mpim denotes 1-mesityl-2-phenyl-1H-imidazole, F-mpim denotes 2-(4-fluorophenyl)-1-mesityl-1H-imidazole, F2-mpim denotes 2-(2,4-difluorophenyl)-1-mesityl-1H-imidazole, acac denotes acetylacetonate, and tpip denotes tetraphenylimido-diphosphinate.