New design of two series of Ir(III) complexes by changing substitute group at main ligand or ancillary ligand from theoretical viewpoint

Using DFT/TDDFT methods to investigate the electronic structure, absorption and emission spectra, charge injection/transport ability and phosphorescence quantum efficiency of two series of Ir(III) complexes. Complexes 1a-1c introduce F atom, acetyl group (-COCH3), 1-fluoro-4-methanesulfonyl-benzene group (-SO2PhF) to substitute methyl on benzene ring of mpmi main ligand (1-(4- tolyl)-3-methyl-imidazole) in complex 1, and complexes 2-4 introduce different ligands to substitute the dmpypz ancillary ligand (3,5-dimethyl-2-(1H-pyrazol-5-yl)pyridine) of complex 1, such as heppy ligand (4-(1-hydroxy-ethyl)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-ol), typy ligand (2-thiophen-2-yl-pyridine), quol ligand (quinolin-8-ol). The introduction of F atom, -COCH3 and -SO2PhF has the important effect on the photophysical properties of all studied complexes. Thereinto, introducing -COCH3 and -SO2PhF have great influence on the transition dipole moment from S-0 to S-1 state (mu(s1)) and can improve electron transport property. Introducing different ancillary ligands can adjust emission wavelength effectively, has great influence on mu(s)1, typy ligand and quol ligand can adjust hole/electron injection ability. Typy ancillary ligand could improve electron balance ability. Complexes 1-1c and 2 have larger HOMO-LUMO energy level, and they are potential blue materials. Complex is has better electron injection ability. Complexes 3 and 4 have the larger mu(s1), so they may have higher quantum efficiency.