Theoretical exploration of the photophysical properties of two series of iridium(III) complexes with different main ligand

On the basis of the thiophene-containing and furan-containing complexes, we design four complexes by introducing thiazole, isothiazole, oxazole, isoxazole on main ligands. The electronic structure, absorption and emission spectra, charge injection/transport properties, absorption and phosphorescence properties have been investigated by density functional theory (DFT) and time-dependent density functional theory (TDDFT). Introducing S atom to substitute O atom could enhance HOMO energy level, blueshift emission wavelength, decrease $\Delta {\text{E}}_{{\text{S}}_{\text{1}}{\text{- T}}_{\text{1}}}$ value. The introduction of N atom on furan ring and thiophene ring could decrease HOMO and LUMO energy levels and energy gaps, blueshift emission wavelength, decrease $\Delta {\text{E}}_{{\text{S}}_{\text{1}}{\text{- T}}_{\text{1}}}$ value, enhance electron transport ability. Introducing thiazole could decrease hole injection ability and $\Delta {\text{E}}_{{\text{S}}_{\text{1}}{\text{- T}}_{\text{1}}}$, and then may have higher Φ_PL. Isoxazole and isothiazole groups could facilitate the electron transition from HOMO to LUMO and enhance hole injection ability. Thiazole and isothiazole groups could increase absorption peak strength and hole transport ability.