DFT/TDDFT investigation on the electronic structures and photophysical properties of two series of heteroleptic iridium(III) complexes with different substituted main ligands and acidic pyrazolyl-pyridine ancillary ligand

The electronic structure and photophysical properties of two series of iridium(III) complexes have been theoretically investigated by using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) method. The effect of the electron-withdrawing and electron-donating substituents on absorption and phosphorescent properties has been investigated. All studied complexes have multiple ultraviolet-visible light absorption peaks. The theoretical emission wavelength for 1a is very close to the experimental value. Complex 2b possibly possesses the largest kr value in all studied complexes. It is anticipated that our findings here can provide a valid way for developing good phosphorescent iridium(III) complexes in organic light-emitting diodes (OLEDs).