Theoretical study of phosphorescence of iridium complexes with fluorine-substituted phenylpyridine ligands

Time-dependent density functional theory (TD-DFT) with linear and quadratic response approaches was applied to calculate absorption and luminescence spectra of a number of facial and meridional iridium complexes with fluorine-substituted phenylpyridine (F_nppy) ligands. The absorption and luminescence spectra were studied to simulate the photophysical properties of electroluminescent devices fabricated on the basis of these iridium complexes used to increase spin-orbit coupling and the triplet-state blue emission of the corresponding organic light-emitting diodes (OLEDs). By using the quadratic response technique, the phosphorescence radiative rate constant and lifetime of the studied iridium complexes were calculated through spin-orbit coupling perturbation and compared with the measured data in experiments. A satisfactory agreement between these data permits us to guide improvements in the design of phosphorescence-based OLEDs by predicting the structure-property relationships through quantum chemical calculations. The phosphorescence of iridium complexes with F_nppy (ppy = phenylpyridine) ligands was studied by linear and quadratic response theory. The 0-0 transition energy and the radiative rate constant were well predicted, thus proving the usefulness of quantum chemical calculations in aiding experiments.