Unveiling the Dual Emission Photo-Deactivation Mechanism of a Neutral Heteroleptic Iridium (III) Complex

In this article, the photo-deactivation mechanism of dual emission of a neutral iridium (III) complex is explored by using density function theory (DFT) and time-dependent density function theory (TD-DFT) calculations. To explore the phosphorescence quantum yield of the iridium (III) complex, the radiative decay constant of each emission excited state was computed by TD-DFT calculations, including spin-orbit coupling (SOC). In these calculations, factors such as the transition dipole moments, energy gaps, and SOC elements between the emission states and singlet excited states are taken into account in the evaluation of the radiative decay constants. Additionally, the non-radiative decay is revealed by considering the temperature-independent and the temperature-dependent non-radiative processes. The computational results indicate that the order of the two emission excited states can exert a significant effect on the phosphorescence quantum yield, which is beneficial for understanding the properties of photo-deactivation of phosphorescent emitters.