Computational Study of the Photophysical Properties and Electronic Structure of Gold (III) Complexes with Different Groups

A series of novel delayed phosphorescent gold(III) complexes, Au(EDG)(EAG) (where EDG = electron‐donating group and EAG = electron‐accepting group), have been reported, exhibiting stable and high‐performance luminescence. The thermally stimulated delayed phosphorescence (TSDP) of these gold(III) complexes has been attributed to phosphorescence emission from the second triplet excited state T 2 . However, the underlying reason why the T 2 state dominates the phosphorescent emitting state remains unclear. Moreover, the effects of different substituent groups on TSDP efficiency have not been fully explored. Thus, this work employs time‐dependent density functional theory (TD‐DFT) calculations to investigate the electronic structures, transition characteristics, and photophysical properties of Au1‐7 complexes, aiming to elucidate the TSDP luminescence mechanism of these complexes. Analysis of electron–hole orbitals reveals that the internal conversion (IC) from T 1 to T 2 is more feasible. We evaluated intersystem crossing (ISC) rates and Huang–Rhys factors to rationalize the experimental observations. Our results indicate that the introduction of electron‐accepting group substituents, such as phenylmethyl group, significantly alters the transition properties of the T 1 state. The nonradiative process from T 1 to T 2 is enhanced, leading to an extended triplet state lifetime. These findings provide valuable insights for the rational design of next‐generation luminescent materials based on gold(III) complexes.