Impact of vibronic coupling effects on light-driven charge transfer in pyrene-functionalized middle and large-sized metalloid gold nanoclusters from Ehrenfest dynamics

Theoretical calculations are an effective strategy to complement and understand the experimental results in atomistic detail. Ehrenfest molecular dynamics simulations based on the real-time time-dependent density functional tight-binding (RT-TDDFTB) approach are performed to reveal for the first time the electron dynamics for the charge separation of pyrene-functionalized middle-sized Au₇₀S₂₀(PH₃)₁₆ and large-sized Au₁₀₈S₂₄(PR₃)₁₆ (R = H, CH₃, C₂H₅, C₆H₅) clusters. The proposed mechanism uncovers an ultrafast and irreversible photoinduced charge transfer from the gold nanocluster (GNC) unit to the pyrene derivative in all cases. By a Fourier transform analysis of the dynamics, the effect of vibronic couplings is highlighted. The Au₁₀₈S₂₄(PPh₃)₁₅PPh₂Pyr system exhibits the best performance for charge separation.