Plasmon-Mediated Electron Injection from Au Nanorods into MoS2: Traditional versus Photoexcitation Mechanism

Using nonadiabatic molecular dynamics simulations combined with time domain density functional theory, we show that electron injection from gold nanorods into MoS2 by the traditional mechanism is still faster than energy relaxation causing charge recombination. Plasmon-like excitations decay into free-electron states within 30 fs after photoexcitation of gold nanorods. Electron transfer follows within less than 100 fs, whereas energy relaxation requires 200 fs. Surface plasmons couple to low-frequency phonons of gold, and free charges also couple to higher-frequency phonons of gold and MoS2. The contribution of the charge-transfer photoexcitation mechanism to plasmon-driven charge separation depends strongly on the type of donor-acceptor interaction, e.g., chemical versus van der Waals, and more weakly on contact area and system geometry. The simulation generates a detailed time-domain atomistic description of the interfacial plasmon-driven charge separation and relaxation that are fundamental to many applications.