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

Zhaosheng Zhang, Lihong Liu, Wei-Hai Fang, Run Long, Marina V. Tokina, Oleg V. Prezhdo

Index: 10.1016/j.chempr.2018.02.025

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Abstract

Using nonadiabatic molecular dynamics simulations combined with time-domain density functional theory, we show that electron injection from gold nanorods into MoS2by 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.