Coexistence of Different Charge-Transfer Mechanisms in the Hot-Carrier Dynamics of Hybrid Plasmonic Nanomaterials.

Hot-carrier dynamics at the interfaces of semiconductors and nanoclusters is of significant importance for photovoltaic and photocatalytic applications. Plasmon-driven charge separation processes are considered to be only dependent on the type of donor-acceptor interactions, that is, the conventional hot-electron-transfer mechanism for van der Waals interactions and the plasmon-induced interfacial charge-transfer transition mechanism for chemical bonds. Here, we demonstrate that the two mechanisms can coexist in a nanoparticle-semiconductor hybrid nanomaterial, both leading to faster transfer than carrier relaxation. The origin of the two mechanisms is attributed to the spatial polarization of the excited hot carriers, where the longitudinal state couples to semiconductors more strongly than the transverse state. Our findings provide a new insight into the photoinduced carrier dynamics, which is relevant for many applications in solar energy conversion, including efficient water splitting, photocatalysis, and photovoltaics.