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

Plasmon induced hot-electron dynamics at the interfaces of metallic nanostructures and semiconductors is of significant importance for photovoltaic and photocatalytic applications. Plasmon-driven charge separation processes were considered to be only dependent on the type of donor-acceptor interactions, i.e., conventional hot electron transfer mechanism for van der Waals interactions and plasmon-induced interfacial charge-transfer transition pathway for chemical bonds. Here we demonstrate the two mechanisms can coexist in a typical metal-semiconductor hybrid plasmonic nanomaterials, both happen on a faster time scale than carrier relaxation process. The origin of the two mechanisms is attributed to the spatial vertical and parallel modes of excited plasmon, where the vertical mode couples to semiconductors much strongly than the parallel one. Our findings provide a new insight into the photoinduced plasmonic carrier dynamics, which is relevant for many potential applications including solar energy conversion, efficient water splitting and photocatalysis.