Photoinduced Carrier Transfer Dynamics in MoSSe/WSSe Vertical and Lateral Heterostructures

Abstract

Ultrafast charge separation and slower electron–hole recombination in semiconductor materials are essential for photocatalyst and photovoltaic applications. By combining time-dependent density functional theory (TD-DFT) with nonadiabatic molecular dynamics (NAMD), MoSSe and WSSe lateral and vertical heterostructures with type-II band alignments show excellent optical capture capability and effective charge separation properties. The electron and hole transfers in the vertical heterostructure occur in 544 fs and 2 ps, respectively, and in the lateral heterostructure, in 103 and 181 fs, respectively. An out-of-plane vibration mode is the main driver of the transfer. Importantly, the electron–hole recombination requires a relatively long time for the MoSSe and WSSe heterostructures. Owing to the weak nonadiabatic coupling and the fast decoherence between the conduction band minimum and valance band maximum, the recombination time of the vertical heterostructure (11.42 ns) is 3 times longer than that of the lateral heterostructure (4.43 ns), making them excellent candidates for photocatalysts.