Study of photogenerated exciton dissociation in transition metal dichalcogenide van der Waals heterojunction A2-MWS4: a first-principles study.

ABSTRACT

In order to explore the photocatalytic hydrogen production efficiency of the MoS2/WSe2 heterostructure (A2-MWS4) as a photocatalyst, it is highly desirable to study the photogenerated exciton dissociation related to photocatalysis. The electronic properties, optical absorption, and lattice dynamic properties of A2-MWS4 were investigated using a first-principles approach. The results show that the type II energy band alignment of A2-MWS4 facilitates the dissociation of photogenerated excitons (electrons and holes). The highly localized d-state electrons of A2-MWS4 induce the formation of internal potentials that promote the dissociation of photogenerated excitons. The hot carrier diffuses its extra energy into the lattice by scattering with phonons and forms a hot spot in the lattice while releasing phonons, which are dragged away from the hot spot by Ridley decay to promote exciton dissociation. These findings could provide insights for research studies on photochemical reactions and photovoltaic devices.