Electrical switching between exciton dissociation to exciton funneling in MoSe₂/WS₂ heterostructure

The heterostructure of monolayer transition metal dichalcogenides (TMDCs) provides a unique platform to manipulate exciton dynamics. The ultrafast carrier transfer across the van der Waals interface of the TMDC hetero-bilayer can efficiently separate electrons and holes in the intralayer excitons with a type II alignment, but it will funnel excitons into one layer with a type I alignment. In this work, we demonstrate the reversible switch from exciton dissociation to exciton funneling in a MoSe₂/WS₂ heterostructure, which manifests itself as the photoluminescence (PL) quenching to PL enhancement transition. This transition was realized through effectively controlling the quantum capacitance of both MoSe₂ and WS₂ layers with gating. PL excitation spectroscopy study unveils that PL enhancement arises from the blockage of the optically excited electron transfer from MoSe₂ to WS₂. Our work demonstrates electrical control of photoexcited carrier transfer across the van der Waals interface, the understanding of which promises applications in quantum optoelectronics.