Abstract
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.
Highlights
The heterostructure of monolayer transition metal dichalcogenides (TMDCs) provides a unique platform to manipulate exciton dynamics
We show that the electron transfer from MoSe2 to WS2 can be blocked by efficient gating of the LaF3 substrate, leading to a transition between photoluminescence (PL) quenching to PL enhancement for the MoSe2 A exciton emission
We construct the MoSe2/WS2 heterostructure on the LaF3 substrate through a layer-by-layer dry transfer technique[29], and the heterostructure is capped by a thin layer of hexagonal boron nitride (BN) on the top
Summary
The heterostructure of monolayer transition metal dichalcogenides (TMDCs) provides a unique platform to manipulate exciton dynamics. 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. 1234567890():,; Two-dimensional (2D) semiconductors are promising candidates for light-harvesting and optoelectronic applications[1,2,3,4,5] due to their strong light–matter interaction from excitonic responses[6,7,8,9,10,11,12,13] Their atomically thin nature further enables engineering exciton dynamics and energy relaxation pathways through ultrafast carrier transfer across 2D van der Waals (vdW) interfaces[14,15,16,17,18,19,20,21]. The ability to electrically control interlayer charge transfer pathways ushers in application concepts, such as light switch and energy steering
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