Ultrafast Charge Transfer in Lithium-Ion and Water-Intercalated MoS<sub>2</sub>/WS<sub>2</sub> Heterostructures.

Wang, Zhijie; Wu, Xi; Yang, Jiali; Duan, Wenhui; Li, Jia · Nano Lett · 2024

basic_science · Level V

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Abstract

Heterostructures of monolayer transition metal dichalcogenides such as MoS<sub>2</sub> and WS<sub>2</sub> are promising for applications in optoelectronics and photocatalysis. However, the strong interlayer coupling in MoS<sub>2</sub>/WS<sub>2</sub> heterostructures results in indirect bandgaps that significantly hinder their performance and efficiency in practical applications. Here, we use first-principles calculations to demonstrate an effective method to weaken interlayer coupling in MoS<sub>2</sub>/WS<sub>2</sub> heterostructures by intercalating lithium ions with water molecules. This approach results in a direct bandgap while maintaining the type-II band alignment. Interestingly, the charge transfer process in the intercalated MoS<sub>2</sub>/WS<sub>2</sub> heterostructures is greatly accelerated, which is attributed to the enhanced nonadiabatic coupling between different energy states and the inversion of the effective electric field within the heterostructures. Our results provide a strategy for achieving ultrafast charge transfer in MoS<sub>2</sub>/WS<sub>2</sub> heterostructures via intercalation and offer insight into modulation of other van der Waals materials for enhanced performance.