Interlayer Coupling Effect in van der Waals Heterostructures of Transition Metal Dichalcogenides

TL;DR

This paper investigates how interlayer coupling in van der Waals heterostructures of transition metal dichalcogenides can be tuned via band offset adjustments and symmetry analysis, impacting electronic and optical properties.

Contribution

It introduces a four-level kp model to analyze interlayer hopping and demonstrates tuning of interlayer coupling through electric polarization without external fields.

Findings

Interlayer coupling strength can be modulated by interlayer electric polarization.

Band offsets influence the formation of interlayer valley excitons.

Janus WSSe monolayer effectively tunes band alignment in heterobilayers.

Abstract

Van der Waals (vdW) heterobilayers formed by two-dimensional (2D) transition metal dichalcogenides (TMDCs) created a promising platform for various electronic and optical properties. ab initio band results indicate that the band offset of type-II band alignment in TMDCs vdW heterobilayer could be tuned by introducing Janus WSSe monolayer, instead of an external electric field. On the basis of symmetry analysis, the allowed interlayer hopping channels of TMDCs vdW heterobilayer were determined, and a four-level kp model was developed to obtain the interlayer hopping. Results indicate that the interlayer coupling strength could be tuned by interlayer electric polarization featured by various band offsets. Moreover, the difference in the formation mechanism of interlayer valley excitons in different TMDCs vdW heterobilayers with various interlayer hopping strength was also clarified.