Engineering the band structure of type-II MoSe2/WSe2van der Waals heterostructure by electric field and twist angle: a first principles perspective.

Type-II heterostructures composed of transition-metal dichalcogenides have attracted enormous attention due to their facilitation in efficient electron-hole separation. In this work, we performed density-functional theory calculations to systematically investigate the atomic and electronic structures of MoSe₂/WSe₂van der Waals heterostructure. Its six high-symmetry configurations with different interlayer coupling under external electric field and twist angle were addressed. Our results reveal that all the configurations exhibit type-II band alignment and their band gaps can be effectively modulated by the electric field. Notably, the direct to indirect band gap transition only occurs in the configurations with strong interlayer coupling. Moreover, twist-induced symmetry breaking weakens the interlayer interactions, thus decreasing interlayer charge transfer. Owing to large interlayer distance and weak interlayer coupling, the band structure of the heterostructure remained unchanged for the twist angles ranging from 13.2° to 46.8°. These findings demonstrate the great potential of the MoSe₂/WSe₂heterostructure for applications in optoelectronic and nanoelectronic devices.