Band structure engineering in a MoS2/PbI2 van der Waals heterostructure via an external electric field.

Band structure engineering in a MoS2/PbI2 van der Waals (vdW) heterostructure under an external electric field (Efield) is investigated using density functional theory (DFT). It is demonstrated that the MoS2/PbI2 vdW heterostructure has a type-II heterojunction with a direct bandgap, and thus the lowest energy electron-hole pairs are spatially separated. Meanwhile, the band structure could be effectively modulated under an Efield and the bandgap shows linear variations with the Efield, indicating a giant Stark effect. This gets further support from the band edges of MoS2 and PbI2 in the heterostructure. Moreover, the MoS2/PbI2 vdW heterostructure experiences transitions from type-II to type-I and then to type-II under various Efields. Our calculated results pave the way for experimental research and provide a new perspective for the application of the vdW heterostructure in electronic and optoelectronic devices.