Strain engineering on the band alignment transition and photocatalytic property in MoS2/MSe (M = In, Ga) heterojunctions

Two-dimensional van der Waals heterojunctions are seen as a powerful strategy to tune the electronic properties and enhance their performance in devices. In this study, we have systematically investigated the electronic properties and energy band alignments of MoS₂/MSe (M = In, Ga) heterojunctions using first-principles calculations. The MoS₂/InSe heterojunction exhibits a type-I band alignment, whereas the MoS₂/GaSe heterojunction presents a type-II band characteristic. Furthermore, the MoS₂/InSe heterojunction achieves a transition from type-I to type-II energy band alignment in the strain range of −3 % to −4 % biaxial strain. In contrast, the MoS₂/GaSe heterojunction consistently maintains the type-II energy band alignment. In addition, the tensile strain effectively enhanced the optical absorption of MoS₂/GaSe in the visible spectral interval, and a red-shift/blue-shift of the absorption peaks with increasing tensile/compressive strains was observed. The MoS₂/InSe heterojunction at −3 % and the MoS₂/GaSe heterojunction at −2 % to −1 % strain intervals exhibited suitable band gaps with strong photocatalytic capabilities. These results demonstrate that the MoS₂/MSe heterojunctions are expected to significantly improve the photocatalytic efficiency, suggesting the promising application prospect of MoS₂/MSe heterojunctions in photocatalytic technology.