Tunable electronic and optical properties of InSe/InTe van der Waals heterostructures toward optoelectronic applications

Forming novel van der Waals (vdW) heterostructures by combining different two-dimensional (2D) materials is significant to achieve more desirable properties. Using first-principles calculations, we demonstrate the electronic and optical properties of the InSe/InTe van der Waals heterostructure. Our results suggest that this heterostructure has an intrinsic type-II band alignment with a direct band gap. The electrons and holes are respectively localized in the InSe and InTe layers. The spatial separation of the lowest energy electron-hole pairs can occur, implying that the InSe/InTe heterostructure is a good candidate for a high-efficiency solar cell. In addition, the optical absorption in heterostructures can be enhanced compared with both of the monolayers. Moreover, tuning of the values with a direct band gap can be induced by applying normal strain, and the band gap exhibits linear variation. Meanwhile, an intrinsic type-II band alignment can be tuned to become type-I, which is suitable for light emission applications. These results indicate that the flexible InSe/InTe vdW heterostructure can provide new ways to utilize two-dimensional materials in future optoelectronic devices.