Tunable electric properties of bilayer InSe with different interlayer distances and external electric field

Using density functional theory we explore the band structure of bilayer Indium selenide (InSe), and we find that the van der Waals interaction has significant effects on the electric and optical properties. We then explore the tuning electronic properties by different interlayer distances and by an external vertical electric field. Our results demonstrate that the band gaps of bilayer InSe can be continuously tuned by different interlayer coupling. With decreasing interlayer distances, the tunable band gaps of bilayer decrease linearly, owing to the enhancement of the interlayer interaction. Additionally, the band structure of bilayer InSe under external vertical fields is discussed. The presence of a small external electric field can make a new spatial distribution of electron-hole pairs. A well separation based on the electrons and holes, localized in different layers can be obtained using this easy method. These properties of bilayer InSe indicates potential applications in designing new optoelectronic devices.