Efficient Carrier Separation in Graphitic Zinc Oxide and Blue Phosphorus van der Waals Heterostructure

Efficient carrier separation is the key to the application of photoelectric device. However, photogenerated electron–hole pairs in simplex semiconductors generally occupy the same regions spatially and are easy to recombine. Here we design a graphitic zinc-oxide-based (g-ZnO) intrinsic type-II heterostructure, g-ZnO/blue phosphorus (BP), based on first-principles calculations. The type-II band offsets and large built-in electric field ensure the photogenerated electrons easily migrating from g-ZnO to BP, which significantly enhances the separation of electron–hole pairs. Improved optical absorption is also observed in the heterostructure. Furthermore, the perpendicular external electric field can greatly modulate band edges and achieve a direct band gap at Γ point, which provides further promotion in the separation of carriers.