A theoretical study on the electronic properties of in-plane CdS/ZnSe heterostructures: type-II band alignment for water splitting

Abstract

Lateral heterostructures fabricated by using two-dimensional (2D) building blocks have attracted a great deal of attention in materials science and device physics. Here we report a novel type of lateral heterostructures within 2D CdS and ZnSe by means of first-principles calculations. Interestingly, the armchair configuration possesses a direct bandgap with type-II band alignment. Simultaneously, the interfacial charge transfer from ZnSe to CdS results in a built-in field which can efficiently separate the electrons and holes. Moreover, the high carrier mobilities are also identified in both armchair and zigzag configurations, even one order of magnitude higher than those of 2D transition metal chalcogenides. More remarkably, both the bandgap and band edges of the lateral heterostructures can meet the requirement of the reduction and oxidation levels in water splitting. These results make these in-plane heterostructures promising candidates for applications in next-generation electronic and optoelectronic devices.