Stability and Electronic Properties of SnS/ZnS Interfaces: A First-Principles Investigation

In this study, we investigate the stability and electronic properties of bulk, surface, and interface structures between tin sulfide (SnS) and zinc sulfide (ZnS) by using first-principles calculations and high-throughput interface structure search methods. Our analysis reveals significant differences in the electronic structures of these materials, with distinct bandgaps observed for SnS and ZnS in bulk and surface configurations as well as at their pristine interface. The pristine SnS/ZnS interface exhibits a staggered (type-II) band alignment, which is favorable for solar cell applications. We further explore the impact of interface defects, finding that an equal distribution of atoms from both SnS and ZnS surfaces at the interface offers optimal stability and maintains semiconducting properties. In contrast, interfaces with an excess of any single element tend to exhibit metallic characteristics. These findings highlight the critical role of atomic composition in the design of stable and efficient SnS/ZnS interfaces, paving the way for improved thin-film solar cell performance.