First-Principles and Experimental Insights into Interfacial Structures and Properties between MAPbI₃ and ZnIn₂X₄ (X = S, Se)

The interface between the MAPbI₃ perovskite and layered ZnIn₂S₄ was investigated by first-principles calculations combined with the experimental study. To begin with, four different types of interfacial configurations were established and carefully examined. The interaction occurring between MAPbI₃ and ZnIn₂X₄ is mainly determined by weak van der Waals forces. The interfacial charge reorganization implies electron transfer from the MAPbI₃ layer to the ZnIn₂X₄ layer across the interface. The PbI/ZnIn₂X₄ interface exhibits stronger interfacial interactions compared to those of the MAI/ZnIn₂X₄ counterpart. The interfacial adhesion work was found to depend more on the surface termination of MAPbI₃ than on that of ZnIn₂X₄. Conversely, it was discovered that the interface potential drop, work function, and dielectric function within the MAPbI₃/ZnIn₂X₄ interfaces are predominantly regulated by ZnIn₂X₄ termination rather than MAPbI₃ termination. Chalcogen vacancies cause enhanced interfacial interactions owing to electron rearrangements at the interfaces. In the end, the MAPbI₃/ZnIn₂S₄ heterostructure was successfully fabricated and then characterized, which effectively verified first-principles calculations. This study offers fundamental insights into the development of MAPbI₃/ZnIn₂X₄ heterostructures, advancing perovskite-based optoelectronic devices.