Two-Dimensional Heterostructure of MoS₂/BA₂PbI₄2D Ruddlesden-Popper Perovskite with an S Scheme Alignment for Solar Cells: A First-Principles Study

Molybdenum disulfide (MoS₂) and a layered organic-inorganic Ruddlesden-Popper perovskite (RPP) show promising optoelectronics applications due to the splendid photoresponse. On consideration that each material has a specific favorable window for light excitation, it is naturally of interest to integrate both for broadening absorption and synergistic interlayer coupling. Herein, on the basis of density functional theory (DFT) computations, we investigate a two-dimensional (2D) MoS₂/BA₂PbI₄RPP van der Waals (vdW) heterostructure by stacking monolayer MoS₂and 2D BA₂PbI₄vertically. We find that the MoS₂/BA₂PbI₄vdW heterostructure maintains a robust direct band gap with an enhanced light absorption that has a high solar to energy conversion efficiency. Moreover, the conduction band minimum (CBM) and the valence band maximum (VBM) are staggered and separately distributed within MoS₂and BA₂PbI₄, respectively. Interestingly, the MoS₂/BA₂PbI₄heterostructure shows a typical type II and S scheme interface arising from appropriate alignments of the Fermi levels and band edges between MoS₂and BA₂PbI₄. Such a heterostructure enables the efficient separation of photoexcited electrons toward the MoS₂side and holes via the BA₂PbI₄layer and thus a strong redox ability that is ideal for photocatalyst and solar cell applications.