Two-Dimensional Heterostructure of MoS₂/BA₂PbI₄ 2D 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/BA2PbI4 RPP van der Waals (vdW) heterostructure by stacking monolayer MoS2 and 2D BA2PbI4 vertically. We find that the MoS2/BA2PbI4 vdW 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 MoS2 and BA2PbI4, respectively. Interestingly, the MoS2/BA2PbI4 heterostructure shows a typical type II and S scheme interface arising from appropriate alignments of the Fermi levels and band edges between MoS2 and BA2PbI4. Such a heterostructure enables the efficient separation of photoexcited electrons toward the MoS2 side and holes via the BA2PbI4 layer and thus a strong redox ability that is ideal for photocatalyst and solar cell applications.