Interfacial engineering in lead-free tin-based perovskite solar cells

Lead (Pb)-free Tin (Sn)-based perovskite solar cells (PSCs) have been favored by the community due to their low toxicity, preferable bandgaps, and great potential to achieve high power conversion efficiencies (PCEs). Interfaces engineering plays important roles in developing highly efficient Sn-based PSCs via passivation of trap defects, alignment of energy levels, and incorporation of low-dimensional Sn-based perovskites. In this review, we summarize the development of Pb-free Sn-based perovskites and their applications in devices, especially the strategies of improving the interfaces. We also provide perspectives for future research. Our aim is to help the development of new and advanced approaches to achieving high-performance environment-friendly Pb-free Sn-based PSCs.