Recent advances in Pb–Sn mixed perovskite solar cells

Organic-inorganic hybrid lead-tin perovskite solar cells (Pb–Sn PSCs) have attracted much attention because of their advantages of low toxicity, variable bandgap, and feasibility for all-perovskite tandem solar cells, and the current power conversion efficiency (PCE) has exceeded 23%. However, due to the rambunctious crystallization process, easily oxidized Sn(Ⅱ) and inadequate energy level arrangement, there are many defects in perovskite films resulting in serious carrier recombination, which makes PCE still lag Pb-based PSCs. The quality of perovskite films is an important factor affecting the overall device performance. The selection and optimization of transport layers not only determines the interface energy level arrangement but also affects the carrier transport. In this paper, the research progress in improving performance of Pb–Sn PSCs in recent years is reviewed from aspects of perovskite layer and transport layers. The profound understanding of different promotion methods is summarized as well. These results have certain guiding significance for the future development and commercial application of Pb–Sn PSCs.