Additive Engineering Towards Suppression of Sn2+ Oxidation in Sn‐Pb Perovskite Solar Cells: Mechanisms, Advances and Outlook

Inorganic hybrid tin‐lead mixed perovskite solar cell (Sn‐Pb PSCs) have attracted widespread attention in virtues of adjustable/narrow bandgaps, low toxicity and application prospects in all‐perovskite tandem solar cells, and the recorded power conversion efficiency has reached to 24.1%. However, the easy oxidation of Sn2+ brings about abundant Sn vacancies and high concentrations of p‐type self‐doping, leading to the efficiency and durability of Sn‐Pb PSCs still lagging behind those of Pb‐based counterparts. To inhibit the oxidation of Sn2+, the feasible additive engineering was proposed and showed impressive effects. In this paper, we have discussed and reviewed the recent research progress about additive engineering for Pb−Sn PSCs in depth. The additive molecules were classified into the antioxidant additives, reducing additives and competitive additives, according to different action objects, namely Sn2+, Sn4+ and oxygen. Meanwhile, the corresponding functional groups, antioxidant properties, the effect on optoelectronic performances of device as well as underlying mechanisms were systematically summarized. Finally, we provided an outlook for future directions in the additive engineering towards suppression of Sn2+ oxidation in Sn‐Pb perovskites.