Lead Sources in Perovskite Solar Cells: Toward Controllable, Sustainable, and Large-Scalable Production

Organic–inorganic hybrid Pb halide perovskites have gained much attention as the most promising next generation photovoltaics, and the certificated power conversion efficiency of perovskite solar cells (PSCs) has recently reached 25.5%. For the typical solution-processed film, the features of solutes in the precursor solution greatly influence the characteristics of the deposited film. While for Pb-based perovskites, PbI₆ octahedral is the key component of the perovskite framework, and thus the Pb source particularly plays a significant role in determining the crystallization, structural, and optoelectronic properties of the solution-processed perovskite film. In this review, the state-of-the-art studies that focus on disclosing the key role of Pb source in the performance improvement of PSCs are systematically summarized. In addition, a comprehensive discussion on the effect of various Pb sources (e.g., Pb halides, Pb salts, Pb chalcogens, metallic Pb, and recycled Pb compounds) on the crystallization kinetics and photovoltaic characteristics of perovskite film is given. Also, the significant role of Pb source in producing large-scale PSCs in a controllable and sustainable manner is highlighted. This review is expected not only to put steps forward for the future commercialization of PSCs, but also to inspire more ideas in many other optoelectronic devices regarding raw material engineering.