Progress towards lead-free, efficient, and stable perovskite solar cells

Solar energy production requires an environmentally friendly, efficient, and stable light absorber. Perovskite solar cells (PSCs) have emerged as excellent candidate materials for photovoltaic (PV) energy conversion because of their low cost, ease of fabrication, flexibility, and versatility. However, typical high-efficiency PSCs, like methylammonium lead iodide (MAPbI(3)), rely on the use of the chemical lead (Pb), whose toxicity and detrimental impact on human health and the environment raise strong concerns. Therefore, less toxic substitutes that produce the same high performance as MAPbI(3) are of interest to enable a wide deployment of PSCs. Hence, much effort has focused on replacing Pb with other elements, such as tin (Sn), bismuth (Bi), antimony (Sb), and germanium (Ge) in perovskite materials, with the dual objectives of maintaining the superior optoelectronic properties of the perovskite and reducing its toxicity. In this review, the structure, optoelectronic properties, as well as recent advances in device performance of Pb-free PSCs are highlighted. Moreover, the stability challenges of Pb-free perovskite are detailed, and strategies to overcome them are discussed. Finally, a conclusion and outlook towards Pb-free perovskite photovoltaics (PV) is provided. (c) 2021 Society of Chemical Industry (SCI).