Possible Perovskite Substitutes, Advances, and Future Prospects

Tin-based perovskites, particularly Sn-iodide (ASnI3), exhibit a notable power conversion efficiency (PCE) of 14.6%, making them promising lead-free alternatives for solar cell applications. Despite challenges in stability due to rapid Sn2+ oxidation, recent chemical engineering advancements achieved over 1300 h of operational stability in a nitrogen environment. Sn/Ge mixed perovskite absorbers show potential but require efficiency enhancements. Notably, Sn-iodide perovskites with low bandgaps could serve as foundation materials for tandem solar cells. Among alkaline-earth metals, magnesium iodide perovskites offer a tunable visible bandgap (0.9 to 1.7 eV), while calcium, strontium, and barium halide perovskites face limitations with high bandgaps (2.95 to 3.6 eV) and humidity sensitivity. Metal chalcogenide perovskite semiconductors, designed through split-anion or anion alloying, present a non-toxic alternative with the potential for efficient solar energy conversion. Theoretical calculations indicate favorable bandgaps and increased optical absorption in the visible range, highlighting the potential of metal chalcogenide perovskite semiconductors for advancing photovoltaic technologies.