Defect-less formamidinium Sn–Pb perovskite grown on a fluorinated substrate with top-down crystallization control for efficient and stable photovoltaics

A highly efficient and stable ideal-bandgap perovskite solar cell based on a defect-less formamidinium (FA) Sn–Pb perovskite light-absorbing layer is grown on a fluorinated substrate via top-down crystallization.