Congruent and Oriented Crystallization of Mixed Sn-Pb Perovskite From the Nano- to Centimeter Scale.

Metal halide perovskites have garnered widespread attention for research and applications, thanks to their high adaptability in elemental composition and optoelectronic properties. The mixed Sn-Pb perovskite FASnPbI (FA is formamidinium) features a narrow bandgap of 1.25 eV, appropriate for building tandem solar cells, but faces challenges in fabricating uniform, compact films having protected surfaces and scalable dimensions.