Defect mitigation using multi-dentate ligand in FASnI3 perovskite films

Tin-based perovskite shows a more rational band gap, along with lower exciton-binding energy, and is noted to be suitable for solar cell fabrication. One of the open questions is their lower environmental stability due to poor crystallinity and surface inhomogeneity. We probed the impact of sulfur-containing multi-functional additives in FASnI₃ thin films, which interacts intensely with the Sn-based perovskites, and in turn, regulate the crystallization process to allow the preferential crystal growth along (h00) planes at the microscale. The single sulfur-containing ammonium cation (Isothio-Br) based perovskites showed improved crystallinity and microstructure as compared to the double sulfur-containing Disulfo-Cl molecule.