A tin based perovskite solar cell is a special type of perovskite solar cell, where the lead is substituted by tin. It has a tin-based perovskite structure (ASnX3), where 'A' is a 1+ cation and 'X' is a monovalent halogen anion. The maximum solar cell efficiency reported was 6.4% for methylammonium tin iodide (CH3NH3SnI3), 5.73% for CH3NH3SnIBr2, 4.8% for formamidinium tin iodide (FASnI3), and 2.02% for CsSnI3. The methylammonium tin iodide (CH3NH3SnI3) has a band gap of 1.2-1.3 eV.
Tin-based perovskite solar cells are still in the research phase and there are relatively few publications about them, compared to their counterpart, lead-based perovskite solar cells. This is mainly due to the instability of the 2+ oxidation state of tin (Sn2+) in methylammonium tin iodide (CH3NH3SnI3), which can be easily oxidized to the more stable Sn4+, leading to a process called self doping, where the Sn4+ acts as a p-dopant leading to the reduction in the solar cell efficiency.
The main advantage of tin-based perovskite solar cells that they are lead-free. There are environmental concerns with using lead-based perovskite solar cells in large-scale applications; one such concern is that since the material is soluble in water, and lead is highly toxic, any contamination from damaged solar cells could cause major health and environmental problems.