Large organic cations are beneficial for slowing tin-based perovskites crystallization rate and improving efficiency

Abstract In the past few years, the efficiency of perovskite cells has been improved rapidly, and the current efficiency can reach 25.8%. Since the lead in perovskite materials will pollute the environment, so people turn their attention to lead-free tin-based perovskites. Tin-based perovskites are becoming a research hotspot recently due to their nontoxic properties. However, due to the fast crystallization rate of tin-based perovskite, the improvement of the efficiency of tin-based perovskite cells is limited. In this work, by introducing ethylammonium iodine (EAI) into FA0.98SnI3 perovskite, it not only slowed down the crystallization rate of tin-based perovskite cells, but also improved the film morphology and slowed down the rate of Sn2+ oxidation, and finally achieved a solar cell conversion efficiency of 7.6%. This work provides a new strategy for the study of lead-free perovskites.