A single crystal derived precursor for improving the performance of CsSnI3 perovskite solar cells

Abstract

Reducing the toxicity of halide perovskites is critical in the pathway toward perovskite photovoltaic commercialization. Low toxicity CsSnI₃ is emerging as a possible alternative in this regard. However, the preparation of high-quality CsSnI₃ thin films remains a great challenge due to the uncontrollable crystallization of tin-based perovskites. Herein, for the first time we prepared high purity CsSnI₃ single crystals by the wet chemical method. Utilizing these pre-synthesized CsSnI₃ single crystals for preparing precursor solutions, larger grain and pinhole-free CsSnI₃ thin films with low defect density can be obtained. Hence, the CsSnI₃-based perovskite solar cells with a device configuration of ITO/PEDOT:PSS/CsSnI₃/PC₆₁BM/BCP/Ag achieved an excellent power conversion efficiency of 6.53%, which is the highest value for CsSnI₃ photovoltaics without additives. Moreover, the optimized device exhibits excellent stability by retaining 91% of its initial efficiency after 1000 hours of storage in a nitrogen atmosphere. This work indicates a promising protocol for perovskite single crystal derived precursors for processing efficient tin perovskite solar cells.