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Growing MASnI3 perovskite single-crystal films by inverse temperature crystallization

Perovskite single-crystal films are promising candidates for high-performance perovskite optoelectronic devices due to their optoelectrical properties. However, there are few reports of single-crystal films of tin based perovskites. Here, for the first time, we realize the controllable growth and preparation of lead-free tin perovskite MASnI3 single crystals via inverse temperature crystallization (ITC) strategy with γ–butyrolactone (GBL) as solvent. The solubility characteristics of MASnI3 in GBL are clarified by quantitative analytical method. Highly repeatability experiments are further demonstrated using this unique solubility and ITC properties. Sequentially, using space limiting method, tin perovskite MASnI3 single-crystal thin films are fabricated with micron-scale thickness, which is highly desired for efficient tin perovskite solar cells. Our MASnI3 single-crystal thin films show typical single-crystalline features including strongly optical absorbance with sharp absorption edges, pure-phase x-ray diffraction patterns, and absence of Sn(IV) x-ray photoelectron spectroscopy. We believe that our findings will further broaden the application prospects of tin perovskite MASnI3 single crystals and cause a new upsurge in exploring the field of lead-free perovskite single-crystal growth.