Growing MASnI 3 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 MASnI 3 single crystals via inverse temperature crystallization (ITC) strategy with γ-butyrolactone (GBL) as solvent. The solubility characteristics of MASnI 3 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 MASnI 3 single-crystal thin films are fabricated with micron-scale thickness, which is highly desired for efficient tin perovskite solar cells. Our MASnI 3 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 MASnI 3 single crystals and cause a new upsurge in exploring the field of lead-free perovskite single-crystal growth.