Formamidinium lead iodide perovskite (FAPbI3) stands out as an exemplary absorber material for high-efficiency single-junction solar cells, thanks to its superior optoelectronic properties, cost-effectiveness, and robust thermal stability. Nonetheless, pure FAPbI3 perovskite encounters hurdles in practical applications due to its intricate crystallization dynamics and metastable thermodynamic behavior at room temperature, stemming from a mismatch in the size tolerance factor. This mismatch adversely affects crystallization quality and stability. Component alloying strategies, involving the addition of substances like methylammonium chloride and Cs+, have been employed to fine-tune the crystallization process and photoelectric properties of the thin film. However, these additives can introduce unwanted side effects, such as phase separation, thermal instability, and potential nucleophilic chemical reactions. Consequently, the pursuit of high-quality, genuinely pure α-FAPbI3 perovskite has emerged as a pivotal area of research.