Centimeter-sized Cs3Cu2I5 single crystals grown by oleic acid assisted inverse temperature crystallization strategy and their films for high-quality X-ray imaging

Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging, yet the issues of the poor chemical stability of hybrid halide perovskite, the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization. Here, we developed a solution inverse temperature crystal growth (ITCG) method to bring-up high quality Cs3Cu2I5 crystals with large size of centimeter order, in which the oleic acid (OA) is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently, as well as to decelerate the crystallization rate remarkalby. Based on these fine crystals, the vapor deposition technique is empolyed to prepare high quality Cs3Cu2I5 films for efficient X-ray imaging. Smooth surface morphology, high light yields and short decay time endow the Cs3Cu2I5 films with strong radioluminescence, high resolution (12 lp/mm), low detection limits (53 nGyair/s) and desirable stability. Subsequently, the Cs3Cu2I5 films have been applied to the practical radiography which exhibit superior X-ray imaging performance. Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.