In‐situ Synthesis of CsPbBr3 Nanocrystals/Polyvinyl Pyrrolidone Ethanol Sol and High Resolution Fingerprint Identification

Abstract CsPbBr 3 perovskite nanocrystals have potential applications in fingerprint identification due to their excellent optical properties. Unfortunately, the current synthesis methods need harsh conditions as well as large quantities of expensive and toxic organic solvents. Attention has been considerably attracted for the preparation of all inorganic perovskite nanocrystals with ethanol and water as solvents. However, due to the strong polarity of ethanol, the ligands have been dissolved and thus the perovskite nanocrystals have been destroyed. Here, we employed a remarkably simple strategy, using the adsorption of Br − by N + and the formation of the spatial network structure of polyvinyl pyrrolidone (PVP) and the polish of perovskite surface defects by trace water, successfully prepared CsPbBr 3 nanocrystals in ethanol. The effects of PVP molecular weight and its concentration and the amount of water on the luminescence properties have been studied by XRD, FTIR, ultraviolet‐visible absorption and photoluminescence spectra. The prepared CsPbBr 3 nanocrystals sol maintained 70 % of the initial photoluminescence intensity after 110 days of storage. By adding alcohol‐soluble thermoplastic acrylic resin, the fingerprint identification films have been prepared simply and quickly, and the three‐level structure of fingerprint can be clearly emerged. This strategy offered a great application prospect in the field of fast and high‐resolution fingerprint identification.