Encapsulation of Pb-Free CsSnCl Perovskite Nanocrystals with Bone Gelatin: Enhanced Stability and Application in Fe Sensing.

The toxicity of the Pb element limits the large-scale application of inorganic cesium-lead halide (CsPbX, with X = Cl, Br, and I) perovskite nanocrystals (NCs). Pb-free cesium-tin halide (CsSnX) NCs have emerged as a viable alternative because of its excellent photoelectric conversion efficiency. However, the applications are hampered by its poor stability and low photoluminescence quantum yield (PLQY). In this study, extraordinarily stable CsSnCl NCs were prepared by exploiting bone gelatin as surface capping agents, which retain 95% of the photoluminescence intensity in water for 55 h. Additionally, after bone gelatin encapsulation, the PLQY of CsSnCl NCs was found to increase from 2.17% to 3.13% for the uncapped counterparts because of an improved radiative recombination rate. With such remarkable optical properties of the bone gelatin-CsSnCl NCs, metal ions like Fe in aqueous solutions can be readily detected and monitored, signifying the potential application of such stable bone gelatin-CsSnCl NCs in the development of fluorescence sensors and detectors.