Eco-friendly synthesis of Cs3Bi2Br9 perovskite quantum dots using castor oil as solvent and ligand for leather anti-counterfeiting.

All-inorganic cesium bismuth bromide perovskite quantum dots(Cs3Bi2Br9 PQDs) have emerged as promising alternatives to lead-based perovskite quantum dots with excellent performance due to their low toxicity, drawing extensive attention over recent decades. However, challenges remain in terms of their stability and the reliance on organic solvents during the preparation process. Herein, a novel synthesis method for Cs3Bi2Br9 PQDs is introduced, utilizing eco-friendly castor oil as both the solvent and ligand (CO-Cs3Bi2Br9). These PQDs display a vivid blue emission at 430 nm, with an impressive photoluminescence quantum yield (PLQY) of 21.2%. Furthermore, they maintain 97.3% of their fluorescence intensity after 72 h of environmental exposure. The effects of various components of castor oil, including ricinoleic, oleic and linoleic acid, on crystal growth and properties of the Cs3Bi2Br9 are investigated. Significantly, the presence of conjugated double bonds in linoleic acid, when used as a solvent, results in a PLQY of up to 53% for the synthesized Cs3Bi2Br9 PQDs. Moreover, CO-Cs3Bi2Br9 PQDs are introduced into leather by a layer-by-layer self-assembly method, the bright blue fluorescent pattern can be observed in the CO-Cs3Bi2Br9/leather under ultraviolet irradiation, indicating the leather anti-counterfeiting potential of CO-Cs3Bi2Br9 PQDs. This study opens a novel pathway for the sustainable synthesis of PQDs through the utilization of castor oil-derived natural green solvents.