Surface Modification Strategy Synthesized CsPbX₃ Perovskite Quantum Dots with Excellent Stability and Optical Properties in Water

Abstract The poor stability of CsPbX 3 (X = Cl, Br, I) perovskite quantum dots (PQDs) in polar solvents such as water, seriously hinders their practical application. Herein, 5‐Bromovaleric acid (BVA) is used to replace oleic acid (OA), the most common surface ligand in CsPbX 3 PQDs synthesis. Under the synergic action of oleylamine (OLA), CsPbX 3 PQDs with high water stability can be synthesized directly in water. Because the carboxyl ligands provided by BVA, and the long chain amines provided by OLA formed hydrophobic shells on the surface of CsPbBr 3 PQDs, the obtained CsPbBr 3 PQDs still has high luminescence intensity and photoluminescence quantum yield after being dispersed in water for several days, and the luminescence peak is always maintained at 518 nm. In contrast, the luminescence intensity of CsPbBr 3 PQDs synthesized with OA and OLA is <1% of the initial intensity after only 30 min. CsPbCl 3 and CsPbI 3 PQDs synthesized directly in water by this method also show high water stability. In this study, for the first time the synthesis method of CsPbX 3 PQDs with high water stability using BVA/OLA as surface ligands is proposed, which provides an effective way to explore the synthesis of PQDs that can maintain stability in water.