Aqueous-Phase Preparation of Core–Shell Perovskite Nanorods Encapsulated in Polydopamine with Ultrahigh Water Stability

All-inorganic perovskite CsPbBr₃ (CPB) nanocrystals (NCs) are not widely applied in aqueous environments due to their readily decomposable nature. Therefore, the aqueous-phase preparation of CPB NCs has been a considerable challenge. In this work, a feasible method is proposed for preparing aqueous-phase core–shell CPB nanorods (NRs) encapsulated with polydopamine (PDA) by employing a multifunctional additive cesium trifluoroacetate (Cs-TFA). Highly luminescent TFA-CPB NRs are obtained via a chemical transformation of Cs₄PbBr₆ NCs in water. Subsequently, PDA constitutes a robust shell on the surface of TFA-CPB NRs through the covalent oxidative polymerization, which effectively reduces the original dynamic properties of surface ligands, retards the decomposition of ligands and inhibits the leakage of Pb²⁺ ions. The results demonstrate that the fluorescence intensity of TFA-CPB@PDA NRs maintains 49.3% of the initial intensity after 136 days. Meanwhile, the NRs exhibit low cytotoxicity, and the cell viability remains at 80% when the concentration of the NRs is 200 μg mL⁻¹. The reliable preparation of aqueous-phase core–shell perovskite NRs (PNRs) will facilitate their development in many fields, such as materials science, biology, medicine, and their applications in aqueous environments.