Highly lipophilic nanocrystals (NCs) of cesium lead halides were successfully embedded in polystyrene (PS) particles by deliberately controlling the swelling of the PS particles in the mixtures of good and bad organic solvents. The resulting composite particles were readily transferred into water via simple stepwise solvent exchange, which yielded water-borne perovskite NC-based inks with outstanding structural and chemical stability in aqueous media. Minimal change in the photoluminescence (PL) of the NCs loaded in the PS particles was visible after 1 month of incubation of the composite particles in water in a broad pH range from 1 to 14, which could otherwise be hardly realized. Loading into the PS particles also made the NCs highly stable against polar organic solvents, such as ethanol, intense light irradiation, and heat. The NC PL intensity slightly changed after the composite particles were heated at 75°C and under irradiation of strong blue light (@365 nm) for 1 h. Furthermore, the PS matrices could effectively inhibit the exchange of halide anions between two differently sized perovskite NCs loaded therein, thereby offering a considerable technical advantage in the application of multiple perovskite NCs for multicolor display in the future.
Keywords: lead halide perovskites; luminescence; polystyrene; quantum dot; water-borne ink.