Ultrasonic cavitation-enabled microfluidic approach toward the continuous synthesis of cesium lead halide perovskite nanocrystals

Ligand assisted reprecipitation (LARP) is a widely used method for cesium lead halide perovskite nanocrystals (NCs) synthesis. Nevertheless, the ultrafast kinetics of LARP, as well as the inefficient transport properties and discontinuity of batch reactors, challenge the particle size control and experimental repeatability. To address these issues, an ultrasonic cavitation-enabled microfluidic approach was developed to achieve the continuous synthesis of cesium lead halide perovskite via LARP. It was found that the mixing between the good solvent and antisolvent in the microchannel was greatly enhanced by intensive ultrasonic cavitation. The mixing time could be reduced to below 10 ms under the irradiation of 35 W ultrasound. By modulating the mixing degree, LARP was proved to be a mixing-sensitive process. The effects of ultrasonic power, ultrasonic treatment time, total flow rate, water additive, and reprecipitation temperature on the synthesis of CsPbBr 3 NCs were systematically investigated. As compared to CsPbBr 3 NCs synthesized in the batch reactor, the sample synthesized via the ultrasonic cavitation-enabled microfluidic approach possessed stronger photoluminescence intensity and better repeatability. Moreover, the ultrasonic cavitation-enabled microfluidic approach could also realize the continuous synthesis of cesium lead halide perovskite NCs with different halide compositions to cover a wide visible spectrum (426–661 nm). The ultrasonic cavitation-enabled microfluidic approach paved the way for the large-scale of high-quality cesium lead halide perovskite NCs.