Aqueous Continuous Flow Synthesis of Cadmium Chalcogenide Quantum Dots: Opportunities and Challenges

Cadmium chalcogenide quantum dots (CdX QDs, X = S, Se, Te) are among the most extensively studied semiconductor nanocrystals due to their size-tunable optical properties and wide potential applications in optoelectronics, bioimaging, and sensing. While early syntheses relied on high-temperature organometallic routes in organic solvents, the demand for safer, greener, and more biocompatible approaches has driven increasing interest in aqueous-based methods. These two strategies differ substantially in terms of precursor chemistry, surface passivation, and control over nanocrystal quality. In parallel, continuous flow technology has brought transformative assets to the field, offering precise reaction control, scalability, and reproducibility, which are essential for both fundamental studies and industrial translation. This review summarizes the evolution of CdX QDs synthesis, contrasting organic and aqueous batch approaches, and focuses on recent advances in aqueous continuous flow strategies. Finally, we highlight perspectives on the integration of automated machine learning and artificial intelligence approaches with continuous flow, which may accelerate the discovery, optimization, and scalable production of high-quality QDs for next-generation technologies.