Fully Aqua‐Mediated Ripening of Perovskite Quantum Dots with 98% PLQY and Self‐Assembly into Bioimaging Nanoparticles

Abstract Ongoing research on perovskite quantum dots (PQDs) spanning diverse areas such as crystallography and biology represents a rapidly expanding frontier in nanotechnology, yet is still limited by the poor water stability and inadequate biocompatibility. Herein, this study reports an ultra‐simplified, eco‐friendly, cost‐effective, and industrial‐grade fully aqua‐mediated ripening (FAMR) technique for aqueous‐PQDs (APQDs) with tunable spectra, achieved by directly stirring the raw precursors with zwitterionic ligands in water at a set pH via Ostwald ripening crystallization.These APQDs exhibit high photoluminescence quantum yields (PLQYs) of up to 82.8% (blue), 98.2% (green), and 92.4% (red), respectively. Owing to the highly efficient bidentate binding of zwitterionic ligands onto APQDs surfaces, as confirmed by theoretical studies, the APQDs demonstrate excellent water storage stability for over 1 month and can retain an impressive 83% of the initial PL intensity after 3 months when transferred to EtOH. With elevated exciton binding energy, extended carrier lifetimes, and lower defect density, APQDs also outperform conventional oil‐phase PQDs in terms of thermal and UV irradiation stability. Based on this, water‐soluble fluorescent nanoparticles (NPs) are synthesized through self‐assembly of APQDs and DSPE‐PEG 2000 using EtOH and water as biphasic solvents. Finally, the APQDs@NPs, possessing desired luminescence and biocompatibility, exhibited excellent bioimaging performance in U251 cells.