Cation‐Exchange‐Driven Topochemical Engineering of Multicomponent Quantum Dots: Synthesis Strategies and Luminescence Modulation

Abstract Colloidal quantum dots (QDs) are promising materials for optoelectronic and biomedical applications due to their size‐tunable properties. However, conventional synthetic approaches often struggle to produce complex multicomponent QDs with controlled doping profiles and sharp interfaces due to phase segregation and self‐purification effects. This review highlights cation exchange (CE) as a powerful topochemical strategy to overcome these limitations, enabling atomic‐level compositional control and the synthesis of doped, core–shell, and alloyed QDs. A systematic overview of CE‐driven syntheses is presented, emphasizing the underlying thermodynamic and kinetic principles that govern cation substitution. By elucidating the relationship between QD composition, structure, and luminescence properties, including emission wavelength, quantum yield, and photostability, this review demonstrates how CE facilitates the rational design of QDs with tailored functionalities. Finally, current challenges and future opportunities for CE in advancing multicomponent QD synthesis and their applications in optical modulation are discussed, providing a comprehensive perspective on the unique capabilities of this approach.