Abstract
Lead halide perovskite quantum dots (PQDs) exhibit properties tunability and solution processability, rending them highly promising for optoelectronic applications. To overcome the compositional limits of thin-film perovskite and achieve mixed A-site PQDs, a post-synthetic cation-exchange process, driven by the intrinsic ionic character as well as the dynamic surface structure within the PQDs, emerges as a highly efficient approach. The cation-exchange process can be precisely regulated by manipulating PQD-situated environment, such as the cation species, stoichiometric ratios, and surface ligand conditions, leading to tunable optical bandgap, improved stability, and enhanced carrier lifetime over the single A-site PQDs. These advancements hold immense potential for elevating the performance of PQD-based optoelectronic devices. In this perspective, a timely summary and outlook on the emergence and developments of cation exchange in functional PQDs is presented, as well as the intrinsic cation-exchange mechanism and properties of these resultant-mixed-cation PQDs. It is believed that these detailed discussions are beneficial for advancing further development of cation exchange and utilization of mixed-cation PQDs toward functional optoelectronic applications.