Cation Exchange in Lead Halide Perovskite Quantum Dots toward Functional Optoelectronic Applications.

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.