A General Crystallization Picture of Quantum Dots: The Underlying Physical Chemistry

Since the discovery of quantum dots (QDs) in the 1980s, crystallization theory has played an important role in developing their synthetic chemistry. In this mini-review, we summarize current progress on the crystallization theory related to QDs, including the Gibbs free energy theory, Gibbs-Thomson relation, Fick’s first law-based growth kinetics, Avrami model, LaMer model, Sugimoto model, continuous nucleation model, monomer-attachment model, and particle-mediated growth models. With the consideration of these models, a general picture was conceived to guide the understanding of the crystallization of QDs, including four key stages: prenucleation, nucleation, growth, and postgrowth. The prenucleation theory focuses on the convention from precursors to monomers and subsequent aggregation of monomers. Nucleation theory focuses on burst nucleation and continuous nucleation models, as well as the basic concepts of critical size of nuclei, nuclei number, and nucleation rate. Growth theory concerns diffusion-controlled growth and reaction-controlled growth, in particular the size-dependent growth rate, as well as the size-focusing and size-limitation effects. Postgrowth models include Ostwald-ripening, digestive-ripening, and oriented-attachment. Hopefully, this general picture could help design optimal synthetic routes toward high-quality materials and scale-up fabrications.