2, Columbia University, New York, New York, United States
3, Centre National de la Recherche Scientifique (CNRS), Lyon, , France
4, Northwestern University, Evanston, Illinois, United States
Metal chalcogenice nanocrystal synthesis relies heavily on control over solute supply kinetics. We have developed libraries of substituted thiourea and selenourea precursors whose conversion, and therefore, solute supply kinetics are determined by the nature of their substituents. With these libraries, we observe well-defined relationships between solute supply and number of crystals, enabling quantitative study of the nucleation and growth processes. By making kinetic measurements in situ using optical spectroscopy and synchrotron X-ray scattering, we have begun to make estimates of the solute concentration at nucleation, the first stable nucleus size, and per-particle growth rates. This synthetic platform is broadly applicable to other sulfides and selenides, including luminescent quantum dots used in commercial displays, representing a paradigm shift in colloidal synthesis.