CAREER: Semiconductor Clusters: Chemistry at the Interface of Small Molecules and Quantum Dots

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This CAREER award by the Macromolecular, Supramolecular, and Nanochemistry (MSN) program supports work by Professor Jonathan Owen at Columbia University - endowed to understand the nucleation and growth of nanocrystalline semiconductors and their relationship to the conversion of precursor molecules. The core focus of the proposed work consists of two parts: (i) The kinetics and mechanisms of precursor conversion and their relationship to the crystallization of clusters and their subsequent conversion into larger nanocrystals, whether by assembly or atom-by-atom growth processes; (ii) To characterize and modify the surface structural features that cause surface state luminescence in these materials by systematic tailoring of cluster coordination chemistry. By studying atomically precise clusters, the assignment of specific structural elements responsible for trapping of excitons and investigations of crystal growth mechanisms all become possible with a level of detail not possible using traditional materials and methods. The broader impact of this proposal rests in its importance to classical models of surface tension and the nucleation of colloidal crystals. Understanding the origins of cluster stability will clarify how clusters are distinct from larger nanocrystals where the stability increases with the particles dimensions according to the Gibbs-Thompson relationship. This difference has important consequences for nanocrystal nucleation and growth mechanisms and is in stark contrast to the free energy arguments that underpin classical nucleation theory. The study of structure function relationships is integrated into a K-8 curriculum that teaches the importance of molecular structure to tangible aspects of everyday life. By integrating this context into the teaching of scientific concepts, chemical structure is made relevant to young students, promoting broad interest in scientific thinking.