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Workshop / Seminar

Chemistry Seminar — Phase Determination of Colloidal Nanocrystals

This is a Zoom event. Please contact Sarah Oesch Miller for the Zoom information.

About the event

Speaker: Dr. Richard L. Brutchey
Professor of Chemistry
University of Southern California

Host: Assistant Professor Liane Moreau

Title: Molecular Programming the Phase Determination of Colloidal Nanocrystals

Abstract: A great deal of progress has been made in the synthesis of colloidal nanocrystals, which now allows for exacting control over nanocrystal size, shape, polydispersity, and composition. Despite these numerous achievements, most colloidal nanocrystals are synthesized in their thermodynamically preferred structural polymorphs. That is, most of the work to date has focused on “nanosizing” the known phases of bulk materials. An underdeveloped area of colloidal nanocrystal chemistry is the discovery of metastable structural polymorphs with emergent properties. Such metastable phases – that is, kinetically trapped phases with positive free energies above the equilibrium state – are pervasive in Nature, but much of our current understanding of synthetic design is based on materials operating at the condition of thermodynamic equilibrium. Moving beyond thermodynamically preferred phases to metastable materials will reinvent and greatly expand the scope of functional materials available for exploration. Here, we will discuss efforts to introduce rational design principles to direct phase determination in multinary chalcogenide nanocrystal syntheses using diorganyl dichalcogenide molecular precursors. Exerting kinetic control through the molecular programming of precursor functional groups allow us to access several metastable polymorphs not observed for the bulk analogues. We expounded these initial results to next understand the mechanisms of phase determination in metastable chalcogenide nanocrystals using dichalcogenide precursors.