Metrics such as absorption spectroscopy and transmission electron microscopy are suitable to characterize the size distribution, crystal structure and hence the band-edge electronic states of collodial nanocrystal quantum dots. However, many applications of QDs depend sensitively on chemical reactivity or surface-mediated non-radiative decay rates, which depend strongly on interfacial structure. The achievement of suitable metrics to permit precise descriptions of QD samples is complicated by the fact that the surfaces of collodial nanocrystals are subject to dynamic exchange with solution-phase species.We have prepared highly purified nanocrystal QDs using gel permeation chromatography, and we are using these QDs to study the effect of ligand association on quantum yield, quantitative measurements of ligand exchange and shell growth, and preparative use in the development of robust, biocompatible QD fluorophores. By correlating these outcomes with analytical measurements of purified NCs, we hope to arrive at a set of metrics for colloidal QDs that allows their performance to be abstracted from the details of the recipe used to make them.

Quantum dot purification and metrics for rational control of shell growth, ligand exchange, and quantum yield

248th National Meeting (2014)

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