Over the past few years, we have developed modular methods to integrate colloidal nanocrystals into amorphous inorganic matrices such that a tunable and high density of nanocrystal-glass interfaces are distributed throughout the nanocomposite material. Our approach has been to form chemical bonds linking inorganic clusters to colloidal nanocrystals and subsequently to condense the clusters into a continuous amorphous matrix surrounding, and covalently linked to, the embedded nanocrystals. In ITO-in-NbOx nanocomposites the structure of the glassy niobia, probed by Raman spectroscopy, is strongly perturbed near the interface, which we previously correlated with a five-fold enhancement in optical contrast under electrochemical switching. Now, we use impedance spectroscopy to uncover the improvement charge transport properties responsible for such changes in electrochromic performance. Furthermore, our preliminary results suggest that the chemistry at such interfaces can strongly modify the crystalline phase stability of the nanocrystals.  The temperature at which thermally-triggered metastable-to-stable phase transformations occur for nanocrystals in a composite can be tuned by 100 C by changing the nature of the matrix. These observations suggest new strategies for processing of thin film photovoltaic materials from nanocrystals.

Nanocrystal-inorganic interfaces in composite electrodes

248th National Meeting (2014)

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