461291 Influence of Surface Reactions on the Infrared Localized Surface Plasmon Resonance of Indium Tin Oxide Nanocrystals

Monday, November 14, 2016: 3:31 PM
Golden Gate 5 (Hilton San Francisco Union Square)
Weize Hu and Michael A. Filler, School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA

Heavily doped oxide nanocrystals exhibit a tunable plasmonic response in the infrared, a capability that is promising for future nanoscale photonic technologies. Nanocrystal carrier density, and thus spectral response, is adjustable via chemical reaction; however, the fundamental processes governing this behavior are poorly understood. Here, we study the oxidation and reduction of indium tin oxide (ITO) nanocrystals with O2 and H2, respectively, with in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). We show that the main absorption feature redshifts upon oxidation more than 1000 cm-1 and blueshifts to its original position upon reduction. The same magnitude spectral shift is observed over many cycles of oxidation and reduction. A kinetic model, which includes surface reaction and bulk diffusion, allows us to quantitatively rationalize the process, revealing that surface reaction is rate limiting under the conditions studied. Our experiments provide a deeper understanding of the connection between surface reaction and carrier density in oxide nanocrystals, and open the door to a priori control of plasmonic response.

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See more of this Session: Nanoelectronic and Photonic Materials
See more of this Group/Topical: Materials Engineering and Sciences Division