(637f) Structural and Compositional Engineering of Visible and Near-Infrared Optical Resonances in Ternary Metal Chalcogenide Nanocrystals

Careful control over composition and morphology are critical in virtually every materials system, and plasmonic semiconductor nanostructures have recently emerged as a powerful class of materials since they exhibit localized surface plasmon resonances that can be tuned over a wide spectral range through compositional engineering of the free charge carrier density. This contrasts with metallic nanostructures where the tuning of plasmonic resonances is typically achieved by changing the polarizability of the nanostructure through shape control. In particular, the copper chalcogenides have been studied widely in recent years due to their intrinsic plasmon band in the near-infrared spectral range, generated via resonant excitation of free hole carriers in the valence band caused by the large concentrations of copper vacancies present in nonstoichiometric nanocrystals. Herein, we discuss our recent efforts to control optical resonances and photothermal transduction in ternary metal chalcogenide nanocrystals through morphological and compositional tuning. We investigate changes in the plasmon response via control over shape and polarizability and demonstrate compositional tuning of the localized surface plasmon resonance frequency and photothermal transduction efficiency via careful control over chalcogen composition, defect density, and oxidation, as well as the introduction of additional optical resonances through the gradual incorporation of metallic impurities.