Cu_2–<i>x</i>S_1–<i>y</i>Se_<i>y</i> Alloy Nanocrystals with Broadly Tunable Near-Infrared Localized Surface Plasmon Resonance

Abstract

We report facile methods for synthesizing monodisperse Cu2–xS1–ySey alloy nanocrystals (NCs) with tunable composition and size. The near-infrared (NIR) localized surface plasmon resonance (LSPR) in these self-doped Cu2–xS1–ySey alloy NCs can be tuned over a broad range from 975 to 1650 nm. The LSPR shifted to longer wavelength with increasing sulfur content and with increased concentration of oleic acid used in the synthesis. This method provides new possibilities for broadly tuning LSPR wavelength by controlling the anion composition, cationic vacancy concentration, and surface ligands in heavily doped Cu2–xS1–ySey alloy NCs. This opens up access to LSPR absorbance across a broad portion of the near-IR using small colloidal quasi-isotropic NCs.