Room-Temperature Synthesis of Covellite Nanoplatelets with Broadly Tunable Localized Surface Plasmon Resonance

Preparation of nanomaterials with controllable sites and shapes at ambient conditions, without heating or cooling extreinely attractive from the perspective of cost and energy efficiency. However, highly reactive precursors must be used to obtain NCs at ambient conditions, and this can niake the control of particle forniation extreiriely challenging. Degenerately p-doped copper sulfide NCs have attracted much recent interest based on the,observation of idealized surface plasmon resonance (LSPR) in these materials. These earth-abundant semiconductor NCs have potential applications ranging from plibtoycltaicS to biomedical imaging Here, we provide the first report of ambient temperature Preparation cf covellite nanoplatelets. The lateral IdimenSions of;these are controllable over a wide range while Maintaining a constant thickness of 4 nm. The crystalline phase of the NCs is shown here to be controlled by the oxidation state of the Copper,reagent, with a Cu(II) precursor required to prepare phase pure covellite NCs. The NCs exhibit LSPR absorbance that depends upon their aspect ratio (their lateral dimension, at fixed thickness) and Can be tuned over a range of more than 600 nm. Their optical absorbance was modeled quantitatively to extract consistent values of free carrier concentration and background polarizability that apply over a wide range Of NC sizes.