Doped metal oxides for plasmonic electrochromic applications (Invited Paper)

Selective modulation of both visible and near-infrared (NIR) radiations are looked for advanced energy efficiency fenestration solutions. Smart windows made of highly doped metal oxides (ITO, AZO, or WO3-x vacancies) are of peculiar interest due to the possible electrochemical modulation of the localized surface plasmon resonance (LSPR) of the associated nanocrystal in the NIR. In this context, oxygen-deficient molybdenum-tungsten hybrid oxides (MoWOx) displaying a very strong LSPR signal astride visible and NIR regions [1] are good candidates for novel electrochromic formulation. The goal of this presentation is twofold: on one hand present two MoWOx formulations compared to their respective parents WOx oxides via comparative TEM, EDX, XRD, XPS and spectroelectrochemical characterizations and on the other hand analyze the plasmonic character of those emerging oxides. For the latter, we thoroughly investigated the use of the Kubelka-Munk formalism in plasmonic configurations. We derived an analytical model respecting all the required hypotheses of the formalism. Our model fully describes the plasmonic properties of metal oxides, consistently with experiments on ITO and MoWOx.