Doped metal oxide nanostructures are emerging as key components of next-generation electrochromic systems, notably enabling selective and independent modulation of near-infrared (NIR) radiation while preserving visible (VIS) light transparency, thanks to localized surface plasmon resonance (LSPR) effects. This capability specifically enhances current smart glazing technologies, further improving energy efficiency in buildings through a more targeted optical filtering, thereby consolidating the reduction of heating, cooling, and lighting costs.

Among the most promising materials, indium-tin oxide (ITO) achieves NIR modulation in the 1500–2000 nm range while maintaining high VIS transmittance, while substoichiometric tungsten oxide (WO_3-δ), bimetallic Mo-W oxides, and Nb-W oxides all three exhibit dual-band VIS-NIR responses (800–1200 nm). These nanostructures are typically synthesized via solution-based methods (thermal decomposition under Schlenk conditions, hydro/solvothermal processes) and deposited as thin films using wet-based methodologies (spin-, spray-, blade-coating).

Crucially, their optical absorption is made dynamically tunable through the application of an external electrical bias, which modifies charge carrier concentration, enabling real-time modulation of LSPR intensity and spectral position – thus achieving NIR-selective electrochromism. This effect is typically realized in a three-electrode setup with a usually liquid electrolyte, which formulation is acknowledged to play a pivotal role in performance: indeed, in a recent study focusing on plasmonic ITO nanostructured electrodes, Zn²⁺-based electrolytes have been shown to deliver stronger optical modulation within narrower potential windows compared to Li⁺-based ones.

This contribution will therefore summarize some of the latest corresponding contributions from our team and collaborators, while opening new perspectives for electrochromic metal oxide nanofabrication, electrolyte engineering, and interfacial optimization, notably. This will overall pave the way for more and more advanced plasmonic electrochromic materials and devices, including self-powered systems with enhanced architectures, functionalities, and performances.

electrochromism,metal oxides,electrolytes,nanostructures,Localized surface plasmon resonance (LSPR),near-infrared