Enhanced electrochromic performance and stability of nanostructured MoO3 via Nb doping and protective layer integration

Although alpha-MoO3 is known for its excellent electrochromic properties, such as large optical modulation, coloring efficiency, and short coloring and bleaching times, its layered structure presents a stability challenge. This study explores the enhancement of electrochromic properties of nanowall structured alpha-MoO3 films with limited reaction kinetics through Nb doping and the addition of a novel protective Indium Tin Oxide (ITO) layer. Nanowall structured alpha-MoO3 thin films are formed by converting MoS2 sputtered layers with thermal oxidation, as confirmed by a series of analyses. Electrochemical measurements, such as cyclic voltammetry, chronoamperometry, and galvanostatic charge/discharge, have revealed that Nb-doped films exhibit a fast ion response and increased durability due to their surface electrochemical activity and charge storage acceleration through surface processes. An ITO layer is sputtered onto the highest Nb-doped film to address degradation from repeated ion diffusion, providing ion diffusion rate regulation and structural support. In-situ transmittance measurements have confirmed consistent optical modulation over extended cycling. The combined Nb-doping and ITO layer effectively optimized electrochromic performance, yielding films with rapid switching and longterm stability.