Tungsten oxide is regarded as the most promising electrochromic material owing to its continuously tunable optical properties, low cost, and high coloration efficiency. Further improving its optical modulation, switching speed, and coloration efficiency is important to electrochromic smart windows and related devices. Here, we demonstrate an enhanced electrochromic film composed of a WO3 nanosheet and ITO nanoparticles developed by an all-solution technology. The WO3 nanosheet is fabricated by an acid-assisted hydrothermal process with high product efficiency. The introduction of an ITO into the WO3 nanosheets significantly improved the electrochemical activity and the conductivity of the composite film. Compared with a reported electrochromic film without ITO doping, our synthesized composite WO3 film exhibited optical modulation up to 88% and a high coloration efficiency of 154.16 cm2 C-1. Particularly, our electrochromic film was based on the dispersant solution and spin-coating technology, which may also be realized with nano-spray coating for large scale applications. The results offer an effective way to develop large-area electrochromic film and devices.
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