Enhanced dual-band modulation of visible and near-infrared light transmittance in electrochromic composite films based on Preyssler-type polyoxometalates and W18O49

Abstract

A W₁₈O₄₉/[PEI/P₅W₃₀]₂₀ film modulated for visible and near infrared light was prepared by a layer-by-layer method on an FTO glass substrate, and had a significant coloration efficiency (149.78 cm² C⁻¹), fast response time (2.62 and 0.94 s at 650 nm, and 1.98 and 1.92 s at 1167 nm, respectively), and good cycling stability (500 cycles) in 0.5 M AlCl₃ electrolyte. Furthermore, the W₁₈O₄₉/[PEI/P₅W₃₀]₂₀ film was successfully assembled into an electrochromic device, which can realize color reversibility conversion under a small voltage. Overall, the experimental results showed that W₁₈O₄₉/[PEI/P₅W₃₀]₂₀ film preparation allows the production of an electrochromic film for next-generation smart windows, which are able to evenly control the solar light and heat gain in buildings.