Tandem design of conductivity-enhanced electrochromic electrode for multi-spectra modulation smart window

Abstract Overcoming the constraint of single-color display by integrating diverse electrochromic materials within a single electrode can facilitate the practical utilization of electrochromic devices. However, the mutual interference between different electrochromic materials during operation is always inevitable. In this study, a multimode electrochromic electrode is demonstrated by assembling the porous anodic (NiO nanosheets) and cathodic (W18O49 nanowire networks) electrochromic materials in a tandem structure with a conductive ITO interlayer inserted in between on the same electrode. The open framework ensures sufficient electrolyte penetration for the anodic and cathodic materials to operate independently, and the incorporation of the ITO interlayer lowers the effective work function of the electrochromic electrode and facilitates electron transport, leading to a 14.46% and 53.4% reduction in coloring and bleaching time of the outer-layer W18O49 nanowire network from 10.1/7.06 to 8.64/3.29 s, as well as a 31.7% enhancement in coloration efficiency from 54.02 to 71.15 cm2/C. Thus, the electrochromic electrode employing a tandem structural design effectively achieves dynamic transparent, brown, and blue optical states under different biases, while achieving modulation of the visible and near-infrared spectral bands, offering a viable pathway for high-performance multimode smart windows and multicolor displays.