Pulsed electrochemical deposition of porous WO3 on silver networks for highly flexible electrochromic devices

Electrochromic devices (ECDs) have attracted considerable attention due to their high coloration efficiency and low power consumption. However, the development of flexible ECDs is still at a rudimentary stage due to the poor chemical stability of flexible electrodes, which prevents the fabrication of widely used WO3 electrochromic (EC) materials via traditional techniques. Herein, uniform and lamellar porous WO3 films were successfully prepared on a flexible Ag nanofiber (Ag NF) network film via a pulsed electrochemical deposition method. The sandwich structure with configuration WO3/Ag NFs/WO3 (W/Ag NFs/W) could not only protect the Ag networks from oxidation and corrosion in the oxidizing electrolyte, but also promote the electrodeposition of WO3 films in the gaps among the Ag networks. The obtained porous WO3 film is beneficial for electrolyte infiltration and alleviates mechanical stress. An 89.7% optical modulation with excellent cycling stability was achieved when the hybrid electrode was utilized as the EC film. Moreover, we demonstrated the practical suitability of our hybrid films in all-solid-state ECDs by fabricating EC sunglasses and a smart window.