Electrochromism in Polymer‐Electrolyte‐Enabled Nanostructured WO₃: Active Layer Thickness and Morphology on Device Performance

Abstract Herein, we showcase the ease and feasibility of integrating a quasi‐solid semi‐IPN electrolyte supporting Li⁺‐ion conduction with nanostructured WO₃ to achieve a functional electrochromic device with impressive performance and stability. Co‐continuous WO₃ electrodes, obtained layer‐by‐layer, reveal interesting changes in morphology from plate‐like structures to nanoparticles. The nanostructured electrodes offer a large surface area and a sufficiently open architecture for realizing effective permeation of the polymeric electrolyte. WO₃ films (∼300 nm) achieved with five repetitive deposition‐spin cycles (5 L) provide best coverage, electrolyte wetting and device characteristics. Redox efficiency and reversibility >2000 cycles indicates a stable electrode‐electrolyte interface and device performance. A considerably high coloration efficiency of ∼134 cm² C⁻¹, an appreciably fast switching response (<2 s), full coloration/bleaching at competitive time scales of 5.9 s and 5.1 s, respectively, along with device reversibility of ≈97 % underline the viability of electrode architecture and polymer electrolyte combination.