Sol–Gel Engineered WO ₃ /PEDOT:PSS Nanocomposite Films with Enhanced Optoelectronic Dynamics for High-Performance Automotive Smart Windows

Current electrochromic materials face challenges in balancing conductivity, switching speed, and long-term stability for automotive applications. This study presents a novel sol–gel synthesis strategy for fabricating nanostructured tungsten oxide (WO 3 ) and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) composite films. The method is based on precursor complexation regulation, where the peroxo-complexation state of tungsten is precisely controlled to moderate hydrolysis rates. The sulfonic acid groups of PEDOT:PSS provide coordination constraints, guiding the confined nucleation and uniform growth of WO 3 nanocrystals within the conductive polymer matrix. This in-situ hybridization results in a nanocomposite film characterized by continuous electron pathways and rapid ion diffusion interfaces. Comprehensive optoelectronic characterization reveals that the optimized film exhibits an optical contrast of 62.9% at 550 nm and a high coloration efficiency of 72.1 cm 2 · C −1 . The device demonstrates fast switching kinetics, with coloring and bleaching times of 3.1 s and 4.7 s, respectively. Critically, the film maintains 92% of its optical modulation after 10,000 electrochemical cycles, highlighting exceptional durability. The enhanced performance is attributed to the synergistic nano-architecture, which facilitates efficient charge transport and minimizes inter-facial resistance. These results underscore the potential of this nanocomposite film as a high-performance electrochromic material for next-generation automotive smart windows.