Novel WO3-PEDOT core–shell inverse opal films with enhanced electrochromic performance for smart windows

Abstract

Electrochromic (EC) materials have been widely studied in energy-saving smart windows due to their reversible control of optical performance under electric fields. Novel tungsten oxide-poly (3, 4-ethylenedioxythiophene) (WO3-PEDOT) core–shell inverse opal (IO) films are obtained by electrochemical polymerization of PEDOT onto WO3 IO templates. The WO3 IO templates are prepared through the electrodeposition of WO3 into the voids of a polystyrene (PS) colloidal crystal, followed by calcination to remove the polystyrene microspheres. The designed microstructure and chemical composition of the WO3-PEDOT IO films are determined by SEM, XRD, XPS and Raman spectroscopy. The WO3-PEDOT IO films exhibit promising optical contrast ([Formula: see text]52% at 600 nm and [Formula: see text]77% at 1020 nm), indicating their bifunctional potentials in both visible and near infrared (NIR) region modulation. The WO3-PEDOT IO films also show excellent EC properties of much shorter response time (6.7 s for coloring and 5.8 s for bleaching) and superior cycling stability than that of the bare WO3 IO. These results suggest that the synergistic effect between the WO3 IO core and PEDOT shell may greatly increase the electrolyte accessibility to active sites and improve the interaction between the inorganic/organic interfaces to obtain enhanced EC performance.