Poly(hydroxymethyl 3,4-ethylenedioxythiophene) (PhmEDOT) and Poly(3,4- ethylenedioxythiophene) (PEDOT) thin films are prepared by electropolymerization method on indium tin oxide conducting glass in this study. Surface morphology of the thin films is observed using a scanning electron microscopy. Electrochemical and electrochromic properties including redox behaviors, UV–Vis absorbance spectra at different applying potentials, coloring/bleaching response times and transmittance modulation ability of the thin films are investigated. Photoelectrochromic devices (PECDs) composed of the PhmEDOT or the PEDOT thin films and dye-sensitized TiO2 photoanodes were assembled, and their photoelectrochromic performances compared. According to the obtained results, the PECD using the PhmEDOT thin film has faster photoelectrochromic coloring/bleaching rates and better transmittance modulation ability than the one using the PEDOT thin film.
