GRAFTING MECHANISM OF ELECTROCHROMIC PAA-WO3 COMPOSITE FILM

摘要

A micro-Raman spectroscopic study has been carried out to investigate the electrochromic process in a porous and nanocrystalline tungsten oxide film. The film was prepared by dipping the Sn-doped indium oxide glass into an aqueous mixture solution of PAA (polyacrylic acid) and WO3-NH4OH. After heating at low temperature, around 100 C, the film was treated in 1 N HCl in order to achieve polycondensation, where the ammonium ion was replaced with a proton. In the micro-Raman spectra for the bleached and colored PAA-WO3 films, it was evident that the coloration accompanies a peak reduction at approx 960 cm-1 and a peak enhancement at approx 810 cm-1. Based upon the present Raman observation, we can confirm that the electrochromism of the nanocrystalline tungsten oxide is dominated by the grafting process, i.e., the surface modification of -WVI=O bonds into -WV=O(1-delta)+-Mdelta+ (M=H, Li) ones. 20 refs.