Grafting Mechanism of Electrochromic PAA–WO3Composite Film

✍ Scribed by J.-H. Choy; Y.-I. Kim; B.-W. Kim; G. Campet; J. Portier; P.V. Huong

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 202 KB
• Volume: 142
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1998.8050

✦ Synopsis

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 tin-doped indium oxide glass into an aqueous mixture solution of PAA (polyacrylic acid) and WO 3 -NH 4 OH. 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-WO 3 films, it was evident that the coloration accompanies a peak reduction at &960 cm\ 1 and a peak enhancement at &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 -W VI ‫؍‬O bonds into -W V ‫؍‬O (1؊ )؉ -M ؉ (M ‫؍‬ H, Li) ones.