A RAMAN MICROPROBE STUDY OF THE ELECTROCHROMIC AND PHOTOCHROMIC THIN-FILMS OF MOLYBDENUM TRIOXIDE AND TUNGSTEN TRIOXIDE

Raman microprobe spectroscopy has been used to study the electrochromic thin films of MoO3 and WO3. It was found that the MoO3 thin films, after subjecting to cathodic polarization or UV irradiation, exhibited several Raman peaks at 112, 124, 150, 283, 336, 376, 663, 820 and 994 cm-1 which could be ascribed to those of crystalline MoO3. The presence of these Raman peaks suggested that the MoO3 films had transformed from a disordered amorphous state to a more ordered crystalline state. In contrast, no improvement in the crystallinity of the WO3 thin films was evident when they had undergone similar electrochromic and photochromic processes.