Electrochromism and Electronic Structures of Nitrogen Doped Tungsten Oxide Thin Films Prepared by RF Reactive Sputtering

Abstract

The doping effect of nitrogen on amorphous tungsten trioxide (a-WO3) thin films was investigated with regard to electrochromism and electronic structures. The N-doped thin films exhibit a change in electrochromic coloration from transparent yellow to black, whereas the un-doped thin films exhibit blue coloration. In addition, a new absorption peak related to nitrogen doping is observed at 2.3 eV in photoabsorption spectra during the electrochemical coloration/bleaching process. To explain these experimental results, the electronic structures of N-doped tungsten oxide were calculated by the DV-Xα molecular orbital method.