Electrochromic mechanism in a-WO{sub 3{minus}y} thin films
- National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
The electrochromic mechanism in amorphous tungsten oxide films is studied using Raman scattering measurements. The Raman spectra of as-deposited films show two strong peaks at 770 and 950 cm{sup {minus}1} due to vibrations of the W{sup 6+}{endash}O and W{sup 6+}{double_bond}O bonds, respectively, and a weaker peak at 220 cm{sup {minus}1} that we attribute to the W{sup 4+}{endash}O bonds. When lithium or hydrogen ions and electrons are inserted, extra Raman peaks due to W{sup 5+}{endash}O and W{sup 5+}{double_bond}O bonds appear at 330 and 450 cm{sup {minus}1}, respectively. Comparison of the Raman spectra of sputtered isotopic a-W{sup 16}O{sub 3{minus}y} and a-W{sup 18}O{sub 3{minus}y} films confirms these assignments. We conclude that the as-deposited films contain mainly the W{sup 4+} and W{sup 6+} states, and the W{sup 5+} states are generated as a result of reduction of the W{sup 6+} states when lithium or hydrogen ions and electrons are inserted. We propose that the optical absorption in the colored films is caused by transitions between the W{sup 6+} and W{sup 5+}, and W{sup 5+} and W{sup 4+} states. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 289257
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 2 Vol. 74; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
Similar Records
Grafting mechanism of electrochromic PAA-WO{sub 3} composite film
Gasochromic mechanism in a-WO{sub 3} thin films based on Raman spectroscopic studies