Electrochromism of W-oxide-based films: Some theoretical and experimental results
- Uppsala Univ. (Sweden). Dept. of Technology
- Univ. of Technology, Sydney, New South Wales (Australia). Dept. of Applied Physics
- Univ. of Latvia, Riga (Latvia). Inst. of Solid State Physics
- Los Alamos National Lab., NM (United States). Theoretical Division
Electrochromic thin films are of much interest in contemporary and emerging technology, where they can be used for regulating the throughput of radiant energy in ``smart windows``. The authors survey some recent work related to electrochromic W-oxide-based thin films. The electronic structure of cubic (perovskite) WO{sub 3} and HWO{sub 3} was calculated from first principles. It was found, among other things, that hydroxide formation was energetically favored. Experimental studies were made on films prepared by reactive magnetron sputtering in Ar + O{sub 2} with and without CF{sub 4} addition and substrate bias. Structural studies by atomic force microscopy, X-ray diffraction, infrared reflectance spectroscopy, and Raman spectroscopy indicated that the electron bombardment associated with a positive substrate bias led to grain growth and partial crystallization while maintaining a high density of W{double_bond}O double bonds presumably on internal surfaces. Electrochemical and spectrophotometric measurements demonstrated, in particular, that tandem films -- with a thin protective layer of electron bombarded oxide covering a thicker oxyfluoride layer -- were able to combine rapid dynamics of the electrochromism with good durability. Oblique angle sputtering in Ar + O{sub 2} gave films whose microstructure comprised inclined columns, as seen from scanning electron microscopy. Pronounced angular selective transmittance was found to coexist with electrochromism.
- OSTI ID:
- 197608
- Report Number(s):
- CONF-950793--; ISBN 0-8194-1890-0
- Country of Publication:
- United States
- Language:
- English
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