Variable transmittance coatings using electrochromic lithium chromate and amorphous WO{sub 3} thin films
- EIC Labs., Inc., Norwood, MA (United States)
Thin film, electrochromic coatings with an electrically tunable transmittance may be useful for modulating solar heat load and daylight entering a building or automobile through a window aperture. A thin film, Li{sup +} counterion, variable transmittance electrochromic device is described with the structure: glass{vert_bar}ITO{vert_bar}Li{sub z}Li{sub y}CrO{sub 2+x}{vert_bar}Li{sub 2}O-B{sub 2}O{sub 3}{vert_bar}WO{sub 3}{vert_bar}ITO. The structure is prepared by sequential deposition of the layers using a combination of sputtering and evaporation processes. The Li{sub z}Li{sub y}CrO{sub 2+x} counterelectrode has a Li capacity of {approximately}0.5 mC/cm{sup 2}nm and exhibits weak anodic coloration with a luminous efficiency of 3 to 4 cm{sup 2}/C. Variable transmittance devices, with an area of 20 cm{sup 2}, have been fabricated using 40 to 80 nm thick Li{sub z}Li{sub y}CrO{sub 2+x} films and cathodically coloring a-Li{sub x}WO{sub 3}. The luminous transmittance range and switching speed of as-fabricated devices are typically 10 to 70% and 30 s, respectively. Multicycle switching reveals a decrease in switching speed over the first 5,000 cycles while the luminous transmittance range is unchanged.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-87SF16733
- OSTI ID:
- 483788
- Journal Information:
- Journal of the Electrochemical Society, Vol. 144, Issue 3; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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