The relationship between conditions for preparing WO
3 films and their electrochromic properties was investigated.
WO
3 thin films were prepared by RF magnetron sputtering with various Ar gas pressures and RF powers.
Their optical density, coloring efficiency, and response time for coloration and bleaching were measured in a 0.5M solution of KH
2PO
4.
The chemical composition, optical gap, and morphology of prepared WO
3 films were measured, and their relationship and electrochromic properties were discussed.
The results are as follows:
1. The WO
3 film prepared under an Ar gas pressure of 1.0×10
-2torr or under an RF power of 100-150W showed the best electrochromic properties. This seems closely related to chemical composition and the optical gap of WO
3 films.
2. The coloration response time grew slower with increased Ar gas pressure or decreased RF power.
The bleaching response time remained virtually unchanged. These characteristics depend on obtaining fine grains and on the nonhomogeneity of the prepared WO
3 films.
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