Effect of Pt-catalyst on gasochromic WO3 films: optical, electrical and AFM investigations

WO3 thin films were prepared using DC sputtering technique in 1% O2 and 99% Ar atmosphere from a high purity target of 99.99% tungsten. Different amounts of Pt-catalyst were sputtered onto the WO3 thin films in Ar atmosphere from a high purity target of 99.99% platinum. Electrical and optical properties of the WO3/Pt films were studied during the coloration/bleaching processes and several optical parameters were measured. The coloration takes place in a hydrogen atmosphere and the bleaching in oxygen gas. The best electrical and optical results were reached with an amount of Pt-catalyst of 2.12–2.65 μg/cm2. The electrical properties of the Pt-catalyst sputtered onto glass substrate were studied in different atmospheres such as air, Ar, O2 and H2 gas. The sheet resistance shows a time dependence. Its stable values are dependent on the atmosphere. They are lower in Ar and H2, and higher in air and O2 gas. To find a correlation between the properties and the morphology of the films, AFM images of the samples were taken. The roughness and the height distribution of the different amounts of Pt on WO3 were obtained.