Ti-WO3 film is more favorable for the electrochromic reaction than the undoped WO3 film. Experts said that comparing the SEM image of WO3 and Ti-doped WO3 film, as shown below, you can see:
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After doping with Ti, the surface morphology of the film changes, from round particles to lamellar particles, and the film particle size becomes smaller. The particle size decreases to increase the specific surface area, which is more conducive to the electrochromic reaction. Experts also tested the surface roughness of WO3 and WO3: Ti films using AFM and found that the film roughness became smaller after Ti doping. At the same time, the experts also tested the surface roughness of the colored samples, and they found that the surface roughness of the film after coloring increased, while the roughness of WO3: Ti film changed less than that of WO3 film. It is indicated that the roughness of the film is increased after the lithium ions are injected into the film, and the lattice strain of the WO3: Ti film is smaller than that of the WO3 film, so the roughness variation is also small.
