Structures and electrochromic properties of Ta₀.₃W₀.₇0ₓ thin films deposited by pulsed laser ablation
By Yang, D. & Xue, L.
Published in Thin Solid Films
2006
Abstract
Electrochromic materials based on mixed metal oxides are of growing importance since improved durability, coloration efficiency and chemical stability, as well as a desirable neutral color could be accomplished in those multicomponent films. In this work, we have used the pulsed laser deposition technique to deposit thin films of Ta₀.₃W₀.₇0ₓ on ITO-coated glass substrates in reactive O₂ gas environment at a substrate temperature range of 200 to 700 °C. X-ray diffraction results showed that Ta₀.₃W₀.₇0ₓ films begin to crystallize to a cubic phase at substrate temperatures near 700 °C, while films with amorphous structure were obtained at lower substrate temperatures. The lattice constants of the polycrystalline films are similar to those of stoichiometric Ta₀.₃W₀.₇O₂.₈₅ bulk materials. Optical transmittance of Ta₀.₃W₀.₇0ₓ films decreases as the O₂ pressures during deposition decreasing from 5.32 Pa to 0.13 Pa. Electrochromic properties of the Ta₀.₃W₀.₇0ₓ films were evaluated in 0.1 M H₃PO₄ electrolyte and the results were compared to those of WO₃ and Ta₀.₁W₀.₉Oₓ films deposited also by pulsed laser ablation. The results have demonstrated that the addition of one metal oxide (e.g., Ta₂O₅) into another (e.g., WO₃) is an effective way to alter the electrochromic properties of the individual constituents.