Direct current and radio frequency plasma sources of titanium dioxide doped in tungsten trioxide for all-solid-state electrochromic devices

The purpose of this research is to use direct current (DC) and radio frequency (RF) magnetron sputtering of titanium dioxide (<i>T</i><i>i</i><i>O</i>₂) doped in tungsten trioxide (<i>W</i><i>O</i>₃) as the main electrochromic upper module, and the power changes were 10, 20, 40, 60, and 80 W, respectively. The lower module, a nickel oxide (NiO) auxiliary color-changing module, was prepared by 100 W DC magnetron sputtering. The electrolyte uses <i>P</i><i>C</i>+<i>L</i><i>i</i><i>C</i><i>l</i><i>O</i>₄, and 15% PMMA was added to thermally cure and form a gel polymer electrolyte. The upper and lower modules and electrolytes were combined to complete the <i>I</i><i>T</i><i>O</i>/<i>T</i><i>i</i><i>O</i>₂:<i>W</i><i>O</i>₃/<i>P</i><i>C</i>+<i>L</i><i>i</i><i>C</i><i>l</i><i>O</i>₄+<i>P</i><i>M</i><i>M</i><i>A</i>/<i>N</i><i>i</i><i>O</i>/<i>I</i><i>T</i><i>O</i> all-solid-state electrochromic device (ECD), which has the advantages of inorganic, long life, no leakage, low voltage, and high stability. The experimental results demonstrated that the best electrochromic performance was obtained when <i>T</i><i>i</i><i>O</i>₂ was prepared by 40 W DC power in co-sputtering. The transmittance of the coloring and bleaching was 12.6% and 82.6% at 550 nm, respectively, and the difference in transmittance <i>Δ</i><i>T</i> reached 70%. In addition, the optical density (<i>Δ</i><i>O</i><i>D</i>) and coloring efficiency (CE) reached 0.82 and 48.6<i>c</i><i>m</i>²/<i>C</i>, respectively. Compared with the other <i>T</i><i>i</i><i>O</i>₂ prepared by 40 W RF power, the coloring and bleaching transmittance were 12.7% and 80%, respectively, and the <i>Δ</i><i>T</i> reached 67.3%. The <i>Δ</i><i>O</i><i>D</i> and CE are 0.8 and 47.3<i>c</i><i>m</i>²/<i>C</i>, respectively. Based on the results, the efficiency of DC power was better than that of RF power at the same wattage. This indicates that the film doped by DC power is looser and has more oxygen vacancies than RF power, and that this is conducive to the embedding and extraction of <i>L</i><i>i</i>⁺ ions. In the drive voltage test of ±1.0, ±1.5, ±2.0, and ±2.5<i>V</i> of the whole device, the <i>T</i><i>i</i><i>O</i>₂ doped by DC power at ±2.5<i>V</i> had the highest <i>Δ</i><i>T</i>=54.5<i>%</i>. The coloring and bleaching times were <i>T</i>_c=7.5<i>s</i> and <i>T</i>_b=8<i>s</i>, respectively. This indicates that the all-solid-state ECD device of <i>T</i><i>i</i><i>O</i>₂ doped in <i>W</i><i>O</i>₃ prepared by 40 W DC power has good electrochromic performance.