Department of Chemistry, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom.
ACS Appl Mater Interfaces. 2013 Jun 26;5(12):5675-82. doi: 10.1021/am401025v. Epub 2013 Jun 10.
Aerosol-assisted chemical vapor deposition (AACVD) was used for the first time in the preparation of thin-film electrochromic nickel(II) oxide (NiO). The as-deposited films were cubic NiO, with an octahedral-like grain structure, and an optical band gap that decreased from 3.61 to 3.48 eV on increase in film thickness (in the range 500-1000 nm). On oxidative voltammetric cycling in aqueous KOH (0.1 mol dm(-3)) electrolyte, the morphology gradually changed to an open porous NiO structure. The electrochromic properties of the films were investigated as a function of film thickness, following 50, 100, and 500 conditioning oxidative voltammetric cycles in aqueous KOH (0.1 mol dm(-3)). Light modulation of the films increased with the number of conditioning cycles. The maximum coloration efficiency (CE) for the NiO (transmissive light green, the "bleached" state) to NiOOH (deep brown, the colored state) electrochromic process was found to be 56.3 cm(2) C(-1) (at 450 nm) for films prepared by AACVD for 15 min followed by 100 "bleached"-to-colored conditioning oxidative voltammetric cycles. Electrochromic response times were <10 s and generally longer for the coloration than the bleaching process. The films showed good stability when tested for up to 10 000 color/bleach cycles. Using the CIE (Commission Internationale de l'Eclairage) system of colorimetry the color stimuli of the electrochromic NiO films and the changes that take place on reversibly oxidatively switching to the NiOOH form were calculated from in situ visible spectra recorded under electrochemical control. Reversible changes in the hue and saturation occur on oxidation of the NiO (transmissive light green) form to the NiOOH (deep brown) form, as shown by the track of the CIE 1931 xy chromaticity coordinates. As the NiO film is oxidized, a sharp decrease in luminance was observed. CIELAB Lab* coordinates were also used to quantify the electrochromic color states. A combination of a low L* and positive a* and b* values quantified the perceived deep brown colored state.
气溶胶辅助化学气相沉积（AACVD）首次用于制备薄膜电致变色镍（II）氧化物（NiO）。沉积的薄膜为立方 NiO，具有八面体状晶粒结构，光学带隙随着薄膜厚度的增加（在 500-1000nm 范围内）从 3.61 减小到 3.48eV。在水性 KOH（0.1mol dm（-3））电解质中进行氧化循环伏安时，形态逐渐变为开放多孔 NiO 结构。通过在水性 KOH（0.1mol dm（-3））中进行 50、100 和 500 次条件氧化循环伏安来研究薄膜的电致变色性能。随着条件循环次数的增加，薄膜的光调制增加。对于 NiO（透明浅绿色，“漂白”状态）到 NiOOH（深棕色，着色状态）电致变色过程，通过 AACVD 制备的薄膜在 15 分钟后，最大着色效率（CE）为 56.3cm（2）C（-1）（在 450nm 处），经过 100 次“漂白”到着色条件氧化循环伏安。电致变色响应时间小于 10s，着色时间通常比漂白过程长。测试表明，这些薄膜在经过长达 10000 次的着色/漂白循环后仍具有良好的稳定性。使用国际照明委员会（Commission Internationale de l'Eclairage）的比色法系统，通过电化学控制下记录的原位可见光谱，计算出电致变色 NiO 薄膜的颜色刺激以及可逆氧化到 NiOOH 形式时发生的变化。当 NiO（透明浅绿色）形式氧化为 NiOOH（深棕色）形式时，色调和饱和度发生可逆变化，如 CIE 1931xy 色度坐标的轨迹所示。随着 NiO 薄膜的氧化，亮度急剧下降。CIELAB Lab坐标也用于量化电致变色颜色状态。低 L和正 a和 b值的组合量化了感知到的深棕色着色状态。
