Reactive Sputter Deposition of WO3/Ag/WO3 Film for Indium Tin Oxide (ITO)-Free Electrochromic Devices
Reactive Sputter Deposition of WO3/Ag/WO3 Film for Indium Tin Oxide (ITO)-Free Electrochromic Devices
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用于无氧化铟锡 (ITO) 电致变色器件的 WO3/Ag/WO3 薄膜的反应溅射沉积
DOI：
10.1021/acsami.5b10665
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发表时间：
2016-02-17
影响因子：
9.5
通讯作者：
Li, Chun
中科院分区：
文献类型：
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作者：
Yin, Yi;Lan, Changyong;Li, Chun
WO_3/Ag/WO_3（WAW）三层薄膜兼具电致变色（EC）和导电变色（TC）功能，在无ITO的电致变色器件中显示出良好的应用前景。热蒸发WAW膜的报告显示，这些双功能WAW膜具有明显的EC特性，然而，它们的粘合性能差，导致快速降解的着色漂白循环。在这里，我们表明，WAW膜具有改善的EC耐久性，可以通过反应溅射使用金属靶制备。我们发现，通过在沉积外部WO 3之前引入一层钨（W）牺牲层，可以有效地避免银的氧化，从而导致薄膜绝缘和表观光学雾度。我们还发现，光透射率和方块电阻是敏感的钨和银层的厚度。优化后的TC薄膜结构为WO 3（45 nm）/Ag（10 nm）/W（2 nm）/WO 3（45 nm），薄膜的方块电阻为16.3 WE，透光率为73.7%。这种膜表现出引人注目的EC性能，具有29.5%的良好透光率调制Δ T-lum，快速开关时间，（着色时间为6.6秒，漂白时间为15.9秒），和长期循环稳定性（2000次循环），外加电位为+/-1.2 V。（45/10/2/100 nm）导致更大的调制，最大Δ T-lum为46.4%，但以显著增加薄层电阻为代价。通过引入金属牺牲层来避免银氧化的策略可以推广到通过低成本的反应溅射来制备其他氧化物-银-氧化物透明电极。
Functioning both as electrochromic (EC) and transparent-conductive (TC) coatings, WO3/Ag/WO3 (WAW) trilayer film shows promising potential application for ITO-free electrochromic devices. Reports on thermal evaporated WAW films revealed that these bifunctional WAW films have distinct EC characteristics; however, their poor adhesive property leads to rapid degradation of coloring bleaching cycling. Here, we show that WAW film with improved EC durability can be prepared by reactive sputtering using metal targets. We find that, by introducing an ultrathin tungsten (W) sacrificial layer before the deposition of external WO3, the oxidation of silver, which leads to film insulation and apparent optical haze, can be effectively avoided. We also find that the luminous transmittance and sheet resistance were sensitive to the thicknesses of tungsten and silver layers. The optimized structure for TC coating was obtained to be WO3 (45 nm)/Ag (10 nm)/W (2 nm)/WO3 (45 nm) with a sheet resistance of 16.3 WE and a luminous transmittance of 73.7%. Such film exhibits compelling EC performance with decent luminous transmittance modulation Delta T-lum of 29.5%, fast switching time (6.6 s for coloring and 15.9 s for bleaching time), and long-term cycling stability (2000 cycles) with an applied potential of +/- 1.2 V. Thicker external WO3 layer (45/10/2/100 nm) leads to larger modulation with maximum Delta T-lum of 46.4%, but at the cost of significantly increasing the sheet resistance. The strategy of introducing ultrathin metal sacrificial layer to avoid silver oxidation could be extended to fabricating other oxide-Ag-oxide transparent electrodes via low-cost reactive sputtering.