大面積高效能之薄膜型全固態電致色變元件系統開發(I)

Abstract

電致色變節能窗（Electrochromic Windows）係一種可根據外界環境變化調整顏色及穿透率之大尺 寸玻璃顯示元件，獨特的光電性質使其可與太陽能電池搭配進行自動日照調控，可有效降低能源使 用。此類節能窗在國內外有相當多的研究，但是對於全固態薄膜式的變色節能元件(All-Solid-State ECD) 之研究卻不多，再加上電致色變元件目前仍存在有大面積變色不易、去/著色反應時間慢及價格昂貴等 缺點，造成應用上的限制，本計劃針對上述問題提出改善方法，研究重點著重在氧化鋅-鋁薄膜（AZO） 電極、陣列式氧化鎢（WO3）奈米棒、無機固態電解質層及大面積元件製程的研發。 本計劃元件中之導電層及變色層分別選用為AZO 及WO3 兩種材料，首先於玻璃基板上以溶膠- 凝膠的方式成長AZO 薄膜取代現有昂貴ITO 薄膜，接著在AZO 上方披覆一層結晶WO3 薄膜晶種層， 後續利用水溶液法製程來成長陣列式WO3 奈米棒，該陣列以直立的陣列形式直接成長於AZO 薄膜 上，預期能有效控制陣列奈米線密度避免其遮蔽效應，增加其Li+的擴散路徑縮短反應時間提高變色 效率，無機固態離子導電層預計利用溶膠-凝膠法來製備LiBO2:LiF(doped)薄膜，LiF 的目的為增加Li+ 的濃度而更進一步提高LiBO2 薄膜主體中離子導電率。 綜觀上述研究主題的執行，其本計劃最終目的為製備出大面積薄膜型全固態電致色變元件系統 （Glass/AZO/WO3/LiBO2:LiF(doped)/NiO/AZO/Glass），後續也將進行一系列的分析，包含去/著色的響 應時間、循環次數、變色對比以及元件的穩定性等，預期目標可達到20 cm × 20 cm 的面積規格，變 色驅動電壓約需要±5 V，其切換速度約5 sec，並有效阻擋80~95 %的紅外線與熱幅射之高效能電致色 變元件。

Electrochromic windows are windows that can be darkened or lightened electronically. A small voltage applied to the windows will cause them to darken; reversing the voltage causes them to lighten. They can be used for energy saving in buildings. Although such electrochromic windows have been studied by many research groups, but there are very limited studies on all-solid-state electrochromic device. In addition, the disadvantages such as non uniformity in large area device, slow response time in changing color, expensive etc. need to be solved in order to realize their practical applications. The main subjects of this proposal to be investigated include: preparation of the aluminum-doped zinc oxide (AZO) transparent conductive thin film of electrode material、the density control of aligned tungsten oxide nanorods、process development for an inorganic solid electrolyte (LiBO2:LiF(doped) film), and the large-area deposition technology for all solid electrochromic device. In this study, we will grow the AZO thin film on the glass substrate by using sol-gel process. The tungsten oxide thin films will be deposited on AZO film coated glass via a spin coating method. Then the aligned arrays tungsten oxide nanorods which perpendicular to the AZO film substrate will be grown by low-temperature solution growth method. The good control of WO3 nanorod density is important to avoid self-shadowing effect. Using nanorod nanostructure can provide a short diffusion length for Li+ insertion, which can enhance the coloration efficiency of electrochromic thin-film devices. In addition, the LiBO2:LiF(doped) thin film using as an inorganic solid electrolyte of our electrochromic device will be fabricated by sol-gel process. When lithium fluoride is added to lithium borate, the ionic conductivity in the composites will increase. The technologies for making large area of an all-solid-state electrochromic device (Glass/AZO/WO3/LiBO2:LiF(doped)/NiO/AZO/Glass) will be developed in this study. The device with large area (20 cm × 20 cm), low operating voltage (±5 V), and color/bleach response time (~5 sec.) will be expected to be obtained.