結合Lift-off及薄膜沈積技術製作固態電致色變影像顯示元件

Fabrication of Solid-State Electrochromic Display Devices by Combining Lift-Off and Thin Film Deposition Technology

本專題主要重點在開發一雙面變色的電致色變系統，使元件中有兩層電致變色層，可透過反覆切換正負電壓，來顯示出這兩層薄膜中不同的圖案。元件之影像圖案係利用lift-off 製程在ITO 玻璃上來產生，並成長氧化鎢薄膜，以固態封裝方式製作一低耗能之電致色變影像顯示元件，極小的驅動電壓即可呈現影像。在薄膜沈積技術上，本專題使用濺鍍法與溶膠凝膠法分別沈積氧化鎢薄膜，並比較其特性與薄膜在著色態與去色態時之穿透率變化（ΔT），選擇具有較佳視覺對比的薄膜沈積技術來製作本專題的影像顯示元件。製作完成之元件在驅動電壓 ±3 V 時之著色響應時間為3.87 秒、去色為2.86 秒，同時並利用拉曼光譜分析來探討氧化鎢電致色變薄膜之變色機制。此外，本專題製作的影像顯示元件，其操作電壓範圍在 -4 V 至 +4 V 間，可透過調整驅動電壓大小來改變顏色的深淺，提高元件的視覺對比。再者，此元件亦可製作在PET 軟性基板上，達到可撓式之功能。未來期望能透過曝光顯影製程道數的增加及電路的設計與控制來提高影像的複雜度與多樣性。

This work has been concentrated on the fabrication of solid-stateelectrochromic display devices with double-sided electrochromic layers.The different images in the double-sided electrochromic layer can berevealed by applying positive and negative potential alternately. Thespecific patterns of the display were made on ITO glass by the lift-off process. And the tungsten oxide electrochromic layers of the display wereprepared by RF sputtering because it can provide better electrochromicproperties than sol-gel process. A reversible color change between blueand colorless was observed when appropriate positive and negative voltagewere applied alternately to the electrochromic display device. Thetungsten oxide electrochromic film has short bleach-coloration transitiontime when applying appropriate voltage of –3 V/+3 V. Switch- ing thecolour takes about 3.87 seconds while the associated memory time isseveral hours. Turning off the colour takes about 2.86 seconds. Thecolor depth of electrochromic film can be controlled by adjusting themagnitude of driving voltage. Furthermore, monitoring the changes inRaman spectra of the electrochromic films with bleach-coloration statesenables the discussion of the mechanism of colouration. Finally, theelectrochromic layers can also be made on PET substrate to produce aflexible electrochromic display device. In the future, the multiplicity ofimages of the electrochromic display devices may be enhanced byimproving lift-off process and designing circuit.