應用薄管壁二氧化鈦奈米管於準固態電解質之染料敏化太陽能電池

Abstract

本論文探討的主題是藉由鹽酸蝕刻而使二氧化鈦奈米管管壁削薄帶來的影響，並且配合膠態電解液的應用。為了不讓二氧化鈦奈米管在鹽酸處理時的蝕刻速率太快，因此必須先進行第一次的燒結提升結晶強度，在不影響的長度減縮的情況下，經由適當的鹽酸濃度與處理時間，調整二氧化鈦奈米管的管壁厚度。接著將薄管壁奈米管陣列做為光電極並製造成正向入射的染料敏化太陽能電池。文章中，我們找到有效率的條件，使奈米管管壁從23nm削薄成12nm，並且使元件的電流密度從13.0 mA/cm2提升到16.2 mA/cm2。從交流阻抗頻譜顯示出對於管壁削薄之後的差異，較薄的管壁對於載子的收集影響較小，最主要提升光電流密度的原因則是奈米管的 孔洞拓寬，使的電解液有較好的滲透性並且使的離子較容易傳導。 最後一部分則是為了提升穩定度，使用兩種方法使電解液呈現膠態的狀態。可以看到當電解液成膠時，會使的電流密度與導電度有明顯的下降，從交流阻抗頻譜顯示兩種不同的成膠方法對於奈米管陣列有所差異，以奈米管的結構來說，電解液參雜PVDF-HFP是比較好的選擇，也較能提升的穩定度。

In this work, we studied the influence of nanotube sidewall thickness trimmed by HCl and applied gel electrolyte to it. In order not to etch titanium dioxide nanotube sidewall too fast, the first sintering to enhance the crystallinity of the nanotube is required. Under the hypothesis that it didn’t shorten the length of nanotube, we tuned the sidewall thickness by moderate acidic concentration and treating period. And then, we applied the thin-wall nanotube-arrays as the photoanode to fabricate the front-side illuminated dye-sensitized solar cells. In this thesis, We report an efficient trimming method to fabricating titanium dioxide nanotube-arrays with sidewall thicknesses ranged from 23 nm to 12 nm. The photocurrent density of the dye-sensitized solar cell improved from 13.0 mA/cm2 to 16.2 mA/cm2. Electrical impedance spectroscopy showed a difference between the as-prepared and with thin-wall nanotube-arrays. The thinning of the sidewall of the nanotubes had little influence on the collection of the carriers. The main reason for the improvements on photocurrent density are the more infiltrated electrolyte and the more easily transported ions because of wider voids. At final part, in order to enhance the stability we used two methods to gel the electrolyte. When the electrolyte gelled, it made photocurrent density and conductivity decrease obviously. From EIS, it showed the difference of two different gelation methods of titanium dioxide nanotubes. With nanotube structure, it was a good choice to mix PVDF-HFP with electrolyte and also can enhance the stability more.