二氧化鈦奈米材料的製備與染料敏化太陽能電池特性研究：從一維結構到銀的表面改質

Fabrication of Titania Nanomaterial and Study Characters of Dye-Sensitized Solar Cells: from One-dimension to silver surface modification of TiO2

洪維成(Wei-Cheng Hung)

指導教授 ： 蘇昭瑾 ； 簡淑華

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00062

摘要

在本研究中我們將商用二氧化鈦粉體Degussa P25 (DP25) 置於強鹼溶液中以水熱法製得氧化鈦奈米棒(Tnr)及奈米管(Tnt)，並探討在染料敏化太陽能電池光陽極的應用。將600 °C 煅燒處理的奈米棒和DP25 做不同比例混掺(5/95、20/80、50/50、80/20)並加入聚乙二醇和去離子水配製成漿料，均勻地塗佈在導電玻璃上，活性面積為0.25 cm2，以450 °C煅燒製備成光陽極，並浸泡於染料(N-719)中，相對電極是將鉑濺渡在導電玻璃上，加入電解液(I3-/I-)，組裝成電池元件，以模擬太陽光AM 1.5，光強度為100 mW/cm2的光源照射，進行電池的光電轉換效率測試。發現20/80(20 % Tnr，80 % DP25)表現最佳，其光電轉換效率為7.56 %。
接著將酸洗至不同pH值(3.55、5.1及7)的Tnt做光電轉換效率比較，結果顯示pH為3.55的Tnt因吸附的染料最多，電流值最大，故有較好的效率表現(2.83%)。將此樣品在不同溫度(500、550、600及650 °C)鍛燒後發現，經550 °C鍛燒處理之樣品其光電轉換效率為四者間最佳，效率最高可達8.35 %。透過電化學阻抗分析(EIS)顯示，這是因為550 °C鍛燒處理樣品擁有不錯的電子傳輸速度所致。
之後我們利用光化學沉積法，將金屬銀沉積在Tnt上，發現效能有顯著的提升，從2.83 %提高到5.29 %，因此我們進一步在經550 °C鍛燒處理之Tnt上也沉積金屬銀，結果顯示，在相同膜厚下，可以有效將光電轉換效率從7.1 %提升至8.1 %，最佳的銀含量則為2 wt.%。入射單色光子-電子轉化效率(IPCE)測量實驗顯示，於樣品中沉積金屬銀，可使電池光電轉換效率在全波長區域皆有明顯增加，可能是由於增加了吸附染料的面積且銀粒子扮演散射點的角色而提高了光的使用率。

關鍵字

染料敏化太陽能電池 ； 氧化鈦奈米棒 ； 氧化鈦奈米管 ； 銀 ； 電子傳遞

並列摘要

In this study, Titania nanorod (Tnr) and nanotube (Tnt), which were prepared from commercial Degussa P25 powders (DP25) by alkaline hydrothermal method, were applied to fabricate the dye-sensitized solar cells (DSSCs) photoanodes. In the fabrication of dye-sensitized solar cells (DSSCs), the TiO2 paste was prepared by mixing Tnr which calcined at 600 °C and DP25 with various weight ratio (5/95、20/80、50/50 and 80/20) followed by adding the polyethylene glycol (PEG) and DI water. The TiO2 paste was uniformly dispersed on the fluorine-doped tin oxide (FTO) glass with an active area of 0.25 cm2 and calcined at 450 °C to prepare photoanode. The counter electrode was the sputtered platinum FTO glass. The electrodes, electrolyte (I3-/I-), and dye (N719) were assembled into a cell module and illuminated by a light source of simulated AM1.5 with light intensity of 100 mW/cm2 to perform the photoelectron conversion efficiency test. It was found that the 20/80 sample (20 % Tnr，80 % DP25) showed the best conversion efficiency of 7.56 %.
Following, we compare the conversion efficiency of Tnt which pickling to different pH values (3.55, 5.1 and 7). The result showed that the Tnt of pH value 3.55 has better efficiency (2.83 %) as the amount of dye adsorption at most, and the current is largest. When Tnt was calcined at different temperatures (500, 550, 600 and 650 °C), the conversion efficiency of the sample calcined at 550 °C was the best among the tested samples with conversion efficiency of 8.35 %. Electrochemical impedance analysis (EIS) demonstrated that the better cell performance of 550 °C calcined sample was attributed to reasonable electron transport property.
We found that the efficiency enhanced from 2.83 to 5.29 % which deposited metal silver on the Tnt with photocatalytic deposition. Therefore, we further deposited metal silver also on the 550 °C calcined Tnt, the result showed it could effectively enhance conversion efficiency from 7.19 to 8.15 % at the same film thickness, and the best silver content is 2 wt.%. Incident monochromatic photon-to-current efficiency (IPCE) measurements revealed that deposited metal silver on the sample enabled the conversion efficiency substantially to increase in full-wavelength spectrum as enhancing the area that adsorbing dye, and the higher light-harvesting efficiency enhanced by silver playing the part of scattering point.

並列關鍵字

Dye-sensitized solar cells ； Titania nanorod ； Titania nanotube ； silver ； Electron transport

參考文獻

72. 蕭光宏，碩士論文，”二氧化鈦微結構對染料敏化太陽能電池光電效能的影響”，國立台灣大學化學系，(2008) 台北。

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