探討二氧化鈦表面電荷對於染料敏化電池中界面反應之影響

The Study of Surface Modified Titanium Dioxide in the Interfacial Reaction of Dye-sensitized Solar Cell

陳婷婷

指導教授 ： 李紫原 ； 裘性天

國立清華大學/工學院/材料科學工程學系/碩士(2009年)

摘要

在染料敏化電池中，TiO2/dye/electrolyte 之界面性質扮演著關鍵性的角色。光電轉換效率主要受限於界面上之電子再結合反應。本實驗以酸/鹼處理的方式於 TiO2 表面產生多餘電荷，藉以調整 TiO2/dye/electrolyte 之界面性質，提高光電轉換率。酸/鹼處理僅造成 TiO2 表面電荷的改變，形貌與晶體結構仍維持顆粒狀的 anatase 晶相。酸處理過後的表面帶有多餘的 H+ 離子，使得平帶電位朝正電位位移，費米能階下降，而鹼處理的表面則是呈現 OH- 離子居多的情形，造成平帶電位往負電位移動。將處理過的粉末以刮刀法的方式作成電極，並且組裝成電池進行光電轉換效率的量測。經過酸處理的 TiO2 擁有較高的光電流與低的光電壓，相反的，經過鹼處理 TiO2 的電池其光電壓上升而光電流下降。進一步利用電化學阻抗分析儀探討酸/鹼處理對於界面反應的影響。

關鍵字

染料敏化電池 ； 表面電荷 ； 界面再結合反應

並列摘要

In dye-sensitized solar cells (DSSCs), the property of TiO2/dye/electrolyte interface affects photoelectron conversion greatly owing to the electron recombination reaction. Here, acid treatment generates excess surface charge on anatase TiO2 nanoparticles, resulting in the change of the TiO2/dye/electrolyte interface property, which leads to improvement of photoelectron conversion.
Acid-treated TiO2 analyzed by SEM, EDS, XRD, zeta-potential meter, and flat band potential, were made as the working electrode in DSSC device. The surface treatment only resulted in the change in surface charge, while the structure and composition of the modified TiO2 remained unchanged. Acid-treated TiO2 had excess H+ on the surface and lowed flat band potential than that of untreated TiO2. The modified TiO2 provided remarkably improved photocurrent performance but reduced photovoltage. Additionally, electrochemical impedance spectroscopy was employed to study the interfacial reaction of the cell. It is found that using acid-treated TiO2 as the electrode reduces the charge-transfer resistance at the TiO2/dye/electrolyte interface by lowering the possibility for the recombination reaction, which strongly improved photoelectron conversion.

並列關鍵字

dye-sensitized solar sell ； surface charge ； interfacial recombination reaction

參考文獻

[2] S. Y. Huang, G. Schlichthorl, A. J. Nozik, M. Gratzel, A. J. Frank, The Journal of Physical Chemistry B 1997, 101, 2576.

[3] N. Kopidakis, N. R. Neale, A. J. Frank, Journal of Physical Chemistry B 2006, 110, 12485.

[4] G. K. Mor, K. Shankar, M. Paulose, O. K. Varghese, C. A. Grimes, Nano Letters 2006, 6, 215.

[10] A. J. Nozik, M. D. Archer, Nanostructured and Photoelectrochemical Systems for Solar Photon Conversion, World Scientific Pub Co Inc 2008.

[11] N.-G. Park, J. v. d. Lagemaat, A. J. Frank, Journal of Physical Chemistry: B 2000, 104, 8989.