染料敏化太陽能電池工作電極之結構最佳化研究

Abstract

染料敏化太陽能電池(DSSC)具有製程簡單、成本低、可作成彩色透明薄膜以及可撓曲等傳統太陽能電池所沒有的特性，因此最值得探討。本篇論文介紹DSSC原理、製作方式以及量測方法，尤其專注於三種製備TiO2薄膜的方式：(1)旋轉塗佈法；(2)壓桿法；(3)網版印刷法。研究的主題包括了不同漿料所製得的TiO2薄膜、高電阻電極、散射層以及氧化鎂摻入的比例對電池元件效能的影響、此外我們亦發展以網版印刷法來改進及簡化TiO2薄膜的製程。實驗結果顯示電池的電阻太高會降低元件的填充因子而使光電轉換效率變差。當解決電阻問題後，我們發現TiO2漿料分散的好壞會直接影響薄膜的光穿透性。再將透明TiO2薄膜上加上一層散射層，可以藉由將光侷限在TiO2結構中，以增加染料對光的吸收而增加元件效率。另外，在TiO2結構中摻入MgO後可以大大地減緩電子與電洞之間的復合機率而增加元件的填充因子與整體效率。在各條件最佳化後製成之DSSC元件其效率最高可達6.77%。

Dye sensitized solar cell (DSSC) is one of the most promising photovoltaic devices due to its simple fabrication procedure, low cost, light weight, being semi-transparent and flexible, and it may be in different colors when different dyes and electrolytes are used. This dissertation demonstrates the principles, fabrication processes and I-V characteristics of DSSCs, which are related to the structure of the TiO2 layers prepared using spin-coating, doctor-blading and screen-printing methods. The topics of the dissertation include series resistance reduction, characterization the effect of an additional diffusion layer, and MgO-modified TiO2 layer. In addition, we developed a new screen-printing method to simplify and improve the fabrication procedure of the TiO2 layers. The experimental results show that the fill-factor and conversion efficiency of DSSCs were low when high series resistance were induced. The transparent TiO2 layer can be obtained by reducing the aggregation of the TiO2 paste. The conversion efficiency of DSSCs was improved when the light-harvesting was increased via a diffusion layer. In addition, the performance of a DSSC device can be enhanced when the TiO2 layer was treated with MgO, which gives the best photovoltaic performance of the device to be 6.8%.