於本篇論文之研究，我們將無機半導體二氧化鈦奈米粒子摻混於poly(3-hexylthiophene) (P3HT)和C60之衍生物[6,6]-phenyl-C61-butyric acid methyl ester(PCBM)以1：1重量比混合所組成之有機感光層中，二氧化鈦奈米粒子具有高電子傳導性質及高表面積，故常被應用於作為染料光敏化太陽能電池中之電子接受體，實驗結果顯示相較於未摻混二氧化鈦奈米粒子之基本元件，於A.M.1.5G、100 mW/cm2模擬太陽光下，摻混二氧化鈦奈米粒子於感光層使元件之串聯電阻隨二氧化鈦奈米粒子濃度之增加而大幅降低、填充因子隨二氧化鈦奈米粒子濃度之增加而提升，開路電壓隨二氧化鈦奈米粒子濃度之改變而增加超過0.1 eV，短路電流則受二氧化鈦奈米粒子濃度影響，由SEM圖觀察到感光層表面有二氧化鈦奈米粒子之聚集形成，我們推測加入二氧化鈦奈米粒子改變了熱蒸鍍鋁陰極和感光層間之表面型態以及電子傳輸性質，降低了電子傳遞至鋁電極之能障，另一方面，二氧化鈦奈米粒子之高折射率特性有可能增加入射光被限制於元件內部的機率，增加載子生成量，改善元件整體之光電轉換效率，於最佳化二氧化鈦奈米粒子摻混濃度時元件整體的光電轉換效率有50 %之提升。本研究針對效率提升之原因做探討，包括二氧化鈦奈米粒子如何對影響元件之串聯電阻、短路電流、開路電壓、填充因子以及光學性質，希望能提供一個有效方法提升有機共軛高分子太陽能電池之光電轉換效率。

In this work, we report enhanced power conversion efficiency of polymer based solar cell using blend films of poly(3-hexylthiophene)(P3HT), [6,6]-phenyl-C61-butyric acid methyl ester(PCBM) and TiO2 nanoparticles. TiO2 nanoparticle is a promising candidate as electron acceptor for organic solar cell because of its good electron transport property. From J-V characteristics of devices under (A.M.1.5) simulated solar illumination (100 mW/cm2), we observed the devices with TiO2 nanoparticles showed reduced series resistance, increased open circuit voltage and improved fill factor when increasing the concentration of TiO2 nanoparticles. The S.E.M cross-sectional images revealed the aggregation of TiO2 nanoparticles formed on the surface of active layer. Thus the improved power conversion efficiency of solar cell is attributed to the modification of electron-collecting contact causing reduced energy barrier for electron transport between active-layer and aluminum electrode. Furthermore, the highly refractive TiO2 nanoparticles may increase the probability of internal light-trapping by scattering the light reflected from metal electrode, causing more photo-induced charge carrier to be generated in device. The enhanced open circuit voltage was likely to result from the reduced electron barrier height between aluminum electrode and TiO2 nanoparticles. A two fold enhancement in power conversion efficiency is achieved at optimized doping concentration of TiO2 nanoparticles.

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