本研究主旨在研究Ag摻雜於TiO2後對光敏效果的影響。成膜方式是使用溶膠凝膠法將溶液以旋轉塗布的方式塗布在導電玻璃上，經退火處理後製作成光電極。TiO2之優點為製程步驟簡單、成本低廉，且薄膜品質佳、摻雜物分散均勻。而TiO2薄膜具備相當穩定的物理以及化學性質，能夠在電解液中長時間工作。但是由於TiO2之能隙較大，尚需藉由其他摻雜以達到降低能隙的效果，然而當能隙降低後仍會有嚴重的再結合產生，造成光電流的抑制。因此在此吾人研究Ag摻雜於TiO2後有效的降低電子電洞再複合的機率。吾人分別嘗試自高濃度的摻雜至低濃度摻雜比較對光電流效應的影響，而後又在低電流下對薄膜製作濃度梯度觀察其效能。發現薄膜在低濃度下，濃度梯度的存在能夠有效的降低電子-電洞對的再結合，使光電流能夠提升近3倍的比例，自0.065mA/cm2提升到0.180mA/cm2。 In this study, we try to study the effect of photosensitive on Ag doping in TiO2. The TiO2 solution is prepared by sol-gel method and then spinning coated on FTO glass. After annealing process, we get the photoelectrode. The advantages of TiO2 are simple processed, economic, well-performanced, and with more uniform doping. TiO2 thin film is very stable in physical property and chemistry, therefore it can work in electrolyte for a long time. But the band gap of TiO2 is too large that we need doping some elements to decrease its band gap. However, when the band gap is decreased and the recombination becomes, the photocurrent is decreased. Therefore, we study in decreasing the recombination rate of electron and hole after Ag doping in TiO2. We try to analyses the effect from high concentration to dilution and observe the efficiency after doing concentration gradient under dilution. We find that the concentration gradient can be more observable in decreasing the recombination rate between electron and hole, to increase the photocurrent almost three times higher, from 0.065mA/cm2 to 0.180mA/cm2.