中文摘要：

应用光电化学方法研究了两种菁类染料Cy3和Cy5复合敏化TiO2纳米晶电极的光电化学行为.结合两种染料的紫外-可见光谱和循环伏安曲线,确定了Cy3和Cy5的电子基态和激发态能级位置.结果表明两种染料的激发态能级位置能与TiO2纳米粒子导带边位置相匹配,复合敏化可以显著提高TiO2纳米晶的光电流,使TiO2纳米晶电极吸收波长由紫外光区红移至可见光区和近红外区.复合敏化降低了染料Cy3在电极吸附时的聚集程度,使其单色光的转换效率（IPCE）提高了169%,复合敏化电极总的光电转换效率η为2.09%,分别是Cy3和Cy5单独敏化时光电转换效率的2.069和1.229倍.

英文摘要：

The photoelectrochemical behavior of the TiO2 nanocrystalline electrode composite sensitized by Cy3 and Cy5 was studied. The ground state level and the excited state level of the two dyes were deter- mined by using the cyclic voltammetry and the optical absorption spectroscopy. The results show that the excited state level of the two dyes matches the conduction band edge of TiO2 nanoparticles. Therefore, the composite sensitization can increase the photocurrent density of TiO2 nanocrystalline electrode obviously and results in a red-shift of optical absorption from the ultra-violet region to the visible and near infrared re- gion. The composite sensitization reduced the aggregated extent of Cy3 when it was adsorbed on the TiO2 nanocrystalline electrode, and incident monochromatic photon-to-current conversion efficiency （IPCE） of Cy3 increased by 169%. The overall photoelectric conversion efficiency η of the composite sensitized elec- trode was 2.09%, which was as 2.069 and 1.229 times as that when Cy3 and Cy5 were individually used to sensitize the TiO2 electrode.