铂分布形式对TiO_2薄膜光电化学行为的影响

Effect of Pt Distribution in TiO_2 Films on the Photoelectrochemical Behaviors

采用Sol-Gel法通过交替浸渍提拉工艺制备了Pt以不同形式分布的TiO_2薄膜(均匀分布,底层分布).采用三电极体系研究薄膜的光电化学行为,并用制备的薄膜组装成染料敏化纳米晶太阳能电池(DSSC),考察了DSSC的光电转换性能.结果显示:Pt底层分布的TiO_2薄膜在紫外光照射下,三电极体系的光电流增强,乙醇作为空穴捕获剂添加到电解质体系中光电流进一步增强,且从线性伏安曲线可知,Pt底层分布的TiO_2薄膜中有更多的自由空穴存在;这些结果表明:Pt底层分布的TiO_2薄膜光生载流子得到有效分离,且光生空穴分布在表层;由于Pt底层分布的TiO_2薄膜具有表层空穴富集的趋势,DSSC在光照下,敏化剂产生的电子易于向Pt底层分布的TiO_2薄膜转移,表现在短路电流I_(sc)和开路电压V_(oc)的显著增大.

TiO2 films with Pt distributing in bottom layer（PT） or uniformly（PP） were prepared by a sol-gel method through alternate dip-coating process. The photoelectrochemical behaviors of the films were measured by a three-electrode system, and the dye-sensitized solar cells （DSSC） with these films as anodes were assembled to investigate the photoelectric conversion capacities. The results show that the photocurrent of PT film is higher than that of TT and more enlarged by ethanol addition into the electrolyte as the holes＇ capture agent. The above phenomena can be explained based on the separation of photogenerated carriers and photoholes＇ accumulation in the surface layer. Due to photoholes＇ accumulating in the surface, the excited electrons can transfer to TiO2 film more easily. The short-circuit Isc and the open-potential Voc are increased obviously.