染料敏化太阳电池中双层结构TiO_2薄膜空间的电子分布与接触界面转移过程

Electron Distribution and Contact Interface Transfer Process in Bilayer TiO_2 Films of Dye Sensitized Solar Cell

采用电化学阻抗谱(EIS)研究了双层结构TiO2薄膜的电子积累和与电解液接触界面的电子转移过程.通过制备纳米颗粒单层和纳米颗粒/亚微米颗粒双层2种不同微结构的TiO2薄膜电极,对其电容分布、局域态密度、薄膜内部电子传输和固/液界面电子转移过程进行了研究.分析了纳米颗粒/亚微米颗粒双层结构电极对染料敏化太阳电池(DSC)性能的影响.结果表明,一定数量的电子会积累在亚微米颗粒层中引起薄膜电极化学电容的增加.在纳米颗粒层上端覆盖亚微米颗粒后降低了界面复合电阻,但对薄膜电极的传输性能影响较小.因此在筛选和制备DSC散射层材料时除应具有良好的光散射性能外,还应考虑材料的化学电容和界面转移电阻等因素.

The electron accumulation and transfer process at the nano/micro-scale bilayer structure of TiO2 film were investigated by electrochemical impedance spectroscopy（EIS）. Two kinds of films with different microstructures were prepared through adding a micro-scale TiO2 layer at the top of the nano-scale monolayer TiO2 film. The intrinsic properties of these films, such as the capacitance distribution, the density of electronic states, the electron transportation and the solid/liquid interfacial electron transfer process, were studied detailedly. The effect of the nano/micro-scale bilayer structure of TiO2 film on dye sensitized solar cell （ DSC ） was analysed. Chemical capacitance increase caused by a certain number of electrons was accumulated in micro-scale TiO2 layer. The electron transport resistance had no significant effect when adding a micro-scale TiO2 layer. In addition to its good performance of light scattering, the material chemical capacitor and transfer resistance should be considered in selecting and preparing materials for DSC scattering layer.