染料敏化太阳能电池的内部阻抗分析

Internal Impedance Analysis of Dye-Sensitized Solar Cells

为了进一步研究染料敏化太阳能电池的性能与内部阻抗的关系,应用电化学阻抗谱来研究电池内部电子转移过程的阻抗特性．结合适当的等效电路和理论模型对电池的阻抗谱图进行分析,结果表明,电池的内部阻抗主要来自至少3个方面:高频区域为铂和电解质界面的阻抗;中频区域为电子在二氧化钛薄膜中的传输和复合阻抗;低频区域为电解质内部的扩散阻抗．其中电子在二氧化钛薄膜中的传输和复合阻抗是影响染料敏化太阳能电池内部阻抗的主要方面,电解质的扩散对电池内部阻抗的影响较小．

To analyze the internal impedance affecting the performance of dye-sensitized solar cells （DSC）, electrochemical impedance spectroscopy （EIS） was applied to investigate the impedance characteristic of charge-transfer. Appropriate equivalent circuit and theoretical model of DSC were developed to interpret and analyze the impedance spectra. Impedance spectroscopy of cells shows their internal resistance consisted of at least three components. The high-frequency region corresponds to charge-transfer at Pt Ⅰ electrolyte interface. Intermediate-frequency region reflects charge-transfer in TiO2 films and compound impedance, while the low-frequency region corresponds to diffused impedance in electrolyte. Resistance of charge-transfer in TiO2 films and compound impedance is the key of affecting internal impedance of DSC. The impedance stemming from the diffusion of the electrolyte had little effect on the performance of the cells.