石墨/TiO_2共混碳薄膜对电极的电学与电化学性能研究

Electrical and electrochemical properties of graphite/TiO_2 based carbon counter electrode

本文将石墨、TiO2纳米晶以及TiO2胶体共混,采用旋涂法制备了碳薄膜对电极,并用于组装染料敏化太阳能电池。采用场发射扫描电子显微镜观察薄膜的表面形貌,采用四探针电阻率测试仪、电化学交流阻抗图谱及太阳能电池综合测试仪对碳对电极的电学、电化学性质以及电池的光电性能分别进行测试;研究了薄膜厚度对碳对电极导电性能与电化学催化性能的影响。结果表明随着厚度增加,碳对电极的方块电阻和界面电荷传输电阻均变小,分别可达到26.6Ω.sp-1和11.8Ω.cm-2,而电池的填充因子及光电转换效率增大。当碳薄膜厚度为19.5μm时,光电转换效率可达到Pt对电极的70%。

Carbon counter electrodes was prepared by Spin-coating the carbon paste which was prepared by ball milling graphite particles and TiO2 nanocrystalline along with certain amount of TiO2 hydrogel on substrates,and used to assemble dye sensitized solar cells.Morphological,electrical properties and electrochemistical properties of the electrodes were characterized by scanning electron microscopy,four probe method and electrochemical impedance spectroscopy respectively.Photovoltaic performance of the cells was examined.It is found that,with the increase of film thickness,both sheet resistance and charge transfer resistance decreased quickly first,and then changed a little,the least value is just 26.6Ω.sq-1 and 11.8Ω.cm-2 respectively.Meanwhile,effect of film thickness on photovoltaic performance of the cells was studied;it reached 70% of the cells assembled from Pt counter electrode when the film thickness is 19.5μm.