Photoelectrochemical Analysis of the Dyed TiO2/Electrolyte Interface in Long-Term Stability of Dye-Sensitized Solar Cells

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• 作者：Changneng Zhang ; Yang Huang ; Shuanghong Chen ; Huajun Tian ; Li鈥檈 Mo ; Linhua Hu ; Zhipeng Huo ; Fantai Kong ; Yingwen Ma ; Songyuan Dai
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：September 20, 2012
• 年：2012
• 卷：116
• 期：37
• 页码：19807-19813
• 全文大小：418K
• 年卷期：v.116,no.37(September 20, 2012)
• ISSN：1932-7455

文摘

The interface structure induced by electrolyte cations was found to play a significant role in determining the performance and stability of dye-sensitized solar cells. The trap state density in the nanostructure TiO₂ electrodes was affected by the adsorbed 1,2-dimethyl-3-propylimidazolium cation (DMPI⁺) or alkali cations, such as Li⁺, Na⁺, K⁺, and Cs⁺, on the dyed TiO₂ electrode and was found to increase with the order of decreasing cation radius DMPI⁺ < Cs⁺ < K⁺ < Na⁺ < Li⁺. The change in interface structure resulted from the accumulation of the adsorbed cations to increase trap states in the nanostructure TiO₂ electrodes during long-term accelerated aging tests. The size effect of electrolyte cations on the cell performance suggested that the reduced surface cations, when small cations penetrated into titania lattice, resulted in a negative shift of the TiO₂ conduction band edge and a weaker interaction of Li⁺ with dyes to obtain the decline in photocurrent and efficiency. The overall efficiency of dye-sensitized solar cells with large DMPI⁺ in the electrolyte retained over 110% of its initial value after 2100 h. Also, no obvious differences in the efficiency for dye-sensitized solar cells with electrolyte cations, such as Li⁺, Cs⁺, and DMPI⁺, were observed after 1270 h under one sun light soaking in our experiment. The results suggested that large DMPI⁺ chemisorbed on TiO₂ surface could not intercalate into the TiO₂ lattice for the enhanced stability of dye-sensitized solar cells in practical application.