Characterization of the TiO2/Dye/Electrolyte Interfaces in Dye-Sensitized Solar Cells by Means of a Titania-Binding Nitroxide

详细信息    查看全文

• 作者：Alberto Fattori ; Michela Cangiotti ; Luigi Fiorani ; Susanna Lucchi ; Maria Francesca Ottaviani
• 刊名：Langmuir
• 出版年：2014
• 出版时间：November 18, 2014
• 年：2014
• 卷：30
• 期：45
• 页码：13570-13580
• 全文大小：514K
• ISSN：1520-5827

文摘

Dye-sensitized solar cells (DSSCs) have been characterized in several literature examples by using relatively complex methods and/or modified DSSC conditions with respect to the usual working ones. In this study, we propose a method for the investigation of the interfaces TiO₂/dye/electrolyte in a DSSC at its usual working conditions. This method implies the use of a computer-aided analysis of the electron paramagnetic resonance (EPR) spectra of the spin probe 4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl (4-carboxy-TEMPO, indicated as 4-cT). This probe well-mimics the dyes in their interactions with TiO₂ surface, but does not perturb dye adsorption onto TiO₂ surface, as verified by UV鈥搗is measurements. First, we investigated the interacting ability toward 4-cT of commercially available TiO₂ used for assembling the DSSC. It was found that interactions are modulated by the different distribution of interacting sites at the solid surface and powder aggregation. Further, experiments on 4-cT were carried out in the presence of a series of other molecules coded as N3, N719, and D149, which are commonly used as dyes in DSSCs. Then, the effect of solutions added to the electrodes was investigated. On the basis of the interactions occurring at the TiO₂/dye/electrolyte interfaces, we selected the ingredients of the DSSCs. Electrical and EPR characterizations of these DSSCs miniaturized to enter the EPR cavity, together with time-dependent laser-light on鈥搊ff experiments, were carried out, which demonstrated the ability of the EPR analysis to monitor the types and strengths of the interactions occurring at the cell鈥檚 different interfaces. This method using the standard continuous wave EPR technique at room temperature may be profitably used to characterize the quality and performances of a DSSC.