Corrosion Resistance of Metallic Substrates for the Fabrication Dye-Sensitized Solar Cells

A novel method of monitoring corrosion activity when an iodide/ triiodide dye-sensitized solar cell redox electrolyte is placed in contact with a range of metallic substrates is described. Corrosion of the metallic substrate results from anodic dissolution of the metallic surface coupled with cathodic reduction of triiodide (I-3(-)) to colorless iodide ions in solution. In the work described here, UV/Vis spectrophotometry in reflectance mode is used in conjunction with encapsulation cells which incorporate a 25 mu m thick electrolyte layer, prepared using a range of polished metallic substrates. The corrosion rate is quantified by monitoring changes in the absorption spectra with respect to time. Of the metals evaluated, only titanium was wholly resistant to corrosion and did not show evidence of reaction with the electrolyte for periods of up to 3 months. Other metals such as zinc reacted within seconds and complete and irreversible loss of I-3(-) was observed after only a few minutes.