Counter electrode system of Pt on stainless steel (SS) for electron injection into iodide redox couple

Abstract

To study the effect of stainless steel (SS) surface morphology as a counter electrode and a flexible substrate in dye sensitized solar cells (DSCs), SS surface was treated with chemical mechanical polishing process or etched with hydrochloric acid for various times. Pt catalytic layer was deposited either with sputtering at room temperature or thermal decomposition of precursor solution (H2PtCl6). From the electrochemical impedance measurement on the symmetric cell, the charge transfer resistance at the electrolyte/counter electrode interface and the internal resistance were obtained. When Pt was deposited on polished SS with sputtering, fill factor (FF) and efficiency were decreased due to the decrease in surface area. On the other hand, the catalytic activity was improved with etching due to the increase in the surface area leading to the improvement in FF and efficiency (71.0% and 7.7%). When the Pt layer was formed with thermal decomposition on the SS substrate, FF and efficiency were significantly decreased with poor catalytic activity regardless of the surface area, due to the oxidation of the SS surface during the thermal decomposition process at high temperatures. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.015201jes]