Electrochemical impedance spectroscopy analysis of iodine/potassium iodide electrolyte influence on spin-coated platinum counter-electrode on FTO glass

Abstract

Very low concentrated precursor solution has been carried out for producing catalytic platinum layers by a spin-coating method. Direct deposition of platinum nanoparticles from low concentrated precursor solution on a conductive substrate results in many nanoparticles remaining in solution. They are not adhesive enough to be able to load them onto another submerged element. The spin-coating method has been applied to use them for catalytic layer preparation. Electrochemical impedance spectroscopy measurements were carried out using a symmetrical setup with the test electrolyte showing, in general, the better properties if more layers are applied. The circuit model for the symmetric setup, containing two identical Pt layers with electrolyte between them, has been proposed. It was found deteriorating layer properties expressed by charge transfer resistance increasing while the platinum layers were influenced by the electrolyte due to a decrease in the amount of platinum on the electrode surfaces. Layers of platinum retain their properties for some hours in contact with electrolyte without measurable decreasing of properties. The spin-coated platinum layer obtained by described method can be used in laboratory tests of Dye Sensitised Solar Cells different components filled with iodide-triiodide electrolyte.