Morphological and chemico-physical study of dye-sensitized solar cell counter electrode degradation

Due to the high solar energy conversion efficiency, dye-sensitized solar cells (DSCs) represent one of the most promising new generation devices. A DSC consists of 3 main components: (i) photo-anode sensitized with dye molecules, (ii) hole-conducting material and (iii) counter electrode. The whole structure is sealed using hot-melt sealants to avoid electrolyte leakages and protect cell elements from environment. To better understand the behavior of different DSC components, an in -situ analysis should give a help, but it results difficult to be performed without compromising cell integrity. Our novel microfluidic approach for DSCs fabrication is based on a reversible electrodes sealing and allows cell easy assembling and disassembling, making possible a non-destructive components analysis over time. In this study we focused on the counter electrode, which is made by TCO-covered glass coated with a thin (few nm) Pt layer, deposited by 2 different methods: thermal decomposition of a printable transparent Pt catalyst and thermal deposition. Our goal has been to establish which method produces the most reliable Pt film, which can withstand the time -dependent degradation, due to the DSC inner harsh environment. So detailed morphological (FESEM), optical (UV-Visible spectroscopy), electrical (EIS) and surface (XPS) characterizations have been performed on the counter electrodes over a period longer than 4 months.