COORDINATION POLYMERS AS ALTERNATIVE COUNTER ELECTRODE MATERIALS IN DYESENSITIZED SOLAR CELLS

Although silicon-based photovoltaic technology currently leads the market, it is hindered by challenges such as limited raw material availability and reduced performance under low or diffuse light. Dye-sensitized solar cells (DSSCs) present a compelling alternative, offering low cost, simple fabrication, and enhanced versatility, including the potential for flexibility and transparency. DSSCs rely on a photoelectrochemical reaction involving photoanode, dye, redox electrolyte, and counterelectrode (CE). While most of the research focuses on investigating and optimizing dye and electrolyte, the CE plays a critical role in determining the overall photovoltaic performance; yet the most commonly used CEs are based on Platinum and PEDOT. Broadening the range of CEs is essential for improving DSSC efficiency and facilitating the development of novel redox couples and dyes. In this contribution, a series of metal-sulfur coordination polymers have been synthesized, characterized and successfully adopted as counter-electrodes for DSSCs. Even if insoluble, such systems have been effectively processed from liquid dispersions without additives and have been subjected to thorough chemical and physical characterization. These materials appear as highly delocalized systems featuring low activation energies, high electrical conductivity, and good thermooxidative behaviour. They have been adopted as CEs in DSSCs showing comparable photovoltaic performance to standard Pt and PEDOT based CEs and exceeding 10% conversion efficiencies. This research paves the way for the development of innovative metal-coordination polymers for highperforming counter electrodes in solar cells.