Unreported high-performing counter-electrodes for DSSCs based on metal-sulphur coordination polymers

Renewable energy has seen substantial growth in recent years, with photovoltaics accounting for most of new capacity additions in recent years. While silicon-based photovoltaic technology currently dominates the market, it faces limitations such as raw material availability and reduced efficiency under low/diffuse light. A promising alternative are Dye-sensitized solar cells (DSSCs) offering several advantages like low-cost and ease fabrication with greater versatility (i.e. flexibility, transparency). The composition and functionality of DSSCs involve a photoelectrochemical reaction facilitated by a photoanode, dye, electrolyte redox couple, and counter-electrode (CE). Considering the latter, the most performing CEs are restricted to Platinum, PEDOT and carbon-based systems, but they suffer from scarcity, high costs and low stability.1 Increasing the variety of CEs would be fundamental to enhancing the photovoltaic performance of DSSCs, also allowing the use of innovative redox couples and dyes. In this contribution, a series of metal-sulphur coordination polymers have been synthesized and characterized in term of photophysical and electrochemical properties.2,3 Subsequently, the new polymers have been properly processed in solution and successfully adopted as counter-electrodes for DSSCs. Organometallic polymer CEs have been studied in combination with different electrolytes based on copper, cobalt and iodine showing highly promising results with photovoltaic efficiencies close to 10% and comparable to standard Pt and PEDOT CEs. In conclusion, we successfully report for the first time the use of metal-sulphur conductive polymers as high-performing and stable CEs in DSSCs, paving the way for the development and optimization of such innovative materials. References: 1. Ding, S., RSC Advances 13, 12309 (2023) 2. Menon A.K., Adv. Electron. Mater. 5, 1800884 (2019) 3. Sun H., Chem 6, 1310 (2020)