Solution-processable coordination polymers for counter-electrode in DSSCs

Solution-processable coordination polymers for counter-electrode in DSSCs Galliano S.,1 Franzini M.,1 Sasitharan K.,2 Morritt G.H.,2 Zanetti M., Borri M.,4 Reale A.,3 Freitag M.,2 Barolo C.1 1Department of Chemistry and NIS Interdepartmental and INSTM Reference Centre. University of Turin, Torino, Italy. 2School of Natural and Environmental Science, Newcastle University, Newcastle upon Tyne, UK. 3Department of Electronic Engineering, University of Rome Tor Vergata-CHOSE, Roma, Italy. 4Martur Italy srl, Via Stefano Scoffone 3/5, Grugliasco 10095, Turin, Italy. 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 counter-electrode (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 [1]. In this contribution, a series of metal-sulfur coordination polymers have been synthesized, characterized and successfully adopted as counter-electrodes for DSSCs [2]. 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 thermo-oxidative 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 high-performing counter electrodes in solar cells. [1] Ding, S.; Yuan, J.; Li, H.; Yuan, X.; Li M. An overview of the preparation and application of counter electrodes for DSSCs. RSC Advances 2023, 13, 12309. [2] Sun, Y.; Sheng, P.; Di, C.; Jiao, F.; Xu, W.; Qiu, D.; Zhu, D. Organic Thermoelectric Materials and Devices Based on p- and n-Type Poly(metal 1,1,2,2-ethenetetrathiolate)s. Adv. Mater. 2012, 24, 932.