Top-ranked efficiency under indoor light of DSSCs enabled by iodide-based DES-like solvent electrolyte

This work presents the next paradigm shift in solar energy technology in which a novel iodide-based DES-like mixture has been first investigated as an active electrolyte solvent in dye-sensitized solar cells (DSSCs) in the absence of any co-solvent and any external iodide source. The optimization of the cell design jointly with a bespoke dye functionalized with a hydrophobic chain, properly positioned along the molecular backbone, ensures (a) one of the highest power conversion efficiencies (PCEs) up to 4% for DSSCs based on non-VOC solvents, and (b) a remarkable temporal stability of nearly 95% over a period longer than 2 months. Higher power conversion efficiency values (up to 8.0%) than those reported in the literature with traditional sensitizers and environmentally friendly electrolytes (e.g., water-based electrolytes) have been achieved under low-light illumination. These results are very promising for the realization of next-generation nature-inspired low-cost and high-performing DSSC devices for indoor and outdoor applications. DSSCs based on a DES-like mixture containing choline iodide as main component have been tested, in combination with a properly hydrophobic dye, achieving top-ranked efficiency without any other iodide source under both outdoor and indoor conditions.