Remarkable 8.3% efficiency and extended electron lifetime towards highly stable semi-transparent iodine-free DSSCs by mitigating the in-situ triiodide generation

Achieving highly stable and efficient dye-sensitized solar cells (DSSCs) remains a major challenge for future industrial development. In the present work, a series of ionic conductors, such as ionic liquids (ILs), polysiloxane-based poly(ionic liquid)s (PILs), and their blends are employed as electrolytes in quasi-solid-state DSSCs. In particular, we study the effect of PILs ionic functionality interaction with the ILs and ethylene carbonate (EC) on the photovoltaic performance of DSSCs with and without iodine (I2). Omitting I2 from the electrolytes in fabricated DSSCs enhances both Voc and Jsc due to the reduced charge recombination and extended effective electron lifetime. We confirm through Raman spectroscopy that in I2-free DSSCs, the in-situ generated tri-iodides (I3−) ions are sufficient enough to complete the reaction mechanism. Additionally, the I2-free DSSCs exhibit enhanced transparency, encouraging our efforts towards BIPV suitable applications. When plasticized with EC, the ionic conductivities of the highly functionalized I2-free PIL-based DSSCs exceeds 10−3 S cm−1 at 30 °C, giving record PCE of 8.3% and 9.1% under standard (1 sun) and modest (0.3 sun) illumination, respectively. These devices also show excellent long-term stability, retaining about 84% of their initial efficiency after 26 months.