Investigation of the Binary Cation Effect and the Irradiance Level Dependence on the Efficiency of Dye-sensitized Solar Cells

The development of photoelectrochemical energy conversion devices holds immense significance in addressing the escalating demand for energy and the depleting supply of nonrenewable energy sources. Dye-sensitized solar cells (DSSCs) need improvements to make them a competitive contender for 1st and 2nd generation solar cells. The development of suitable electrolytes for highly performing DSSCs is critical for that purpose. By harnessing the synergistic effects of salt mixtures that encompass both large and small counter ions, notable advancements in DSSC performance have been realized. The investigated DSSCs with a novel organic electrolyte complex that contains LiI and (tetrahexylammonium) Hex 4 NI exhibited significant efficiency enhancement compared to that of their individual salt end components. The ionic conductivity variations and frequency-dependent AC conductivity in the electrolyte, and dielectric properties were analyzed using complex impedance data. The conductivity in the electrolyte at room temperature is 11.44 mS cm − 1 . The investigated DSSCs are comprised of improved TiO 2 multi-layer photoelectrodes and Pt counter electrodes. Under an irradiance of 1000 W m − 2 , the energy conversion efficiency of the binary salt system reached 8.37%, marking an impressive enhancement of 86.83% and 76.21% compared to the Hex 4 NI and LiI-based single salt counterparts, respectively. The associated open-circuit voltage, fill factor, and short-circuit current density values are 710 mV, 0.69, and 16.33 mA cm − 2 . Additionally, an impressive efficiency of 10.57% is shown when the light intensity drops to 400 W m − 2 . Furthermore, the cells exhibited commendable short-term stability, likely attributed to the elimination of volatile solvents in the electrolyte. This study underscores the pivotal role played by binary counter ions in the electrolyte, as they elicit synergistic effects that amplify DSSC performance enhancements, effectively overshadowing the effects imposed by conductivity variation.