Modifying the Semiconductor/Electrolyte Interface in CuO p-Type Dye-Sensitized Solar Cells: Optimization of Iodide/Triiodide-Based Electrolytes

Studies related to novel electrolyte concepts for p-type dye-sensitized solar cells (p-DSSCs) set focus on developing alternatives to the iodide/triiodide (I^-/I₃^-) redox couples, while attempts to improve the performance of the latter are scarce. In this study, we report on the first complete optimization of an I^-/I₃^--based electrolyte for p-DSSCs employing CuO-based photocathodes. Optimization of the electrolyte solvent, the effect of ionic liquids, and the concentration-dependent properties of various electrolyte additives were at the focal point. Electrochemical impedance spectroscopy and intensity-modulated photovoltage and photocurrent spectroscopies complemented basic electrochemical and device characterization, leading to a sound understanding of charge injection, charge recombination, and charge transport. To this end, optimization of the aforementioned parameters enabled 2-fold device efficiencies of 0.156% compared to 0.078% for nonoptimized devices.