Electrolyte Tuning in Iron(II)-Based Dye-Sensitized Solar Cells: Different Ionic Liquids and I2 Concentrations

The effects of different I2 concentrations and ionic liquids (ILs) in the electrolyte on performances dye-sensitized solar cells (DSCs) containing an iron(II) N-heterocyclic carbene dye I–/I3– redox shuttle have been investigated. Either no was added to electrolyte, or initial were 0.02, 0.05, 0.10, 0.20 M. short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (ff) influenced by changes concentration for all ILs. For 1-hexyl-3-methylimidazole iodide (HMII), low VOC ff values led poor DSC performances. Electrochemical impedance spectroscopy (EIS) showed causes be increased diffusion resistance charge transfer at counter electrode. DSCs 1,3-dimethylimidazole (DMII) 1-ethyl-3-methylimidazole (EMII) highest JSC when 0.10 M present initially. Short alkyl substituents (Me Et) more beneficial than longer chains. lowest transport photoanode semiconductor found DMII, EMII, 1-propyl-2,3-dimethylimidazole (PDMII) [I2] less 0.05 Higher decreases electrode resistance. electron lifetime length depended upon [I2]. Overall, DMII most IL. A combination 0.1 produced best performing with average maximum photoconversion efficiency 0.65% a series fully-masked cells.