An ionic transfer investigation of tri-iodine of solvent-free oligomeric electrolytes in dye-sensitized solar cells

A series of novel solvent-free oligomeric electrolytes based on poly (ethyl glycol) methyl ether methacrylate for dye-sensitized solar cells (DSSCs) are currently under development. The aim of this study was to investigate the effects of tri-iodine (I₃^-) ionic transport on the side-chain length of ethylene-oxide (EO), and its overall influence on the performance of dye-sensitized solar cells. Solvent-free oligomeric electrolytes with EO side chains of the shortest length enhanced the diffusion coefficient of I₃^-, thereby promoting redox reactions in DSSCs, and increasing the short circuit current density (J_sc). In addition, free volume measurements of oligomeric electrolytes provided a possible explanation regarding the ionic transfer mechanism and a conceptual framework related to the influence of the length of the EO side chain. Finally, a 30-day long-running test demonstrated that these oligomer systems are robust and stable. The current-voltage (I-V) characteristics of the oligomeric electrolyte produced the best results, with values of 0.62 V for V_oc, 9.71 mA cm^-2 for J_sc, 0.59 for fill factor (FF), and 3.56% cell efficiency under AM 1.5.