Influence of Different Electrolytes on the Reaction Mechanism of a Triiodide/Iodide Redox Couple on the Platinized FTO Glass Electrode in Dye-Sensitized Solar Cells

The reaction mechanisms of a triiodide/iodide redox couple at the platinized FTO glass electrode/electrolyte interface with different electrolytes were studied by cyclic voltammetry, steady polarization curve, and chronocoulometric methods. It was found that the reaction process of the triiodide/iodide redox couple in electrolytes without nitrogenous heterocyclic additives was controlled by adsorption, and different iodide concentrations could affect the reaction mechanism of the triiodide/iodide redox couple on the platinized FTO glass electrode by changing the adsorption characteristic of iodide (triiodide). After nitrogenous heterocyclic additives were added into the electrolytes, the reaction process was controlled by a diffusion process. The nitrogenous heterocyclic additives can absorb on the electrode and change the reaction mechanism of the triiodide/iodide redox couple by forming complex compounds with triiodide. The radius of the redox active species in the electrolyte with nitrogenous heterocyclic additives was bigger than that in electrolytes without nitrogenous heterocyclic additives.