Influence of salts on ionic diffusion in oligomer electrolytes and its implication in dye-sensitized solar cells

The diffusion coefficients of I− and I3− in poly(ethylene glycol) (PEG) oligomer electrolytes as a function of salt type and salt concentration were measured. It was found that the diffusion coefficient of I3− in PEG oligomer electrolytes with potassium iodide (KI) was much lower than that with imidazolium iodide (MPII) because of the difference in the interactions of polar oxygen atoms in the PEG oligomer with K+ or MPI+. In addition, it was also confirmed that this phenomenon affected the recombination process, electron lifetime and consequently, the performance of the DSSCs.