Electrochemical Impedance Spectra of Dye-Sensitized Solar Cells: Fundamentals and Spreadsheet Calculation

Figure 9

(a) Charge transfer kinetics involved in dye-sensitized solar cells where dark arrow shows loss mechanism: (1) injection of electrons, (2) diffusion of electrons in the TiO₂, (3) regeneration of dye, (4) regeneration of redox mediator , (5) diffusion of , (6) diffusion of , (7) back reaction of TiO₂ conduction band electrons with , (8) recombination of electrons with oxidized dye, and (9) back reaction of electrons from FTO to . (b) Typical impedance spectra of a DSSC presented in complex plane and (c) Bode imaginary (blue solid line) and phase (green solid line) plot. In the order of decreasing frequency, the characteristic frequencies , , , and correspond to the charge transfer processes at the Pt/electrolyte interface, electron diffusion in the TiO₂ film, electron back reaction with oxidized redox species in the electrolyte, and diffusion of redox species in the electrolyte solution, respectively.

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