Wide frequency range diagnostic impedance behavior of the multiple interfaces charge transport and transfer processes in dye-sensitized solar cells

The special “sandwich” structure of dye-sensitized solar cells (DSC) provides multiple electron transfer interfaces and two charge transport channels inside the cell. Some processes that take place on such interfaces have generally been left unnoticed when electrochemical impedance spectroscopy was used to study charge transfer process on these interfaces and charge transport process in these channels. In this paper, by dramatically varying the values of parameters of the impedance components of a DSC full-interface equivalent circuit containing 4 interfaces and 2 layers, we have studied the interaction between the charge interface transfer impedance and transport impedance and its effect on the overall impedance of the cell. We have also conducted a detailed study of the impedance characteristics of the internal charge transport, transfer, and collection processes of DSC. The results show that some previously ignored interfaces, such as the TCO/TiO2 and TCO/EL interfaces, as well as Nernst diffusion impedance in the electrolyte solution, can also influence the overall impedance characteristics of DSC under certain circumstances.

► Model the interaction among multiple interface processes of charge transport and transfer in DSC with wide frequency range.
► Diagnostic changes of impedance behavior over a wide range of changing conditions in DSC.
► The TCO/TiO2 and TCO/EL interfaces, as well as Nernst diffusion impedance can also influence the overall impedance characteristics of DSC under certain circumstances.