Studies on Simulation and Application of Characteristics of Constant Phase Element and in Dye-sensitized Solar Cells

Electrochemical impedance spectroscopy(EIS)may be used to study the internal impedance information of dye-sensitized solar cells(DSC)in the range of wide frequency.There is capacitance dispersion effect due to the roughness and inhomogeneity of main contact interfaces in DSC.A constant phase element(CPE)is an equivalent electrical circuit component that models the behavior of an imperfect capacitance.This paper simulates and analyzes the frequency response characteristic of CPE with several different indexes.The effect of CPE index on impedance of RC circuit and the conversion between CPE and a pure capacitance are studied.CPE and capacitance are used respectively in three distinct frequency ranges to fit EIS spectrum through experiments.The application of CPE in the interfacial electron transfer process and extraction of kinetic parameters are analysed.The results show that the CPE index determines the element performance and it is more suitable to use a CPE instead of a pure capacitance for constructing EIS equivalent circuits.DSC internal electron transfer kinetic constants can be obtained by using CPE after a simple calculation.