Influence of electrolyte in transport and recombination in dye-sensitized solar cells studied by impedance spectroscopy

The main features of the characteristic impedance spectra of dye-sensitized solar cells are described in a wide range of potential conditions: from open to short circuit. An equivalent circuit model has been proposed to describe the parameters of electron transport, recombination, accumulation and other interfacial effects separately. These parameters were determined in the presence of three different electrolytes, both in the dark and under illumination. Shift in the conduction band edge due to the electrolyte composition was monitored in terms of the changes in transport resistance and charge accumulation in TiO2. The interpretation of the current–potential curve characteristics, fill factor, open-circuit photopotential and efficiency in the different conditions, was correlated with this shift and the features of the recombination resistance.