Preparation and performance of dye-sensitized solar cells based on ZnO-modified TiO_2 electrodes

The ZnO-modified TiO_2 electrode was prepared by adding Zn(CH_3COO)_2·2H_2O to the TiO_2 colloid during the sol-gel production process, and was used in dye-sensitized solar cells (DSCs). The open circuit voltage (Voc) and fill factor (ff) of the cells were improved sig-nificantly. The performances of the ZnO-modified TiO_2 electrode such as dark current, transient photocurrent, impedance, absorption spectra, and flat band potential (V_(fb)) were investigated. It is found that the interface charge recombination impedance increases and V_(fb) shifts about 200 mV toward the cathodic potential. The effect mechanism of ZnO modification on the performance of DSCs may be that ZnO occupies the surface states of the TiO_2 film.