Abstract:

As one-dimensional (1D) TiO2 nanostructures can benefit charge transport and improve the performance of dye-sensitized solar cells (DSCs), they have attracted much attention recently. However, studies on how 1D nanostructures affect the charge transport have rarely been reported. In this study, an electrochemical impedance spectroscopy (EIS) analysis was carried out to scrutinize the charge transport properties of a TiO2 particle-titania nanotube composite film. The composite TiO2 film was prepared by electrophoretic deposition using two kinds of nanoparticles with different sizes (25 and 100 nm) and titania nanotubes (TNTs) as the starting powder. The influence of the powder's composition on DSCs based on the composite film was investigated to yield an optimum composition. It was found that large particles (LPs) increase the charge diffusion and cell performance before the mass fraction of the large particles reaches 20%. Compared with films fully consisted of particles, TNTs prove to facilitate electron transport within the TiO2 film. The optimummass ratio of TNTs:LPs:PPs (25 nmparticles) is 20:16:64.

Key words: Dye-sensitized solar cell, Electrophoretic deposition, Electrochemical impedance spectroscopy, Titania nanotube, Charge transfer