Effect of structure and surface morphology of sol-gel derived TiO2 photoelectrode on the performance of dye-sensitized solar cells

Abstract

Nanocrystalline TiO2 photoelectrodes were successfully deposited on SnO2:F coated glass substrate by sol-gel technique with different polyethylene glycol (PEG) concentrations. Low cost chlorophyllin based dye was used along with carbon paste on SnO2:F glass as a counterelectrode. All the TiO2 electrodes show good crystallinity. The x-ray diffraction result indicates that the TiO2 thin film without PEG has more compact structure with high density of crystallite. For TiO2 film with the same number of coatings, introduction of PEG induces porous structure with less number of crystallites. The amount of dye incorporation was found to be highly dependent on the microstructure of electrodes, as apparent from optical measurements. The result shows that the photoelectric conversion efficiency increases with PEG concentration, but the fill factor decreases monotonically. The variation of photoelectric conversion efficiency of the solar cells with different TiO2 electrodes prepared with various PEG concentrations is discussed with the analysis of different microstructures of the TiO2 photoelectrodes and the corresponding dye incorporation.