Abstract: Transparent titanium oxide (TiO2) photoelectrodes for dye-sensitized solar cells (DSCs) were deposited on fluorine doped tin oxide substrate by a sol-gel dip coating technique with acetic acid as an acid catalyst, where crystallinity can be achieved at a relatively low annealing temperature. Repetitive dip-coating and drying, with two intermediate annealing has made this technique easier to prepare TiO2 thin film with desired thickness within a short period of time. The TiO2 photoelectrodes were annealed at various temperatures to study the effect of annealing temperature on the photovoltaic property of the DSCs. The structure of the TiO2 films, prepared at various annealing temperature, shows different crystallinity. Good crystallinity has been observed for 300C annealing temperature and it improved with increasing annealing temperature. The surface morphology, investigated by field emission scanning electron microscope and atomic force microscope measurement, revealed that with the increase of annealing temperature surface of TiO2 photoelectrode showed more porous structure with higher roughness. The DSCs with TiO2 photoelectrode, annealed at 300 C, showed best photovoltaic characteristics among the three samples of investigation. Measurement of optical properties and incident photon to current conversion efficiency indicated the maximum dye incorporation in TiO2 electrode, deposited at 300 C. The solar cell efficiency and fill factor of this above mentioned sample are 0.96% and 46.3% respectively. The results indicate a strong correlation between the microstructure, dye absorption and photovoltaic property of the sample.
Abstract: In our present study, the porous zinc oxide (ZnO) films were deposited on SnO2: F coated glass by sol–gel technique zinc acetate as precursor, ethanol as solvent and diaethanolamine as chelating agent. Two sets of ZnO films with equal number of coatings and same film thickness were deposited with various zinc acetate concentration. The surface morphology of the porous ZnO film strongly depends on the zinc acetate concentration. It was also revealed from optical study that the dye absorption increases with the increase of zinc acetate concentration. The ZnO film with 1.0 mol/L zinc acetate concentration has shown best porous structure and maximum rms roughness value (187 nm). The maximum photoelectric conversion efficiency: 0.64 and 0.8 % was achieved for ZnO films with 1.0 mol/L of zinc acetate concentration in sample set of equal number of coatings and same film thickness, respectively.
