Improved Energy Conversion Efficiency of TiO_2 Thin Films Modified with Ta_2O_5 in Dye-Sensitized Solar Cells

摘要

Tantalum-doped TiO_2 thin films [(TiO_2)_1-x(Ta_2O_5)_x, x = 0-0.8%] were prepared on fluorine-doped tin oxide (FTO)-coated substrates by sol-gel technology for uses in dye-sensitized solar cells (DSSCs). The effects of Ta content on the growth and properties of the TiO_2 thin films were investigated. The crystallization and microstructures of the thin films were examined by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller analyses. The performance of DSSCs based on Ta-doped TiO_2 thin films was also studied. From the obtained results, the increases in J_(sc) and V(oc) may be due to the increased electron concentration of TiO_2 thin film and the flat-band potential of the TiO_2 shifted by tantalum doping, respectively. The optimum properties of DSSCs of V_(oc) = 0.68V, J_(sc) = 7.84mA/cm~2, FF = 45.1%, and η = 2.4% were obtained using the Ta-doped TiO_2 thin film with x = 0.5%.