Enhancement of Photocurrents in Dye-Sensitized Solar Cells Fabricated Using Al-Incorporated TiO2 Powders Thermal Treated at Different Temperatures

摘要

In this study, an attempt was introduced to enhance the high photoelectric currents on dye-sensitized solar cells (DSSC) by increasing the level of dye adsorption on the hydrophilic surface of an Al-incorporated TiO2 anode. Nanometer-sized Al (0, 1.0, 2.5, 5.0, 7.5, and 10.0 mol-%)-incorporated TiO2 as a working electrode material was prepared using a common solvothermal method, and the anodes were treated thermally at 400, 500 and 600 degrees C to improve their fill factors and photoelectric currents in the DSSCs as a result of the strong connections between nano-particles. The photoelectric current on the 5.0 mol-% Al-TiO2-DSSC and the fill factors increased gradually with increasing treatment temperature: the photo-conversion efficiency was improved to approximately 6.81% for the 5.0 mol-% Al-TiO2-DSSC-600 degrees C. The added Al imparted a lower band-gap to TiO2, and the conduction band of Al-TiO2 in the potential energy diagram was located between the LUMO of the N719 dye and the valence band of TiO2, suggesting that the electrons excited from the N-719 dye moved easily to the surface of the conduction band of TiO2 through the conduction band of Al-TiO2.