Studies Of Nanoporous TiO₂ Photoelectrodes Of Dye-sensitized Solar Cells

With high photoelectric efficiency and low cost, the dye-sensitization solar cells (DSSC) have attracted considerable attention in scientific research and for practical application. This kind of solar cell is considered to be one of the most promising cells in the future for its advantages.In this work, emphasis is focused on the optimizing microstructure of nanocrystalline TiO₂ film for the purpose of improvement of photoelectrical conversion efficiency and stability of the solar cells based on the nanocrystalline TiO₂ films.1. Nanocrystalline TiO₂ electrodes with different thickness were prepared as the screen printing method by which the proportion of the PEG in TiO₂ colloid and printing layers were controlled. The measurement of I-V curve was employed to calculate the photoelectric conversion efficiency, which is related to the thickness of the mesoporous nanocrystalline film. In our experiment, the thickness was optimized.2. The conductivity and the electrons transport behaviors of the nanocrystalline TiO₂ electrodes are increased and the interaction between dye molecules and TiO₂ surface is also improved as well as the performance of the cell, which is favorable to the injection of photo-excited electrons to the conduction band of TiO₂, resulting from the improvement of microstructure of the electrodes by chemical treatments of titanium tetrachloride.3. The TiO₂ powder in the Nano-scale makes it easier to create the accumulation due to the surface charge interaction, on the basis of electrostatic force, HNO₃ solution is used to modify the TiO₂ powder to enhance dispersion. Hence, the electrode material reduces the surface cracks and the aggregation between particles and advantageous to increasing the surface area of the films. More dye adsorption increases the photocurrent, and then greatly improves the photoelectric conversion efficiency.4. The titanium dioxide nanotube (TiNT) which has a high surface area can be directly fabricated from commercial titanium dioxide particle under the strong alkali condition via reflux reaction. The yield is higher than the previous art. Dye-sensitized solar cells (DSSC) were constructed with films made of grown TiO₂ nanotubes as working electrodes, and the I-V curve was measured. As a result, the open-circuit voltage and fill factor of DSSC with TiO₂ nanotubes increased availably, and the dark current decreased. TiO₂ nanotube is proved to be a promising material in DSSC.