Solution processed nanostructures for solar cell applications
Tan, Gerard Yung Kiat.
Date of Issue2009
School of Materials Science and Engineering
This report contains insights into the theory of Dye-Sensitized Solar Cells (DSSCs), encompassing its construction from zinc oxide (ZnO) nanostructures, Liquid Phase Deposited (LPD) processing and post Titanium (IV) Chloride (TiCl4) treatments, to experiments conducted to evaluate its efficiency and various properties. Important characterizations such as electron microscopy, X-ray diffraction and DSSC testing will be done across all the individual categories of experiments. The maximum length of zinc oxide nanowires grown using hydrothermal method of growth is 10.543 μm in a total of 24 hours, with 4 hour refresh cycles to continually provide growth precursors. The zinc oxide nanowires DSSCs performance has shown an approximate trending of decreasing efficiency over increasing amounts of dye loading time. The 3.6 μm length (a total of 8 hour growth cycle utilizing hydrothermal method of growth) ZnO nanowire has shown a decreasing efficiency of 0.22% to 0.014%, from 0.5 hours to 48 hours dye loading time. Also, the greatest reduction in efficiency occurs during the first 2 hours, and subsequently the efficiency arrests to a decreasing plateau. LPD-processing on ZnO nanostructures yielding amorphous TiO2 was carried out at 50°C, and there was a reduction in height from 5.94 μm to 4.73 μm with the average diameter of rods increasing dramatically to approximately 430 nm. DSSCs constructed utilizing LPD-processed ZnO nanostructures were dye-loaded in similar conditions and durations with the earlier ZnO experiment, and found to have increasing efficiencies over the same durations. The most remarkable jump in efficiency was during the first 2 hours, while increasing efficiency indicates more room for dye adsorption mechanism to take place. Lastly, the TiCl4 post-treatment of LPD-processed nanostructures and ZnO was carried out with no remarkable improvement in cell performance, albeit a single jump in Fill Factor value to 0.697. As the mechanisms of the hydrolysis of TiCl4 are not fully understood up to date, more areas remain for further improvement.
Final Year Project (FYP)
Nanyang Technological University