Design and Fabrication of Efficient Electrodes for Dye Sensitized Solar Cells

Dye sensitized solar cells (DSSCs) represent a cheap and clean technology to harnesses solar energy efficiently. To further decrease the production cost while improving the device performance is a bottleneck for large scale application and commercialization of DSSCs. The thesis focuses on the development of economically competitive photoelectrodes with the motivation to further enhance energy conversion efficiency of DSSCs. Practical and scalable device fabrication is also proposed and studied in details. In this research, several novel structures of TiO₂ photo-anode beside the TiO₂ nanoparticls thin film have been prepared. A composite of TiO₂ nanoparticles/ 8 nm TiO₂ nanotubes was successfully fabricated as a stand- alone, paper-like structure for a photoanode of dye- sensitized solar cells by using a simple pressing method. The best power conversion efficiency of 5.38% was obtained on micropaper with a combination of TiO₂ nanospherical particles and a 1D nanostructure. Incorporation of double- walled carbon nanotubes (DWCNTs) into a TiO₂ photo-anode layer has been studied. A significant improvement in the performance in the DSSC was obtained from the DWCNTs-TiO₂ photoanode. Comparing to the standard TiO₂ anode, the carbon nanotube-containing TiO₂ anode with 0.2 wt.% DWCNTs has boosted up the photocurrent density (Jsc) by 43%. In order to mitigate the severe performance deterioration in larger size DSSC solar cells, the use of anodized TiO₂ nanotubes was introduced on Ti foil. Instead of FTO glass, the photoanode was made of Ti foil. Elimination of the highly resistive FTO glass in the anode structure, as well as the enhanced charge collection via the nanotube-coated Ti substrate, resulting in improving mechanical and electrical connections, electron conduction and possibly improving the light trappin

Titania Nanotube Architectures Synthesized on 3D-Printed Ti-6Al-4V Implant and Assessing Vancomycin Release Protocols

The aim of this study is to synthesize Titania nanotubes (TNTs) on the 3D-printed Ti-6Al-4V surface and investigate the loading of antibacterial vancomycin drug dose of 200 ppm for local drug treatment application for 24 h. The antibacterial drug release from synthesized nanotubes evaluated via the chemical surface measurement and the linear fitting of Korsmeyer–Peppas model was also assessed. The TNTs were synthesized on the Ti-6Al-4V surface through the anodization process at different anodization time. The TNTs morphology was characterized using field emission scanning electron microscope (FESEM). The wettability and the chemical composition of the Ti-6Al-4V surface and the TNTs were assessed using the contact angle meter, Fourier transform infrared spectrophotometer (FTIR) and the X-ray photoelectron spectroscopy (XPS). The vancomycin of 200 ppm release behavior under controlled atmosphere was measured by the high-performance liquid chromatography (HPLC) and hence, the position for retention time at 2.5 min was ascertained. The FESEM analysis confirmed the formation of nanostructured TNTs with vertically oriented, closely packed, smooth and unperforated walls. The maximum cumulative vancomycin release of 34.7% (69.5 ppm) was recorded at 24 h. The wetting angle of both Ti-6Al-4V implant and the TNTs were found below 90 degrees. This confirmed their excellent wettability