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Fabrication of Plasmonic Structures and Investigation of the Effect of Surface Plasmon Resonance on Dye Sensitized Solar Cell

Sharifi, Nafiseh | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43930 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Irajizad, Azam
  7. Abstract:
  8. Dye-sensitized solar cells (DSCs) are third generation of solar cells, which composed of a porous layer of wide band gap semiconductor such as TiO2, covered with a molecular dye that absorbs sunlight, and a counter electrode contacted by a liquid redox electrolyte. Photovoltaic performance is the collective measure of light harvesting, charge separation and charge collection efficiencies. Light harvesting has a significant role in improvement of photovoltaic performance. Molecular engineering of dyes to improve absorption spectrum or to have a broad absorption spectrum,andlight scattering layes are approaches for this porpuse. This research is focused on photon management in DSCs using different metallic structures. In this study,various metallic structures were fabricated to investigate the effect of far-field or light scattering from metallic structure, as well as the effect of near-field or surface plasmon resonance of as well as light absorption in DSCs.
    In this research, silver, the metal with the highest reflection was used as reflector. This reflecting layer was deposited on the photoanode to bend and redirecte the un-absorbed light into the photoanode. 66% enhancement is observed in current density compared to reference cell (the cell without reflecting layer). In anoher configuration, synthesized hollow silver spheres (HSSs) were covered with silica to protect them from electrolyte. Having incorporating freestanding hollow silver spheres in the electrolyte, they act as light scattering centers to augment JSC and η by ca. 50% and 21%, respectively. In third configuration, 300nm-sized TiO2 particulate layer was compared to 300nm-sized silver particulate layer in order to compare the light scattering from silver layer with conventional reflectors (TiO2). Since TiO2 particulate layer has higher diffuse reflectance compared to silver particulate layer, current and efficiency enhancements are higher for the earlier.
    A layer of gold was deposited on photoanode and in another configuration, a mixture of gold and TiO2 was prepared. In both configurations, the electrical connection between gold and TiO2causes to disturb the electron collection toward external circuit. In addition, it should be considered that gold is unstable in the electrolyte. Therefore, having synthesized gold-silica core-shell nanoparticles (ACSS NPs), different photoanodes with 0, 5, 10, and20%wt ACSS NPs were prepared. These NPsconfine as well as scatter more light inside the photoanodes. The balance between positive effect of diffuse light scattering from ACSS NPs inside the photoanode (far-field), positive effect of SPR (near-field), and negative effect of light absorption by these NPs (ohmic dissipation) determines final photo-current. 5% wt is the optimum in which52%, and 50% enhancement are observed in current density and conversion efficiency, respectively when it compares to the 0% wt
  9. Keywords:
  10. Near Field ; Dye Sensitized Solar Cells ; PLasmonic Structure ; Light Scattering ; Silver ; Gold ; Metallic Structures ; Far Field

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