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Improvement of Light Scattering Effect of Dye –sensitized Solar Cells Aided by Different Structures of Titanium Dioxide

Sarvari, Najmeh | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49349 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Mohammadi, Mohammad Reza
  7. Abstract:
  8. Structure and morphology of titanium dioxide have an excessive effect on the photovoltaic properties of dye-sensitized solar cells (DSCs). Different approaches have been used to improve the efficiency of these cells. One is using a scattering layer. Studies have been shown that properties of scattering layer such as composition and morphology have great effect on photovoltaic properties of solar cell. In this project, the effect of cubic morphology of TiO2 as a scattering agent in photoanode of DSCs is studied. Titanium dioxide with various morphologies including nanoparticles, solid and hollow cubic structures have been synthesized by solvothermal and hydrothermal methods, respectively. The effect of processing parameters such as time, temperature, heating rate and precursor ratio on morphology of cubic structures have been investigated. The impact of cubic structures (hollow and solid) on photovoltaic characteristics of DSCs was compared with spherical TiO2 nanoparticles. X-ray diffraction (XRD) results showed that TiO2 nanoparticles and hollow cubic morphology had anatase phase, whereas the solid cubic morphology showed TiOF2vcrystal structure. Field emission scanning electron microscope (FE-SEM) images showed that dimension of nanoparticles, hollow cubic structures and solid cubic structure were 20-30 nm, 200-400 nm and 100-600 nm, respectively. The results of diffuse reflectance spectroscopy (DRS) showed that both solid and hollow cube morphologies had higher diffusion reflectance than the nanoparticle due to thier few hundred nanometers dimensions and cubic morphology, being suitable to use as an appropriate scatterer. Therefore, two kinds of single-layer cells containing mixed cubic structures and nanoparticles as well as two active layers containing nanoparticles and scattering layer which contains cubic particles were made. In case of mixed cubic structures and nanoparticles in the active layer no improvement in efficiency of cell was observed. However, by adding both cubic structures (hollow and solid) in the scattering layer higher efficiency than the single-layer cell with optimum thickness was observed. For example, by adding 50% solid cubic structures in the scattering layer, the efficiency was increased up to 8.21% (i.e., 17% increase compared with the single-layer cell containing nanoparticles). In addition, by adding 25% hollow cubic structures in the scattering layer, the efficiency increased up to 9.39% (i.e., 34% increase compared with the single-layer cell)
  9. Keywords:
  10. Light Scattering ; Titanium Dioxide ; Nanoparticles ; Dye Sensitized Solar Cells ; Cubic Particles

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