Loading...

Design of Doped TiO2 Dye-sensitized Solar Cells with Different Arrangement Modes of Photoanode Electrodes

Vafaei, Maral | 2016

865 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49350 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Mohammadi, Mohammad Reza
  7. Abstract:
  8. In this thesis, pure –known as T- and chromium doped titanium dioxide nanoparticles –known as -CTx- with different dopant atomic ratio (0.1 to 5 %at.) were synthesized using a facile, fast and efficient method. FESEM and XRD studies showed no morphologic and structural change via Cr doping of nanoparticles (size in the range of 20-30 nm). However, according to DRS analysis, Cr intrusion in TiO2 crystal structure, drastically reduced band gap energy of pure TiO2 from 3.14 eV to 1.81 eV for CT3 powder and improved absorption range of UV-Vis spectrum. Mott-Schottky plots indicated that, Cr doping, caused reduction in donor density of TiO2 and an upward shift in the conduction band edge. Furthermore, surface defects caused by doping process, reduced the ability of dye adsorption. Using data of electrochemical impedance spectroscopy applied under dark condition for T and CT0.3 dye sensitized solar cells, useful information about density and distribution of trap states were achieved. Cr introduction may induce surface trap states and deep states which can increase electron lifetime by trapping them. Furethermore, induced acceptor levels near conduction band edge will decrease electron diffuction rate and consequently electrical conductivity of the mesoporous layer. As a result of all mentioned changes, electrical conversion efficiency for CT0.3 (ca. 5.85%) decreased with respect to T monolayer cell with optimum thickness (ca. 6.92%). Also, employing a doped layer sandwiched between dye and pure layer, increased efficiency (ca. 6.75%) with respect to doped monolayer cells owing to the probable diode properties of the junction, but it still was lower than pure one
  9. Keywords:
  10. Dye Sensitized Solar Cells ; Titanium Dioxide Nanoparticles ; Electrochemical Impedance Spectroscopy ; Electrical Properties ; Band Structure ; Energy Surface ; Trap Energy States ; Chromium Doped Titanium/Dioxide

 Digital Object List

 Bookmark

No TOC