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Preparation of Ag-doped TiO2 Nanostructured Films for Dye-Sensitized Solar Cells Applications

Rahnejat, Bibi | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 46016 (56)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Mohammadi, Mohammad Reza
  7. Abstract:
  8. Dye-sensitized solar cells (DSSCs) have been intensively studied duringthe last decade as a promising third solar cellgeneration due to their potential low-cost manufacturingprocess. DSSCsare based on a semiconductor (i.e., TiO2), formed between a photo-sensitized anode and an electrolyte. In order to reach high conversion efficiencies, it isimportant to increase the electron injection and opticalabsorption. One promising solution to increase the electroninjection is to decrease the large band gap of TiO2 bydoping a foreign ion into TiO2 lattice.
    In the present study, Ag- doped TiO2 powders and films with different Ag:Ti molar ratios are reported. The effect of dopant at.%, annealing time, and TiCl4 solution concentration on thephotovoltaic performance of dye-sensitized solar cells were studied.The powders were synthesized using an aqueous sol–gel process, followed by annealing at 500°C at various times.X-ray diffraction and field emissionscanning electron microscope (FE-SEM) analyses revealedthat the synthesized nanoparticles had a uniform and nanometer sizegrains. Additionally, no silver and silver oxide phases were detected after heat treatment.Based on simultaneous differential thermal (SDT) analysisthe minimum annealing temperature to obtain organic-free TiO2 paste was determined at 400°C, being one of the lowest crystallizationtemperatures of TiO2photoanode electrodes for solar cell application.UV–vis absorption showed that Ag introduction into the samples were enhanced the visible light absorption of TiO2nanoparticles by shifting the absorption onset to visible light region. It was found that, 0.1 at.% Ag-doped TiO2 DSSC (i.e., DSSC 9) had the highest power conversion efficiency of 5.9%, short current density of 13.12 mA/cm2 and open circuit voltage of 788 mV. This can be related to achievement of a balanceamong the electron injection, light scattering effect and dyesensitization parameters.The employed sol-gel method showed a good potential for synthesis of Ag-doped TiO2nanopowders and films for DSSCs applications
  9. Keywords:
  10. Silver ; Titanium Dioxide ; Dye Sensitized Solar Cells ; Titanium Dioxide Nanostructure

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