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Optimized Pt Coating for High Charge Transfer- High Transparency Cathodes of Dye Sensitized Solar Cell

Mashhoun, Sara | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43989 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Taghavinia, Nima
  7. Abstract:
  8. Counter electrode of dye sensitized solar cell is prepared by deposition of a thin catalytic layer onto a conducting substrate and is responsible for reduction of iodide/triiodide redox electrolyte. Conventionally, counter electrode is made of platinum.
    Depending on the method of deposition, the thickness of Pt layer varies. The Pt layer may be so thick that it acts as reflector and returns the incident light back to the cell. In this case, large amount of Pt is used and a rise in cost is been made, but only the Pt particles in the interface of counter electrode/electrolyte take part in the reduction reaction.
    The aim of this project is optimization of making a counter electrode, with minimum amount of Pt loading, high transparency and acceptable catalytic activity. Transparency is of importance especially when the cell is illuminated from rare side, e.g. in flexible DSCs with metal substrate for photoanode and w-series modules. Optical transmittance can be improved through decreasing the layer thickness, but as the Pt coating on the surface, catalytic properties and charge transfer resistance diminish simultaneously. This project tries to find an easy method and optimum conditions for making a transparent Pt electrode (transmittance over 80%) with acceptable catalytic properties and charge transfer resistance. To reach this, pastes of low Pt concentrations was made and Pt layers was prepared by screen printing. Layers of 0.6 - 5.8 µg/cm2 Pt loadings were made, and transmittances from 80% to 99% were reached. Optical and catalytic properties, morphology and charge transfer resistance were characterized. DSCs were fabricated with prepared electrodes and current-voltage curves were obtained through rare and front illumination. Efficiencies gained from front and rare side showed a difference of 0.61%-1.06%
  9. Keywords:
  10. Platinum ; Dye Sensitized Solar Cells ; Counter Electrode ; Charge Transfer Resistance ; Screen Printed Electrode

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