Document Type

Thesis - University Access Only

Award Date

2012

Degree Name

Master of Science (MS)

Department / School

Electrical Engineering and Computer Science

First Advisor

Hongshan He

Abstract

Dye sensitized solar cells have emerged as a potential photovoltaic technology using low cost materials and simple fabrication techniques to substitute the expensive crystalline silicon technology. Dye sensitized solar cells employ liquid electrolytes which dry out or leak over time. Solid electrolytes such as polymer gel electrolytes, nanocomposites of ionic liquids, inorganic p-type materials and organic polymers have been used to replace liquid electrolytes. However, low conductivity and inability of these solid electrolytes to penetrate into TiO2 film have resulted in poor cell efficiency. A need exists to develop for a less corrosive and more conductive solid electrolytes that can penetrate into TiO2 film to improve efficiency and robustness of dye sensitized solar cells. The objective of this research was to develop, characterize and optimize iodine free liquid and solid electrolytes and fabricate dye sensitized solar cells with these electrolytes. Dye sensitized solar cells use semiconductor surfaces to hold light harvesting dyes, an electrolyte as a hole transporting medium and platinum as counter electrode. A solid metal-complex compound was prepared by mixing lithium iodide and cyanoacetic acid in a 1:4 molar ratio in a nitrogen atmosphere. The compound was dissolved in acetonitrile solvent for use as a liquid electrolyte while the solvent was evaporated for use as a solid electrolyte. The addition of silica nanoparticles and tert-butylpyridine into the liquid metalcomplex electrolyte improved the efficiency of the dye sensitized solar cells by 160% and that of the cells using solid metal-complex electrolyte by 1800%. This was attributed to the increase in conductivity of the electrolyte due to reduction of the electrostatic interaction between metal-complex cation and iodide anion; a decrease in electron recombination at TiO2/electrolyte interface; and faster triiodide reduction rate at electrolyte/platinum interface. It appears feasible to replace the traditional iodine-based liquid electrolyte with the liquid and solid metal-complex electrolytes. Although the efficiencies of the metalcomplex electrolyte cells were lower than the iodine-based liquid electrolyte, the liquid and solid metal-complex electrolytes are less corrosive and the solid cells don't dry out or leak.

Library of Congress Subject Headings

Electrolytes
Metal complexes
Photovoltaic power generation

Publisher

South Dakota State University

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Rights Statement

In Copyright