Abstract
In this thesis, quaternary ammonium salt-based ionic liquids are used to serve as a low-volatility solvent for electrolytes in dye-sensitized solar cells (DSSCs). There are three main advantages for the use of volatile organic solvents for electrolytes, including fast diffusion rates, high ionic conductivities, and low viscosities. However, because of the high volatility of the electrolyte solvent, the cell performance decreases when the solvent vapor leaks. In this thesis, a series of quaternary ammonium salts-based ionic liquids are prepared from heating mixtures of quaternary ammonium salts and hydrogen bond donors. This series of liquids has the advantages of cost-effectiveness, easy preparation, low volatility, and excellent ionic conductivity when used as the solvents for electrolytes in DSSCs. A new quaternary ammonium salts (Acetylcholine iodide, ACI) is developed in this thesis. When used in DSSCs, constructed from P25 powders and D149 dye (a metal-free iodoline dye), the electrolyte gives a Jsc of 8.57 (mA/cm2), a Voc of 0.645 (V), a fill factor of 0.61, and an efficiency of 3.36%, which is 78% of that achieved by using the AN based electrolyte (efficiency of 4.3%) under the same measurement condition.