Molten phosphonium iodides as electrolytes in dye-sensitized nanocrystalline solar cells

We have synthesized new room temperature ionic liquids and test them as new potential electrolytes for dye-sensitized nanocrystalline solar cells (DNSCs) of Grätzel type based on asymmetric tetraalkylphosphonium iodides. A systematic study on the conductivity behavior of BH3PI, iBH3PI, OH3PI and iBO3PI molten salts and the effect of the addition of low concentrations of iodine with and without 3-methoxypropionitrile is presented. Solar cells using iBH3PI-based electrolyte reached an overall light-to-electricity efficiency of 5.7% under moderate light intensity (27 000 lx) conditions and those results are compared to similar systems using alternative ionic liquids as electrolytes.