Quasi-solid electrolyte based on polyacrylonitrile for dye-sensitized solar cells

A quasi-solid gel–polymer electrolyte for dye-sensitized nanostructured TiO2 sensitized by N719 ruthenium dye has been developed. The electrolyte comprises of polyacrylonitrile along with plasticizers, ethylene carbonate and propylene carbonate in the 15:35:50 ratio and the redox couple consists of tetrabutyl ammonium iodide and iodine along with tertiary butyl pyridine. The concentration of iodide:iodine was optimized and optimal activity was found when the molar ratio is 1.50:0.05. This gel electrolyte has a high electrical conductivity of 4.33 mS cm−1 and overall conversion efficiencies of over 7% were obtained for solar to electrical energy conversion which is higher than the values reported for other similar gel–polymer electrolytes. The reduction in efficiency compared to a solar cell employing a liquid electrolyte can be attributed to incomplete wetting of pores and due to mass transfer limitations of redox species through a more viscous medium.