Quasi-solid-state dye-sensitized solar cells based on gel electrolytes containing different alkali metal iodide salts

Gel electrolytes were prepared by adding different alkali metal iodide salts RI (R+ = Li+, Na+, K+, Rb+ or Cs+) and I-2 into acetonitrile gelated with poly(ethylene-oxide) (PEO). KI, RbI and CsI, poorly soluble in liquid electrolyte. call dissolve completely in PEO gel electrolyte due to a strong interaction of cation and PEO chains. All gel electrolytes exhibit high conductivity in the range of 10(-3) S/cm and contain I- with concentration of 0.3 M. The effect of R+ in PEO gel electrolyte on the performance of quasi-solid-state dye-sensitized solar cells (DSCs) was investigated. The results showed that the open circuit voltage (V-oc) increases with the increased radius of alkali metal cation. It is explained by the rise of electron Fermi level (E-F) of TiO2 caused by a decrease in I-3(-) diffusion with the increase of radius of R+. (C) 2008 Elsevier B.V. All rights reserved.