Effective cationic dye sensitized nanocrystalline titania solar cells employing an elastomeric copolymer of ethylene glycol and epichlorohydrin as electrolyte and I-/I-3(-) as mobile redox carrier system have been developed by these authors. The key feature of the copolymer is its ability to penetrate the pores of the TiO2 film in spite of its high molecular weight. Unsealed prototype cells show 1.6-2.6% energy conversion efficiency, thus demonstrating that polymer electrolytes are an attractive alternative to previously reported hole-transporting materials.