Binary Polyethylene Oxide/Titania Solid-State Redox Electrolyte for Highly Efficient Nanocrystalline TiO2 Photoelectrochemical Cells Poly(ethylene oxide)/titania polymer electrolyte based photoelectrochemical cells have been fabricated with Ru(dcbpy)2(NCS)2 complex as the sensitizer and nanoporous TiO2 films as photoanodes. The introduction of the titania filler into the poly(ethylene oxide) matrix reduces the crystallinity of the polymer and enhances the mobility of the 1-/13 - redox couple, resulting in outstanding overall conversion efficiency (4.2% under direct sunlight illumination) of the corresponding dye-sensitized nanocrystalline TiO2 solar cell, one of the best efficiencies reported to date for a solid-state device. 2 11 1259 - 1261 1259 - 1261 American Chemical Society