TiO2 FILMS WITH VARIOUS CRYSTAL STRUCTURES FOR SINGLE AND BILAYER PHOTOANODES OF DYE-SENSITIZED SOLAR CELLS

Abstract

Phase pure and composite TiO2 nanopowders exhibiting various crystal structures (anatase, rutile and brookite) are used asphotoanode in dye-sensitized solar cells. The nanopowders are deposited in paste form onto a conducting oxide glass usingdoctor blade method in single layer and bilayers. The highest solar efficiency achieved by the single layer photoanode composedof > 99 wt % anatase crystals was 2.86 %. The solar efficiency of 4.93 % has been harvested via bilayer photoanode built byapplying a layer consisting 55 wt % anatase and 45 wt % rutile phase nanoparticles on top of the layer composed of a mixtureof > 99 wt % anatase crystals. The improved photovoltaic performance is attributed to anatase dominated bottom layer whichfacilitates electron charge generation with high surface area and charge transport by proper crystal structure as well assynergistic effect of binary phase content of the photoanodes. The porous structure of top layer enhances diffusion of theI−/I3−electrolyte in the bilayer TiO2 photoanode.