The application of inverse titania opals in nanostructured solar cells

The synthesis and characterization of nanostructured heterojunction solar cells based on inverse opal titanium dioxide (TiO2) films is discussed. Photonic films with thicknesses of 0.9 and 3.7 μm are deposited using self-organisation of latex spheres with diameters of 400 and 100 nm. The voids between the spheres are filled with a TiO2 precursor and a subsequent heat treatment yields a highly organized porous structure. Sensitization with Ru 535-dye (cis-[L2Ru(SCN)2] in which L is 2,2′-dipyridine-4,4′-dicarboxylic acid), yields solar cells with a power conversion efficiency of 0.6% under simulated solar light. At present, the small area of the ordered structure is limiting the performance of the cells. These cells may be promising for future applications, if improved fabrication techniques will enable an enlargement of the ordered area.