Structural characterization of solar cell prototypes based on nanocrystalline TiO2 anatase sensitized with Ru complexes.: X-ray diffraction, XPS, and XAFS spectroscopy study

Prototype solar cells made up of nanocrystalline anatase supported on a conducting glass and sensitized with two Ru2+ complexes (cis-dithiocyanatobis(2,2'-bipyridine-4,4'-dicarboxylate)ruthenium(II), or red dye, and (4,4',4-tricarboxy-2,2':6',2-terpyridine)ruthenium(II), or black dye) are characterized with out-of-plane X-ray diffraction, X-ray photoelectron spectroscopy, and Ti K-edge XAFS (XANES and EXAFS), as well as by powder X-ray diffraction of the pure dyes used for a coating of a TiO2 layer. The data indicate, within the sensitivity limits of the methods applied, that the dyes most probably form (partial coverage) a monolayer at the surface of anatase nanoparticles. Coating with the dyes leads to a stronger distortion of the local environment of Ti atoms in anatase nanoparticles.