COMPARATIVE RAMAN, XRD, HREM AND SAXS STUDIES OF GRAIN SIZES IN NANOPHASE TIO2

Dye-sensitized cells differ from conventional semiconductor devices in that they separate the function of light absorption from charge carri er transport. The device is based on a 10-mu m thick optically transpa rent film of titanium dioxide particles of a few nanometers in size, c oated with a monolayer of charge-transfer dye to sensitize the film fo r light harvesting. The nano-size properties of TiO2 obtained by the s ol-gel method have been studied by Raman spectrometry, X-ray diffracti on, high-resolution electron microscopy and small-angle X-ray scatteri ng. Grain sizes and distributions obtained by these four methods agree d, varing from 4 to 12 nm with the temperature of TiO2 calcination. (C ) 1997 Elsevier Science B.V.