Dye-Sensitized Nanocrystalline Titanium-Oxide-Based Solar Cells Prepared by Sputtering:  Influence of the Substrate Temperature During Deposition

Nanocrystalline titanium oxide films were prepared by DC magnetron sputtering onto SnO<INF>2</INF>:F-coated glass substrates kept at temperatures in the 50 &lt; τ<INF>s</INF> &lt; 300 °C range. Dye sensitization in cis-dithiocyanato-bis(2,2‘-bipyridyl-4,4‘-dicarboxylate) ruthenium(II) yielded solar cells with a conversion efficiency η. The dye incorporation was dependent upon τ<INF>s</INF>, and an optimum value of η = 1.7% was found with ~0.8-μm-thick titanium oxide films prepared at 250 °C. The microstructure then displayed a well-defined parallel penniform pattern, and the luminous transmittance was 42%. The crystallite size was substantially enlarged at τ<INF>s</INF> > 250 °C, and η showed an ensuing decrease.