Deposition of porous titanium oxide thin films as anode material for dye sensitized solar cells

Crystallized nanoporous TiO2 thin films were synthesized by combining reactive magnetron sputtering
and Glancing Angle Deposition (GLAD). The growth temperature, the bias voltage and the rotation speed
of the substrate were studied with the aim to grow nanoporous films presenting anatase constitution
which are suitable for Dye Sensitive Solar Cells (DSSC) applications.
By fixing the tilt angle at 85, we have shown that an increase of the growth temperature up to 450 C
leads to the formation of nanoporous anatase film with a grain size up to 24 nm while by applying a bias
voltage leads to a densification of the films as evidenced by scanning electron microscopy and by X-ray
diffraction. On the other hand, by rotating the substrate (from 0.1 to 10/s) during the deposition process,
films with larger columns and higher surface roughness (from 45 to 60 nm) were obtained due to an
enhanced shadowing effect.
Preliminary dye impregnation experiments have shown that the highest light absorption values are
obtained for the films prepared without bias and with no rotation, which is supported by the microstructure
of these films presenting the highest porosity. These films, presenting an anatase constitution,
are potentially good candidates as an anode in DSSC applications