A comparative study between titania and zirconia as material for scattering layer in dye-sensitized solar cells

The photoanode of dye-sensitized solar cells (DSSC) is typically composed of nanocrystalline titania (TiO₂) layer that has been sensitized with light-absorbing dye molecules. Large portion of the light, however, could not be efficiently absorbed due to some physical reasons, such as TiO₂ crystal size (typically 10-25 nm) that makes the photoanode remains partially transparent to the visible region in the solar spectrum. One of the ways to improve the light harvesting efficiency in DSSC could be achieved by employing an additional scattering layer over the TiO₂ electron transport material. In this contribution, we evaluate the effect of light scattering properties on the performance of DSSC. Specifically, the light scattering properties provided from two different scattering materials, i.e. additional TiO₂ scattering layer and zirconia (ZrO₂) scattering layer, were compared. Both layers were deposited using screen printing technique under the same condition on top of 8 µm thick TiO₂ photoanode layer. All samples subsequently received the same thermal annealing treatment at 500 °C and sensitized with ruthenium-based synthetic dyes. Our results revealed that the thickness of the scattering layer for both TiO₂ and ZrO₂ had a significant effect on the solar cell performance. The best photoconversion efficiency was achieved by samples that were coated with one screen-printing cycle, giving an overall efficiency of 3.50 % and 4.02% for TiO₂ and ZrO₂, respectively.