Sputtered and heat-treated TiO2 electrodes for dye-sensitized solar cells applications

In this work, sputtering method has been used to deposit thin films of TiO2 to be utilized for dye-sensitized solar cells (DSSCs). The obtained TiO2 films have been annealed up to 550 degrees C. X-ray diffraction (XRD) results have shown that there is no change in the crystal structure upon annealing. In addition, two phases of TiO2, anatase and rutile, have been observed; however, the anatase phase is dominant, especially with annealing, and the particle size was between11.6 nm and 20 nm. The optical properties of the prepared and annealed films have been investigated using spectrophotometer. The transmittance was observed to decrease with annealing which can be attributed to the improvement of the crystalinity of the films upon annealing. The absorption and reflectance have been observed to decrease with annealing including some effects from the scattering of light in TiO2 films due to the multilayer structure. The prepared TiO2 films have been used to construct DSSCs. The I-V characteristics of these cells have shown a good performance with an increase of the efficiency from 1.24 to 1.98 for the as-deposited and annealed sample at 550 degrees C, respectively. Furthermore, the constructed DSSCs have exhibited stability and reproducibility over time.