Preparation of TiO₂ layer for dye-sensitized solar cells

Abstract

The suitable conditions for the formation of TiO₂ layer by spray coating technique were investigated for the application of dye-sensitized solar cell. TiO₂ layers were prepared by spray coating technique on 3x3 cm2 ZnO(Al)/SLG substrates. The TiO₂ colloidal solution was prepared from ground TiO₂ powder in acetylacetone and deionized water. The TiO₂ colloidal solution was sprayed on ZnO(Al)/SLG substrate consisting of a very thin sputtered TiO₂ blocking layer. The substrates used in this work were spun at 1800 rpm prior to spraying at room temperature. The as-grown TiO₂ samples were annealed at 450ºC for 1 hour in atmosphere. The characterization tools such as XRD, UV-VIS spectrometer and AFM were used to verify the deposited TiO₂ films for its structural, optical and surface properties, respectively. The counter electrode for the dye-sensitized solar cells in this work was prepared from the electrochemical deposition of Pt on the ZnO(Al)/SLG substrate. The ruthenium 535 bis-TBA dye was used as the sensitizer. The photo-to-current conversion efficiency of the cells was characterized under standard AM 1.5 radiation (100 mW/cm²). The highest efficiency of DSSC was prepared from the TiO₂-blocking-layer (thick ~25 nm), thickness of TiO₂ layer ~13 μm and Degussa TiO₂ P25 which value short circuit current density (Jsc) of approximately 0.368 mA/cm2, open-circuit voltage (Voc) of approximately 730 mV, Fill Factor (FF) 0.59 and efficiency (η) of approximately 0.158%.