Thesis (M.Eng)--Chulalongkorn University, 2008

A titanium dioxide electrode layer for a dye-sensitized solar cell (DSSC) was prepared from ultrasonic spray coating of TiO₂ sol, which was synthesized via a sol-gel method. The effects of sintering temperature, film thickness, and modification of TiO₂ layer by another metal oxide on the efficiency of the dye-sensitized solar cell were studied. The highest efficiency for pure TiO₂ electrode was obtained when the number of coats of TiO₂ layer was 250, corresponding to a thickness of ca. 5 µm, and a sintering temperature for TiO2 layer of 400℃. The preparation of the Fe₂O₃/TiO₂, WO₃/TiO₂ and CeO₂/TiO₂ electrode layers with different weight ratio was also based on sol–gel methods. The mixed metal oxides possessed larger specific surface areas than pure TiO₂ did. Large specific area brought about improvement on short-circuit photocurrent and solar energy conversion efficiency when compared to a cell that was fabricated by pure TiO₂ electrode, except the case of Fe₂O₃/TiO₂. Fe₂O₃/TiO₂ electrode gave rise to DSSC because Fe⁺³ acted as a recombination center for the photogenerated charge carriers, which was evident from decline in both ISC and VOC. The efficiency of the cell with WO₃/TiO₂ electrode was lower when number of TiO₂ coats exceeded 150. The cell that incorporated 1 wt% CeO₂/TiO₂ electrode with number of TiO₂ layers was 250, which was sintered at 400℃, produced the best solar energy conversion efficiency of 3.23%.