Modification of electrodes in nanocrystalline dye-sensitized TiO2 solar cells

Influence of an electrodeposited overlayer and a spin-coated underlayer of TiO2 electrode on the cell performance was studied. The effect of annealing TiO2 electrode in O2 atmosphere was also investigated. XRD analysis made on TiO2 by the sol–gel method showed a pure anatase phase. Electrodeposited TiO2 film showed two times larger surface area and O2 annealed TiO2 showed three times larger surface area than untreated TiO2. Electrodeposition of TiO2 resulted in sub-particles on base TiO2 and increased the surface area and the short-circuit current (Jsc). For an underlayer, TiCl4 treatment caused no noticeable changes in current–voltage characteristics. Annealing in O2 atmosphere did not cause any apparent changes in bonding characteristics judging from XPS measurement. A conversion efficiency up to 5.8% was obtained.