Synthesis of monodisperse-porous microspeheres in composite form and their usage in dye sensitized solar cells

In this thesis, the conversion efficiency of dye sensitized solar cells were investigated. A multi-stage hydrolysis-condensation method was developed for synthesizing metal oxides and their composites in the form of monodisperse-porous microspheres. Afterwards, these microspheres were integrated into dye sensitized solar cells one by one as an electron transfer medium for comparing the energy conversion efficiency. Monodispers, porous silicon dioxide (SiO2), titanium dioxide (TiO2) and cerium dioxide (CeO2) microspheres and their composites in the form of titanium dioxide doped silicon dioxide (TiO2@SiO2), cerium dioxide doped silicon dioxide (CeO2@SiO2), and cerium dioxide doped titanium dioxide (CeO2@TiO2) microspheres were prepared with different doping ratios. Synthesized microparticles were applied on a glass electrode working as an anode. By this way, a layer of semiconductor was formed on the glass substrate as an electron transfer region. Furthermore, synthesized TiO2 and CeO2 microspheres were seperately added onto TiO2 nanospheres and also used in solar cells as semiconductor layer. Ruthenium based N-719 dye and iodide/triiodide (I-3 / I-) redox couple were used as the electron source for current generation and electrolite respectively, in the dye sensitized solar cell. According to the results of performance measurements of dye sensitized solar cells, energy conversion efficiencies were measured as 1.06, 0.025, 0.023 and 0.043 for TiO2 , CeO2, single and double doped TiO2@SiO2 microspheres, respectively. The energy conversion efficiencies of 0.015, 0.064 and 0.031 were obtained with CeO2@SiO2 microspheres for lower to higher amount of doping. The values of the same parameter were also determined as 0.017, 0.2 and 0.01 for CeO2@TiO2 microspheres prepared with dopings with lower to higher amount. In addition, as a second set, TiO2 and CeO2 microspheres were seperately added onto TiO2 nanospheres with different weight ratios and the mixtures were applied to dye sensitized solar cells as semiconductor layers and their energy conversion efficiencies were compared. The energy conversion efficiencies were determined as 0.044, 0.019, 0.150, 0.610 and 0,60 with the mixtures containing (w/w) %1, %5, %10, %20 and %50 percent of TiO2 microspheres respectively. On the other hand, the energy conversion efficiencies were determined as 0.130, 0.10, 0.017, 0.005 and 0.037 with the mixtures containing (w/w) %1, %5, %10, %20 and %50 percent of CeO2 microspheres respectively. 5 μm sized-porous CeO2 and TiO2 and SiO2 composites prepared with different doping ratios were first used in dye sensitized solar cells as semi-conducting layer. Besides, the use of powder mixtures containing both TiO2/CeO2 microspheres and TiO2 nanospheres was the another contribution of this study into the literature, in dye sensitized solar cells.