  The conversion efficiency of dye-sensitized solar cells (DSSCs) is optimized
by modifying the optical design and improving absorbance within the cell. These
objectives are obtained by creating different sized cavities in TiO2
photoanode. For this purpose, carbon nanospheres with diameters 100-600 nm are
synthesized by hydrothermal method. A paste of TiO2 is mixed with various
amounts of carbon nanospheres. During TiO2 photoanode sintering processes at
500C temperature, the carbon nanospheres are removed. This leads to random
creation of cavities in the DSSCs photoanode. These cavities enhance light
scattering and porosity which improve light absorbance by dye N719 and provide
a larger surface area for dye loading. These consequences enhance performance
of DSSCs. By mixing 3% Wt. carbon nanospheres in the TiO2 pastes, we were able
to increase the short circuit current density and efficiency by 40% (from 12.59
to 17.73 mA/cm2) and 33% (from 5.72% to 7.59%), respectively.
