Porous nanocrystalline TiO$_{2}$ thin films for dye-sensitized solar cells

We report a rapid and low cost method to fabricate porous TiO$_{2}$ thin films used as anode electrodes for solid state dye-sensitized solar cells. Polymethylmethacrylate (PMMA) gel was used as template to define a network co-structure with alkali titanium oxide, then spin cast on substrates. After thermally removing polymer, smooth and crack-free large area TiO$_{2}$ thin films with fine pores were generated. Thin film structures were detected by powder {\&} grazing incident X-ray diffraction. Film thickness can be controlled over a range of tens of nanometers to several microns by precursor viscosity, spin coating speed and coating times. The SEM image shows the highest quality porous TiO$_{2}$ film derived from a certain concentration of precursor. The above TiO$_{2}$ thin films were then used to fabricate solid state dye sensitized solar cells. Porphyrine dye and poly(ethylene glycol) electrolyte with I$^{-}$/I$_{3}^{-}$ redox couple were used in the cells. Current-voltage curves were recorded. The open circuit voltage boosts to more than 1.0 V. The reasons for the high open circuit voltage probably will be discussed. Overall photo-electricity conversion efficiency reaches 2.05{\%} under an illumination of one solar unit (AM1.5, 100 mW/cm$^{2})$.