Investigating the effect of molar ratio between TiO2 nanoparticles and titanium alkoxide in Pechini based TiO2 paste on photovoltaic performance of dye-sensitized solar cells

Recombination of electrons in TiO2 conduction band has detrimental effects on the performance of dye-sensitized solar cells (DSSCs). Good connection between TiO2 nanoparticles, in meso-porous TiO2 layer, causes a significant reduction in recombination reaction rate. In the present work, Pechini sol-gel method was used for the synthesis of TiO2 nanoparticle pastes with different amounts of titanium tetra-isopropoxide (TTIP) in their sol precursors. The synthesized paste was used for the fabrication of photoanode of DSSCs. Then, the effect of TTIP content of sol precursor on the photovoltaic performance of DSSCs was investigated. For all pastes, the amount of sol in paste was kept constant which led to the meso-porous TiO2 layers with the same amount of porosity. Results showed that the photovoltaic performance of DSSCs first increases and then decreases with increasing TTIP content of sol precursor. It was concluded that the increase in performance of DSSC is due to the good connection between TiO2 nanoparticles and the decrease in performance is due to the micro-cracks in the meso-porous TiO2 layers with high content of TTIP in their sol precursor.