Study the effect of TiO2 annealing and TiCl4 treatment on the performance of dye-sensitized solar cells

The structure and quality of the TiO₂ is crucial for achieving high efficiency in dye-sensitized solar cells (DSCs). In this work we have studied the effect of annealing temperature, TiCl₄ concentration/ treatment time and the number of the TiO₂ layers on the performance of a DSC device. It is found that increasing the annealing temperature and treatment time with application of diluted TiCl₄ increased the efficiency. These items along with including a bi-layer semiconductor led to a 30% performance increase in comparison to the original solar cell just by considering the best concentration and time product for TiCl₄ treatment step. The enhancement in the performance is likely due to high porosity of the semiconductor layer. Also, the lessened TiCl₄ concentration decreases the harmful effects of the harsh solution but still allows for band edge improvement. Lastly, the bi-layer consisted of transparent and opaque TiO₂ paste. The first consist of 15-20nm particles and the latter comprises of ~100 nm particles. Each contributes to enhancement, as the dye and sunlight have greater absorption and scattering capabilities. Currently in progress is the synthesis and fabrication of new dyes, for compatibility efforts with the semiconductor.