Influence of sintering temperature on energy conversion efficiency in dye-sensitized solar cell

The dye-sensitized nanocrystalline TiO₂ film solar cells were fabricated here. The TiO₂ electrodes were prepared by a sol-gel process and were sensitized by the nature dye extracted from a paper mulberry tree. When the sintering temperature of TiO₂ films rises from 90 to 500°C, the energy conversion efficiency of the solar cell improves considerably and up to an optimum value at 470°C. To investigate this, the nano-TiO₂ films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-Vis spectrum, and the current-voltage (I-V) characteristic of the heterojunction between the nano-TiO₂ and the indium tin oxide (ITO) was measured. The results show the size, crystal phase and band gap of TiO₂ nanoparticles undergo changes at the various sintering temperatures. Besides, the resistance of the heterojunction decreases with increasing the sintering temperature. As the temperature going up and beyond 450°C, the heterojunction begins to develop into a Schottky junction, and its potential barrier decreases.