Improvement of Heat Resistant Properties of TiO₂ Nanowires and Application to Dye-Sensitized Solar Cells

The preparation of thermally stable TiO 2 nanowires (NWs) is reported. Crude TiO 2 NWs were prepared by reacting TiO 2 nanoparticles (P25) with NaOH aqueous. solution (Kasuga method), followed by extracting Na + from the NWs. When the Na + -free NWs were baked at 450–500 °C, the shape of the NWs was affected and the NWs became to nanoparticles. The thermal stabilities of the NWs were improved by treating the NWs with Nb(OEt) 5 solutions. The shape of these Nb-treated NWs did not change even after they were baked at 450 °C. It was found that Nb treatment has roles in decreasing the Na + content effectively and increasing the thermal stability of NWs. Dye-sensitized solar cells were prepared using a mixture of TiO 2 nano-particles (P25) and the Nb-treated NWs (1:1 wt %). The fiber structures remained even after 450 °C baking. The photoelectric conversion efficiency increased, which was associated with an increase in the electron diffusion coefficient and a longer electron lifetime.