Improvement of heat resistant properties of TiO2 nanowires and application to dye-sensitized solar cells

The preparation of thermally stable TiO2 nanowires (NWs) is reported. Crude TiO2 NWs were prepared by reacting TiO2 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 degrees 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 degrees 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 TiO2 nano-particles (P25) and the Nb-treated NWs (1 : 1 wt %). The fiber structures remained even after 450 degrees C baking. The photoelectric conversion efficiency increased, which was associated with an increase in the electron diffusion coefficient and a longer electron lifetime.