Addition of TiO2 nanowires in different polymorphs for dye-sensitized solar cells

TiO₂ (B) and TiO₂ anatase nanowires were prepared at 150 °C for 120 h by a hydrothermal method followed by calcination in air at 400 °C for 2 h and at 700 °C for 2 h for TiO₂ (B) and TiO₂ anatase, respectively. Although dye-sensitized solar cells (DSC) with fully nanowire electrodes showed a rather low light-to-electricity conversion efficiency of 1.33 % for TiO₂ (B) and 2.42% for TiO₂ anatase, 10 wt % nanowire-dispersed electrodes in a P-25 TiO₂-nanoparticle matrix demonstrated improved efficiency of 6.17 % for TiO₂ (B) and 6.53% for TiO₂ anatase, these exceeding that of pure P-25 electrodes in this work (η=5.59%). The dominant mechanisms of the improvement at 10 wt% for the two different polymorphs are thought to be different, i.e., a light-scattering and film-thickness increment for the TiO₂ (B) system, whereas there is an improved conduction path through the matrix for the TiO₂ anatase system.