Ultralong TiO₂ (B) Nanowires/TiO₂ Nanoparticles Composites for Rapid Electron Transport in Dye-Sensitized Solar Cells.

The relatively small electron diffusion coefficient and high charge recombination rate of TiO2 nanoparticle (NP) film limit charge collection in TiO2 NP based dye-sensitized solar cells (DSSCs). Herein, ultralong bending TiO2 (B) nanowires (NWs) were introduced to TiO2 NP photoanode and expected to modify electron transport of DSSCs. The TiO2 (B) NWs/TiO2 NP composite structure was prepared by a facial process combining the stirring hydrothermal method with mechanical mixing method. When the composite structure was applied to DSSCs, the rapid electron transport pathway was formed in photoanode, which was clarified by the small electron transport resistance and long electron diffusion length, improving the charge collection efficiency. Moreover, the scattering effect of TiO2 (B) NWs could enhance the light harvesting, and thus improve the power conversion efficiency (PCE) of DSSCs. The excellent electronic and optical characteristics of TiO2 (B) NWs yield the maximum enhancement of PCE (36.4%) when 50% (wt.%) TiO2 (B) NWs was integrated into TiO2 NP based DSSC. The work provides new insights into the design and tailoring nanowires to enhance the PCE of DSSCs for practical applications.