TiO₂-Grafted Multi-Walled Carbon Nanotubes for Dye-Sensitized Solar Cells

Dye-Sensitized Solar Cells (DSSCs) comprised of TiO₂ porous films with multi-walled carbon nanotubes (MWNT) were prepared at low temperature (150 °C). MWNT were incorporated to facilitate the fast electron transport resulting from metallic properties of carbon nanotubes. In order to enhance the effect of MWNT incorporation, TiO₂-grafted MWNT (TiO₂-MWNT) was synthesized which can increase the electron transport rate further due to proximity of TiO₂ to MWNT. The presence of TiO₂ nanoparticles on the surface of MWNT was confirmed by electron microscopy and energy dispersive X-ray spectroscopy. As in the DSSCs prepared through high temperature sintering of photoanodes, the maximum content of MWNT incorporated into TiO₂ was limited to 0.01 wt% relative to TiO₂. TiO₂ photoanodes including TiO₂-grafted MWNT (TiO₂-MWNT/P25) enhanced the cell efficiencies by ca. 28% and 14%, relative to TiO₂ photoanodes without and with MWNT respectively, reaching the efficiency of 5.0%. Electrochemical impedance spectroscopy (EIS) was utilized to examine the effect of incorporation of TiO₂ nanoparticles grafted to MWNT on the cell performance.