TiO2 Composing with Pristine, Metallic or Semiconducting Single-Walled Carbon Nanotubes: Which Gives the Best Performance for a Dye-Sensitized Solar Cell

Different types of single-walled carbon nanotubes (SWCNTs), pristine (p-), metallic (m-) and semiconducting (s-) are incorporated into TiO2 photoanodes to improve the dye-sensitized solar-cell (DSSC) performance and their effects on the device performance are further investigated. Although all three types of SWCNTs are found to have comparable structural morphologies and a reduced charge transport resistivity for the photoanodes, only the semiconducting one was able to suppress charge-recombination events, resulting in even greater improvement of DSSC performances. This is very likely to be ascribed to the higher energy barrier of s-SWCNTs compared to both m- and p-SWCNTs to block the back flowing of dye-injected electrons for I3- reduction in the charge recombination process.