Tailoring electronic structures of carbon nanotubes by solvent with electron-donating and -withdrawing groups.

Various electron-donating and -withdrawing groups in aromatic and aliphatic backbones of solvent have been introduced to tailor the electronic structures of single-walled carbon nanotubes (SWCNTs). In the case of solvent with a withdrawing group, electrons were extracted mainly from metallic SWCNTs, whereas small charge transfer was also observed in semiconducting SWCNTs. On the other hand, in the case of solvent with a donating group, electrons were donated to both metallic and semiconducting SWCNTs. This effect was less prominent in solvent with an aliphatic backbone than that with an aromatic backbone. The strong correlation between the sheet resistance and electronic structures of nanotubes is further discussed in conjunction with a modulation of Schottky barrier height.