Stable p-type properties of single walled carbon nanotubes by electrochemical doping.

We report a highly stable p-type doping for single walled carbon nanotubes using an electrochemical method. The Raman spectroscopy showed the upshift of the G-band when the applied potential increased. Furthermore, the carbon core level shifted as much as 0.14 eV in binding energy of XPS measurement, which is an evidence of p-type doping with a Fermi level change. The highly doped SWCNTs at an applied potential of 1.5 V during the electrochemical doping process showed long time stability, as long as 28 days.