An in situ Raman spectroelectrochemical study of the controlled doping of single walled carbon nanotubes in a conducting polymer matrix

The interaction of single wall carbon nanotubes (SWCNT) and the conducting polymer poly(3,4-ethylendioxythiophene/polystyrenesulfonate) (PEDOT/PSS) was studied by in situ Raman spectroelectrochemistry. The mixing of SWCNT with PEDOT/PSS caused a partial doping of SWCNT which was indicated by the change of relative intensity of the SWCNT Raman features. We have demonstrated for the first time that in situ Raman spectroelectrochemistry is a method of choice for precise and effective control of doping level of composites of conducting polymers and SWCNT. For electrochemical doping of SWCNT embedded in PEDOT/PSS the bleaching of RBM and TG modes of the SWCNT is delayed as compared to that in pure SWCNT. The delay is of about 0.2 V. This potential difference vanishes at higher potentials. The delayed response to doping is observed for both the SWCNT and the polymer matrix features. In the latter case the response is specific for individual polymer bands. Furthermore, during p-doping most of the polymer bands exhibit a subsequent monotonous bleaching. This contrasts with the behavior of the pristine polymer where the intensity changes are non-monotonous.