Evaluation of the conductivity of the polypyrrole film via its C=C bonds stretching on surface-enhanced Raman spectrum

In this study, the conductivities of various polypyrrole (PPy) films were evaluated via the corresponding surface-enhanced Raman scattering (SERS) spectrum and X-ray photoelectron spectroscopy (XPS). The results indicate that the peak position of C=C bonds stretching of PPy obtained from the SERS spectrum shows more exactly both qualitatively and quantitatively representing the conductivity of PPy than the N⁺/N ratio or the doping level obtained from the XPS analysis does. Namely the peak position of C=C bonds stretching of PPy monotone decreases to a lower frequency side with the increase of the conductivity of PPy. Furthermore, a satisfactory correlated equation between them was obtained. On the contrary, neither the N ⁺/N ratio nor the doping level can be qualitatively reflective on the corresponding conductivity of PPy.