Electrical, Optical, and Morphological Properties of P3HT-MWNT Nanocomposites Prepared by in Situ Polymerization

In situ polymerization of thiophene to poly(3-hexylthlophene) (P3HT) was carried out in the presence of different loadings of multiwall carbon nanotubes (MWNTs) (0.1-10 wt%). It was found that the nanotubes are dispersed uniformly in the polymer matrix and the polymer chains wrap around the nanotube walls. NMR analysis indicated the presence of both CH-pi and pi-pi interaction between P3HT and MWNTs, thereby enhancing the optical. thermal, and electrical properties of the nanocomposite for certain loadings of MWNTs. With an increase in MWNT concentration the head-tail (H-T) regioregularity of the composites was found to decrease. The UV-vis spectra of the composite films show a red shift of the transition hand with increasing MWNT concentration, which was attributed to the uncoiling of the P3HT chain on the MWNT Surface. Additionally, the charge carrier transport phenomenon was studied for these nanocomposites. The temperature-dependent conductivity measurement revealed that the addition of MWNTs into P3HT polymer shifted the main conduction mechanism from variable-range hopping to fluctuation-assisted tunneling, and the polymer acted as a barrier in bundle-to-bundle hopping.