120 MeV Si9+ ion irradiation effects on poly(3-methylthiophene) conducting polymer

Conducting polymers are suitable electrode materials for high performance supercapacitors, for their high specific capacitance and high dc conductivity in the charged state. Swift heavy ion (SHI) {energy > 1 MeV} irradiation of the polymers is a novel technique to enhance/alter their properties like conductivity, density, chain length and solubility. Poly(3-methylthiophene) conducting polymer thin films doped with LiClO4 and LiCF3SO3 are synthesized electrochemically on ITO coated glass substrates and irradiated with 120 MeV Si9+ ions at different fluences of 5 × 1010, 5 × 1011 and 3 × 1012 ions/cm2. The dc conductivity measurements of irradiated films show ∼60% increase in conductivity, which could be attributed to increase of carrier concentration in the polymer film and cross-linking of polymer chains. X-ray diffractogram study shows that the degree of crystallinity of poly(3-methylthiophene) is increased and shows an increasing trend with the increase in fluence of SHI irradiation. SEM micrographs show grain growth and densification of the polymer films upon SHI irradiation.