Enhanced conductivity in iodine doped polyaniline thin film formed by thermal evaporation

Thermal evaporation technique was employed to deposit pristine and iodine doped polyaniline (PANI) thin films on glass substrates. PANI was synthesized by the chemical oxidation method. Iodine doping was carried out by evaporation. The polymer synthesized was characterized by Thermo Gravimetric Analysis (TGA), Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-VIS) spectroscopy. The evaporation temperature was optimized from TGA measurements. The thin film was deposited in vacuum at 1.33 x 10(-4) Pa by thermal evaporation of PANI. The polymer film was characterized by FTIR and UV-VIS spectroscopy. The surface morphology of the films was studied by field emission scanning electron microscopy. The resistivity was measured by van der Pauw technique. The conductivity of the doped films was seen to increase with the iodine concentration and many fold increase in conductivity was observed in comparison to the pristine films. The increase in conductivity is due to the generation of polaron band in the band gap upon iodine doping. (C) 2010 Elsevier B.V. All rights reserved.