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On the interesting optical transitions observed in polyaniline films in the conducting and insulating states

M. AMRITHESH1,* , K. P. CHANDNI1, S. JAYALEKSHMI1, FEBIN KURIAN2, S. J. VARMA1

Affiliation

  1. Department of physics, Cochin University of Science and Technology, Cochin-22, Kerala, India
  2. Sungkyunkwan Advanced Institute of Nanotechnology, Sungkyunwan University, Suwon, South Korea

Abstract

Systematic optical absorption investigations have been carried out on polyaniline (PANI) films. The samples investigated include emeraldine base(EB) form of polyaniline cast from N-Methyl Pyrrolidinone(NMP) and m-cresol and hydrochloric(HCl) acid doped polyaniline and HCl doped polyaniline-Multiwalled Carbon Nano Tube(MWNT) composite films, both cast from m-cresol. Corresponding to the indirect transition, negative energy gaps are observed in PANI (HCl) and PANI (HCl)-MWNT films, which are in the conducting state, whereas the negative energy gap is not observed in the EB films (insulating). This is a new observation in polyaniline films. The structural confirmation is achieved from Fourier Transform Infra Red (FTIR) spectroscopic studies and Transmission Electron Microscopic (TEM) studies.

Keywords

Polymer composites, Optical transitions, Negative energy gap, Doping effect.

Citation

M. AMRITHESH, K. P. CHANDNI, S. JAYALEKSHMI, FEBIN KURIAN, S. J. VARMA, On the interesting optical transitions observed in polyaniline films in the conducting and insulating states, Optoelectronics and Advanced Materials - Rapid Communications, 3, 2, February 2009, pp.149-154 (2009).

Submitted at: Feb. 1, 2009

Accepted at: Feb. 13, 2009