Investigation on Charge Transport Properties of Polyaniline Synthesized on Flexible Cellulose Substrate

Abstract

Flexible organic semiconductors, their charge transport mechanism and functionalization are of recent interest and need for exploring outstanding applicability of such semiconductors. Cellulose (paper) with its flexibility, cost newlineeffectiveness and environment friendliness must find a significant place when coated with a highly functional organic semiconductor. Thus with such an objective a few approaches have been undertaken in preparing p-type semiconductor of polyaniline on cellulose and functionalising those have been achieved. newlineAn easy and cost effective deposition technique called vapour phase polymerization was adopted for housing of conductive polyaniline on cellulose substrate in its desired oxidation state with good electrical conductivity. The prepared film was found in crystalline phase and the optical bandgap obtained from UV-vis spectroscopy becomes suitable for opto-electronic application. Moreover the formation of delocalized charged defect states during polymerization favours a good electrical conductivity of that polymer and the p-type conductivity was justified from See-beck effect. newlineOnce synthesis of conductive polyaniline over cellulose had been done successfully, two distinguished approaches were taken to improve the charge transport properties along with bringing a control on optical band gap. In the first approach the tuning of band gap and also the electrical conductivity of polyaniline was achieved by newlinechanging the concentration of the oxidizing agent during synthesis. The formation of charged defect states in the polymer chain was controlled with the increasing concentration of oxidizing agent. As a result the energy band structure modification and hence optical absorbance and electrical conductivity control was achieved. In the newlinesecond approach a different oxidizing agent of the same chloride salt was used. The physical properties of the obtained polyaniline films were of same kind. The variation in the concentration helps to change the oxidation level of polyaniline which explores the vari