THE EFFECT OF DOPANT, TEMPERATURE AND BAND GAP ON CONDUCTIVITY OF CONDUCTING POLYMERS
Polymers by virtue of light weight and greater easy of fabrication, have replaced and are continuing to replace metals in several areas of applications. Polymers with conjugated π electron backbones displays unusual electronic properties such as low energy optical transitions, low ionization potentials and high electron affinities. They have been considered as good electrical insulators and a variety of their applications have been based upon the insulating property. Polymers which are conjugated exhibit semiconducting behaviour and can be doped to give materials with high conductivity. Conducting polymers represent an important research area with diverse scientific problems of fundamental significance and the potential for commercial applications. The effect of dopant on conductivity, mechanism of conduction, the effect of band gap and temperature has been studied. Conducting polymers like poly pyrrole, poly aniline and poly thiophene etc. have been synthesized and their conductivities have been determined. Some polar organic materials such as poly (ethylene oxide) will complex alkali salts and manifest rapid alkali-ion conductivity. Although the absolute conductivities of such polymer based materials are not as high as those of crystalline solid electrolytes in general, these may be made into thin pin hole-free plastic sheets with sufficient conductance for use in cells and batteries.