Electrical conduction mechanism of poly(3,4-ethylenedioxythiophene) nanofiber bundles at low temperature

The nature of charge transport mechanism in poly(3,4-ethylenedioxythiophene) nanofiber bundles has been studied as a function of temperature, magnetic field and AC electric field. High-resolution transmission electron micrographs show the formation of nanofibers with an average diameter of 14 nm. X-ray diffraction analysis depicts the enhancement of polymer chains ordering with increasing dopant concentration. Analysis of the temperature dependence of resistivity reveals a three-dimensional variable range hopping electrical conduction mechanism in the synthesized nanofibers system. A large positive magnetoresistance has been observed at low temperature, which shows a decreasing trend with increasing temperature as well as dopant concentration. The high value of positive magnetoresistance at low temperature has been explained by the wave function shrinkage model. The decrease in frequency exponent s with increasing temperature suggests that the AC conduction takes place through correlated barrier hopping mechanism.