Temperature dependent charge transport of acid-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is an important opto-electronic material, and its room temperature electrical conductivity can be prominently enhanced by chemical treatment; it is technologically significant to investigate its temperature and magnetic field dependent charge transport characteristics. Here, we analyzed the low temperature charge transport properties of pristine and acid-treated PEDOT:PSS thin films by studying the variation in resistance as a function of temperature and magnetic field (T ∼ 300 to 4.2 K, H ∼ up to 5 T). The acid-treated sample exhibited much improved charge transport behavior at low T, with a resistivity ratio [ρ(4.2 K)/ρ(300 K)] of ∼5.7 × 102, which is three orders of magnitude smaller than that of the pristine sample. Nevertheless, both pristine and acid-treated samples followed hopping conduction, obeying R(T)∝expT−1/2andR(T)∝expT−1/3, respectively, in the low T regime. Furthermore, positive magnetoresistance of ∼16% (at 4.2 K and 5 T) was displayed by acid-treated samples that could be due to the wave function shrinkage phenomenon.