On the Electrical Conductivity of Poly(3,4-Ethylenedioxythiophene):Poly(Styrenesulfonate) Thin Films

Abstract

Prominent enhancement in the room temperature electrical conductivity of spin-coated poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin films has been achieved after treatment with various acids. The conductivity of PEDOT:PSS films could be enhanced from 0.6[Formula: see text]S/cm to over 3300[Formula: see text]S/cm after treatment with trifluoromethanesulfonic acid i.e., by a factor of 5500. It is noteworthy that the conductivity enhancement is nonmonotonic with respect to acid concentration i.e., the magnitude of increase in the conductivity exhibited a strong dependence over the molarity of acids. The possible reason of the conductivity enhancement is the improvement of nanoscale connectivity between the conducting PEDOT chains after acid treatment that results in highly conductive film. The improvement in the nanoscale connectivity is caused due to the loss of PSS from the PEDOT:PSS films after acid treatment that is confirmed through atomic force microscopy and X-ray photoelectron spectroscopy.