Improving Electrical Conductivity of PEDOT:PSS with Phase Separation by Applying Electric Fields

Abstract

Phase separation between poly(3,4‐ethylenedioxythiophene) (PEDOT) and poly(styrenesulfonate) (PSS) induced by vertical electric fields to maximize the conductivity enhancement of the PEDOT:PSS film was introduced in this work. Two different films were prepared to observe the effect of the electric field on phase separation. The first film was a pristine PEDOT:PSS film obtained without the presence of an electric field (PP‐EF0) and the second film was a PEDOT:PSS film obtained by applying an electric field of 3 kV/cm (PP‐EF3). The domains with various sizes were verified on the surface of PP‐EF3 by atomic force microscopy and the oxidation state of PP‐EF3 was different from PP‐EF0 in the UV–Vis spectra. It was revealed that the ratio of the PEDOT/PSS under the surface of PP‐EF3 was higher than that of the PP‐EF0. The conductivities of PP‐EF0 and PP‐EF3 were measured after etching the surfaces of both films with methanol. Two different photovoltaic devices were fabricated to verify the effect in conductivity enhancement by the electric field. One was the device without electric field (d‐PP‐EF0) and the other was the device with an electric field of 3 kV/cm (d‐PP‐EF3). The current density and fill factor of d‐PP‐EF3 improved and therefore, the power conversion efficiency was enhanced up to 13%.