Highly conductive PEDOT/PSS microfibers fabricated by wet-spinning and dip-treatment in ethylene glycol

Highly conductive microfibers made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) were fabricated by wet-spinning and subsequent dip-treatment in ethylene glycol. The electrical conductivity of the PEDOT/PSS microfibers with a diameter of ca. 5 μm was significantly increased from 74 S cm−1 to 467 S cm−1 by the dip-treatment in 3 min. The result was explained by removal of insulating PSS from the surface of the PEDOT/PSS grains and crystallization of PEDOT, which led to the formation of large numbers of higher conductive grains that enhanced the transport of charge carriers in the microfiber. The mechanical properties of the microfibers were also improved by the dip-treatment where Young’s modulus and tensile strength increased from 3.2 GPa and 94 MPa to 4.0 GPa and 130 MPa, respectively.