Sequential Solution Polymerization of Poly(3,4-ethylenedioxythiophene) Using V2O5 as Oxidant for Flexible Touch Sensors

Summary Various in-situ synthesis methods have been developed for the polymerization of 3,4-ethylenedioxythiophene (EDOT) monomers, such as electro-polymerization (EP), oxidative chemical vapor deposition (OCVD) and vapor phase polymerization (VPP). Meeting industrial requirements through these techniques has, however, proven challenging. Here, we introduce an alternative method to fabricate highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) films in-situ by solution means. The process contains sequential deposition of oxidants (V 2 O 5 in this case) and monomers. Excess reactants and by-products can be completely removed from the PEDOT film by MeOH-rinsing. The obtained PEDOT films possess good crystallinity and high doping level, with carrier concentration three orders of magnitude higher than the commercial product (PH1000, Heraeus GmbH). The electrical conductivity of the as-cast PEDOT film reaches up to 1420 S/cm. In addition, this method is fully compatible with large-scale printing techniques. These PEDOT conducting films enable the realization of flexible touch sensors, which demonstrate superior flexibility and sensitivity.