Inkjet printing and vapor phase polymerization: patterned conductive PEDOT for electronic applications

High conductivity poly(3,4-ethylenedioxythiophene) (PEDOT) was synthesized using the vacuum vapor phase polymerization (VPP) process on micro-patterned oxidant tracks. Using inkjet printing to deposit the oxidant solution containing the triblock copolymer, poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol), sub-micron PEDOT tracks are achieved with the conductivity approaching 1000 S cm(-1). This is the highest reported conductivity for patterned PEDOT when compared to patterns obtained by printing or nano-lithographic techniques. In addition, the VPP PEDOT tracks are also shown to be electroactive, making this material suitable as an active component in flexible electronic devices. To demonstrate the principle, an electrical circuit containing the PEDOT tracks as an active component was devised using the concept of an organic electrochemical transistor (OECT).