Combining Vapor Phase Polymerization and Screen Printing for Printed Electronics on Flexible Substrates

Large area manufacturing of printed electronic components on similar to A4-sized substrates is demonstrated by the combination of screen printing and vapor phase polymerization (VPP) into poly(3,4-ethylenedioxythiophene) (PEDOT). The oxidant layer required for the polymerization process is screen printed, and the resulting conductive polymer patterns are manufactured at high resolution (100 mu m). Successful processing of several common oxidant species is demonstrated, and the thickness can be adjusted by altering the polymerization time. By comparing the polymer films of this work to a commercial PEDOT:PSS (PEDOT doped with poly(styrene sulfonate)) screen printing ink shows improved surface roughness (26 vs 69 nm), higher conductivity (500 vs 100 S cm(-1)) and better resolution (100 vs 200 mu m). Organic electrochemical transistors, in which the transistor channel is polymerized into PEDOT through VPP, are also demonstrated to further emphasize on the applicability of this manufacturing approach. The resulting transistor devices are not only functional, they also show remarkable switching behavior with respect to ON current levels (-70 mA at -1 V), ON/OFF ratios (>10(5)), switching times (tens of ms) and transconductance values (>100 mS) in standalone transistor devices, in addition to a high amplification factor (>30) upon integration into a screen printed inverter circuit.