Flexible conductive polymer patterns from vapor polymerizable and photo-cross-linkable EDOT

We explored direct photopatterning of a vapor polymerizable and photo-cross-linkable 3,4-ethylenedioxythiopene (EDOT) to make it suitable for use in electronics applications. We prepared a conductive polymer, PEDOT-MA, using vapor phase polymerization (VPP) of the (2,3-dihydrothieno-[3,4-b][1,4] dioxin-2-yl)methyl methacrylate (EDOT-MA) and photochemically induced a conductivity change of the PEDOT-MA film to ensure a flexible conductive pattern. The room-temperature conductivity (σ_RT) of the PEDOT-MA film on PET was 30-120 S/cm, depending on the oxidant layer thickness and was increased ∼30% when the PEDOT-MA film was doped with aqueous solution of p-toluenesulfonic acid. Photoreaction of PEDOT-M A decreased the σ_RT to 1.7 x 10^-3 S/cm because of the photo-cross-linking of the side chain. The transparency of the conductive films was tuned using the vapor polymerization time to control the film thickness. The photo-cross-linking reaction of the side chain generated micropatterns having line widths of 50-0.9 m, in which the light-exposed areas appeared as bleached and less conductive. A diffractive, flexible, conductive film with 41 % of diffraction efficiency was obtained from the line-patterned film having a spacing of 0.9 m.