Nanometer‐thick patterned conductive films prepared through the self‐synthesis of polythiophene derivatives

The development of flexible electronics requires the patterning of conductive and active semiconductor films. Although inorganic materials such as indium tin oxide and metal nanoparticles have high conductivity and transparency, their poor interfacial adhesion with organic layers, lack of flexibility, high weight and high capital costs are drawbacks. In contrast, organic conducting polymers have great potential for use in commercial flexible electronic applications because of their low production costs, environmental stability and acceptable conductivities. A UV‐curable photoresist containing hydroxyl groups was prepared from a mixture of a photoinitiator, epoxy‐acrylate resin, hydroxyethyl methacrylate and tripropylene glycol diacrylate. Patterns having line widths/spaces of 100/100 µm and 10/5 µm were fabricated on a poly(ethylene terephthalate) (PET) substrate using lithography techniques. (3‐Methyl‐3,4‐dihydro‐2H‐thieno3,4‐b]dioxepin‐3‐yl)methanol (ProDOT‐OH) was self‐synthesized through urethane linkages onto the surface of the patterned photoresist on the PET film, which was then dipped into a solution of another monomer, 3‐thienylethoxybutanesulfonate (TEBS), and initiator and polymerized in situ to form conductive poly(ProDOT‐OH‐co‐TEBS) films covering the surface of the patterned resist. The optimal conductivity of the poly(ProDOT‐OH‐co‐TEBS) films was ca 90 S cm^?1 with an optical transparency of ca 70%. A new bottom‐up technique has been developed for the preparation of patterned organic transparent conductive films: self‐synthesis of the monomer using urethane‐forming reactions and subsequent in situ polymerization. The conductivity of the films can be controlled by the polymerization reaction time and the resolution of the pattern. These conductive patterned films might be applicable to the manufacture of industrial touch panels or chemical/biological sensors. Copyright © 2009 Society of Chemical Industry