All-organic thin-film transistors patterned by means of selective electropolymerization

We have fabricated fully patterned all-organic thin-film transistors on polyimide substrates using selectively electropolymerized poly (3,4-ethylenedioxythiophene) doped with poly (styrene sulfonate) (PEDOT:PSS) for the source and drain contacts, PEDOT:PSS Baytron $P$ dispersion for the gate electrodes, poly (4-vinyl phenol) or polyvinyl alcohol for the gate dielectric layers, and pentacene or poly (3-butylthiophene) for the organic active layers. We have built top-gate structures with gates printed on top of the gate dielectric layer. Carrier mobilities as large as $\text{0.01\hspace{0.5em}}{\mathrm{cm}}^2/\mathrm{V s}$ were measured. Functional all-organic transistors have been realized using a simple and potentially inexpensive technology that does not depend on photolithographical processes and that allows the preparation of feature sizes on the micrometer scale.