Modified mass printing technique for the realization of source/drain electrodes with high resolution

We report on the development of a technique for the realization of source/drain electrodes of organic field-effect transistors (OFETs) with small channel length down to 10 μm. The process uses a combination of two different mass printing technologies (flexographic and gravure printing), which are both highly productive. In a first step a negative image of the electrode pattern was printed from an amorphous perfluorinated poly(alkenyl vinyl ether) (CYTOP™ CTL-809M), a material forming a surface of very low surface energy, followed by a full-tone-print of a conductive material, e.g. poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS). Despite the full-tone-print the conductive ink was transferred in a patterned fashion due to the heterogeneous surface properties and formed very homogenous and smooth source/drain structures. On the basis of these source/drain electrodes OFETs, inverters and ring oscillators were realized by means of mass printing methods only.