Influence of process parameters on the electrical properties of offset printed conductive polymer layers

We report on results of investigating the material–process interaction for the case of offset printed conductive polymers. We interpret the characteristic branched morphology of printed layers of Poly(3,4-ethylenedioxythiophene) doped with Poly(4–styrenesulfonate) in terms of the phenomenon of “viscous fingering”. A comprehensive study of the relevant process parameters reveals that the conductivity of the printed layers results from an interplay between the characteristic wavelength of the fingered structure and the deposited amount of material. Furthermore, optimization of the process parameters allows for significant reduction of the sheet resistance for about 1 order of magnitude to 0.5 kΩ.