Dewetting Effects in Poly(vinylidene fluoride-trifluoroethylene) Thin Films on Poly(3-hexylthiophene) Substrates

Bilayers of ferroelectric polymers [poly(vinylidene fluoride-trifluoroethylene),PVDF-TrFE] on semiconducting poly(3-hexylthiophene) (P3HT) substrateshave been prepared by sequential spin coating. When creating thinlayers of PVDF-TrFE from its solution in methyl ether ketone (MEK),they exhibit dewetting in the form of holes for thicker P3HT substrates,whereas they form continuous layers on thinner P3HT substrates. Thedispersive and polar components of the surface tension of the differentP3HT substrates were obtained through contact angle measurements.An estimation of the shape of the disjoining pressure as a functionof thickness of a liquid film of MEK on top of the different P3HTsubstrates was obtained. Through these estimations, we observe thatthe stability region for continuous film formation shifts toward higherthicknesses for the samples where experimentally the holes are observed.This work provides understanding on the mechanism of stable film formationand effective tools to control the formation of holes, in functionalpolymer bilayers, of special importance in the fabrication of organicthin film-based devices.