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

Abstract

Bilayers of ferroelectric polymers [poly(vinylidene fluoridetrifluoroethylene), PVDF-TrFE] on semiconducting poly(3-hexylthiophene) (P3HT) substrates have been prepared by sequential spin coating. When creating thin layers 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. The dispersive and polar components of the surface tension of the different P3HT substrates were obtained through contact angle measurements. An estimation of the shape of the disjoining pressure as a function of thickness of a liquid film of MEK on top of the different P3HT substrates was obtained. Through these estimations, we observe that the stability region for continuous film formation shifts toward higher thicknesses for the samples where experimentally the holes are observed. This work provides understanding on the mechanism of stable film formation and effective tools to control the formation of holes, in functional polymer bilayers, of special importance in the fabrication of organic thin film-based devices.