Organic thin film transistors with polymer high-k dielectric insulator

With the soluble copolymer poly(vinylidene fluoride–trifluoroethylene) (P(VDF–TrFE)) for the dielectric layer, we fabricate organic field effect transistors with enhanced gate effects, if we use P(VDF–TrFE) layers with a thickness of 2 μm. No hysteresis is observed. We obtain a relative dielectric constant of about 11 (at 1 kHz), which enables operation voltages smaller than for the organic insulator polymethylmetacrylate (PMMA, ε = 3.3 at 1 kHz). In contrast, for thinner films of P(VDF–TrFE) (250 nm), we find the typical ferroelectric hysteresis of the copolymer. This gives opportunities for building up organic transistors with a thin P(VDF–TrFE) ferroelectric layer as nonvolatile memory element.