Functionalized polymer dielectrics for low-operating voltage organic field-effect transistors

The design of appropriate dielectrics plays a crucial role in the performance of organic field-effect transistors (FETs). Along with the active semiconductor layer, the dielectric-semiconductor interface governs charge transport properties in FETs. A viable route for enhancing the dielectric constant of polymer dielectrics is via the incorporation of semiconducting and insulating nanoparticles. Magnetic nanocrystals such as cobalt ferrite (CFO) have received a lot of interest in sensing and biomedical applications. Its insulating property is attractive in polymer gate dielectrics. CFO magnetic nanocrystals, soluble in organic solvents, were synthesized by a thermal decomposition method and coated with poly(vinyl alcohol). Improved performance of organic FETs using CFO-incorporated non-ferroelectric dielectrics is observed. In particular, the threshold voltage and the subthreshold swing are lowered in pentacene FETs using CFO-incorporated cross-linked poly(4-vinyl phenol) dielectric. The application of an external magnetic field allows for another parameter to tune the device performance.