Tuning Performance of Organic Field-Effect Transistors through Modification of Polymer Dielectrics*

For field-effect transistors (FETs) which utilize organic semiconductors, modifying the dielectric layer will largely influence device performance. Ferroelectric polymers are one such material which has been of interest for producing OFETs with low operating voltages owing to their high dielectric constant. Another method of enhancing the dielectric constant has been the incorporation of semiconducting and insulating nanoparticles. Cobalt-ferrite (CoFe₂O₄ or CFO) magnetic nanocrystals have been synthesized using a thermal decomposition method and coated with polymers such as poly(vinyl alcohol) (PVA). The insulating property make them attractive for dispersing in polymer dielectrics. After incorporating CFO nanoparticles into the polymer dielectrics, a decrease in the threshold voltage and subthreshold swing are observed for OFET devices. The application of an external magnetic field to such devices appears to further alter device behavior, acting as another tunable parameter. Pentacene and TIPS-Pentacene are used as the active semiconductor layers, and we will further discuss the use of donor-acceptor polymers based on diketopyrrolopyrrole (DPP) and isoindigo in OFET devices.