A Facile Photo-cross-linking Method for Polymer Gate Dielectrics and Their Applications in Fully Solution Processed Low Voltage Organic Field-effect Transistors on Plastic Substrate

Abstract

A simple and effective photochemical method was developed for cross-linking of polymer gate dielectrics. Laborious synthetic processes for functionalizing polymer dielectrics with photo-cross-linkable groups were avoided. The photo-cross-linker, BBP-4, was added into host polymers by simple solution blending process, which was capable of abstracting hydrogen atoms from polymers containing active C―H groups upon exposure to ultraviolet (UV) radiation. The cross-linking can be completed with a relatively long wavelength UV light (365 nm). The approach has been applied to methacrylate and styrenic polymers such as commercial poly(methylmethacrylate) (PMMA), poly(iso-butylmethacrylate) (PiBMA) and poly(4-methylstyrene) (PMS). The cross-linked networks enhanced dielectric properties and solvent resistance of the thin films. The bottom-gate organic field-effect transistors (OFETs) through all solution processes on plastic substrate were fabricated. The OFET devices showed low voltage operation and steep subthreshold swing at relatively small gate dielectric capacitance.