High conductivity poly (ionic liquid)-based crosslinked dielectrics

Abstract

Emerging applications from organic electronics to batteries require high ionic conductivity that are solid and will not leak, avoiding potential safety concerns. Poly (ionic liquids) (PILs) are an emerging class of materials which benefit from high ionic conductivity of ionic liquids while having the desired mechanical properties of polymers. When developing thin film coatings, for example in the development of organic electronics, the deposition of subsequent layers can wash away initial layers, limiting the choice of processing solvent. We developed a PIL that can be crosslinked with bis-2-bromoethyl ether (BBEE) to be used as a high performing dielectric. Electrochemical impedance spectroscopy was used to establish structure-property relationships between the effect of poly(ethylene glycol) methacrylate ion conducting monomers (mPEGMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) composition in the PIL, the alkylation percentage in the PIL, and amount of BBEE to PIL on corresponding metal-insulator-metal capacitor performance. A balance between polymer composition and BBEE composition was required to produce a robust PIL dielectric with a high electrical double layer (EDL) onset frequency and high capacitance density that is a solid at room temperature. The optimized PIL dielectric was then successfully integrated into a proof-of-concept solution-processed organic thin-film transistor (OTFT).