Extraordinarily High Dielectric Breakdown Strength of Multilayer Polyelectrolyte Thin Films

The increased use of high-voltage electronics requires higher performance dielectric materials. These electrically insulating layers need as high of a dielectric breakdown strength as possible. Herein, multiple polyelectrolyte layer-by-layer assemblies were studied as high-voltage insulators. The influences of molecular weight, polymer backbone architecture, and thermal cross-linking were investigated. It was found that increasing the molecular weight of either the polycation or polyanion increases the breakdown strength due to removal of chain ends that can act as breakdown initiating sites. It was also found that a linear polymer backbone architecture leads to higher breakdown strength when compared to branched polymer architectures. Lastly, through thermal cross-linking, the breakdown strength is increased, and the previously mentioned molecular weight and architecture effects are diminished. These 200–400 nm thick polymer multilayer films exhibit breakdown strengths of ∼300–400 kV/mm. Their simple water-based processing makes them an interesting new option for protecting various types of electronics.