Enhanced Switchable Dielectric Performance of β-Phase-Dominated PVDF Composite Films Modified with Single-Protonated 1,4-Diazabicyclo[2.2.2]octane Fluoborate

We report a new flexible switchable dielectric composite film toward practical application in devices based on β-phase-dominated PVDF modified with single-protonated 1,4-diazabicyclo[2.2.2]octane fluoborate (DabcoHBF4). Our study suggested that incorporating polar molecular filler (DabcoHBF4) into β-phase-dominated PVDF is an effective method to fabricate switchable dielectric thin film, which could avoid sophisticated operation in cultivating bulk crystals of molecular materials. The composite film with 40% of DabcoHBF4 (0.40BF) could exhibit large dielectric change between high and low dielectric states comparable to that of pure DabcoHBF4 at phase-transition temperature. We postulated that the excellent switchable dielectric property of 0.40BF was attributed to the induced orientation alignment of β-phase-dominated PVDF and dielectric confinement effect.