Ultrahigh piezoelectric coefficient of poly(vinylidene fluoride) achieved via electric-poling-induced partial γ-β phase transition

Poly(vinylidene fluoride) (PVDF) with the best piezoelectric property among polymers has great potential applications in many fields. The low performance with a |d₃₃| < 30 pC/N limits, however, its application. Therefore, it is of great significance and importance to improve its piezoelectric property. We have realized the creation of order-to-disorder-to-order transition regions through partial γ-β solid-phase transition via electric poling, which endows the PVDF film a morphotropic phase boundary like behavior and thus enhances the piezoelectricity of PVDF tremendously. As a result, an ultrahigh piezoelectric coefficient of |d₃₃| = 69.9 pm/V has been achieved, which is to our best knowledge the state-of-the-art largest |d₃₃| for randomly oriented PVDF homopolymer films. This paves a simple way for fabricating high performance piezoelectric PVDF homopolymers.