Manipulation of the oriented amorphous fraction of poly(vinylidene fluoride-co-trifluoroethylene) films by thermal annealing for high piezoelectricity†

Poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] shows great promise to be used in flexible and wearable piezoelectric devices, but shows a low piezoelectric coefficient (|d₃₃| < 30 pm V⁻¹). Here, we found that by inducing large amounts of oriented amorphous fraction (OAF) and regulating the OAF structure in the interface of the crystalline and amorphous phase by electrospinning and thermal annealing, the d₃₃ of P(VDF-TrFE) could be greatly improved from −24.5 pm V⁻¹ to −42.4 pm V⁻¹. This work provides a new strategy to improve the piezoelectricity of polymers through the manipulation of the structure of OAF.