Flash annealing boosts piezoelectricity of PVDF-TrFE

Annealing increases β-phase crystal contents of poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE), thus improving its ferroelectricity and piezoelectricity. However, most studies focus on improving piezoelectricity of wet-processed PVDF-TrFE via long-time annealing. Here, we report a flash annealing strategy to boost piezoelectricity of PVDF-TrFE at a temperature above its Curie temperature, which has never been reported for polymer processing. Specifically, electrospun PVDF-TrFE fiber mats show a piezoelectric coefficient d₃₃ of -70.89 pm/V or -68 pC/N after flash annealing, which are superior to that of the mats annealed for 2 h. Besides, the mechanisms for an improvement of β-phase crystal content during flash annealing was interpreted by in-situ Raman spectroscopy, XRD, Fourier transform infrared spectroscopy, and molecular dynamics simulation. The as-fabricated piezoelectric films show promising applications in energy harvesting, high-frequency vibration. It unveils an intriguing way to significantly boost intrinsic piezoelectricity of PVDF-TrFE toward developing advanced flexible electronics and micro-electro-mechanical systems.