“…Polyvinylidene fluoride (PVDF) and its copolymers including poly(vinylidene fluoride- co -trifluoroethylene) (P[VDF–TrFE]), poly(vinylidene fluoride- co -tetrafluoroethylene) (P[VDF–TFE]), poly(vinylidene fluoride-tetrafluoroethylene) ([PVDF-TeFE]), and poly(vinylidene fluoride-hexafluoropropylene) ([PVDF-HFP]) have become the most famous of piezoelectric/pyroelectric/ferroelectric polymers because of high piezoelectric coefficients, mechanical and dielectric properties, flexibility, chemical resistance, toughness, creep resistance, good stability under sunlight, low weight, biocompatibility, and easy processability. 51–54 α, β, and γ phases are the most popular crystalline phases of fluoropolymers that determine their piezoelectricity. The β phase or all- trans conformation is mainly responsible for excellent piezoelectric, pyroelectric, and ferroelectric properties because all the dipole moments are directed in the same direction, resulting in a non-centrosymmetric structure and the largest spontaneous polarization.…”