“…The latter (also known as DFE, i.e., the defective ferroelectric phase) is characterized by incorporating gauche defects in trans sequences. ,− Furthermore, a relaxor FE phase, bearing a combination of trans planar and 3/1 helical conformations, was reported in P(VDF-TrFE) copolymers with VDF content below 55%. − It was further suggested that a morphotropic phase boundary, similar to that previously found in perovskites, bridges the competing FE and relaxor phases and enhances the piezoelectric properties. − The transition temperatures between the different crystalline phases are prone to copolymer composition, , processing (solvent-casting, spin-coating, etc. ), ,, mechanical drawing or poling, − , and thermal treatment. − ,− For compositions higher than 70 mol %, it was demonstrated (i) a strong thermal hysteresis at T c , and (ii) an approximately linear increase at T c with pressure, , suggesting a first-order transition. For copolymers with VDF content below 70 mol %, a second-order transition was proposed based on the negligible thermal hysteresis, ,,, whereas a first-order transition was suggested from isochronal P -dependent measurements. , Hence, there is an inconsistency concerning the exact order of the phase transformation at T c for nearly equimolar compositions.…”