Enhanced Electrocaloric Effect in Relaxor Ferroelectric Terpolymers by Morphotropic Phase Boundary.

Relaxor ferroelectric terpolymers with a disordered helical relaxor conformation are promising candidates for developing electrocaloric cooling applications. However, most current studies focus on the electrocaloric effect in terpolymers with high chiral commoners, which remains relatively small in the low-electric-field regime. In this work, other than using typical helical relaxor compositions, it is reported that poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer with its composition close to the morphotropic phase boundary may enable markedly enhanced electrocaloric effect, especially in the low-electric-field regime. The adiabatic temperature change of 3.2 K is achieved by a low electric field of 50 MV m at room temperature, corresponding to ≈90% enhancement over pure relaxor counterparts. The improved electrocaloric response is attributed to the electric-field-induced disorder-to-order phase transition. These findings offer an alternative, promising route for the practical use of electrocaloric polymers for refrigeration devices.