Giant Electrocaloric Effect of BiFeO3/P(VDF-TrFE) Composite Films Driven by a Small Electric Field

Electrocaloric cooling offers a more eco-friendly and efficient alternative to conventional vapor-compression refrigeration. Composites, incorporating ceramic nanoparticles within a ferroelectric polymer matrix, exhibit both high dielectric breakdown strength and flexibility. In this study, a sandwich-structured composite film of bismuth ferrite (BiFeO 3 )-filled poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) was prepared using a doctor-blade method. Distinct from terpolymers possessing relaxor ferroelectric properties, the material facilitates a more convenient indirect assessment of its electrocaloric performance. At 100 MV·m − 1 , the polymer composite containing 10 wt% BiFeO 3 achieved a maximum isothermal entropy change ( ΔS ) and an adiabatic temperature change ( ΔT ) of 113.4 kJ·K − 1 ·m − 3 and 17.2 K near the Curie temperature ( T C ) of 383 K. The ΔT of the composites is twice that of pure P(VDF-TrFE) films under the same electric field. These values significantly exceed those reported for P(VDF-TrFE)-based composites. The enhanced polar beta phase in P(VDF-TrFE) phase and enlarged local electric field caused by BiFeO 3 heterogeneous segment in the polymer matrix should both contribute to the outstanding electrocaloric performance. This research broadens the application scope of eco-friendly, flexible electronic materials that maintain stable electrocaloric refrigeration properties under high electric fields.