Giant Electrocaloric Effect of BiFeO 3 /P(VDF‐TrFE) Composite Films Driven by a Small Electric Field

ABSTRACT 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.