Large room temperature electrocaloric effect in PbZrO3/Ca3Mn2O7 heterostructure

Electrocaloric effects of antiferroelectric and ferroelectric films have been intensively studied for the applications in refrigeration. However, achieving high electrocaloric performance near room temperature is still very difficult in films. Herein, we report that large and regulable electrocaloric effects at room temperature are achieved in PbZrO ₃/Ca ₃Mn ₂O ₇ bilayer films based on PbZrO ₃ phase transition, and the sign of adiabatic temperature change, ΔT, is determined by Ca ₃Mn ₂O ₇ thickness. The PbZrO ₃-Ca ₃Mn ₂O ₇ heterojunction formed by carrier diffusions reduces the carrier concentration of the film and establishes a built-in electric field in the junction region, and withstanding voltages of the bilayer films are enhanced greatly. The maximum positive ΔT of 66.5 K was obtained in the bilayer film with a thin Ca ₃Mn ₂O ₇ layer, but a negative ΔT of -9.9 K with a thick Ca ₃Mn ₂O ₇ layer, near room temperature. This work presents a simple and effective approach to designing huge electrocaloric based on antiferroelectric-containing multilayers near room temperature.