Universal inverse electrocaloric effect in perovskites

The electrocaloric effect (ECE) offers a promising alternative to the traditional gas compressing refrigeration due to its high efficiency and environmental friendliness. The unusual inverse (negative) electrocaloric effect refers to the adiabatic temperature drops due to the application of electric field, in contrast with the normal (positive) ECE, and provides ways to reach a larger temperature span in refrigeration cycles by combining the normal and inverse ECE. However, the inverse ECE is unusual and requires a clear understanding of microscopic mechanisms. Here, we found the unexpected and extensive inverse ECE in nonpolar orthorhombic, tetragonal, and cubic phases of halide and oxide perovskite at a wide temperature range by means of first-principle-based large-scale Monte Carlo methods. Such an unexpected inverse ECE originates from the octahedral tilting related entropy change rather than the polarization entropy change under the application of electric field. Furthermore, a giant inverse ECE with temperature change of 8.6 K is found at room temperature. This giant and extensive inverse ECE in perovskite opens up a new horizon in the research of caloric effects and broadens the electrocaloric refrigeration ways with high efficiency.