The coexistence of the negative and positive electrocaloric effect in ferroelectric thin films for solid-state refrigeration

The coexistence of the negative and positive electrocaloric effect (ECE) caused by an applied electric field direction different from the dipole direction of 180° domain structures is firstly found in ferroelectric thin films using the phase-field–based simulation. The calculation results reveal that a negative adiabatic temperature change (Δ T = −3.4 K) and a positive adiabatic temperature change (Δ T = 3.1 K) coexist in the PbTiO 3 thin film with 180° domain structures under the dimensional electric field Δ E = 0.1. The coexistence of negative and positive ECE in a thin film can provide a new way to design solid-state refrigerators.