Giant Electrocaloric Cooling via Vertically Aligned BCZT Nanoarrays in Relaxor Polymer Nanocomposites for Low-Field Solid-State Refrigeration

Thermal management has emerged as a pressing challenge for next-generation electronic devices, as miniaturization and escalating power densities further intensify heat-dissipation issues. Herein, we designed a vertically aligned nanoarray of 0.68(BaZr0.2Ti0.8O3)-0.32(Ba0.7Ca0.3TiO3) (BCZT) embedded in relaxor terpolymer P(VDF-TrFE-CFE) (PVTC) to serve as a three-dimensional conductive network to improve electrocaloric (EC) performance. This EC nanocomposite exhibits exceptional EC performance and high breakdown field (Eb), i.e., isothermal cooling energy density (Q = 2.65 × 107 J·m-3), adiabatic temperature change (ΔT = 12.09 K) and isothermal entropy change (ΔS = 48.7 J·kg-1·K-1) at 80 MV/m electric field, nearly 39 times higher than those of the PVTC. BCZT-nanoarrays act as nucleation sites for dipole alignment under electric field when embedded in PVTC. The dipoles are more easily polarized with an electric field, significantly enhancing EC performance. The phase-field simulations reveal the substantial surface tension of BCZT-nanoarrays promotes the dipole alignment along the z-axis, resulting in large domain volume fraction and large z-axis polarization component. This mechanism improves EC properties while maintaining structural stability.