Electrocaloric effect and pyroelectric properties of organic-inorganic hybrid (C₂H₅NH₃)₂CuCl₄

The organic-inorganic hybrid (C₂H₅NH₃)₂CuCl₄ (EA₂CuCl₄) single crystals are prepared by the solvothermal condition method. The x-ray diffraction, scanning electron microscopy, dielectric permittivity, pyroelectric current, and heat capacity are used to systematically investigate the electrocaloric performances of EA₂CuCl₄. The pyroelectric currents are measured under various voltages, and the electrocaloric effect (ECE) is calculated. Its ECE exhibits an isothermal entropy change of 0.0028 J/kg·K under an electric field of 30 kV/cm associated with a relatively broad temperature span. Further, the maximum pyroelectric coefficient (p) is 4×10^-3 C/m²·K and the coefficient β for generating ECE from electric displacement D is 1.068×10⁸ J·cm·K^-1·C^-2 at 240 K. Our results indicate that the ECE behavior of organic-inorganic hybrid EA₂CuCl₄ is in accordance with Jona and Shirane's opinion in which the ECE should occur both below and above the Curie temperature T_c.