High Energy Storage Performance of Opposite Double-Heterojunction Ferroelectricity–Insulators

In this study, the excellent energy storage performance is achieved by constructing opposite double-heterojunction ferroelectricity–insulator–ferroelectricity configuration. The PbZr_0.52Ti_0.48O₃ films and Al₂O₃ films are chosen as the ferroelectricity and insulator, respectively. The microstructures, polarization behaviors, breakdown strength, leakage current density, and energy storage performance are investigated systematically of the constructed PbZr_0.52Ti_0.48O₃/Al₂O₃/PbZr_0.52Ti_0.48O₃ opposite double-heterojunction. The ultrahigh electric field breakdown strength (≈5711 kV cm⁻¹) is obtained, which is beneficial to achieve high energy storage density. Meanwhile, the high linearity of hysteresis loops with low energy dissipation is obtained at a proper annealing temperature, which is induced by partially crystallized and is in favor of achieving high energy storage efficiency η. The PbZr_0.52Ti_0.48O₃/Al₂O₃/PbZr_0.52Ti_0.48O₃ annealed at 550 °C exhibits excellent energy storage performance with a storage density of 63.7 J cm⁻³ and efficiency of 81.3%, which is ascribed to the synergetic effect of electric breakdown strength (E_BDS = 5711 kV cm⁻¹) and the polarization (P_m–P_r = 23.74 µC cm⁻²). The proposed method in this study opens a new door to improve the energy storage performance of inorganic ferroelectric capacitors.