Temperature-optimized energy storage performance achieved in sandwich BaTiO 3 /BiFeO 3 /BaTiO 3 thin films with a tunable antiferroelectric-like behavior

Developing dielectric thin-film capacitors that simultaneously achieve high energy density, high efficiency, and excellent energy-storage stability represents a challenge in advancing highly integrated pulsed-power and power-electronic technologies. While conventional ferroelectric thin films possess high maximum polarization, their large remanent polarization and low breakdown field strength hamper their overall energy-storage performance. In this study, a sandwich BaTiO 3 /BiFeO 3 /BaTiO 3 (BTO/BFO/BTO) thin film was successfully fabricated at a reduced thermal budget of less than 500 ∘ C. This sandwich film exhibits a unique electric field-dependent polarization evolution, that is, it shows antiferroelectric-like polarization behavior under low-to-medium electric fields, which gradually evolves into a slim polarization response characteristic with a high maximum polarization value as the applied electric field increases. Such the antiferroelectric-like-to-ferroelectric evolution driven by the symmetric dual-interface effect of this sandwich structure, enables the synergistic regulation of polarization, breakdown strength, and hysteresis loss. Consequently, this sandwich film delivers enhanced energy-storage performance, achieving a recoverable energy density ([Formula: see text]) of 96.2[Formula: see text]J/cm 3 and an efficiency of 78%, alongside an enhanced energy-storage responsivity ([Formula: see text]) of 233.4[Formula: see text]J/(kV[Formula: see text] ⋅ [Formula: see text]m 2 ). What’s more, the film exhibits good energy-storage stability across a wide temperature range (RT [Formula: see text]C), over a broad frequency band ([Formula: see text] [Formula: see text]kHz), and throughout prolonged cycling test (up to 10 9 ). This work, which modulates polarization behavior via interface engineering to achieve superior overall energy-storage performance at a moderate-to-low thermal budget, provides significant experimental and theoretical insights for developing silicon-process-compatible, highly reliable, and integrated energy-storage devices.