Leakage-Limitation Engineering Derived from an Interfacial Charge Barrier for Dielectric Energy Storage in Relaxation Ferroelectric Films

For dielectric energy storage films, high leakage current always results in larger loss of energy, heating breakdown, and poor stability. This work designs an interfacial charge barrier by combining with Na0.5Bi3.25La1.25Ti4O15 and BaBi3.4La0.6Ti4O15 films with different conductivity and dielectric constant to substantially improve the leakage characteristics, thereby obtaining a breakdown electric field as high as 3683 kV/cm and superior energy storage performances with an energy storage density of 106 J/cm–3 and an efficiency of 73.6%. Meanwhile, excellent frequency, temperature, and fatigue for stable operating states are achieved in the composite films. The interfacial charge barrier plays a key role in limiting the leakage and enhancing the breakdown field due to the scattering or absorption for the space charges. The electric-field and electric-current density distribution simulated by the finite element analysis shows that the interfacial charge barrier impedes the flow of leakage current and raises the breakdown electric field. This work provides a leakage-limitation engineering for designing high-performance film dielectric capacitor devices.