Enhancements of dielectric and energy storage performances in lead-free films with sandwich architecture

High-performance film dielectrics are crucial for capacitive energy storage applications and electronic industries. In this work, improvements of dielectric and energy performance in BiFeO₃-based films are realized by constructing sandwich architectures, which integrates complementary features of spatially organized dielectric layers in a synergistic manner to realize concurrently high permittivity/polarization and low loss/leakage. Moreover, by rationally modifying the sandwich configuration, ie, with insulating layers on the outside, the interfacial Schottky emission is suppressed, leading to further reductions of leakage and conduction loss. Large energy density of ~44 J cm⁻³ (superior to that of either single layer) along with high efficiency of ~76% is thus achieved in the sandwich film. This work proves the feasibility and effectiveness of sandwich architecture in improving dielectric, leakage, and energy storage performances, providing a new paradigm for the development of high-energy-density dielectrics.