Enhanced breakdown strength and polarization behavior in relaxor ferroelectric films via bidirectional design of defect engineering and heterogeneous interface construction

Electronic power systems require the development of dielectric capacitors that combine high energy storage density and high efficiency. However, there are some unavoidable defects such as oxygen vacancies in dielectrics, which seriously deteriorate the energy storage performance. Here, a bidirectional design of defect engineering and heterogeneous interfacial construction is conducted in Fe-doped 0.8Bi0.5Na0.5TiO3–0.2Bi3.25La0.75Ti3O12 relaxor ferroelectric films to reduce leakage current and improve polarization. Simultaneously, the heterogeneous interfacial construction hinders the mass transfer process and forms more interfaces, which impede the formation of electronic pathways. The synergistic action of bidirectional design provides a substantial increase in breakdown strength, combined with excellent dielectric properties and high temperature, frequency and cycle stability. Finally, a great balance between energy storage density (83.6 J cm−3) and efficiency (74.1%) is achieved for 2 mol% Fe-doped films. This work provides a strategy for designing advanced electrostatic capacitors through defect and interface regulation.