Energy storage and ferroelectric properties of La‐doped Bi ₃ TaTiO ₉ thin films affected by La concentration

Abstract Layered perovskite ferroelectric thin films, such as Bi 3 TaTiO 9 (BTT), typically exhibit low remanent polarization, which results in high‐energy storage efficiency. However, enhancing the ferroelectric polarization is crucial for improving energy storage performance. In this study, we investigate the effects of La doping on the energy storage and ferroelectric properties of BTT thin films. The films were deposited on (200) Pt/TiO 2 /SiO 2 /Si substrates with La doping concentrations of 0, 5, 10, 15, and 20 mol%. Structural analysis showed that increasing La concentration led to an expansion of the out‐of‐plane lattice constants, which improved the ferroelectric properties. Additionally, La doping reduced the leakage current characteristics, allowing the films to store energy more effectively under higher electric fields. As a result, the La‐doped BTT thin films exhibited improved recoverable energy densities and energy storage efficiency. The 20 mol% La‐doped BTT thin film achieved the highest energy storage efficiency of 75.2% and the hig hest recoverable energy density of 128.3 J/cm 3 . These findings demonstrate that La doping is an effective strategy for enhancing the ferroelectric and energy storage properties of BTT thin films, offering a promising alternative to lead‐based materials for energy storage applications.