Energy storage performances regulated by layer selection engineering for doping in multi-layered perovskite relaxor ferroelectric films

BaLaxBi4−xTi4O15 relaxor ferroelectric films with multilayered perovskite structure were prepared by the sol-gel method. Structural tunability is realized by layer selection engineering for La doping, which consequently regulates the energy storage performances. As x ≤ 0.2, Bi3+ is substituted by La3+ at perovskite-like layers, which increases the disorder degree of A-site cations and depresses the defects, it results in a high energy storage density of 44.7 J/cm3 and an energy storage efficiency of 60.1% in BaLa0.2Bi3.8Ti4O15 films under an applied electric field of 1667 kV/cm. While continuing to increase x, La3+ tends to enter (Bi2O2)2+ high resistance layers, which decreases the insulating properties and results in the reduction of the energy storage density. Moreover, good fatigue resistance after 108 polar switching and excellent thermal stability from −30 to 150 °C for energy storage performances are obtained by layer selection for La doping. This layer selection engineering for rare-earth doping provides an approach to regulate the energy storage performances in multilayered perovskite relaxor ferroelectric films.