Flexible ultrahigh energy storage density in lead-free heterostructure thin-film capacitors.

Flexible Ba₂Bi₄Ti₅O₁₈ and BiFe_0.93Mn_0.07O₃/Ba₂Bi₄Ti₅O₁₈ heterostructure thin-film capacitors were deposited onto LaNiO₃ buffered fluorophlogopite mica substrates using a cost-effective all-solution chemical solution deposition method. The Ba₂Bi₄Ti₅O₁₈ film showed a high recoverable energy storage density (U_re) of 41.2 J/cm³ and efficiency (η) of 79.1%. The BiFe_0.93Mn_0.07O₃/Ba₂Bi₄Ti₅O₁₈ film showed improved energy storage properties with an ultrahigh U_re of 52.6 J/cm³ and η of 75.9% due to its enhanced breakdown field strength and polarization. Meanwhile, both films showed good mechanical flexibility, excellent fatigue endurance up to 5 × 10⁸ cycles, and excellent thermal stability over a wide temperature range from room temperature to 160 °C. These results indicate that the lead-free, flexible Ba₂Bi₄Ti₅O₁₈ and BiFe_0.93Mn_0.07O₃/Ba₂Bi₄Ti₅O₁₈ heterostructure thin film capacitors show promise in the field of flexible electronics. [ABSTRACT FROM AUTHOR]