Ultra-thin multilayer films for enhanced energy storage performance

The rapid progress in microelectronic devices has brought growing focus on fast charging-discharging capacitors utilizing dielectric energy storage films. However, the energy density of these dielectric films remains a critical limitation due to the inherent negative correlation between their maximum polarization (P_max) and breakdown strength (E_b). This study demonstrates enhanced energy storage performance in multilayer films featuring an ultra-thin layer structure. The introduction of a greater number of heterogeneous interfaces improves E_b, while lattice distortion and phase transitions, facilitated by diffusion and strain at interfaces, contribute significantly to the enhancement of P_max. Remarkably, an energy density of 65.8 J/cm³ with an efficiency of 72.3% was achieved in a 6.7 nm-per-layer BiFeO₃/SrTiO₃ multilayer configuration, surpassing the performance of most multilayer films composed of simple constituents. This ultra-thin multilayer structure, which simultaneously promoted P_max and E_b, provides a promising avenue for the development of high-performance dielectric materials.