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 (Pmax) and breakdown strength (Eb). 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 Eb, while lattice distortion and phase transitions, facilitated by diffusion and strain at interfaces, contribute significantly to the enhancement of Pmax. 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 Pmax and Eb, provides a promising avenue for the development of high-performance dielectric materials.