Ultra-high energy storage performances regulated by depletion region engineering sensitive to the electric field in PNP-type relaxor ferroelectric heterostructural films

Abstract

Based on semiconductor characteristics under a high electric field for dielectric films, PNP-type heterostructural films composed of P-type Na_0.5Bi_3.25La_1.25Ti₄O₁₅ (P-NBLT) and N-type BaBi_3.4Pr_0.6Ti₄O₁₅ (N-BBPT) layers with the same Aurivillius layered perovskite structure are designed to regulate the energy storage performances by depletion region engineering. An ultra-high recoverable energy storage density of 159.7 J cm⁻³ and a high storage efficiency of 70% are obtained in such PNP-type heterostructural films, which are attributed to the regulation of depletion region engineering highly sensitive to the applied electric field. The widths of depletion regions increase with the applied electric field due to the recombination and motion of the majority carriers to induce a high resistance state in depletion regions, which greatly improves the insulation characteristics and the breakdown electric field. Meanwhile, the designed PNP-type heterostructural films also exhibit good stability in terms of temperature, frequency and anti-fatigue, which provides an alternative way to improve the breakdown electric field and realize ultrahigh energy storage performances by depletion region engineering.