High Energy Efficiency and Thermal Stability of BaTiO3–BiScO3 Thin Films Based on Defects Engineering

ABO3 perovskite ferroelectric thin films have gained wide attention in recent years for high density capacitive energy storage applications. In this regard, BaTiO3–BiMeO3, where Me is a metal cation, are particularly promising materials because of their high electrical polarization and low hysteresis losses. However, for a broader adoption of BaTiO3–BiMeO3 thin films in advanced electronics applications, it is necessary to maintain good thermal stability in addition to high energy density and energy storage efficiency. In this work, we show that a superior combination of these characteristics can be obtained through the control of different defect concentrations, viz., A-site cation vacancies (VA) and B-site ionic substitutions (MeTi). It is shown for BaTiO3–BiScO3 thin films that an optimum combination of VA and ScTi leads to a high energy storage density of 40.5 J cm–3 and an efficiency higher than 85%, which could be maintained from room temperature to 200 °C. A mechanistic understanding of the enhanced energy storage performance based on the synergistic effect of random fields introduced by A-site vacancies and strong hole trapping by ScTi acceptor centers is proposed. Perovskite ferroelectric thin films capable of maintaining high performance at high temperatures may facilitate the advancement of power electronics applications in harsh environments.