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 (V_A) and B-site ionic substitutions (Me_Ti). It is shown for BaTiO₃–BiScO₃ thin films that an optimum combination of V_A and Sc_Ti 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 Sc_Ti 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.