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.