Enhancement of Dielectric Breakdown Strength and Recoverable Energy Density in Three‐Dimensional Heterointerfaces on BaTiO ₃ –PbZrO ₃ –PbTiO ₃ Films via Room‐Temperature Nano‐Clustering

Enhancing the energy‐storage performance of dielectric capacitors requires the simultaneous increase of saturated polarization, suppression of remanent polarization, and improvement of dielectric breakdown strength (DBS). Although nanocomposite and multiphase strategies exploiting interfacial effects have been widely investigated to achieve high energy density, it remains thermodynamically challenging to fabricate composite architectures in which multiple ferroelectric phases coexist as discrete nanoscale crystals, making it difficult to sustain true multiphase heterointerfaces. We address these challenges by fabricating a multiphase nano‐clustered (MN) structure composed of three ferroelectrics‐BaTiO 3 (BT), PbZrO 3 (PZ), and PbTiO 3 (PT)‐using a room‐temperature aerosol deposition (AD) process without post‐thermal treatment. This route effectively suppresses interphase reactions and preserves the intrinsic crystal structure of each constituent, thereby enabling the formation of three‐dimensional nanoscale interfaces that cannot be achieved through conventional sintering. Owing to the large work‐function differences among BT, PZ, and PT, interfacial charge trapping is induced, which suppresses space‐charge transport and inhibits breakdown‐path propagation. The MN BT–PZ–PT film exhibits a DBS of 5.8 MV cm −1 (∼260% enhancement) and a recoverable energy density of 68.6 J cm −3 (∼300% increase) compared with a single‐phase BPZT film. Despite room‐temperature fabrication, the composite demonstrates excellent energy‐storage performance, thermal stability, and fatigue endurance, enhanced DBS.