Synergistic breakdown enhancement and polarization regulation in Mn-doped Aurivillius thin films for dielectric energy storage

The polarization–breakdown trade-off is broken in SBLTMO thin films. • P r is suppressed while P max and breakdown strength are enhanced. • Leakage mechanisms and defect activation energy are tailored via defect-chemistry regulation. • A high W rec of 131.1 J/cm 3 with 74% efficiency is achieved. Achieving high energy storage performance in dielectric thin films requires both a high breakdown strength and large polarization difference between maximum and remanent polarization. Although Aurivillius-phase ferroelectrics offer excellent fatigue resistance and high breakdown tolerance, their pronounced ferroelectric hysteresis narrows this polarization difference, especially under high electric fields where intensified leakage conduction further broadens the polarization hysteresis. Herein, to overcome this limitation, Mn-doped SrBi 4.76 La 0.24 Ti 4.5 Mg 0.5 O 18 Aurivillius thin films are designed to realize synergistic breakdown enhancement and polarization regulation. Mn incorporation induces local tensile lattice strain, leading to increased maximum polarization. Meanwhile, leakage current is effectively reduced after Mn doping, and remanent polarization decreases because of the weakened contributions from leakage current and irreversible domain switching, thereby achieving effective polarization regulation. Analysis of leakage-conduction mechanisms reveals that Mn incorporation extends the electric-field range dominated by Ohmic and trap-filled-limited conduction before the onset of rapidly increasing leakage under high electric field, thereby enhancing breakdown strength. Consequently, the optimized Mn-doped SBLTMO thin film achieves a recoverable energy density of 131.1 J/cm 3 and an efficiency of 74.0% under 4.5 MV/cm, together with excellent frequency, thermal, and cycling stability. These findings demonstrate the effectiveness of rational defect design in coupling breakdown enhancement with polarization regulation for high-performance Aurivillius dielectric thin films.