Defect-promoted domain-free dipole growth and optimized energy storage performance in weakly polar dielectrics

The progress of modern electronic devices puts forward higher requirements for the energy storage performance of capacitors. In order to further improve the energy storage density of existing advanced weakly polar dielectrics, we propose an innovative strategy for polarization optimization through the construction of a domain-free polarization configuration achieved by developing substantially grown non-aggregated dipolar entities with sub-nanometer scale and additional polarity sources. This is achieved based on the induction of donor/acceptor-free intrinsic cation vacancy-oxygen vacancy complexes, which regulate the cation-oxygen bonding structures, promote the highly disordered polar displacement distortion of Ti atoms in the oxygen cage, and significantly enhance the local electric field. In addition, this method avoids generating additional impurity energy levels and increases the band gap. The polarization and insulation of the optimized system exhibits a significant enhancement compared to the defect-free system, resulting in a recoverable energy density of 10.74 J/cm³, while maintaining a high efficiency of 94.1% and excellent high-temperature stability. Contrary to conventional paradigms that associate defects with deteriorated polarization response and thermal degradation, our findings establish a novel defect-utilization methodology, paving the way for advancing energy storage capabilities in broader weakly polar dielectrics.