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Abstract Advances in flexible electronics are driving the development of ferroelectric thin‐film capacitors toward flexibility and high energy storage performance. In the present work, the synergistic combination of mechanical bending and defect dipole engineering is demonstrated to significantly enhance the energy storage performance of freestanding ferroelectric thin films, achieved through the generation of a narrower and right‐shifted polarization‐electric field hysteresis loop. The recoverable energy storage density of freestanding PbZr0.52Ti0.48O3 thin films increases from 99.7 J cm−3 in the strain (defect) ‐free state to 349.6 J cm−3, marking a significant increase of 251%. The collective impact of the flexoelectric field, bending tensile strain, and defect dipoles contributes to this enhancement. The demonstrated synergistic optimization strategy has potential applicability to flexible ferroelectric thin film systems. Moreover, the energy storage properties of flexible ferroelectric thin films can be further fine‐tuned by adjusting bending angles and defect dipole concentrations, offering a versatile platform for control and performance optimization.

Abstract Wrinkled ferroelectric polymer films with out‐of‐plane deformation exhibit exotic strain fields that differ from those of conventional epitaxial film systems, offering a new path toward manipulating electrical and mechanical behaviors in ferroelectrics. However, the direct observation of the domain structure evolution in ferroelectric polymer films during continuous deformation is challenging with current experimental approaches. In this study, the strain‐induced evolution of toroidal domain structures in organic poly(vinylidene fluoride‐ran‐trifluoroethylene) (P(VDF‐TrFE)) films with concentric toroidal wrinkle patterns is comprehensively investigated using phase‐field simulations. The results reveal morphology‐ and thickness‐dependent toroidal polar topology in wrinkled P(VDF‐TrFE) films. External strain loading can modulate this ferroelectric domain, which exhibits robust coupling behavior with a mixed strain field of periodic tensile and compressive strains. It is demonstrated that toroidal wrinkled ferroelectric films provide an effective and unique flexible platform for continuously controllable strain engineering in ferroelectrics and a theoretical framework with potential applications in flexible electronic devices.

In this work, we propose an optimized transition structure to realize smooth and high efficiency conversion from the guided wave supported by a conventional rectangular waveguide (CRW) to the domino plasmon polaritons (DPPs) supported by a domino plasmonic waveguide (DPW) and vice versa in the X-band (8.2GHz∼12.4GHz). This transition structure consists of two tapered CRWs connected by a gradient domino array with optimized gradient heights and lateral widths. Experimental results of the S-parameters show excellent agreement with the simulations and the optimization scheme can be readily extended to other bands. Furthermore, a domino plasmonic power divider is implemented to demonstrate the application of the transition structure in the integration of conventional microwave circuits with plasmonic devices.