Synergistic structural and interfacial engineering for enhanced piezoelectric performance in flexible PZT/polydimethylsiloxane composites

3D interconnected PZT skeletons are built via particle-stabilized foaming. • CNT-containing interfacial layers mitigate dielectric mismatch in composites. • High d 33 , g 33 and FOM 33 are achieved with only 13.3 vol% ceramic loading. • Piezoelectric sensors demonstrate high sensitivity of 120 V/MPa and linearity. Flexible piezoelectric materials capable of converting complex mechanical motions into electrical outputs are emerging as key components for wearable electronics, soft robotic systems, and self-powered sensors. However, it remains difficult to combine high mechanical compliance with superior electrical performance. Typically, high ceramic loading is necessary to achieve greatly enhanced piezoelectric properties in ceramic-polymer composites, resulting in poor flexibility. Here, a structural-and-interfacial engineering strategy is proposed to overcome this long-standing trade-off and enable high-performance flexible piezoelectric composites at low ceramic content. By combining a three-dimensional interconnected ceramic framework with effective interfacial modulation, polarization transport and stress transfer are simultaneously improved, while dielectric mismatch is mitigated. As a result, the piezoelectric performance is remarkably enhanced in the composite, delivering d 33  = 249.4 pC·N −1 , g 33  = 214.7 mV·m·N −1 , and FOM 33  = 53.6 pm 2 ·N −1 with only 13.3 vol% lead zirconate titanate (PZT) loading, while maintaining moderate flexibility. A self-powered pressure sensor based on the composite shows high sensitivity (120 V·MPa −1 ) and excellent linearity. This work demonstrates an effective route toward lightweight, high-output piezoelectric composites and offers useful design guidelines for flexible piezoelectric materials in sensing and mechanical energy-harvesting applications.