Electric-assisted 3D printing breaks the piezoelectricity-loss trade-off in PVDF nanocomposites via multiscale synergy

Flexible piezoelectric polymers such as polyvinylidene fluoride (PVDF) are essential for wearable electronics, yet their development is hindered by a fundamental trade-off between piezoelectric response and dielectric loss. Here, we introduce a multiscale synergy strategy that overcomes this limitation by integrating electric-assisted 3D printing with molecular and nanoscale engineering. Molecular chain rigidification promotes β-phase formation, while core-shell nanoparticles (Al₂O₃@BaTiO₃) minimize interfacial polarization loss. Crucially, the printing process applies an in-situ electric field that aligns dipoles during material solidification. This approach produces a flexible film with a piezoelectric coefficient (d₃₃) of −45.3 pC N⁻¹, four times that of commercial PVDF, while maintaining a low dielectric loss of 0.02 at 1 kHz and a high breakdown strength of 501 MV m⁻¹. Multi-scale simulations and in-situ measurements confirm the synergistic mechanisms of homogeneous electric field distribution and efficient stress transfer. The resulting device demonstrates stable performance in energy conversion, establishing a design framework for high-performance polymer-based electromechanical devices.