Direct Ink Writing of High Solid Content Polyvinylidene Fluoride/BaTiO ₃ Composites for Enhancing Piezoelectric Performance

Direct ink writing (DIW) enables the fabrication of complex flexible piezoelectric architectures. However, pure polyvinylidene fluoride (PVDF), despite its excellent electroactivity and mechanical flexibility, shows poor printability in DIW due to its unfavorable rheological properties. In this study, a DIW strategy for fabricating PVDF/BaTiO ₃ (BTO) composites with an ultrahigh BTO content of 70 wt%, enables by an ethylene glycol (EG)‐assisted formulation, is reported. Molecular dynamics simulations reveal that EG molecules form hydrogen bonds with PVDF chains, facilitating effective solvation and dispersion of ceramic particles, while simultaneously modulating slurry rheology. The effects of BTO content on the rheological behavior of the ink, the crystallization and piezoelectric output of the DIW‐printed composites was thoroughly examined. Consequently, BTO nanoparticles serve as efficient heterogeneous nucleation agents, significantly promoting the formation of the electroactive β ‐phase, which reaches a relative content of 66.61%. As a result, the printed composite delivers an open‐circuit voltage of up to 38.6 V and a short‐circuit current of 750 nA. Notably, the sample with 70 wt% BTO successfully charges a 1 μF capacitor to 4.5 V within 300 s and powered 12 commercial light‐emitting diodes, demonstrating the promise of this DIW‐printed composite for advanced energy harvesting applications.