Modulating D₃₃ Coefficients Through In Situ AgF and Ag₂O Growth in PVDF Composites for High-Performance Piezoelectric Nanogenerators

Polyvinylidene fluoride (PVDF) membranes, known for their flexibility, biocompatibility, and piezoelectricity, hold significant promise for energy harvesting applications in bioelectronics. Enhancing the β-phase content is critical for improving device performance. This study presents an effective strategy to boost the relative concentration of β-PVDF through the in situ growth of silver(I) fluoride (AgF) and silver oxide (Ag₂O) nanoparticles (NPs). By optimizing the concentration of NPs, the β-phase content in PVDF composite films increased to 91.4%. Dielectric analysis revealed a remarkable enhancement of the dielectric constant, reaching 30.1—over three times higher than that of pristine PVDF at 1000 Hz. Additionally, the piezoelectric coefficient of the optimized PVDF composite film improved by 50%, reaching ≈12 pC N⁻¹. A prototype nanogenerator based on the optimized composite film achieved an open-circuit voltage of ≈35 V, a short-circuit current of ≈1.6 µA, and an output power density of ≈25 µW cm⁻² under 0.5 MPa compressive stress. The device successfully powered 10 blue LEDs and charged a 50 nF capacitor within 10 s. These findings highlight in-situ growth of silver-based nanoparticle in PVDF matrix provides a scalable approach for energy harvesting and storage technologies.