Dielectric and piezoelectric augmentation in self-poled magnetic Fe3O4/poly(vinylidene fluoride) composite nanogenerators

Abstract

One major discipline of contemporary research in energy harvesting and conversion aims in developing lead-free, biocompatible, easily scalable, flexible and high power-denisty nanogenerators via utilizing poly(vinylidene fluoride) as an electroactive host-network due to its large breakdown strength, interesting polytype electrical order and thermoplastic nature. In this work, surface-functionalized magnetite nanoparticles (MNPs) of two different size having exotic electret and size-dependent magnetic properties are mixed with PVDF gel to fabricate self-poled composite piezoelectric films, which can obstruct electromagnetic interference also for smart device applications. A four-fold enhancement of its polar β-phase is verified from XRD and Raman spectra against incorporation of Fe3O4. Dielectric analysis suggests higher dielectric constant and lower dissipation for the films with tiny MNPs embedded in PVDF. The observations are duly validated from first principles studies. The physisorption process is recognized via geometrical optimization of Fe3O4/PVDF composite structure and significant amount of charge-transfer is demonstrated by the Mulliken charge-analysis. Open-circuit voltage and short-circuit current attain enhancement upto an order due to adequate ion-dipole and dipole-dipole interactions between the polar nanoscopic surface of Fe3O4 and PVDF. Finally, the nanogenerators are employed to light up commercial LEDs.