$δ$-PVDF Based Flexible Nanogenerator

Abstract

Delta (δ ) phase comprising polyvinylidene fluoride (PVDF) nanoparticles are fabricated through electrospray technique by applying 0.1 MV/m electric field at ambient temperature and pressure, which is 10 3 times lower than the typical value, required for δ -phase transformation. The X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns are clearly indicating the δ -phase formation. The piezo-and ferro-electric response of the δ -PVDF nanoparticles has been demonstrated through scanning probe microscopic technique based on piezoresponse force microscopy (PFM). The vertical piezoelectric response, indicated by d 33 coefficient, is found ∼-11 pm/V. Kink propagation model is adopted to justify the δ -phase conversion in electrospray system. The electrical response from δ -PVDF nanoparticle comprised nanogenerator under the external impacts and acoustic signal indicates that molecular ferroelectric dipoles responsible for piezoelectric responses, are poled in-situ during nanoparticle formation, thus further electrical poling is not necessary.