Self‐poled Efficient Flexible “Ferroelectretic” Nanogenerator: A New Class of Piezoelectric Energy Harvester

Abstract

Superior ferro‐ and piezo‐electret properties in a self‐poled, porous hybrid ferroelectretic polymer nanocomposite film for next‐generation device paradigms is introduced by in situ generation of platinum (Pt) nanoparticles (NPs) embedded in poly(vinylidenefluoride‐co‐hexafluoropropylene) P(VDF–HFP). The cooperative functionality between the self‐polarized β‐phase and the micropores as charge trapping sites is realized by using a simple solvent evaporation method. As a consequence, the resulting film exhibits extraordinary ferroelectretic behavior, as demonstrated by the superior electrical square‐shaped hysteresis loop with large remnant polarization (Pr≈61.7 μC cm−2), piezoelectric charge coefficient (d33∼−686 pC N−1), and ultrahigh dielectric properties (εr=2678, tan δ=0.79 at 1 kHz). A new type of ferroelectretic nanogenerator (FTNG) is fabricated using a flexible hybrid nanocomposite film that effectively converts the applied mechanical energy into electrical energy upon compressive normal stress (e.g., by actuating with a human finger). The 18 V of the open‐circuit output voltage with expected 17.7 μA short‐circuit current are generated from the FTNG under 4 MPa of normal stress amplitude. The high piezoelectric energy conversion efficiency (ηpiezo≈0.2 %) of the FTNG shows that the hybrid polymer nanocomposite film is well suited for the next generation of piezoelectric‐based energy harvesters. The operation of more than 50 blue LEDs, 25 green LEDs, and several capacitors without any subsidiary batteries is demonstrated using the FTNG.

Recent Progress on Piezoelectric, Pyroelectric, and Magnetoelectric Polymer‐Based Energy‐Harvesting Devices

“…A ferroelectric NG fabricated from platinum (Pt) nanoparticles/P(VDF‐HFP) nanocomposite films demonstrated an open‐circuit output voltage of 18 V and a short‐circuit current of 17.7 µA under a stress of 4 MPa. The application uses a bridge rectifier connected to the NG film capable of directly providing power to 55 blue LEDs, 25 green LEDs, and charge capacitors for energy storage …”

Surface‐Modified Nanostructured Piezoelectric Device as a Cost‐Effective Transducer for Energy and Biomedicine

“…Surface‐activated Li‐ZnO acts as a piezoelectric response enhancer because of its high dielectric constant as well as a β phase transformer for PVDF. Thus, an unpoled piezoelectric device response could reach a value nearly to that of a poled piezoelectric device …”

Enhanced β‐phase in PVDF polymer nanocomposite and its application for nanogenerator

“…This means that there is good electromechanical coupling for PVDF‐ZnO (15 wt%) . We have also calculated piezoelectric coefficient d 33 value by using this value of Young modulus and the value of remnant polarization ( D R ) by using the relationship d 33 = (− D R )/ Y . The estimated values of d 33 are −0.17, −0.53, −0.69, and −1.17 pC/N for PVDF, PVDF‐ZnO (5 wt%), PVDF‐ZnO (10 wt%), and PVDF‐ZnO (15 wt%) films, respectively.…”