Enhanced energy conversion efficiency in PVDF/WS2 hybrid piezoelectric nanogenerators

The development of flexible piezoelectric nanogenerators (PENGs) has gained considerable attention for harvesting mechanical energy from ambient sources, especially human motion. In this study, we reported the fabrication of PENGs based on PVDF/WS2 nanocomposite thin films. WS2 nanosheets are synthesized by exfoliation method and incorporated into PVDF with varying weight percentages (1, 2, 3, and 5%), and the resulting thin films are analysed using XRD and FTIR studies to evaluate the content of electroactive β-phase. Additionally, Polarization vs. Electric Field hysteresis loops were recorded to evaluate the ferroelectric properties of PVDF/WS2 nanocomposites films. The piezoelectric performance of the nanogenerator was evaluated under periodic mechanical excitation by an electrodynamic shaker. Among all composites, the device containing 2wt% of WS2 exhibited the highest output, delivering an open-circuit voltage of 19.6 V, and short-circuit current of 11.03 µA at a tapping frequency of 7 Hz, with the corresponding power density, calculated to be approximately 20.48 µW/cm2 at a load resistance of 4 MΩ. This enhancement in the device performance is attributed to increased β-phase content, efficient stress transfer, and the intrinsic piezoelectricity and polarization introduced by WS2 nanosheets in the PVDF matrix. Finally, the fabricated nanogenerator is utilized to harvest the mechanical energy from human motions, such as, finger tapping, thumb tapping etc. Thus, the present study provides a versatile, cost-effective, and environment friendly approach for harvesting biomechanical energy from human motions, enabling a wide range of applications from portable electronics to wearable devices.