Flexible piezoelectric energy-harvesting nanogenerator using supersonically sprayed polyvinylidene fluoride and iron oxide nanocubes

Soft wearable electronics are being applied as state-of-the-art self-powered devices based on piezoelectric nanogenerators (PENGs), which provide flexible energy harvesters and sustainable energy generators. We introduce a composite of poly(vinylidene fluoride) (PVDF) and Fe2O3 nanocube fillers coated via supersonic cold spraying to obtain substrate-free and flexible films for PENGs. The hydrothermally synthesized Fe2O3 nanocubes induce shear stress between Fe2O3 and PVDF during supersonic spraying. An optimized sample having 0.77g Fe2O3 in 1g PVDF produces a piezopotential of 25V and a short-circuit current of 70 μA. In addition, a maximum instantaneous power density of 44.4 μW·cm−2 is achieved at a load resistance of 1 MΩ. Tapping and bending tests for 1800 s confirm the consistent generation of piezopotentials of 25V and 1.5V, respectively. The developed Fe2O3/PVDF PENG can power several light-emitting diodes, thus showing promise as a device for sustainable power supply.