Flexible, Lead-Free Nanogenerators Using Poly(vinylidene fluoride) Nanocomposites

A flexible, lead-free piezoelectric nanogenerator is demonstrated, which produces an electrical signal (voltage) under the application of stress. Barium titanate (BaTiO₃) nanoparticles are embedded in the poly­(vinylidene fluoride) matrix to prepare the nanocomposite using the solvent-casting method. Different nanocomposites with varying filler content have been prepared. The nanocomposite eliminates the problems of mechanical stability as the polymer provides it better flexibility as compared to the brittle ceramic material. The structural and morphological studies are performed through X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, and scanning electron microscopy. In response to mechanical deformation, the voltage is generated, and the output voltage increases with increasing the filler content up to 10 wt %, followed by the reduced electrical signal because of agglomeration of the nanoparticles in the composites. Electric poling is also used to enhance the electrical output from the device. The fabricated device exhibits a very high voltage output of 78 V and 120 μW/cm² power density after poling. The prepared device is also able to harvest different biomechanical energies and also able to charge the capacitor, demonstrating the practical applications of the device. The composite with a suitable filler content can be used in wearable smart clothing and small portable devices.