Fabrication of flexible energy harvesting device based on K0.5Na0.5NbO3 nanopowders

•K0.5Na0.5NbO3 (KNN) nanopowders were fabricated by using sol–gel method.•An energy harvesting device based on KNN nanopowders were fabricated.•The mechanism of the device relies on the piezoelectric effect of KNN materials.•The power delivered to the outer load under an external force was estimated.

K0.5Na0.5NbO3 (KNN) powder was synthesized by a novel sol–gel method and used to fabricate an energy harvesting device. The precursor gel and KNN powder were studied by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The elemental composition of the KNN powder was characterized by energy dispersive X-ray analysis (EDAX). Well crystallized single phase perovskite KNN powder with an average particle size on the order of 450 nm was obtained from the gel after calcining at 750 °C for 2 h. A flexible and implantable energy harvesting device fabricated using the KNN nanopowder exhibited an output power of up to 0.13 μW with a load resistance of 100 MΩ. The Young’s modulus of the device was determined to be 10.4 GPa by atomic force microscopy (AFM).