Hydrothermally grown pure and Er-doped ZnS nanocrystals based flexible piezoelectric nanogenerator for energy harvesting and sensing applications

Abstract

Pure zinc sulphide (ZnS) and Er-doped ZnS nanocrystals were grown by hydrothermal method at low temperature. Powder XRD analysis reveals the formation of wurtzite hexagonal phase structure for both pure and Er-doped ZnS samples. Morphology of 2D nanocrystals for both pure and doped ZnS nanocrystals was confirmed by FESEM technique. Presence of Er element in Er-doped ZnS was confirmed by energy-dispersive X-ray spectroscopy. Further, both pure and Er-doped nanocrystals have been used as piezoelectric fillers in polydimethylsiloxane (PDMS) for the fabrication of flexible piezoelectric nanogenerators. The Er-doped ZnS based nanogenerator showed almost 9 times (∼ 36 V) higher open circuit voltage as compared to pure ZnS based nanogenerator (∼ 4 V). Then, Er-doped ZnS nanocrystals based device was used to harvest the mechanical energy under the human walking and running conditions. Also, this device generated significant electrical signal under the human elbow bending. The output performances of Er-doped ZnS based device indicates that it can be a potential candidate for mechanical energy harvesting under various human body motions as well as for wearable piezoelectric sensor applications.