Use of ZnO nanorods grown atomic force microscope tip in the architecture of a piezoelectric nanogenerator

The piezoelectric potential output has been studied using a ZnO nanorods (NRs) grown atomic force microscope (AFM) tip in lieu of the normally used AFM tip. The ZnO NRs were synthesised on the AFM tip and on the fluorine-doped tin oxide (FTO) glass substrate using the aqueous chemical growth method. The as-grown ZnO NRs were highly dense, well aligned and uniform both on the tip and on the substrate. The structural study was performed using X-ray diffraction and scanning electron microscopy techniques. The piezoelectric properties of as-grown ZnO NRs were investigated using an AFM in contact mode. In comparison to the AFM tip without ZnO NRs, extra positive voltage peaks were observed when the AFM tip with ZnO NRs was used. The pair of ZnO NRs on the AFM tip and on the FTO glass substrate together worked as two oppositely gliding walls (composed of ZnO NRs) and showed an enhancement in the amount of the harvested energy as much as eight times. This approach demonstrates that the use of the AFM tip with ZnO NRs is not only a good alternative to improve the design of nanogenerators to obtain an enhanced amount of harvested energy but is also simple, reliable and cost-effective.