Numerical Study of the Zinc Oxide Nanowire Geometry Effect on Nanogenerator Output

Abstract

Piezoelectric nanogenerator (NG) made of nanowires (NWs) is a suitable device for harvesting ambient mechanical energy, applicable for self-powered electronic systems and nanodevices that operate at low power. The coupled piezoelectric and semiconducting characteristics of the zinc oxide (ZnO) NW cause an output voltage generation that made it interesting to use as an energy harvesting device in nanoscale. In this paper, the piezoelectric potential distribution in a bent ZnO NW is investigated, numerically. To do this, a three-dimensional finite element simulation of the device is performed and the results are analyzed and discussed. It is found that the output piezoelectric potential, for a constant nanowire length, is decreased as the diameter of ZnO NW increases. Study on the effect of NW diameters shows the potential will remain constant for nanowire with aspect ratio below 15. Further, the NWs are considered with an inclination of 20 degree relative to the substrate to study by applying force in different directions. The latter indicates an improvement on the output piezoelectric potential. The obtained results show that the ZnO NW can be used as a good energy harvester device by considering a suitable diameter, length and with a justified inclination angle.