Effect of surface and geometrical structures on ZnO piezoelectric output voltage characteristics

Abstract

With the advances in wearable devices, mobile phones, and personal gadgets, the need for an environmentally friendly energy source for these devices is more important than ever. Piezoelectric nanogenerators (PENG) have proven to be one of the main solutions and are advancing quite rapidly to be used in consumer products. The main drawback, however, is the limitation of its output characteristics, and its effect on nature. Researchers have been trying various methods to enhance the ZnO and other Pb-free piezoelectrical materials to be more effective and usable. These could include, doping, an increase in the areal density of ZnO NRs, surface treatment, interfacial modification, and combination techniques. Surface structures, nano-structuring, and geometrical designs have been proven by previous research to have an enhancing effect on the piezoelectrical output properties. In this research, the focus was done, via simulations, on the differences between four different geometries with five different dimensions in terms of their piezopotential output. The simulation results proved that there were significant differences, with the asymmetric nanowire structure giving the highest output voltage; almost 147 and 4.7 times the output voltage of thin films and cylindrical nanowires, respectively. The results also concluded that as the surface area to volume ratio increases, the output voltage increases, which agrees with previous research papers. The results in this research could not only be used to enhance the ZnO piezoelectric nanogenerator output properties but also to give PENG designers a better understanding and opportunity to better optimize their devices depending on their needs. This also helps with the study of using piezoelectrical devices in general as semiconductors and their simulation in COMSOL, as not much research has yet been conducted in this field.