Understanding the piezoelectric response of ZnO nanotetrapods: detailed numerical calculations

The complex tetrapod shape of zinc oxide nanostructure, which is constructed from four one-dimensional arms interconnected together via a central core, is a special 3D geometry with multifunctional applications in advanced technologies. The ZnO hexagonal wurtzite crystal lattice with a non-centrosymmetric structure introduces interesting piezoelectric property in nanorods in the bent state, which has been well reported and utilized in piezo- and tribo-electric nanogenerator applications. Considering the broad technological relevance of tetrapods, it is important to understand the piezoelectric response of zinc oxide tetrapods under different conditions. In this study, we explicate the fundamental mechanical and electrical properties of ZnO nanotetrapods (ZnO NTs) through a detailed finite element method analysis. On this basis, the effects of shape factors (including length, height, and aspect ratio) as well as connection strength and packing density on the deformation and piezoelectric potential of ZnO NTs are examined, offering guidance for the fabrication of ZnO NTs. This theoretical model and numerical simulation provide an avenue for further piezoelectric and piezotronic research of ZnO NTs.