Output power dependence of piezoelectric nanogenerator under mechanical deformation

Piezoelectric nanogenerators (NGs) harvesting mechanical energies have been getting attraction because of their advanced properties, such as continuous operation, low cost, and non-toxic operation. However, the most of research were focused on improvement of piezoelectric materials by applying chemical methods. In this report, we demonstrated the energy conversion efficiency(ECE) difference under different mechanical deformations, bending and twisting. Depending on the deformation conditions, strain distributions are critically changed, resulting in different output performance. For this research, we prepared ZnO-based PNG by sputtering. To understand the effect of external mechanical deformation on the ECE, we characterize the ECE by the ratio of output electrical energy and strain energy of ZnO active layer. To calculate the strain energy in ZnO active layer, we conducted numerical simulation of two mechanical deformations. Finally, we obtained that the ECE under twisting deformation is much higher than that under bending deformation. Our results could provide a design direction to PNG systems as high performance power generators.