Direct-current piezoelectric nanogenerator based on two-layer zinc oxide nanorod arrays with equal c-axis orientation for energy harvesting

Direct current (DC) piezoelectric nanogenerators, that can harvest mechanical energy into electrical power, have been extensively studied for driving low-power electronic devices without pre-rectification. However, the output power of most developed DC generators is generally too low to satisfy the requirements of diverse micro-electronic devices. Herein, we design a high-output Schottky DC nanogenerator consisting of a top gold electrode, the piezoelectric layer of zinc oxide (ZnO) nanorod arrays grown on polarized polyacrylonitrile film, a bottom copper electrode with ZnO nanorod arrays, where the crystallographic c-axis orientation of both ZnO nanorod arrays trends to be the same. The fabricated DC nanogenerator shows the peak voltage and current density as high as 1.6 V and 7.2 μA/cm2, respectively, which are several times higher than that of a pure ZnO-based nanogenerator. It has been demonstrated to harvest ambient tiny mechanical energy, including human activity, impact/collision, and sound vibration, to power commercial microelectronics directly, and to charge a storage capacitor for driving a heath-care device. Such novel DC nanogenerator may have great application prospects in self-powered electronics, structure and human health monitoring, and many more places.