Direct-current flexible piezoelectric nanogenerators based on two-dimensional ZnO nanosheet

Direct current (DC) power generation of piezoelectric nanogenerator (PNG) is promising for the realization of future self-powered electronics. Wurtzite structured two-dimensional (2-D) piezoelectric zinc oxide (ZnO) nanosheets can convert mechanical energy into electrical energy, and it produce DC output power. In this present work, we report DC power generation of PNGs based on the 2-D ZnO nanosheets. The growth condition has been optimized for the power generation, and effects of the surface morphologies and orientations have been investigated. The optimized PNGs produced voltage, current density and power density of up to 0.9 V, 16.5 mu A cm(-2) and 600 nW cm(-2), respectively, for over 4000 cycles upon 4 kgf of force.