High-performance self-powered/active humidity sensing of Fe-doped ZnO nanoarray nanogenerator

High performance self-powered/active humidity sensors have been fabricated from Fe-doped ZnO nanoarrays. When the relative humidity (RH) is 60% at room temperature, the piezoelectric output voltage of the humidity sensor under compressive force decreases from 0.85 (at 5% RH) to 0.21 V. The self-powered humidity sensing performance of Fe-doped ZnO nanoarrays is much higher than that of undoped ZnO nanoarrays. Fe3+ ions have small ionic radius and many positive charges (+3), thus the doping of Fe can lead to a high charge density, which can probably result in a large amount of adsorbed water molecules on the surface of Fe-doped ZnO NWs, enhancing the screening effect and decreasing the piezoelectric output. The present results demonstrate a new material system for high-performance self-powered/active humidity sensors.