Improvement in the Piezoelectric Performance of a ZnO Nanogenerator by a ZnO/Spiro-MeOTAD ps-n Heterojunction

摘要

Piezoelectric nanogeneratorsbased on ZnO nanowires (NWs) have attracted a wide attention in the applications of sustainable power source and selfpowered sensors. However, the output performance of ZnO nanogenerators is significantly suppressed by the piezoelectric potential screening effect due to the large excess electrons in ZnO NWs. In this work, the authors propose a facile and effective method to enhance the performance of ZnO nanogenerators by forming a ZnO/SpiroMeOTAD pn junction. The holes from the ptype polymer remarkably reduce the free electrons in ZnO NWs through a depletion region and the polymer layer effectively decreases the ZnO surfacestateinduced parasitic losses by surface passivation. By spincoating a layer of SpiroMeOTAD on ZnO NWs, a maximum current density of 500nAcm2 is obtained which is approximately 10 times higher than that of the pristine ZnONWs nanogenerators. The results obviously demonstrate the validity of a ZnO/SpiroMeOTAD pn junction structure for strengthening the performance of ZnO nanogenerators and provide a promising approach to realize highperformance energyharvesting nanodevices.