In Situ Observation of Current Generation in ZnO Nanowire Based Nanogenerators Using a CAFM Integrated into an SEM

Identifier:  TFM:595

Handle: https://hdl.handle.net/20.500.11797/TFM595

Authors:  Wen, Chao

Abstract:
Piezoelectric energy generators are promising systems which provide power for wireless electronic devices because they can harvest mechanical energy from the environment. In the last decades, piezoelectric nanogenerators such as zinc oxide (ZnO) nanowire‐based nanogenerators have attracted much attention due to their small size and high current density. However, the origin of currents generated from ZnO nanowire remains unclear. In this report, we systematically characterize current generation in ZnO nanowire using a conductive atomic force (CAFM) microscope head mounted into the scanning electron microscope (SEM) chamber. This set up can help us to monitor the ZnO nanowire bending process and record the in situ information of current generated at the same time. We find that currents generated during ZnO nanowire bending not only come from piezoelectric effect but also from contact potential and triboelectric effect. Since contact potential and triboelectric effect have been ignored in previous work, the power conversion efficiency of piezoelectric nanogenerators has been overestimate. Our work helps to better understand the working mechanism of ZnO nanowire based piezoelectric nanogenerators. Moreover, this setup is very useful for other in situ study of nano‐structured materials in the future.