Flexible Field Emission Devices Based on Barium Oxide Nanowires

In this work, we report on the fabrication of flexible field emission (FE) devices based on BaO nanostructures synthesized by a chemical bath deposition method. The morphology and composition of BaO nanowires were characterized by FE scanning electron microscopy, high resolution transmission electron microscopy, selected area electron diffraction, X-ray diffraction, and energy dispersive X-ray spectrometer. The results confirmed that BaO nanowires with single crystalline cubic structures grew along the [111] direction. The flexible field emitters fabricated using the BaO nanowires on stainless-steel cylinder substrates show superior FE properties, which exhibited a low turn-on field ( ${\sim}{\hbox{1.24}}\ {\hbox{V}}/\mu{\hbox{m}}$ ), a low threshold field ( ${\sim}{\hbox{3.18}}\ {\hbox{V}}/\mu{\hbox{m}}$ ), and a high field enhancement factor $(\beta = 2458)$ . Moreover, the flexible FE devices based on BaO nanowire emitters displayed uniform and bright emission patterns under bending conditions. No obvious degradation of current density was observed during the stability tests. As a result, it is demonstrated that such BaO nanowires are promising for the application in practical flexible FE devices.