Defect-Enhanced Field Emission from WO₃ Nanowires for Flat-Panel X-ray Sources

Abstract

Achieving high current emission from one-dimensional nanowire (NW) field emitters is essential for their application as X-ray sources. In this study, field emission (FE) from tungsten trioxide NWs (WO3 NWs) was studied, and defects were found to be responsible for the high electron emission current density. A high current density of 13.75 mA/cm2 was achieved from large area, uniformly patterned, and defect-rich monoclinic WO3 NWs, which were grown directly on indium tin oxide (ITO) glass. Comparative investigations were carried out on the field emission properties of individual NWs with different defect concentrations. The results indicated that defect-related electrical transport was the source of such high emission current. This conclusion was further confirmed by a theoretical calculation that considered both defect-related electrical transport and Joule heating in the FE process. The conductivity induced by the defects increases with rising temperature, and this mechanism regulated the Joule heating during emission and helped to achieve high current density. Furthermore, a flat panel X-ray source device using as-grown defect-rich WO3 NWs as a cold cathode was fabricated and used to image various objects. Clear X-ray images with a spatial resolution of approximately 25 μm were obtained.

Hexaarylbenzene based high-performance p-channel molecules for electronic applications

“…OLEDs have received great attention due to their applications in solid-state lighting, wide-angle, and at-panel displays. [81][82][83][84][85][86][87] Particularly, electroluminescent molecules with extended p conjugations are potential candidates for hole injection and hole transport within the system. 88 Most of the organic electroluminescent materials developed so far possessed high quantum yield (F) in solution but very low quantum efficiency in solid-state due to the presence of aggregates, exciplexes, excimers, and impurities within the lm that can cause nonradioactive decay.…”

The Effect of Zn and Zn–WO3 Composites Nano-Coatings Deposition on Hardness and Corrosion Resistance in Steel Substrate

“…Electrodeposited coatings resulted in smaller grain sizes in composites. Tungsten trioxide (WO 3 ) is a potential candidate material for zinc composite coatings because of its abundant availability and applications in preparing gas sensors [ 61 ], thin films used as pigments in paints and ceramics [ 62 ], fire resistance fabrics [ 63 ], electrochromic windows [ 64 ], and tungstates for x-ray phosphorus screens [ 65 ]. It was confirmed from the above literature review that WO 3 and Zn-based composites are ideal materials for preparing novel nanocomposite coatings, which are ideally best suited for a wide range of engineering applications.…”

Modeling of Laser-Induced Plasmon Effects in GNS-DLC-Based Material for Application in X-ray Source Array Sensors

“…The two main technical limitations of modern DCT technology are low spatial resolution and long scanning time [ 2 ]. Therefore, a large amount of research [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ] has aimed to replace devices with a rotating or moving X-ray tube with matrix radiation sources. The use of such arrays allows one to provide a double positive effect.…”

“…Reduction in the size of the elementary current source (within the pixel) also contributes to improvement of the quality of the X-ray image. This aspect has determined the orientation of many researchers towards the development of matrix emitters with field electron emission [ 3 , 4 , 5 , 6 , 8 , 9 , 10 , 11 ], which do not require the use of bulky high-temperature heaters. In almost all of these structures, carbon nanotubes were used as sources of field emission.…”

“…In almost all of these structures, carbon nanotubes were used as sources of field emission. Only the authors [ 5 ] synthesized an array of emitters based on tungsten trioxide (WO 3 NW) nanowires with artificially formed defects to increase the field emission current density to about 14 mA/cm 2 .…”