Arrays of vertically aligned tubular-structured graphene for flexible field emitters

Abstract

Arrays of tubular-structured reduced graphene oxide (RGO) were fabricated by a simple method involving filtration of a solution containing highly dispersed RGO sheets. The length and alignment of the tubular-structured RGO arrays were controlled by the filtration rate and by tuning the interactions between the hydrophobic RGO sheets and the porous walls, rather than the top surfaces, of the polycarbonate filter membrane. As expected, the lengths of the RGO arrays increased with higher filtration rates; however, maximum field emission characteristics were obtained at an intermediate filtration rate because field screening reduced electron emission from the longer-length RGO arrays. ZnO-coated RGO arrays showed excellent emission stability without significant current degradation or fluctuations, even under O 2 exposure. The ZnO layer protected the emission site of the RGO arrays from the reactive ion bombardment of oxidative gas species. Moreover, the RGO arrays were highly flexible with preservation of the field emission properties, even at large bending angles. The excellent field emission characteristics of the tubular structured RGO arrays were attributed to the high crystallinity, abundant sharp edges, and the chemical stability of the RGO arrays, as well as the strong interactions between the RGO arrays and the substrate.

Self‐Organized Graphene Nanosheets with Corrugated, Ordered Tip Structures for High‐Performance Flexible Field Emission

“…The sheet resistance of the rGO array cathode did not change significantly, even at a bending angle of 90°. A SWCNT‐coated PET film was used as the cathode substrate, as described in our previous work 39–41. The SWCNT network was highly flexible without incurring a reduction in the electrical conductivity under severe bending conditions, in contrast with the results observed for brittle ITO electrodes 42.…”

“…To remove emission noise and instabilities, an electrical aging process was applied (I–V sweeping and high‐voltage annealing) until the emission currents showed negligible fluctuations. To create a flexible field emission device, SWCNT‐coated polyethylene terephthalate (PET) films were used as cathode and anode substrates 39, 40. A DC pulse mode with a duty cycle of 20% was used to minimize structural damage or modifications to the PET anode substrate by joule heating through high emission currents in the patterned rGO arrays.…”

Laser-Patternable Graphene Field Emitters for Plasma Displays

“…However, a requirement for the graphene utilized in field electron emission devices is that the material should be vertically aligned/protrude from the polymer substrate, providing more individual field emission sites, as flat graphene sheets lack sharp edges and require a high voltage to turn on the FEE process [10]. Several methods for synthesizing graphene nanostructures on polymer substrates, such as spin-casting, electrophoresis, self-assembly, thermal welding, and filtering, have been developed and have employed the obtained nanostructures as efficient field emitters [11,12,13,14,15,16]. A cost-effective process of synthesizing graphene nanostructures on polymers using cheap precursors is needed for the industrial production of display devices.…”

Highly efficient field emission properties of a novel layered VS2/ZnO nanocomposite and flexible VS2 nanosheet

“…In addition, exible display technology has attracted considerable attention in recent years. 22,23 As a newly emerging 2D exible material, we investigate the exible FE properties of VS 2 nanosheets. They were deposited onto a exible PET lm by Au sputtering to constitute a mechanically stretchable and electrical conductive substrate.…”