Abstract
Carbon nanomaterial is drawing keen interest from researchers as well as materials scientists. Carbon nanotubes (CNTs)—and their nanoscale needle shape—offering chemical stability, thermal conductivity, and mechanical strength exhibit unique properties as a quasi-one-dimensional material. Among the expected applications, field emission electron sources appear the most promising industrially and are approaching practical utilization. However, efforts to construct a field emission (FE) cathode with single-walled carbon nanotubes (SWCNTs) have so far only helped average out a non-homogeneous electron emitter plane with large FE current fluctuations and a short emission life-time because they failed to realize a stable emission current owing to crystal defects of the carbon network in CNTs. The utilization of CNTs to obtain an effective cathode, one with a stable emission and low FE current fluctuation, relies on the ability to disperse CNTs uniformly in liquid media. In particular, highly crystalline SWCNTs hold promise to obtain good stability and reliability. The author successfully manufactured highly crystalline SWCNTs-based FE lighting elements that exhibit stable electron emission, a long emission life-time, and low power consumption for electron emitters. This FE device employing highly crystalline SWCNTs has the potential for conserving energy through low power consumption in our habitats.
Highlights
The further development of electronic systems necessitates the production of efficient devices employing carbon nano-materials
Many studies have attempted to employ Carbon nanotubes (CNTs) as field emitters in a display cathode with a lower driving voltage and stable electron emission. These trials mostly involve the vertical alignment of the CNTs in their fabrication that are synthesized by plasma-enhanced chemical vapor deposition (PECVD) or laser abrasion fabrication; for example, screen printing with high-viscosity submicron to micron scale metal-particle paste to fabricate patterned field emitters has been proposed [20–22]. These approaches could not obtain the homogeneous electron emitter plane with small field emission (FE) current fluctuations as they failed to construct a uniform thin film employing a homogeneous dispersion of CNTs
Purified and highly crystalline single-walled carbon nanotubes (SWCNTs) synthesized by arcing and sintered at high temperature in a vacuum have been expected to serve as an electrical source material for a field emitter though the homogeneous dispersion of highly crystalline SWCNTs has yet to be reported. This is because highly crystalline SWCNTs have almost no defects in the carbon network on their surface, nor do they combine with another functional group of dispersants
Summary
The further development of electronic systems necessitates the production of efficient devices employing carbon nano-materials. CNTs express one-dimensional circumscription effects and have characteristics as quantum wires coherently [5–7], and CNTs have the highest Young’s modulus of all known materials mechanically [8] Owing to these outstanding properties, wide-ranging applications for nanotubes are currently under investigation, including their use as electron field emitters [9], probes in scanning-type microscopes [10], gas (e.g. hydrogen) storage materials [11], and as electrode materials for secondary batteries as well as in capacitors [12]. Many studies have attempted to employ CNTs as field emitters in a display cathode with a lower driving voltage and stable electron emission These trials mostly involve the vertical alignment of the CNTs in their fabrication that are synthesized by plasma-enhanced chemical vapor deposition (PECVD) or laser abrasion fabrication; for example, screen printing with high-viscosity submicron to micron scale metal-particle paste to fabricate patterned field emitters has been proposed [20–22]. The author successfully manufactured SWCNT-based field emission lighting elements exhibiting stable electron emission, adequate luminance, and low power consumption for the electron emitters
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