Improved Field Emission Properties of Carbon Nanotube Paste Emitters Using an Electrically Conductive Graphite Binder

Field electron emission properties of carbon nanotube (CNT) paste emitters have been investigated according to binder materials such as acrylic binder, polymethyl methacrylate (PMMA) binder, ethyl cellulose (EC) binder, and graphite binder. Out of the four CNT paste emitters, the graphite binder-based CNT paste emitter demonstrates the best field emission performance, followed by the EC binder, PMMA binder, and acrylic binder in sequence. The obtained result indicates that the field emission properties of the CNT paste emitter are improved with an increase in the electrical conductivity of the binder material. The graphite binder-based CNT paste emitter exhibits a low turn-on field of 3.13 V/μm and a high field emission current density of 882.28 mA/cm2 (corresponding to a current of 50.52 mA) at an applied electric field of 6.7 V/μm. In addition, the graphite binder-based CNT paste emitter shows good emission stability after 10 h of operation with a high initial current density of 122.26 mA/cm2, including a low current degradation rate of 4.84% and a low current fluctuation rate of ±0.59%. The good electron emission stability of the graphite binder-based CNT paste emitter is mainly caused by both the higher electrical conductivity and the higher thermal stability of the graphite binder compared with organic binder materials. The experimental results have shown that the graphite binder-based CNT paste emitter can be widely used in various vacuum electronic devices.