Improved field emission performance of carbon nanotube by introducing copper metallic particles

Yiren Chen,Guoqing Miao,Dabing Li,Hang Song,Haifeng Zhao,Hong Jiang,Xiaojuan Sun,Zhiming Li

doi:10.1186/1556-276x-6-537

Abstract

To improve the field emission performance of carbon nanotubes (CNTs), a simple and low-cost method was adopted in this article. We introduced copper particles for decorating the CNTs so as to form copper particle-CNT composites. The composites were fabricated by electrophoretic deposition technique which produced copper metallic particles localized on the outer wall of CNTs and deposited them onto indium tin oxide (ITO) electrode. The results showed that the conductivity increased from 10-5 to 4 × 10-5 S while the turn-on field was reduced from 3.4 to 2.2 V/μm. Moreover, the field emission current tended to be undiminished after continuous emission for 24 h. The reasons were summarized that introducing copper metallic particles to decorate CNTs could increase the surface roughness of the CNTs which was beneficial to field emission, restrain field emission current from saturating when the applied electric field was above the critical field. In addition, it could also improve the electrical contact by increasing the contact area between CNT and ITO electrode that was beneficial to the electron transport and avoided instable electron emission caused by thermal injury of CNTs.

Highlights

Carbon nanotubes (CNTs) have extensively been investigated since they were discovered by Iijima [1]
By means of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS), we confirm that the electrophoretic deposition (EPD) process is a simple and feasible way of fabricating copper metallic particle-carbon nanotube (Cu-CNT) assembly cathode
The simulation of field distribution, field emission characteristic curve, and electron emission stability curve has been adopted to reveal the effect of Cu-CNT assemblies

Summary

Introduction

Carbon nanotubes (CNTs) have extensively been investigated since they were discovered by Iijima [1]. A simple and low-cost way to improve field emission performance especially stability of carbon nanotube field emission display (CNT-FED) using copper metallic particle-carbon nanotube (Cu-CNT) assemblies through EPD technique is investigated. ITO conductive glass connects to the negative electrode of DC voltage while Cu sheet to the positive one, when 50 V DC applied to them, the CNTs attached to Cu2+ ions will be driven to move to the negative electrode under the electric field. When CNTs arrive at the ITO electrode, Cu2+ ions adsorbed on the CNTs are reduced to form metallic Cu particles by reason of high electrical conductivity of CNT which allows electron to conduct from the Cu sheet to the outer layer of a CNT. The atoms of Cu sheet lose 2e- to form Cu2+ ions and release into the IPA This process can be described as: Cu2+ + 2e− ←→ Cu (1). To evaluate the performance of CNTs by introducing Cu metallic particles, the field emission characteristic curve and electron emission stability curve are acquired by two Agilent 34401A sourcemeters (Agilent Technologies, Inc.) with one as ammeter and the other as voltmeter

Results and discussion

Conclusion

Iijima S