Controlled field emitter distribution for improving field emission properties of screen-printed carbon nanotubes

Abstract

Carbon nanotubes (CNTs) are one of the most promising emitters used in both field emission displays (FEDs) and high current electron sources due to their unique physical and chemical properties. Recently a number of methods such as laser ablation, chemical vapor deposition (CVD) and screen-printing have been extensively developed for the synthesis of CNTs emitter. Among them, the screen-printing of CNTs on glass substrates has attracted much attention. It is very simple to adjust the desity of CNTs by varying the deposition conditions. Furthermore, the screen-printing is a low cost process for commercial large-area FED applications. However, in case of screen-printing method, there are several problems about the uniformity of CNTs emitter distribution. The field emission properties of random distributed CNTs are poorer than those of highly vertically aligned CNTs in terms of uniformity and lifetime. When CNTs are screen-printed on the substrate, the tendency of agglomeration of CNTs also leads to non-uniformity emitter areas because of the screening effect. Therefore, it is necessary to control emitter distribution to enhance the field emission properties of printed CNTs for FED. In this paper, we report a simple method can control the CNTs distribution. The emission properties of screen-printed CNTs were improved after using with a wetting and dispersing additive simultaneously. Morever, the screening effect of the agglomerated CNTs emitters are also numerically studied.