CNT Twisted Yarns as Low Threshold Cold Electron Sources for Displays.

Carbon nanotubes are known as best field emitters of electrons, which emit at low threshold electric fields of E$_{thr} \quad \sim $ 1-3 V/$\mu $m with typical, stable current densities of J $\sim $ 100 mA/cm$^{2}$. Our team has recently created strong CNT fibers, yarns and ribbons by dry twist-spinning from oriented arrays of long MWCNTs prepared by CVD [1]. Here we show that such twisted yarns (TY) of typical diameters of 10 $\mu $m show phenomenally low E$_{thr}<$0.5 V/$\mu $m with very high J and steep I-V curves. If used as cathode for phosphorescent screens the horizontally placed CNT TY FE show rather bright and uniform light emission. The high luminosity lamp and also numeric displays prototypes are created and their properties described. The mechanism of low threshold E$_{thr}$ and high J is discussed in terms of high porosity structure and linear geometry of CNT TY. [1] M. Zhang, Ken Atkinson, Ray Baughman, Science (2004)