Growth of vertically aligned carbon nanotubes by pyrolysis of iron phthalocyanine and their field emission properties

Carbon nanotubes are promising as new optoelectronic materials such as new electron field emitters in panel displays. For most of applications, it is highly desirable to prepare aligned carbon nanotubes ( ACNTs) so that the properties of individual nanotubes can be easily assessed and they can be incorporated effectively into devices for the applications in panel field-emitting displays. By pyrolysis of iron (II) phthalocyanine (FeC ₃₂N₈H₁₆) at 800 - 1 100 °C under low pressure ( Ar/H₂ ), we have synthesized large-scale of vertically aligned carbon nanotubes on quartz glass plates. The character and structure of ACNTs were analyzed by SEM and TEM, respectively. The results indicate that the average length of ACNTs is about 20 μm with a larger diameter ranging from 40 to 70 nm. These ACNTs have a cylindrical and bamboo-like structure and are multi-walled carbon nanotubus ( MWNTs ). By the investigation of preparation parameters, we have found that the growth temperature, flowing rate or proportion of gases and system vacuum have larger influences on the synthesis of such nanotubes. The field emission properties of ACNTs were measured. The result shows a very powerful ability of electron emission with a turn-on voltage of 0.67 V · μm^-1 ( I = 1 pA) and a threshold voltage of 2.5 V · μm^-1.