We present a self-assembling method for the high-efficient field emission applications, which uses a colloidal monolayer as a supporting frame in the presence of an electric field. We show that the interstices of the colloidal particle assembly maintain the alignment of the single-walled carbon nanotubes in the absence of an electric field. Unlike the previous assembling techniques, this method affords the alignment of well-dispersed SWNTs with a high aspect ratio on ITO substrates at room temperature, which results in the highly efficient use of the SWNTs and deposition over a large area. The significance of this approach was verified by assessing the field emission characteristics of the SWNT array with and without the support of the colloidal monolayer. The emission values of this assembling method is the highest one other compared to other self-assembling methods reported thus far, and is in the suitable range of mass production.
We present a self-assembling method for controlling the ring-shape of SWNTs through a non-covalent interaction with porphyrin (5, 10, 15, 20-tetrakis(4-(11- mercaptoundecyl)oxyphenyl)-21H, 23H-porphine). This self-organization behavior of π-conjugated porphyrin-SWNTs was found to be dependent of the concentration of SWNTs and porphyrin, the ratio of composition of SWNTs to porphyrin, and the type of substrate surface. Absorbance spectroscopy shows strong π-π interactions between the porphyrin and SWNTs are confirmed by the absorbance bands resulting from J-aggregates of porphyrin. SEM and TEM images shows that the SWNT rings are located over the entire substrate surface and most of the rings have a diameter distribution typically ranging from 0.5 and 1.2 m. The ring-structure of SWNTs can be deposited on various substrates after a simple treatment, which is a remarkable advantage for potential applications such as electronic devices and biosensor.