Comparative studies of carbon nanotubes functionalization for future electronics

Carbon nanotubes (CNTs) are tubular particles with nanoscale diameters and lengths on the micrometer scale. They possess unique properties such as exceptional electrical conductivities that are relevant to multiple future applications including solar energy conversion, supercapacitors, and field-effect transistors. However, many envisioned CNT-based electronic devices have not yet been commercialized because of the limited water processability of CNTs. A widely accepted approach to increase their aqueous phase polydispersity involves functionalization: introducing functional groups to the exterior surfaces of CNTs as handles to interact with water and/or assemble with other materials. We report here the results of destructively functionalizing CNTs utilizing harsh reaction conditions and nondestructive grafting; these different syntheses routes created CNTs with varied structures and self-assembling behavior. Grafted/functionalized CNT nanomaterials were mixed with both surfactants and LAPONITE® nanoparticles to facilitate the formation of stable colloidal dispersions. As the solvent was removed, these dispersions afforded solid-state self-assemblies containing CNT nano-networks. These solid composites were deposited on conductive glass surfaces as electrodes for the development of flexible solar films. Nanocomposite electrical performances were investigated by conductive atomic force microscopy (cAFM) and surface morphologies were studied using tapping mode AFM analyses. These methods to functionalize/graft CNTs, when combined with dispersing agents and surfactants, have proven successful for fabricating water processable conductive nanocomposites for electronic applications.