Towards flexible electronics based on single walled carbon nanotube networks
P.N. Nirmalraj, J.N. Coleman and J.J. Boland
CRANN & Trinity College Dublin, IE
Keywords: electronic properties, single walled, carbon nanotube, SWNT
Abstract:We report on efforts to develop highly conducting transparent electrodes materials based on single walled carbon nanotube (SWNT) networks. We probe the local structure and electronic properties of these networks using conductance AFM (C-AFM) imaging and high resolution STM. The resistance at network junctions is shown to dominate charge transport with values that are at least five times the resistance of individual tubes. An analysis of individual junctions reveals a striking dependence on the size of the interconnecting tubes, with the resistance increasing as the diameter and number of tubes forming the junction increases. Acid treatment, which is known to introduce tube defects, is shown to reduce junction resistance, with 3x reduction observed for junctions involving individual tubes. Controlled elimination of defects by high temperature annealing resulted in a 5x increase in the junction resistance over that of pristine tubes, thus demonstrating that the presence of defects is critical in the formation of low barrier junctions. These results were corroborated by Raman and high resolution STM analysis and the implications for flexible transparent conductors, sensors and active electronic components based on SWNT networks are discussed.