Nano‐Engineering of SWNT Networks for Enhanced Charge Transport at Ultralow Nanotube Loading

Abstract

We demonstrate a simple and controllable method to form periodic arrays of highly conductive nano-engineered single wall carbon nanotube networks from solution. These networks increase the conductivity of a polymer composite by as much as eight orders of magnitude compared to a traditional random network. These nano-engineered networks are demonstrated in both polystyrene and polythiophene polymers.

Ordered and Highly Conductive Carbon Nanotube Nano‐Networks in a Semiconducting Polymer Film by Solution Processing

“…[ 27 ] The much increased charge transport is due to the formation of an interconnected network of nanotubes inside the patterns from top to bottom of the fi lm. [ 27 ] The conductivity of a regio-regular semiconducting polymer and SWNT composite fi lm was increased by a factor of ≈14 at a low concentration of 0.11 wt% SWNTs. However, the relatively high pressures (15-50 bar) and temperatures needed (150-200 °C) may not be suitable for materials whose properties may change under these conditions.…”

“…[ 27,31 ] The method presented is controllable, scalable and the low amount of SWNT necessary reduces bundling, increases transparency, and provides an economical solution for electronic applications. Finally, the use of room temperature prevents any unwanted change in materials' properties which may be caused by high temperatures.…”

“…[32][33][34] The thermally produced nano-engineered networks were prepared as described in detail previously by fi rst spin-coating a layer of SWNTs, and next by spinning a P3HT fi lm until dry. [ 27 ] The two layer fi lm was imprinted at 200 °C, 20 bar, and 300 s before cooling to room temperature. The patterns dimensions were identical by either solvent or thermal imprinting.…”

“…Here we demonstrate a simple, room-temperature, and low pressure solution based method to produce well defi ned arrays of nano-engineered SWNT networks ( Figures 1 and 2 ) with much improved charge transport in a P3HT matrix compared to thermally produced nano-networks. [ 27,31 ] The method presented is controllable, scalable and the low amount of SWNT necessary reduces bundling, increases transparency, and provides an economical solution for electronic applications. Finally, the use of room temperature prevents any unwanted change in materials' properties which may be caused by high temperatures.…”

“…In the random network ( Figure 6 a), the nanotubes are not well separated and do not form conducting pathways in an optimal way as confi rmed by electrical characterization. [ 27,31 ] In the thermal method (Figure 6 c), the nanoscale fl ow of the composite melt helps with vertical re-orientation of the tubes and increases signifi cantly the number of pathways from top to bottom compared the random network. Finally, in the solvent method the tubes are more easily separated from each other (Figure 6 b), leading to less bundling and the creation of more interconnected pathways, thereby further increasing charge transport.…”