Horizontally aligned carbon nanotube networks: a route toward highly conductive, flexible & controllably transparent electrodes, field emitters and infra-red sensors

Flexible, highly conductive and transparent electronic materials are critically important areas of active research. Metals, although being excellent conductors are largely brittle and have increasingly poor conductance when strained. Moreover, metals are optically opaque at the technologically relevant sub-100 nm node. Serpentine Au thin films embedded in elastomeric membranes have gone some way towards solving the flexibility problem. Transparent conducting metal oxides, such as increasingly expensive indium tin oxide, open up the field of optoelectronics. Simultaneously achieving high transparency and high conductivity is the ultimate goal. Conductive polymers including untreated, and poly-ethyl glycol enhanced, Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) have had some success, however sheet resistances require further improvement and the observed non-constant variation in optical transmission with wavelength across the NIR-vis spectra result in an undesirable characteristic blue hue in most PEDOT:PSS derivatives. Carbon-based materials show significant promise and solve many of these problems. Here we report on the fabrication, characterisation and application of thin films comprised of random and aligned horizontal carbon nanotube (H-CNTs).