Transparent electrodes made from metal oxides suffer from poor flexibility and durability. Highly transparent and electrically conductive thin films were assembled as a potential indium tin oxide (ITO) replacement using layer-by-layer (LbL) assembly of single-walled carbon nanotubes (SWNTs), stabilized with negatively charged deoxycholate (DOC), and positively charged poly(diallyldimethylammonium chloride) [PDDA]. Ellipsometry, quartz crystal microbalance, and UV-vis were used to measure the linear growth of these films as a function of the number of bilayers deposited, while TEM and SEM were used to visualize the morphology of these films. The PDDA/ (SWNT + DOC) system produced transparent (>82% visible light transmittance) and electrically conductive (~160 S cm-1) 20-bilayer films with a 38.4 nm thickness. Moreover, a series of post treatments, involving heating and nitric acid doping, were used to increase conductivity to 1430 S -1 (Rs = 300 Ω sq-1), with no change in transparency, owing to the removal of PDDA and the charge transfer doping. This study demonstrates high visible light transmittance and electrical conductivity of SWNT-based thin films, which are potentially useful as flexible transparent electrodes for a variety of optoelectronic applications.
Park, Y.T., A.Y. Ham, J.C. Grunlan
Journal of Materials Chemistry
363 - 8