Spray deposition of carbon nanotube thin films

Random carbon nanotube (CNT) networks have raised a continuously increasing interest among a broad and multidisciplinary community of researchers over the last decade. The remarkable and concurrently diverse properties of such networks have rendered them suitable for a wide range of applications in science and engineering. Among the most promising applications are transparent conductive electrodes [1-3], thin-film transistors and circuits [4,5], and mechanical and chemical sensors [6-8]. The desired functionality of the CNT films produced for different applications depends primarily on the choice of the appropriate raw material. Nevertheless, it is strongly influenced by major process-specific aspects. A random CNT network can either be directly grown by chemical vapor deposition (CVD) or processed from a solution of well-dispersed nanotubes. The CVD process involves catalyst nanoparticles acting as seeds for the growth of the CNTs. Although this method leads to films with individually separated tubes and better inter-tube junctions, it is a high vacuum/temperature process that is not suitable for the emerging field of low-cost flexible electronics. Solution-based methods, on the other hand, have several advantages. In general, relying on this kind of low-temperature processes overrides most constraints on the choice of the substrate material, enabling fabrication even on plastic substrates. The omission of a high-vacuum process further reduces costs significantly.