Order of magnitude improvement in the transport performance of carbon nanotube films by completely removing surfactants

Surfactant-based separation techniques have been developed for the high-efficiency production of high-purity semiconducting single-wall carbon nanotubes (s-SWCNTs), which establish an important material foundation for the preparation of high-performance carbon-based electronic devices. However, surfactant molecules wrapping around SWCNTs during structural separation inevitably degrade the resulting device performances due to increasing contact resistance between the SWCNTs and electrodes and between individual SWCNTs. Here, we developed a simple and effective strategy for completely removing the surfactant molecules around separated s-SWCNTs by annealing and rinsing. With this technique, defects were not clearly increased in the crystal structure of SWCNTs, and the transport performances of SWCNT-based thin film transistors (TFTs), including the on-state current and mobility, were improved by approximately an order of magnitude, while the on-off ratio increased by nearly 1.5 orders of magnitude. Upon shortening of the channel lengths of the devices, high-performance TFTs were fabricated based on an increase in the proportion of individualized SWCNTs that directly connected the source and drain electrodes. The present technique provides an important foundation for promoting the development of carbon-based electronic devices.