New insights into the oxidation of single-walled carbon nanotubes for the fabrication of transparent conductive films

Transparent conductive films (TCFs) based on oxidized single-walled carbon nanotubes (SWCNTs) are not typically fabricated because this type of SWCNT includes sp3 carbon centers, which impede carrier transport. The acidic carbonaceous fragments (ACFs) that are created during oxidative reactions act as dispersing agents, enabling the dispersion of SWCNTs without additives. However, the structure of ACFs prohibits carrier transport in networks; thus removal of ACFs from the SWCNT networks is essential for improving TCF performance. In this work, we used this idea in order to fabricate ACF-free high-performance TCFs based on oxidized SWCNTs. The ACFs were initially used as dispersing agents. They were then dissolved and removed after the formation of a SWCNT network. The functional groups introduced onto the oxidized SWCNTs were mainly distributed across ACFs, whereas the SWCNTs remained unmodified. The removal of the ACFs improved the performances of the TCFs. As the sizes of the unmodified SWCNT bundles decreased, the performances of the oxidized-SWCNT-based TCFs improved (σdc/σop = 14.7), providing properties comparable to those of films prepared using a surfactant-stabilized dispersion.