The team behind the research used the LOQ instrument at ISIS to gain vital information on the structure of the ink.
Transparent conductive thin films used in high tech displays and touch screens rely primarily on the use of Indium Tin Oxide. However, this is expensive to process and brittle, making it unsuitable for touchscreens and flexible displays. Single walled carbon nanotubes (SWNTs) present an ideal alternative, but to be useful it must be possible to isolate individual, purified nanotubes with specific optoelectronic properties. Existing techniques using sonification or ultracentrifugation limit scalability and introduce damage into the SWNT structure.
A new, scalable method was developed for producing solutions of individual SWNTs. The process uses sodium metal dissolved into liquid ammonia to reduce the SWNTs. The liquid ammonia is evaporated to leave an expanded nanotubide salt. The charged SWNTs can then be dissolved in an organic solvent to create a solution of charged individual SWNTs.
The role of ISIS
The initial treatment of SWNTs in a metal ammonia solution is a key step in the separation process. A team from the London Centre for Nanotechnology used in situ small-angle neutron scattering (SANS) on LOQ at ISIS. SANS is a powerful technique for probing the structure of nanoparticles in solution, and showed that the SWNTs were unbundled to individual tubes in the liquid ammonia.
The benefits to industry
Siân Fogden from Linde Nanomaterials says, “SEERe- Ink doesn’t use harsh processing techniques, meaning the SWNTs maintain their length and can be used to create excellent quality transparent conductive films. ISIS played a vital role in confirming that the process of reducing SWNTs in liquid ammonia really worked.”