The power of polymer wrapping: Selection of semiconducting carbon nanotubes, interaction mechanism, and optoelectronic devices

Carbon nanotubes have great electrical, mechanical and thermal properties. If we make the carbon nanotubes soluble in organic solvents, we can use these nanotube inks to produce electronic devices such as solar cells and field effect transistors. The ability to make inks from carbon nanotubes allows the possibility of preparing electronic devices in a similar fashion as printing newspapers.

For the production of carbon nanotube inks, it is important to ensure that the semiconducting carbon nanotubes are separated from the metallic carbon nanotubes to obtain semiconducting carbon nanotubes at a high purity. During my PhD project, we used conjugated polymers to perform this separation. Our results show which polymers interact better with the carbon nanotubes in order to isolate the semiconducting nanotubes. By analyzing the chemical structures using simulations, we identified the mechanism of the polymer-carbon nanotube interaction. We also found that the addition of specific additives to the ink allows the control of the polarity of the transistors, which is important for the production of different technological applications.

From the semiconducting carbon nanotube inks, we succeeded to fabricate tailor-made high performing field effect transistors. This knowledge will help make them easier and cheaper to manufacture. We furthermore discovered that a layer of semiconducting carbon nanotube ink in a solar cell greatly improves the stability, which might lead to a broader use of solar cells as a source of green energy.