Scientists from the Skolkovo Institute of Science and Technology (Skoltech) have proposed a fast and waste-free method for chemical processing of carbon nanotube films, which will improve their properties for further use in the production of touch screens and solar batteries.
Properties of Carbon Nanotube Films:
Carbon nanotube films are excellent conductors of electricity and transmit visible light, making them ideal for use in transparent electrodes for solar panels and touch screens.
These films offer advantages over traditional indium tin oxide electrodes, which are brittle and less sustainable.
Need for Doping:
Doping carbon nanotubes with small amounts of other substances can enhance their conductivity, transparency, and flexibility.
Current production technologies cannot produce carbon nanotubes with all the desired properties, making doping essential to adjust their characteristics.
Challenges with Existing Dopants:
The choice of dopants involves a trade-off between increasing conductivity, maintaining film transparency, and ensuring stability.
Common dopants:
Hydrogen Tetrachloroaurate: Improves conductivity and transparency but has a short-term effect.
Copper Bromide: Provides stability and conductivity but reduces transparency.
Solution with Nitrogen Dioxide Doping:
Skoltech scientists found that doping with gaseous nitrogen dioxide ("foxtail") solves the trade-off issue, improving conductivity, transparency, and stability simultaneously.
Nitrogen dioxide doping is fast, scalable, and waste-free, integrating easily into existing synthesis processes.
Excess nitrogen dioxide can be easily removed by cooling to 20°C, where it liquefies.
Advantages of Nitrogen Dioxide as a Dopant:
Stability: The effect of nitrogen dioxide doping decreases only by one and a half times over time, compared to a threefold reduction for hydrogen tetrachloroaurate.
Uniform Coating: As a gas, nitrogen dioxide achieves molecular thickness without forming multiple layers, simplifying its use in production.
Applications: The improved carbon nanotube films are suitable for producing electrodes for photovoltaics, touch screens, and automotive applications.