Carbon nanotubes have potential applications in light-emitting diodes, single-electron transistors, or as single-photon sources. These carbon nanotubes are made from graphene that is twisted in specific ways. However, this twisting is critical for allowing the desired properties to emerge.
Creating devices with desired properties requires precise manipulation of the position and orientation of the nanotubes, along with a property known as “chirality,” which essentially describes how much it is twisted. However, it is difficult to manipulate the molecules precisely as using solvents, or high-temperature treatment inevitably leaves the nanotubes dirty, hampering their optical characteristics.
Scientists solved this problem by looking for a way to engineer the nanotubes without using solvents. To do so, they experimented with using anthracene, a chemical derived from oil, as a sacrificial material.
More importantly, they picked up the nanotube on a scaffolding of anthracene to convey it any place they needed. Afterward, they utilized heat to sublimate the anthracene, leaving the nanotube in an optically pristine condition.
They also developed a method for monitoring the photoluminescence of the nanotubes during the transfer, ensuring that a nanotube with the desired optical properties would be placed at the right location.
After the dry transfer, the group affirmed that the remaining nanotubes have bright photoluminescence, up to 5,000 times as bright as the original molecule. This quality makes them ideal for optical devices. Furthermore, the group could decisively situate the nanotube on top of a nanosized optical resonator, upgrading the light emanation properties.
Keigo Otsuka from the RIKEN Cluster for Pioneering Research, the first author of the paper, “We believe that this technology could contribute not only to the creation of nanodevices from carbon nanotubes with desired properties but also to the construction of higher-order systems that are based on the free combination of atomic layer materials and other nanostructures.”
Yuichiro Kato, the leader of the group, said, “Beyond that, this technology has the potential to contribute to the development of atomically defined technologies that go beyond nanotechnology, in which materials with precise structures at the atomic level are used as building blocks to design and build functions that are different from those of existing materials.”
- Otsuka, K., Fang, N., Yamashita, D. et al. Deterministic transfer of optical-quality carbon nanotubes for atomically defined technology. Nat Commun 12, 3138 (2021). DOI: 10.1038/s41467-021-23413-4