25 October 2021
Two-dimensional materials on a roll
Published online 22 March 2021
Rolling together layers of 2D materials opens a new dimension of exotic behaviour.
2D materials that are made of a layer of atoms or molecules just one or a few atoms thick have interesting electronic and optical properties. A research team, with members in China, the US, and Saudi Arabia, has now taken the possibilities into another dimension by rolling several layers of 2D materials into higher order structures.
“This offers a versatile artificial materials platform to investigate emergent properties and realize new device functions,” says Xidong Duan of Hunan University in China.
The individual layers do not have strong chemical bonds between them; only weak inter-atomic forces called van der Waals interactions. Rolling up the layers, which can have different compositions, creates materials whose properties vary depending on their chemical composition and the arrangements in which they are rolled together.
Duan says this is the first time that such higher order superlattices have been made, which opens up a new world of properties to explore. Their creation was challenging because it requires switching between different chemical environments and temperatures, which can damage the fragile atomically thin crystals.
The researchers expect that the novel electronic and optical properties they are discovering in their structures might be used to make improved photodetectors, light-emitting diodes, transistors, lasers and other devices that exploit unique quantum mechanical effects. They could also shed light on some exotic aspects of quantum physics.
The researchers are now exploring the effects of subtle geometric variations for further interesting and potentially useful behaviour.
Zhao, B., et al. High-order superlattices by rolling up van der Waals heterostructures. Nature 591, 385-390 (2021).