In 1884, Edwin Abbott wrote the novel Flatland: A Romance in Many Dimensions as a satire on the Victorian hierarchy. He imagined a world that only existed in two dimensions, where beings are 2D geometric figures. The physics of such a world somewhat resembles that of modern 2D materials, such as graphene and transition metal dichalcogenides, which include tungsten disulfide (WS2), tungsten diselenide (WSe2), molybdenum (MoS2) and molybdenum diselenide (MoSe2).
Modern 2D materials are made up of single atom layers, where electrons can move in two dimensions, but their movement in the third dimension is limited. As a result of this “compression”, 2D materials have improved optical and electronic properties which hold great promise as next-generation ultra-thin devices in the fields of energy, communications, imaging and technology. quantum computing, among others.
Typically, for all of these applications, 2D materials are envisioned in flat layouts. Unfortunately, the strength of these materials is also their greatest weakness – they are extremely thin. This means that when illuminated, light can only interact with them to a tiny depth, which limits their usefulness. To overcome this shortcoming, researchers are starting to look for new ways to bend 2D materials into complex 3D shapes.
In our 3D universe, 2D materials can be arranged on top of each other. To extend Flatland’s metaphor, such an arrangement would literally represent parallel worlds inhabited by people destined never to meet.
Now, scientists in the Department of Physics at the University of Bath in the UK have found a way to organize 2D sheets of WS2 (previously created in their lab) into a 3D configuration, resulting in a heavily altered energy landscape. compared to that of flat WS2 plates. This particular 3D arrangement is known as “nanomesh”: a webbed network of densely packed and randomly distributed stacks, containing twisted and / or fused WS2 sheets.
Changes like this in Flatland would allow people to enter each other’s worlds. “We did not seek to afflict the people of Flatland,” said Professor Ventsislav Valev who led the research, “But because of the many flaws we have nano-designed in 2D materials, these hypothetical inhabitants would find their rather strange world indeed.
“First, our WS2 sheets have finished dimensions with jagged edges, so their world would have an oddly shaped end. In addition, some of the sulfur atoms have been replaced with oxygen, which would be simply wrong for any inhabitant. More importantly, our sheets intersect and merge, and even twist on top of each other, changing the energetic landscape of materials. To the Flatlanders, such an effect would resemble the laws of the universe having suddenly changed throughout their landscape. “
Dr Adelina Ilie, who developed the new material with her former doctoral and post-doctoral fellow Zichen Liu, said: “The altered energy landscape is a key point in our study. It is proof that the assembly of 2D materials in a 3D arrangement it just results in “thicker” 2D materials – it produces entirely new materials. Our nanomesh is technologically simple to produce, and it offers adjustable material properties to meet the demands of future applications. “
Professor Valev added: “Nanomesh has very strong nonlinear optical properties – it efficiently converts one laser color to another over a wide range of colors. Our next goal is to use it on Si waveguides. to develop quantum optical communications. “
PhD student Alexander Murphy, also involved in the research, said: “In order to reveal the altered energy landscape, we have devised new methods of characterization and I look forward to applying them to other materials. Who knows what we are doing. could we find out more? “
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Material provided by University of Bath. Note: Content can be changed for style and length.