| Jan 24, 2025 |
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(Nanowerk News) Stretching or bending, which is better? A lucky discovery led researchers to a new understanding of how ultrathin materials absorb and reflect light. The new model — if confirmed — could change the way ultrathin materials are developed and used.
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The discovery came when researchers at the United Kingdom’s National Physical Laboratory were examining thin semiconducting materials known as transition metal dichalcogenides (TMDs). These materials have potential applications in nanoelectronics and quantum computing, but two-dimensional TMDs are especially interesting because of their ability to absorb and emit light. Bending or stretching these materials can result in the emission of individual photons from specific areas, which is extremely useful for secure quantum communication.
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Their findings were published in the journal Science and Technology of Advanced Materials (“Curvature-enhanced localised emission from dark states in wrinkled monolayer WSe2 at room temperature”).
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| Schematic diagram illustrating the distinction between strain and curvature in wrinkled material. (Image: NPL)
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The team was using these materials to test an instrument when they made an unexpected discovery. “When we started this study, we were simply trying to use the localised light emission from wrinkles as a way to test the resolution of our instrument but experimental science is full of surprises!” says lead author Sebastian Wood. “It wasn’t possible to explain the results we found using existing models, so this stimulated us to think further.”
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Existing models proposed that single-photon emission by TMD materials was a result of the strain on the materials, but they don’t distinguish between strain caused by stretching or bending. The team’s detailed analysis enabled them to differentiate the two types of strain. “We propose that bending is more important than stretching for achieving localised emission, which has major implications for how the materials are developed and used,” explains Wood.
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“Discovering that the accepted models in literature were not able to explain our results presented an exciting challenge. We had to think again about the fundamental physics of the experiment, resulting in this important insight,” adds Wood.
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“The next step is for other groups to scrutinise our work and reproduce our results. We’re also discussing with some other research groups about a theoretical study of the proposed model.”
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If confirmed, researchers can use the curvature of ultrathin TMD materials to control photon emission, offering a valuable tool for engineering optoelectronic materials and quantum technology.
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