BY SIMON FROST | 18 OCTOBER 2023
Prize shared by three pioneers in the development of semiconductor nanocrystals.
The highest prize in chemistry has been awarded to three scientists who pioneered research into quantum dots – semiconductor nanocrystals measuring a few nanometres, with applications ranging from solar cell technology to medical imaging.
Moungi Bawendi (MIT, US), Louis Brus (Columbia University, US) and Alexei Ekimov (Nanocrystals Technology, US) were announced as the joint recipients of the Nobel Prize in Chemistry by the Royal Swedish Academy of Sciences on 4 October, 2023.
Ekimov, a Russian solid-state physicist, was the first to synthesise quantum dots in a glass matrix, in 1981; while Brus, an American chemist, became the first to do so in a colloidal suspension in 1983. Ten years later, Bawendi, an American chemist of French-Tunisian descent, developed the rapid injection method – the most widely used method for quantum dot synthesis.
‘For a long time, nobody thought you could ever actually make such small particles,’ Johan Aqvist, the Chair of the Academy’s Nobel committee for chemistry, said at a news conference announcing the 2023 laureates.
Speaking from a desk with five colourful flasks containing quantum dots in a liquid solution, he said: ‘This year’s laureates succeeded.’
Dialling in to the live conference, Bawendi described his reaction to the award as ‘very surprised, sleepy, shocked, unexpected, and very honoured’.
The names of the three laureates had been accidentally leaked several hours earlier, although Bawendi confirmed that he had not been informed. ‘I was awakened by the Swedish academy – I was sound asleep!’
Asked about the applications of quantum dots, Bawendi noted: ‘They are already widely used as colour downshifters in the display industry, and as biological tags [...] The world will see in the future where it will go – it’s hard to say at the beginning.’
Wide applications
Jean-Marc Pecourt, Senior Scientific Analyst at CAS, US, said: ‘There are certainly many promising applications in solar cells and the push for greater energy conversion efficiency. That is a big push, and I think quantum dots will play a part.
‘We’ve also seen a lot of different quantum dot materials being used as biomarkers for diseases like cancer, and I think we’re going to find more and more applications of that.
‘I don’t know how soon we’ll get there, but I think that quantum dots could have a very prominent role to play in the development of quantum computing, because it’s all based on optical transmission of information rather than electronic.’
One of the most important properties of quantum dots is their ability to emit light of different colours depending on their size. When a quantum dot is illuminated by light, it can absorb a photon and excite an electron to a higher energy level.
When the electron falls back to its ground state, it emits a photon of light. The wavelength of the emitted light depends on the size of the quantum dot. Larger quantum dots emit longer wavelength light (red), while smaller quantum dots emit shorter wavelength light (blue).
Dr Gilles Georges, Vice President and Chief Scientific Officer at CAS, said: ‘Moungi Bawendi, Louis Brus, and Alexei Ekimov have done highly impactful work on the discovery and synthesis of quantum dots.
The unique quantum mechanical properties of these nanoscale wonders are finding applications today in fields like biomedical imaging and energy-efficient LED displays, but we are also seeing significant emerging research advancing fields such as sustainable energy and consumer electronics including making solar cells more efficient, more flexible, and less expensive to manufacture, which will usher in a brighter and more sustainable future.’
The Swedish academy notes: ‘Researchers believe that in the future quantum dots can contribute to flexible electronics, miniscule sensors, slimmer solar cells and perhaps encrypted quantum communication.
‘One thing is certain – there is a lot left to learn about amazing quantum phenomena.’
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