Paris:

Quantum dots are tiny crystals that scientists can tune to different colours, giving an extra-vivid pop to next-generation TV screens or illuminating tumours inside bodies so surgeons can hunt them down. Three scientists won the Nobel Chemistry Prize on Wednesday for their work turning an idea first theorised in the 1930s into a reality that now has pride of place in living rooms across the world.

What are quantum dots?

Quantum dots are semiconducting particles just one-thousandth the width of a human hair. In 1937, the physicist Herbert Froehlich predicted that once particles were small enough — so-called nanoparticles — they would come under the strange spell of quantum mechanics.

To explain this quantum phenomenon, American Chemical Society president Judith Giordan said to “think of it like a little box”.

When a particle is shrunk down small enough, the electron is “going to whack into the sides of the box,” she told AFP.

In a larger box, the electrons would whack the sides less often, meaning they have less energy.

For quantum dots, the larger boxes emit red light, while the smaller ones show up blue.

This means that by controlling the size of the particle, scientists can make their crystals red, blue and everything in between.

Leah Frenette, an expert on quantum dots at Imperial College London, told AFP that working with the nanomaterial was like “watching rainbows all day”. 

But it would be 40 years after Froehlich’s prediction that anyone was able to actually observe this phenomenon.

In the early 1980s, Russian-born physicist Alexei Ekimov — one of Wednesday’s new laureates — melted coloured glass and X-rayed the results. 

He noticed that the smaller particles were more blue, also recognising that this was a quantum effect.

But being glass, the material was not easy to manipulate — and being published in a Soviet scientific journal meant few noticed.

At around the same time in the United States, another new laureate Louis Brus — oblivious of Ekimov’s work — became the first to discover this colourful quantum effect in a liquid solution.

“For a long time, nobody thought you could ever actually make such small particles, yet this year’s laureates succeeded,” Nobel Committee member Johan Aqvist said.

“However, for quantum dots to become really useful, you needed to be able to make them in solution with exquisite control of their size and surface.”

The third new Nobel winner, French-born Moungi Bawendi, found a way to do just this in his lab at the Massachusetts Institute of Technology in 1993.

By precisely controlling the temperature of a liquid mixture of particles called colloids, Bawendi was able to grow nanocrystals to the exact size he wanted, paving the way for mass production.

What are quantum dots used in?

The most common everyday use of quantum dots is probably in “QLED” televisions.

Cyril Aymonier, head of France’s Institute of Condensed Matter Chemistry, told AFP that the nanocrystals “improve the resolution of the screen and preserve the quality of the colour for longer”.

Doctors also use their bright fluorescence to highlight organs or tumours in the bodies of patients.

Frenette said she is working on diagnostic tests which would use the dots as “little beacons” for diseases in medical samples. 

One problem is that most quantum dots are made using cadmium, a toxic heavy metal.

Both Aymonier and Frenette said they are working on quantum dots that are not toxic.

What’s quantum dots’ future use?

In the future, quantum dots could have the potential to double the efficiency of solar cells, Giordan said.

Their strange quantum powers could produce twice as many electrons as existing technology, she explained.

“That’s amazing because we are coming closer to the limit of current solar materials,” she added.

Were quantum dots used in the past?

While quantum dots are considered on the cutting edge of science, people have probably been using them for centuries without knowing it.

The reds and yellows in stained glass windows as far as back as the 10th-century show that artists of the time unwittingly took advantage of techniques that resulted in quantum dots, according to scientists.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

The 2023 Nobel Prize in Chemistry has been awarded to Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov for the discovery and synthesis of quantum dots, the Royal Swedish Academy of Sciences said in Stockholm.

Quantum dots have unique properties and now spread their light from television screens and LED lamps. They catalyse chemical reactions and their clear light can illuminate tumour tissue for a surgeon, the Academy said in a press release.

Researchers have primarily utilised quantum dots to create coloured light. They believe that in the future quantum dots can contribute to flexible electronics, miniscule sensors, slimmer solar cells and perhaps encrypted quantum communication.

Today quantum dots are an important part of nanotechnology’s toolbox. The 2023 NobelPrize laureates in chemistry have all been pioneers in the exploration of the nanoworld, said the Academy.

In the early 1980s, this year’s chemistry laureates Louis Brus and Alexei Ekimov succeeded in creating — independently of each other — quantum dots, which are nanoparticles so tiny that quantum effects determine their characteristics.

In 1993, chemistry laureate Moungi Bawendi revolutionised the methods for manufacturing quantum dots, making their quality extremely high — a vital prerequisite for their use in today’s nanotechnology.

“Quantum dots are thus bringing the greatest benefit to humankind. Researchers believe that in the future they could contribute to flexible electronics, tiny sensors, thinner solar cells and encrypted quantum communication – so we have just started exploring the potential of these tiny particles,” the release added.

Last year the prestigious Prize was cinched by Carolyn R. Bertozzi, Morten Meldal and K. Barry Sharpless for the development of click chemistry and bioorthogonal chemistry. Their work in click chemistry has been used to develop pharmaceuticals, mapping DNA while bioorthogonal chemistry refined the pharmaceuticals used to treat cancer.

On October 3, the Royal Swedish Academy of Sciences announced the winners of this year’s Nobel Prize in Physics which was shared by Pierre Agostini, Ferenc Krausz and Anne L’Huillier for “experimental methods that generate attosecond pulses of light for the study of electro dynamics in matter.”

The Nobel Prize for Medicine or Physiology was granted to Katalin Karikó and Drew Weissman for their “discoveries concerning nucleoside base modification that enabled the development of effective mRNA vaccines against COVID-19.”

The recipients of the Nobel Prize in Literature will be announced on October 5 followed by the Prize for Peace on October 6 while the Prize for Economic Sciences will be released on October 9.

The prizes carry a cash award of 10 million Swedish kronor (nearly $900,000) and will be awarded on December 10. The money comes from a bequest left by the prize’s creator, Swedish inventor Alfred Nobel, who died in 1895.