Nobel Prize in Chemistry for revolutionizing nanotechnology with quantum dots

This Wednesday, the Nobel Prize in Chemistry awarded the Frenchman Moungi Bawendi, the American Louis Brus and the Russian Alexei Ekimov for the discovery and development of quantum dots, which have revolutionized nanotechnology and have multiple applications in electronics, medicine and chemistry.

Those very small particlesthat its size determines its properties” illuminate computer and television screens, as well as LED lamps, and are used to provoke chemical reactions or to remove tumors, explains the Royal Swedish Academy of Sciences, the institution that awards the prize each year.

Ekimov and Brus independently created quantum dots and Bawendi transformed the methods for producing them by improving their quality, allowing their use in nanotechnology.

This year, the name of the winners had been revealed in a statement, hours before the official announcement, sent by mistake by the Academy to several Swedish media.

The secretary general of the Royal Swedish Academy of Sciences, Hans Ellegren, today lamented “deeply” the shipment, for “a reason still unknown“, of the statement, although he highlighted that “The important thing is that it did not affect in any way the granting of the prizes”.

Ellegren made these statements at the press conference in which the award was officially announced, to which one of the Bawedi winners also connected by phone.

The new Nobel Prize winner assured that he was “very surprised” and “very honored” for an award that he did not expect and that he found out about when he received the call from the Swedish Academy, since he was sleeping.

The president of the Nobel Committee for Chemistry, Johan Åqvist, was in charge of explaining the award and what quantum dots are, which have many fascinating and unusual properties and, most importantly, have different colors depending on their size.

For decades, scientists speculated that nanoparticles might have unusual characteristics and, using mathematical tools, predicted numerous size-dependent quantum effects, but they lacked the technology to test it in practice.

In the late 1970s, Ekimov, then working at a state optical institute in the Soviet Union, became interested in how the same substance could produce glasses of different colors and used semiconductors to examine these glasses.

He decided to make colored crystals with copper chloride, heated the molten glass and, once cooled and hardened, passed it through X-rays, discovering that light absorption was affected by the size of the particles: for the first time, someone had produced deliberately quantum dots.

Ekimov published his discovery in a Soviet scientific journal, difficult to access outside the USSR, in 1981.

Two years later, Brus became the first researcher to discover size-dependent quantum effects in particles floating freely in a fluid.

While working on how to use solar energy to cause chemical reactions, Brus decided to use cadmium sulfide particles, which can capture light, with a surprising result: the largest ones absorbed light at the usual wavelength, but the smallest They had an absorption that changed towards the blue color.

Brus noted that he had observed a size-dependent quantum effect and published his finding.

But the method developed by this American scientist had a problem: the quality of the nanoparticles was unpredictable and many often contained defects, which limited their applications.

Bawendi, then a postdoctoral student, joined Brus’ laboratory in 1988, where he worked on developing methods to improve the production of quantum dots, a task he later continued at the Massachusetts Institute of Technology (USA).

And in 1993 the definitive breakthrough occurred: by injecting the substances that would later form nanocrystals into a heated solvent, he saturated the solution, which caused tiny crystal embryos to begin to form simultaneously and, by varying the temperature, they created crystals of different shapes. size.

The crystals produced were “almost perfect” and caused different quantum effects, which paved the way for more scientists to start working with nanotechnology and the unique properties of quantum dots.

Born in 1945 in the former USSR, Ekimov earned his doctorate in 1974 at the Ioffe Physical-Technical Institute in Saint Petersburg and later received the Soviet State Prize for Science and Engineering before emigrating in 1999 to the United States, where he works in private research.

Louis Brus (Cleveland, United States, 1943) received his doctorate from the American Columbia University in 1969, where he is an emeritus professor and where he currently researches.

Moungi G. Bawendi (Paris, 1961) received his doctorate in 1988 from the American University of Chicago and currently teaches at the prestigious Massachusetts Institute of Technology (MIT).

The three will share the 11 million Swedish crowns (almost one million euros) with which all Nobel Prize winners are endowed this year and succeed the Americans Barry Sharpless and Carolyn Bertozzi and the Danish Morten Medal in the prize list, distinguished in 2022 for the development of click chemistry.

The round of Nobel winners will continue tomorrow with the Literature prize.