Context: The 2023 Nobel Prize in Chemistry was awarded jointly to Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov for the discovery and synthesis of quantum dots.

• Quantum dots are nanoparticles of semiconducting materials. Their very small size gives them properties that differ from those of larger particles of the same material. For example, their absorption and emission of light varies with size. This is due to quantum effects arising from electrons in the particles being squeezed together.

• Last year Carolyn R Bertozzi, Morten Meldal and K Barry Sharpless have been awarded the Nobel Prize 2022 in Chemistry “for the development of Click Chemistry and Bioorthogonal Chemistry”.

Importance of the Research

• QLED televisions use quantum dots to enhance the colours displayed on screen. They are also used in some LED lamps. Future applications could include flexible electronics, tiny sensors, and thinner solar cells.

• The light from quantum dots can also be used in biochemistry and medicine. “Biochemists attach quantum dots to biomolecules to map cells and organs. 

• Doctors have begun investigating the potential use of quantum dots to track tumour tissue in the body. 

• Chemists instead use the catalytic properties of quantum dots to drive chemical reactions.

About their Contribution

• In 1981, Alexei Ekimov produced glass tinted with copper chloride. He controlled the size of the copper chloride nanoparticles that formed in the glass and noticed that particle size affected the colour of the glass, with smaller particles absorbing more blue light.

• In 1983, Louis Brus created solutions of cadmium sulfide nanoparticles, and noticed that the properties of freshly made and older solutions differed. He also discovered that the smaller the nanoparticles, the bluer the light they absorbed.

• In 1993, Moungi Bawendi grew nanocrystals of cadmium selenide of a specific size in a solvent which produced smooth and even particles. This effective method for producing quantum dots paved the way for their use in wider applications.

What are quantum dots?

• The properties of any element depends on how many electrons it has. However, when matter is really tiny, of nano-dimensions, its properties depend on its size. 

• The smaller a particle, the more its electrons are squeezed together, and that affects its properties. Such particles, whose size determines their behaviour, are called quantum dots.

• While in theory, scientists had known for long that such particles could exist, the three Nobel laureates, through their work over decades — Bawendi did his postdoctoral research under Brus — succeeded in creating quantum dots of a high quality, which could be put to practical use.