This year’s chemistry Nobel Prize rewards the discovery and development of quantum dots, nanoparticles so tiny that their size determines their properties. These smallest components of nanotechnology now spread their light from televisions and LEDs, and can also guide surgeons when they remove tumor tissue, among many other things.

Everyone who studies chemistry learns that an element’s properties are governed by how many electrons it has. However, when matter shrinks to nano-dimensions quantum phenomena arise; these are governed by the size of the matter. The Nobel laureates in chemistry 2023 have succeeded in producing particles so small that their properties are determined by quantum phenomena. The particles, which are called quantum dots, are now of great importance in nanotechnology.

“Quantum dots have many fascinating and unusual properties. Importantly, they have different colors depending on their size,” says Johan Åqvist, chair of the Nobel committee for chemistry.

Physicists had long known that in theory size-dependent quantum effects could arise in nanoparticles, but at that time it was almost impossible to sculpt in nanodimensions. Therefore, few people believed that this knowledge would be put to practical use.

However, in the early 1980s, Alexei Ivanovich Ekimov (Nanocrystals Technology Inc, New York, USA) succeeded in creating size-dependent quantum effects in colored glass. The color came from copper chloride nanoparticles and Ekimov demonstrated that the particle size affected the color of the glass via quantum effects.

A few years later, Louis Eugene Brus (Columbia University, New York, USA) was the first scientist in the world to prove size-dependent quantum effects in particles floating freely in a fluid.

In 1993, Moungi Gabriel Bawendi (Massachusetts Institute of Technology, Cambridge, USA) revolutionized the chemical production of quantum dots, resulting in almost perfect particles. This high quality was necessary for them to be utilized in applications.

Quantum dots now illuminate computer monitors and television screens based on QLED technology. They also add nuance to the light of some LED lamps, and biochemists and doctors use them to map biological tissue.

Researchers believe that in the future quantum dots contribute to flexible electronics, tiny sensors, thinner solar cells and encrypted quantum communication – so humankind has just started exploring the potential of these tiny particles. (Source: nobelprize.org)

Further reading: Stuart Stubbs (Quantum Science): How the hidden quantum realm reveals the invisible – tunable quantum dots offer a sought-after breakthrough in SWIR sensing and imaging, PhotonicsViews 19(6), December 2022/January 2023, pages 38-41; DOI: 10.1002/phvs.202200046