The Nobel Prize in Chemistry 2023 to Quantum dots!!

Quantum dots absorb light and then emit it at another wavelength depending on the size of the quantum dots. The photograph is taken by Dr. Anamul Haque at Centre for Nano and Soft Matter Sciences, India.

The Royal Swedish Academy of Sciences has announced the names of the scientists winning the Nobel Prize in Chemistry for the year 2023 for the fundamental discovery in nanotechnology.

Nobel Prize in Chemistry 2023

1. Prof. Moungi G. Bawendi, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA

2. Prof. Louis E. Brus, Columbia University, New York, NY, USA

3. Prof. Alexei I. Ekimov Nanocrystals Technology Inc., New York, NY, USA

“For the discovery and synthesis of quantum dots.”

What are Quantum Dots(QDs) and what changes does this discovery make in the world?

The Quantum Dots which are also described as artificial atoms are nanometer-sized crystals displaying semiconducting properties. They are produced by combining transition metals and non-metal or metalloid elements (e.g. cadmium selenide (CdSe) and cadmium telluride (CdTe)). Due to their really small size (just 2 – 10 nm in diameter), these dots exhibit quantum mechanical behaviors. Owing to their semiconductor properties, they can move electricity around, similar to the ‘bulk’ material semiconductors. However, due to its tiny size, the electrons of the quantum dot experience quantum confinement in all three spatial dimensions. This confinement leads to the quantized energy levels, which allow them to interact with light of specific wavelengths by fine-tuning a single parameter, the particle’s size.

Quantum dots – The essential seed for nanotechnology

In chemistry, we learn that elemental properties are governed by the number of electrons it consist of. However, when matter shrinks down to a few nanometers, quantum phenomena governed by the size of the matter arise. The Nobel Laureates in Chemistry 2023 have successfully synthesized semiconductor crystals so tiny that their properties are determined by quantum phenomena. These nanocrystals, which are called quantum dots, are now of great importance in nanotechnology.

“Quantum dots have many fascinating and unusual properties. Importantly, they have different colours depending on their size,” says Johan Åqvist, Chair of the Nobel Committee for Chemistry.

This concept has been known to Physicist since the 1930s when Physicist Herbert Fröhlich theoretically proposed and pioneered the concept that material properties can depend on the macroscopic dimensions of a small particle, but at that time it was almost impossible to sculpt in nanoscales. Therefore, it was a far-fetched idea and was believed to be put to practical use. Few researchers fabricated nanostructures in the 1970s and demonstrated that their optical properties indeed varied depending on size. However, these observations were related to nanostructures designed on top of bulk materials, which could not be attributed to the materials by themselves. 

In 1979, Alexei Ekimov, a solid-state physicist working at the Vavilov State Optical Institute in Soviet Russia alongside theoretician Alexander Efros, began studying semiconductor-activated glasses, known as Schott glasses. In the early 1980s, they successfully created size-dependent quantum effects in coloured glass. This was the first time when someone succeeded in intentionally producing quantum dots. The colour came from nanoparticles of copper chloride and Ekimov demonstrated that the particle size affected the colour of the glass via quantum effects.

A few years later, Louis Brus at Bell Laboratories in New Jersey, US became the first scientist in the world to showcase size-dependent quantum effects in particles floating freely in a liquid medium.

In 1993, Moungi Bawendi moved a step further and revolutionized the production of quantum dots, and generated almost perfect particles. The high quality of the quantum dots was necessary for them to be utilized in an ever-growing range of commercial products thanks to their tuneable properties.

What are the applications of Quantum dots?

The applications of the quantum dots are in the following fields.

1. QDs in Light-Emitting Diodes (QLED technology) for display applications such as computer monitors and television screens.

2. To boost energy conversion efficiency in photovoltaic devices.

3. In the biomedical and environmental fields, the high luminescence, low toxicity, and biocompatibility of quantum dots arise as a perfect candidate for bioimaging, diagnostics, and biosensing applications.

4. Quantum dots are used in photocatalysis technology to convert light into chemical energy. They have also been utilized to improve existing or to create new catalytic routes.

We have entered the field of flexible electronics, and researchers believe that in the near future, they could contribute to, tiny sensors, thinner solar cells, and encrypted quantum communication. The Nobel Prize in Chemistry 2023 recognizes that nanoscience, particularly quantum dots has matured and we have just started exploring the potential of these tiny particles. 

Read more: Nobel Prize in Physics 2023