• The 2023 Nobel Prize in chemistry was awarded to Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov for the discovery and synthesis of quantum dots.
• These nanoparticles have wide-ranging applications across fields like electronics, advanced surgery, and quantum computing.

ABOUT QUANTUM DOTS

• Quantum dots are particles that are a few nanometres wide.
• They exhibit unique optical properties due to their small physical size.
• Their structure and atomic composition are the same as bulk materials, but the properties of the latter don’t depend on their size.
• In fact ,the properties of quantum dots can be changed by changing their size.
• At the scale of nanometres, materials and particles are capable of new, size-dependent properties because quantum physical forces start to dominate.
• At the macroscopic scale, on the other hand, like in our day to day lives, gravity and the rules of classical physics dominate.

THE NOBEL-WINNING RESEARCH

• In the early 1980s, Ekimov succeeded in creating size-dependent quantum effects in coloured glass.
• In 1983, Brus and his colleagues went a step ahead and prepared similar crystals in a liquid solution, rather than in a glass. This allowed the researchers to better manipulate and study the crystals.
• Finally, in 1993, Bawendi and his coworkers developed a technique to make the quantum dots of well-defined sizes and with high optical quality.
  • This process began by injecting some substance (of which the dot would be made) into a hot solvent and then heating the solution. Nanocrystals automatically began to take shape, and larger particles formed when the solution was heated for longer. The solvent also ensured that the crystals had a smooth outer surface.
  • This method was quite easy, which meant many scientists could use it to make quantum dots that they required and study them.

APPLICATIONS

• One of the simplest applications of quantum dots is to light computer monitors and television screens.
  • Blue LEDs behind the screen excite these dots, causing them to emit light of different colours.
• Nanoscale-sized quantum dots are also used to map biological tissues by biochemists.
• Quantum dots are also used in photovoltaic cells to improve the absorption and efficiency in converting solar light into electricity.
• Certain cancer treatments use quantum dots for targeted drug delivery and other therapeutic measures.
• Quantum dots can be used as security markers on currency and documents as an anti-counterfeit measure. Broadly, they can be used as fluorescent markers to tag and track objects.