The 2023 Nobel Prize in Chemistry, Quantum Dots

The 2023 Nobel Prize in Chemistry recognizes the groundbreaking discovery and development of quantum dots,

“nanoparticles so minuscule that their size dictates their characteristics.”

These tiny building blocks of nanotechnology are now widely used in television and LED lighting, and have even revolutionized surgical procedures by assisting surgeons in removing cancerous tissues, among other applications.

History

 In the early 1980s, Alexei Ekimov succeeded in creating size-dependent quantum effects in colored glass. The color 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 was the first scientist in the world to prove size-dependent
quantum effects in particles floating freely in a fluid.

In 1993, Moungi Bawendi revolutionised the chemical production of quantum dots, resulting in almost perfect particles. This high quality was necessary for them to be utilised in applications.

Quantum Dots

 Quantum dots are incredibly small, typically ranging in size from just a few nanometers to tens of nanometers in diameter, thousands of times smaller than the width of a human hair.

 Quantum dots are usually made from semiconductor materials like silicon, cadmium selenide (CdSe), or indium arsenide (InAs). These materials have electronic properties that can be precisely controlled.

 Quantum Confinement

What makes quantum dots special is their ability to confine electrons in a way that quantizes their energy levels. This means that electrons within a quantum dot can only have certain discrete energy levels, similar to how electrons orbit an atomic nucleus. The specific energy levels depend on the size and composition of the quantum dot.

Optical Properties

 Quantum dots have unique optical properties. When you shine light on them, they can absorb photons and then re-emit them at specific wavelengths, which can be controlled by adjusting the size of the quantum dot. This property makes them valuable for applications like displays, lighting, and even medical imaging.

Applications:

Quantum dots have a wide range of applications, including:

1. Quantum Dot Displays: They are used in high-quality displays, including some types of LED and QLED TVs, where their ability to emit specific colors of light enhances image quality.
2. Solar Cells: Quantum dots can be used to improve the efficiency of solar cells by capturing a broader range of solar energy.
3. Biological Imaging: In biology and medicine, quantum dots are used as fluorescent markers for tracking and imaging cells and molecules. Their tunable emission wavelengths are particularly useful in this context.
4. Quantum Computing: Researchers are exploring the use of quantum dots as potential building blocks for quantum computers due to their ability to trap and manipulate individual electrons.

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Courtesy: Nobel Prize Org, pngtree, wikipedia