Nobel Prize in Chemistry 2023, Quantum Dots, Applications of Quantum Dots

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Nobel Prize in Chemistry 2023

Context (TH | IE | IE): The Nobel Prize in Chemistry 2023 has been awarded to Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov for discovering and synthesising quantum dots.

What are Quantum Dots?

Each element’s properties are defined by its atomic structure, primarily the number and arrangement of electrons around the nucleus.
All pure elements display consistent properties, regardless of their size. For example, every piece of gold, whether a large 100 gm or a small 10 mg, has the same properties (fundamental facts).
However, at the nanoscale, when the matter is really small, the electrons are squeezed together, so its properties depend on size.
Quantum dots are semiconductor nanoparticles that exhibit size and composition-dependent optical and electronic properties.

Nanoscale materials exhibit size-dependent properties due to quantum forces, while gravity and classical physics govern at the macroscopic scale.
Nanoparticles: Particles whose sizes range between 1 to 100 billionth of a metre.
Semiconductor: A material with an electrical conductivity value falling between a conductor (such as copper) and an insulator (such as glass).

Quantum dots constitute a new class of materials that is neither molecular nor bulk material.
They have the same structure and atomic composition as bulk materials, but their properties can be tuned using a single parameter, i.e., the particle’s size.

What did Ekimov, Brus, and Bawendi do?

Dr. Ekimov’s Research

Dr. Ekimov used copper chloride to colour glass under various heating and cooling conditions.
He discovered that the glass’s light absorption depended on the particle size of copper chloride.
Larger particles behaved as expected, but smaller particles absorbed bluer light.
Ekimov recognised this as a size-dependent quantum effect.

Dr. Brus’s Reseacrh

Dr. Brus prepared similar size-dependent particles (crystals) of cadmium sulphide in a liquid solution rather than in a glass. This allowed the researchers to manipulate better and study the crystals.

Dr. Bawendi Research

Dr. Bawendi developed a technique to make these peculiar crystals, i.e. quantum dots, of well-defined sizes and with high optical quality.

What is the Discovery of Quantum Dots Important

At the nanoscale, quantum dots attain new, size-dependent properties that can be harnessed and controlled for novel applications.

Applications of Quantum Dots

Optoelectronics and Displays: Quantum dots are used in displays and lighting to enhance colour accuracy, brightness, and energy efficiency. QLED (Quantum-dot Light Emitting Diode) technology has led to the developing of high-quality, vivid displays in televisions and monitors.
Biological Imaging: Quantum dots are valuable in biological and medical imaging. They offer bright, stable fluorescence for precise cell and biomolecule tracking in living organisms.
Solar Cells: Quantum dots are studied for use in solar cells to boost efficiency and broaden the light absorption spectrum.
Quantum Dot Lasers: They are used to develop lasers with low threshold current and tunable emission, which find applications in telecommunications and optical signal processing.
Quantum Dot Computing: Quantum dots may serve as qubits (quantum bits) in quantum computing, advancing the development of robust, efficient quantum computers.
Sensors and Detection: Quantum dots can be used in sensors for substance detection and environmental monitoring due to their sensitivity and tunable traits.
Telecommunications: Quantum dots can amplify and transmit optical signals efficiently.
Material Science: Quantum dots provide insights into nanoscale quantum effects and material behaviour, driving innovation for novel materials and technologies.
Energy Storage: Quantum dots are explored for use in energy storage devices (like batteries and supercapacitors), where their unique properties can enhance energy storage and efficiency.
Drug Delivery: Quantum dots serve as drug delivery carriers in medicine, enabling precise and controlled pharmaceutical release. E.g., cancer treatments.
Environmental Remediation: Quantum dots have applications in environmental remediation, such as removing pollutants from water and soil through photocatalysis.
Security and Authentication: Tunable optical properties of quantum dots enhance their value in anti-counterfeiting measures used in document and product security features.