Why is it in the news?

• Recently, Nobel Prize in Chemistry 2023 was awarded to Moungi G. Bawendi, Louis E. Brus, and Alexei I. Ekimov for the discovery and synthesis of quantum dots.

About Quantum Dots

• Quantum dots are nanoparticles with unique properties that depend on their size, challenging traditional understanding of material properties.
• These tiny particles have applications in various fields, from LED lamps to guiding surgeons during tumor tissue removal.
• While the concept of such particles existed in theory, the Nobel laureates made high-quality quantum dots suitable for practical applications.
• Quantum dots have unique optical properties due to their small size. Their properties can be changed by altering their size, as quantum physical forces dominate at the nanoscale.
• Prior to their discovery, adding certain elements to glass could change its optical properties, but true quantum dots had not been synthesized.

 Contributions of Alexei Ekimov, Louis Brus, and Moungi Bawendi

• Alexei Ekimov, working in the Soviet Union, published research in 1981, where he observed size-dependent quantum effects in glass-colored with copper chloride.
• Louis Brus, unaware of Ekimov’s work, experimented with cadmium sulphide particles in the US, discovering that the size of particles altered their light absorption characteristics.
• Moungi Bawendi improved methods for creating nanocrystals, producing almost perfect quantum dots with distinct quantum effects.

Applications of Quantum Dots

• Quantum dots are considered an essential part of nanotechnology. Quantum dots are nanoparticles where quantum effects determine their characteristics.

Quantum dots are used in various applications, including:

• Computer and television screens based on QLED technology for better display.
• LED lamps to adjust light temperature.
• Biochemistry and medicine for mapping cells, tracking tumor tissue, and catalyzing chemical reactions.
• Mapping biological tissues in biochemistry.
• Improving the efficiency of photovoltaic cells in converting solar light into electricity.
• Targeted drug delivery in cancer treatments and nanomedicine.
• Use as security markers for anti-counterfeit measures and as fluorescent markers for tracking objects.
• Potential future applications include flexible electronics, minuscule sensors, slimmer solar cells, and encrypted quantum communication.

More about Quantum Dots

• It is a semiconductor nano crystal which is made of specific materials.
• It has a discrete quantized energy spectrum.
• It contains a small finite number of conduction band electrons, valence band holes, or excitons.
• They are typically between 10 and 50 nm in size
• They glow a particular color after being illuminated by light.
• The color they glow depends on the size of the nanoparticle. The smaller the nanoparticle, the higher the energy difference between valence band and conduction band, which results in a deeper blue color. For a larger nanoparticle, the energy difference is lower, which shifts the glow toward red.
• It has many applications in several areas such as solar cells, transistors, LEDs, medical imaging and quantum computing.