QUANTUM DOTS

3. Significance of the Quantum dots

• Quantum dots behave in ways that neither atoms nor bulk materials do. One particular behaviour distinguishes them: the properties of a quantum dot change based on how big it is.
• Just by tweaking its size, scientists can change, say, the quantum dot's melting point or how readily it participates in a chemical reaction.
• When light is shined on a quantum dot, it absorbs and then re-emits it at a different frequency.
• Smaller dots emit bluer light and larger dots, redder light. This happens because light shone on the dot energises some electrons to jump from one energy level to a higher one, before jumping back down and releasing the energy at a different frequency.

4. The Nobel Laureates' Contributions

The 2023 Nobel Prize laureates for chemistry made groundbreaking contributions to the field of quantum dots:

4.1. Ekimov's Discovery in Glass (Early 1980s)

• Alexei Ekimov and his colleagues pioneered the creation of quantum dots.
• In the early 1980s, they introduced varying amounts of copper chloride into glass and subjected it to different heating conditions.
• Remarkably, they observed changes in the glass's colour, a clear indication of the presence of copper chloride nanocrystals of different sizes of quantum dots.

4.2. Brus's Quantum Dots in Liquid (1983)

• Louis Brus's group in the United States achieved a significant milestone by successfully creating quantum dots in a liquid medium in 1983, breaking free from the confinement of glass.
• Both Ekimov and Brus went on to study quantum dots extensively, developing mathematical descriptions of their behaviour and structure.

4.3. Bawendi's Hot-Injection Method (1993)

• Moungi Bawendi's team at the Massachusetts Institute of Technology revolutionized quantum dot synthesis in 1993 with the hot injection method.
• This technique involved injecting a reagent into a carefully chosen solvent with a high boiling point until saturation, followed by heating to facilitate nanocrystal formation in the solution.
• By controlling the heating duration, they could produce quantum dots of different sizes, each with smooth surfaces.
• This method greatly accelerated the adoption of quantum dots across various technologies.

5. Applications of quantum dots

Quantum dots have a wide range of potential applications, including:

• Quantum dots can be used to create brighter, more energy-efficient displays with wider viewing angles than traditional displays.
• Quantum dots can be used to create solar cells that are more efficient and less expensive than traditional solar cells.
• Quantum dots can be used to label cells and tissues for imaging, which can help doctors diagnose diseases and monitor the effectiveness of treatments.
• Quantum dots can be used to deliver drugs to specific cells in the body, which can reduce side effects and improve the efficacy of treatments.
• Quantum dots are a potential candidate for use in quantum computers, which could revolutionize many fields, including medicine, materials science, and finance.

Image Source: Science

6. Conclusion