Quantum Dots 

07 Oct Quantum Dots 

This article covers “Daily Current Affairs”, and the topic details “Quantum Dots”. This topic has relevance in the “Science and Technology” section of the UPSC CSE exam.

For Prelims:

What is Quantum Dot?
What are the applications of the Dots?

For Mains:

GS3:  Science and Technology

Why in the news?

The Nobel Prize in Chemistry for the year 2023 was conferred upon Moungi G. Bawendi, Louis E. Brus, and Alexei I. Ekimov in recognition of their groundbreaking work in the discovery and synthesis of quantum dots.

What are Quantum dots?

• Quantum dots are incredibly small particles, typically only a few nanometers in width, and their distinctive optical characteristics primarily stem from their minute dimensions.
• While their atomic structure and composition are similar to bulk materials, their properties vary due to size differences.
• Remarkably, the characteristics of quantum dots can be manipulated by adjusting their size.
  • At the nanometer scale, materials and particles exhibit size-dependent properties influenced by quantum forces.
  • In contrast, as encountered daily, macroscopic scales are governed by classical physics, where gravity and traditional rules hold sway.
• In the 1970s, scientists discovered that adding small amounts of elements like gold, silver, cadmium, sulfur, or selenium could modify the optical properties of glass.
• However, quantum dots had not yet been synthesised despite an understanding of the mechanisms behind these property changes.

Quantum Dots in Modern Applications:

• Visual Enhancement: The dots are pivotal in modern computer monitors and TV screens. Stimulated by blue LEDs behind the screen, they emit varied colours, broadening the colour spectrum and enhancing screen brightness.

• Biological Tissue Mapping: Nanoscale quantum dots assist biochemists in precise biological tissue mapping.

• Solar Cell Enhancement: They boost light absorption and efficiency in solar cells.

• Advanced Cancer Therapies: They aid in targeted drug delivery and advanced cancer therapies with applications in nanomedicine.

• Anti-Counterfeit Measures: They act as security markers on currency and documents, thwarting counterfeiting. They serve as versatile fluorescent markers for tracking and ensuring security and authenticity.

Nobel-Winning Quantum Dot Research

• Dr. Ekimov’s Pioneering Work (Early 1980s):

• • Dr. Ekimov’s research in the early 1980s focused on creating size-dependent quantum effects in coloured glass.
  • In 1979, he examined glasses tinted with copper chloride, subjected to high temperatures, and cooled.
  • He discovered that the glass absorbed light differently based on the preparation method.
  • This phenomenon arose because tiny copper chloride crystals formed, and these crystals, varying in size according to the preparation process, interacted with light in distinctive ways.

• Dr. Brus and Liquid Solution Crystals (1983):

• • In 1983, Dr. Brus and his colleagues took a significant step forward by preparing similar crystals in a liquid solution rather than glass.
  • This approach allowed for better manipulation and study of the crystals.
  • These crystals also exhibited differing light interactions based on slight size variations.

• Dr. Bawendi’s Quantum Dot Technique (1993):

• • In 1993, Dr. Bawendi and his team introduced a technique to produce precisely-sized quantum dots with high optical quality.
  • The process involved injecting a specific substance into a hot solvent and heating the solution.
  • Nanocrystals automatically formed, with longer heating times resulting in larger particles.
  • The solvent ensured these crystals had smooth outer surfaces.
  • This user-friendly method enabled scientists to create and study the needed quantum dots.

Sources: 2023 Chemistry Nobel Prize: What are quantum dots, and what research won the prize?

Q1. With reference to Quantum Dots, consider the following statements: 

1. They are minuscule particles, measuring just a few picometers in width. 
2. They possess unique optical properties primarily due to their tiny size.
3. Their atomic structure and composition are different from the bulk materials.

Which of the statements given above is/are correct?

(a) 1 and 2 only

(b) 2 only

(c) 3 only 

(d) None 

Answer: (b) 

Q2. Consider the following:

1. Tissue Mapping
2. Cancer Therapies
3. TV and PC Screens
4. Building materials

How many of the abovementioned are applications of Quantum Dots?

(a) Only one 

(b) Only two 

(c) Only three 

(d) All Four 

Answer: (c)

Q3. What are quantum dots, and how do they impact various fields of science and technology? Discuss their unique properties and their applications in modern contexts.

Gaurav N