What is a Quantum Dot?

A quantum dot is a nanometer-sized semiconductor particle traditionally with a core-shell structure. Quantum dots are widely used for their unique optical properties, as they emit light of specific wavelengths if energy is applied to them. These wavelengths of light can be accurately tuned by changing various properties of the particle, including shape, material composition, and size.

This blog post will answer the question ‘What is a Quantum Dot?’ in more detail.

Quantum Dot Production

There are various methods of producing quantum dots. The most typical is via a colloidal synthesis, which is the process of heating a solution, causing the precursors to decompose to form monomers, which then produce nanocrystals.

Quantum dots produced using this method can consist of compounds including indium arsenide, lead sulfide, lead selenide, and cadmium sulfide. Colloidal synthesis is a popular method as quantum dots can be produced in batches large enough to be potentially used for commercial applications.

Plasma synthesis is another popular technique for the production of quantum dots. This process enables the control of the composition, surface, size, and shape of the quantum dot, and it also reduces the challenges associated with doping.

Working Principle of a Quantum Dot

Within a quantum dot, there are confined valence band holes, conduction band electrons, or excitons. These are the particles that carry the electricity, and because of this confinement, the quantum dot has a distinct energy level.

The electrons within a quantum dot have to occupy an energy level that ‘fits’ inside it, and when excitation occurs these electrons emit a photon. Excitation can be caused by the quantum dot coming into contact with a light or electricity source.

The longest wavelengths of light (red light) are produced by the biggest quantum dots, and the shortest wavelengths of light (blue light) are generated by the smallest quantum dots.

Quantum Dot Applications

Quantum dots are proving to be a very promising solution for a range of optical applications, due to their outstanding properties.

One of the most typical applications is for displays, including televisions, and smart phones. Quantum dots provide greatly enhanced colors for displays due to the high level of fine-tuning possible. They also help to improve quality control of displays, reducing the risk of variations.

Quantum Dots from Avantama

Avantama have a long history in the development and manufacture of quantum dots. If you would like any more information about quantum dots and how they may benefit your application, please contact us.