What do LEDs, bio sensors, and lasers have in common? Well, as stated by a recent scientific breakthrough: they all use quantum dots!

In 2023, Moungi G. Bawendi, Louis E. Brus, and Aleksey Yekimov were awarded the Nobel Prize in Chemistry for their discovery and development of quantum dots, which are semiconductor nanocrystals that exhibit quantum size effects in their optical and electronic properties.

But what purpose do quantum dots serve, and why should we care about them? Let’s find out!

Table of Contents

• Structure & How They Work
• Applications of Quantum Dots: Present & Future
• Challenges & Future Prospects

Structure & How They Work

A quantum dot is usually comprised of a semiconductor core made with heavy metals such as cadmium selenide (CdSe) or lead selenide (PbSe), along with an outer shell made out of zinc sulfide (ZnS) or cadmium sulfide (CdS).

It has a core-shell structure where electrons are confined in all three spatial directions such that discrete energy levels can be obtained. In simpler terms, the way a quantum dot works to emit colour is by absorbing photons and re-emitting them at different wavelengths depending on their size.

The size of a quantum dot is microscopic, ranging between 1nm and 10nm. One thing to note is that the size of a quantum dot correlates with its colour: larger quantum dots have a small band gap, so the light is redder because of the lower frequency wavelength emitted (less energy), while smaller quantum dots have a larger band gap, thus the light they emit is bluer (more energy).

This is important because scientists can fine-tune the size of quantum dots to change colours with higher levels of precision.

Applications of Quantum Dots: Present & Future

Consider a television. The colours we see produced on the television screen are created by light-emitting diodes, or LEDs, which emit three basic colours: red, green, and blue. To create other colours, the LEDs combine these three colours in various proportions. However, due to LEDs having broad colour profiles, it’s difficult to emit colours with high precision.

In comparison, quantum dots are able to emit colours much more accurately. Many newer televisions today use quantum dots because they produce clearer colours in more energy-efficient ways than conventional LED televisions.

Moreover, television screens are not the only use of quantum dots. Medical imaging, solar cells, and quantum computing all harness the unique properties of quantum dots to enhance their precision and efficiency. The bright, pure colours that they are able to emit coupled with high efficiencies and longer lifetimes makes quantum dots all the more worthwhile, as scientists have been trying to improve their uses for maximum performance.

Future Prospects

• Quantum dots can be used to expand the properties of cameras for imaging in unstable environments, such as in low light;
• Screen displays will have greater contrast and more saturated colours;
• Provides the foundation for the field of quantum mechanics;
• Predicts how upcoming scientific and technological innovations will develop in industries such as renewable energy and medicine.

All in all, quantum dots demonstrate all the exciting ways quantum science can be harnessed and reveal how the interactions of light and molecules impact us in our daily lives. They represent a promising future for the field of chemistry, as well as for the area of quantum mechanics.