Quantum dots: the tiny crystals that won a Nobel and lit up your TV

Some of the most vivid colours on a modern television come from crystals a few billionths of a metre across. They are called quantum dots, and the science behind them was honoured with the 2023 Nobel Prize in Chemistry — awarded to Moungi Bawendi, Louis Brus and Alexei Ekimov for discovering and learning to make them.

What a quantum dot is

A quantum dot is a tiny crystal of a semiconductor — often just a few nanometres wide, containing only a few thousand atoms. At that size something strange happens: the dot's electrons are squeezed so tightly that quantum mechanics starts to dictate which colours of light it can absorb and emit.

The remarkable result is that the colour depends on the size. Make the crystal slightly larger or smaller and its glow shifts across the spectrum — larger dots tend toward red, smaller ones toward blue — even though every dot is made of the same material. Size becomes a dial for colour.

How the discovery unfolded

In the early 1980s, Alexei Ekimov saw this size-dependent colour in coloured glass, and Louis Brus observed the same effect in particles floating in a liquid. The problem was control: early dots were uneven and hard to reproduce.

The breakthrough came in 1993, when Moungi Bawendi's group developed a way to grow quantum dots of precise, uniform size and high quality. That method turned a laboratory curiosity into a material engineers could actually use.

Where they show up

• Displays. In QLED televisions and monitors, quantum dots convert backlight into pure, saturated reds and greens, giving brighter and more accurate colour.
• Medical imaging. Because their glow is bright, stable and tunable, quantum dots can tag and light up specific cells or molecules in biological research.
• Solar cells and sensors. Researchers use quantum dots to capture light in new kinds of solar cells and to build sensitive light detectors.
• Lighting. They can tune the colour of LED lighting toward warmer, more natural tones.

The honest caveats

Many high-performing quantum dots have contained cadmium, a toxic heavy metal, which raises environmental and safety concerns — so a major research push is toward cadmium-free dots based on materials such as indium phosphide. Manufacturing at scale while keeping the dots uniform and stable is also an ongoing engineering challenge.

Quantum dots are a rare case where a deep quantum-mechanical effect — confinement in a nanocrystal — travelled all the way from a strange observation in coloured glass to the screen in your living room in about four decades.

For students, quantum dots are a vivid lesson that at the nanoscale, size is not just a measurement but a material property you can engineer.

Frequently asked questions

What is a quantum dot?

A quantum dot is a semiconductor nanocrystal only a few nanometres wide. At that size, quantum confinement squeezes its electrons so that the colour of light it emits depends on its size, not just its chemical composition.

Why did quantum dots win the 2023 Nobel Prize in Chemistry?

The 2023 Nobel Prize in Chemistry went to Moungi Bawendi, Louis Brus and Alexei Ekimov for discovering quantum dots and developing methods to produce them with precise, uniform size — turning a quantum effect into a usable technology.

What are quantum dots used for?

They are used in QLED televisions and monitors for brighter, purer colour, in medical and biological imaging as glowing tags, and in research on solar cells, sensors and LED lighting.