What is a quantum dot?

• Quantum dot research won three scientists the Nobel Prize in chemistry.
• A quantum dot is a tiny particle that changes color based on its size.

Three scientists won the Nobel Prize in chemistry for their research on quantum dots, but what really are the bright-colored dots that help power your television screen?

Quantum dots are essentially minuscule, inorganic particles that shine different colors when exposed to light.

And they are tiny — so tiny that they are roughly the same size in comparison to a soccer ball as a soccer ball is to planet Earth, Professor Heiner Linke, a member of the Nobel Committee for Chemistry, said.

Scientists create the particles from different materials, including gold, graphene, and cadmium. What color the dots will emit depends on their size and can be controlled by the researchers, Linke said in a video posted by the Nobel Prize Committee.

"This is completely unusual," Linke said in the video.

Normally, for something to change colors, you would have to use a different molecule with "different atoms in different constellations that give you different colors," Linke said. "That's what chemistry is all about."

But with quantum dots, researchers can use the same atoms in the same constellations and simply change their size to get different colors and properties.

How quantum dots are used

Linke said that quantum dots are now found in daily life, inside "the very best TV screens" with the brightest colors.

"The pixels consist of red and green quantum dots, and the blue light from the back controls those colors," Linke said.

According to Linke, quantum dots can also be used in LED lights to simulate sunlight and create a more natural-seeming light from the bulbs.

Quantum dots are also used in biological research, according to science writer Chris Woodford of Explain That Stuff. The tiny dots are used like light bulbs to color-code specific cells that need to be studied, Woodford wrote.

Dyes made from quantum dots are extremely bright and can — theoretically — last indefinitely, different from organic dyes that decay at quicker speeds, according to Woodford.

Scientists are also testing whether quantum dots can be used as "tissue-specific beacons" to pick up tumors and other health problems, according to The American Association for the Advancement of Science.

The idea includes covering quantum dots in organic material to make them compatible inside the body, and then using them to "map blood vessels and lymph nodes," the report says.

Researchers Moungi Bawendi of MIT, Louis Brus of Columbia University, and Alexei Ekimov of Nanocrystals Technology Inc. were awarded the 2023 Nobel Prize in Chemistry for their work with quantum dots.