How Did That Flat Screen TV Get So Vivid?
Professor Louis Brus won the 2023 Nobel Prize in Chemistry for his work on quantum dots. Turn on your TV, and you might see some.
If you happened to buy a cutting-edge new television in 2013, you may have noticed sharper, more vivid colors than ever before. That new level of vividness was thanks to quantum dots. A novelty just over a decade ago, those dots are now in almost half of all flat-screen TVs sold in North America, helping power their striking color displays while maintaining a slim profile.
Quantum dots can now be found in an ever-growing number of high-performance electronic displays, and they are helping to enhance the performance of solar panels and improve the sensitivity of biomedical imaging.
Louis Brus, Samuel Latham Mitchill Professor Emeritus at Columbia University, first delved into dots in the early 1980s as a scientist at Bell Labs, an innovative research facility located just outside New York City in Murray Hill, New Jersey. At the time, he was exploring ways to speed up chemical reactions using tiny crystals of a light-capturing semiconductor called cadmium sulfide.
One day, he forgot about a beaker containing some cadmium sulfide. When he found it the next day, he noticed their optical properties had changed. Left unattended, he suspected his original crystals had grown. Brus and his colleagues began intentionally experimenting with several different sizes of cadmium sulfide crystals and found that each yielded a different color.
They had discovered a size-dependent quantum effect. The smaller the crystal, the smaller the space its electrons have to ripple about; that wavelength determines the color the crystal produces in response to light. Larger crystals skew red; smaller ones, blue and violet.
“In the beginning, I thought they would be important just to scientific understanding, but I never really appreciated how widely they might be used,” Brus told Columbia News after his Nobel was announced.
Today’s commercially used crystals range from about 2 to 10 or so nanometers wide (over 10,000x smaller than human hair)—a dot indeed! That means billions of quantum dots, as they are now referred to, can be packed into a television to produce a greater display of colors than prior technologies could achieve. Working them into photovoltaic cells can boost how efficiently solar panels capture light and convert it into energy across a wider range of wavelengths. And in medicine, these tiny-but-bright crystals are helping doctors create high-resolution maps of tissues and tumors and increase the precision of targeted drug delivery.
It’s a simple tweak—size, at quantum scales—that’s having a big impact anywhere we need to see some light. The “discovery of quantum dots and how to make them has opened up a new way of designing materials and helped catalyze the field of nanoscience,” noted Heiner Linke, chair of the Nobel committee for chemistry, when he awarded Brus and two other scientists the Nobel Prize. “This is a truly great achievement for the benefit of humankind.”
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