If you are an AV enthusiast, you have likely heard of quantum dots by now. These nanoscale semiconductor structures—the size of molecules—have optical qualities that are harnessed to vastly expand the color expression available on consumer televisions. During a recent tour of a Nanosys, Inc. facility in Silicon Valley, I had an opportunity to see firsthand how these microscopic particles are manufactured.
The trick performed by quantum dot particles is that while light of various wavelengths can enter, only one wavelength exits. The precise size of the particles determines the wavelength of the emitted light, with larger particles creating warmer (reddish) hues and smaller particles creating colder (blueish) hues. By carefully controlling the size of the quantum dots during the manufacturing process, it’s possible to create particles that emit pure red, or green, or blue. These primary color-specific particles are the quantum dots that are of great interest to television manufacturers.
There were two parts to the Nanosys visit. The first half involved a board room presentation by president and CEO Jason Hartlove. He turned on the information fire hose and doused us with quantum dot-related data for an hour, then he took our group on a tour of the 60,000 square-foot fabrication facility.
Current quantum-dot implementations are of the transmissive LED-lit LCD variety. However, Samsung and Nanosys predict that emissive quantum dot TVs (QLED) are perhaps 3 to 4 years away. In today’s TVs, quantum dots are used to improve the spectral qualities of the LED backlight that illuminates the screen on LCD flat panel TVs, not to create the light itself on a per-pixel basis.
By converting light from blue LEDs into both pure red and pure green, quantum dots create a white light with the spectral qualities needed to reproduce an expanded color gamut once filtered through the LCD panel. In the following video, Jason Hartlove discusses the advantages of using red and green quantum dots in conjunction with blue LEDs in a LED-lit LCD TV.
Today’s quantum dots TVs can reproduce most of the DCI/P3 color gamut, which is the commercial cinematic standard. Going forward, quantum dots will allow for TVs that can reproduce the BT.2020 color space that encompasses about 70% of the colors the human eye can see.
Quantum dots are the product of chemistry. You create them by heating the right chemicals under the right conditions, and when the dots take form and possess the desired qualities, you stop the reaction and filter out the impurities. Parts of the process reminded me of a modern liquor distillery, except with a lot more pipes and a much more laboratory-like environment.
I wish I could show you the parts of the factory where quantum dot synthesis takes place but that was a no camera zone. What I can show is the part of the facility where quantum dots and associated materials like the polymer film that holds them are tested under accelerated conditions. This is necessary because quantum dots are such a new technology and the development cycle for new products is so short.
It isn’t practical to wait around for years to see how quantum dots age, so Nanosys speeds up the process. Check out the following video about the need for accelerated ageing tests:
With their ability to efficiently convert blue light into optimized, full-spectrum white light, quantum dots have already provided significant benefit to the television industry. With Ultra HD Blu-ray supporting the BT.2020 color space, further progress in quantum dot technology is needed. But ultimately the potential of the technology rests in its ability to be used to create QLED emissive displays that can compete with OLED. As part of the tour, I did see a postage stamp-sized demo of emissive quantum dots. It will be interesting to see how quickly that can be developed into a prototype display that’s shown at CES and eventually into TVs consumers can buy.