How quantum dots could challenge OLED for best TV picture
It won't happen this year, but when Samsung figures out how to make quantum dot TVs without depending on decades-old LCD technology, watch out LG.
Geoffrey Morrison is a writer/photographer about tech and travel for CNET, The New York Times, and other web and print publications. He's also the Editor-at-Large for The Wirecutter. He has written for Sound&Vision magazine, Home Theater magazine, and was the Editor-in-Chief of Home Entertainment magazine. He is NIST and ISF trained, and has a degree in Television/Radio from Ithaca College. His bestselling novel, Undersea, and its sequel, Undersea Atrophia, are available in paperback and digitally on Amazon. He spends most of the year as a digital nomad, living and working while traveling around the world. You can follow his travels at BaldNomad.com and on his YouTube channel.
We've said it before but it bears repeating: Samsung's QLED TV technology is not the same as LG's OLED TV technology.
Sure they have similar names, down to the little slash that makes an "O" into a "Q," but according to CNET's tests for picture quality, OLED is superior. It's also fundamentally different from the LCD-based TVs that comprise the vast majority of the market today. Samsung's latest QLED TVs are still based on LCD, and while they have their strengths, they can't compete with OLED.
The "Q" in QLED, however, could change the game a few years down the road. It stands for quantum dot, a microscopic particle that could have a big impact on TV image quality. Samsung and other TV makers are working on technologies beyond QLED that could finally ditch LCD, and potentially challenge the picture quality dominance of OLED.
No, I'm not talking about MicroLED. I'm talking about better uses for quantum dots. QLED is just the beginning of the quantum dot revolution, and it's only going to get cooler. Here's how.
The short version is that a quantum dot is a ridiculously tiny molecule that has many special properties, but the one we're most interested in is its ability to glow when supplied with energy. Depending on the dot's size it glows at a specific wavelength of light. So one tiny dot might glow green, and a slightly larger dot might glow red.
Currently quantum dot displays, like Samsung's QLEDs, use a thin layer of quantum dots in front of blue LEDs. The LEDs create, you guessed it, blue light. That blue light is not only all the blue you see on screen, but also the energy required to make the green and red quantum dots glow their respective green and red. So now you have all three primary colors, and all you did was run power to a bunch of really efficient blue LEDs.
You can see this in practice in the image at the top of this article. A blue LED backlight is causing two squares of red and green quantum dots to glow.
Since the colors created by the quantum dots is easily tunable, TV manufacturers are able to create the ultra-deep colors required by wide color gamut and HDR. QDs are also extremely efficient, so the TV can be brighter while using less energy than what'd be required with separate RGB LEDs or blue LEDs with a yellow phosphor.
But this is just the beginning.
The near future: Quantum dot color filters
While the current use of QD increases the color and efficiency of LCD TVs, there's still an issue: the color filter. Right now quantum dots are essentially part of the LCD's backlight. Which is to say, the QDs and the blue LEDs create "white" light, which is polarized, sent through the liquid crystal, and then through a color filter. All these steps, and several more I didn't include, are required for you to see an image.
Color filters technically block light. They let through one specific color, but all the other colors are blocked. So in a standard LED/QD LCD, the backlight is creating red, green, and blue, but for each pixel, two of those are blocked and essentially "thrown away" to create a pixel the color you see on screen. Significantly more energy is being used to create the light than necessary.
The next step in QD and LCD is to replace the color filter with quantum dots. This improves efficiency dramatically. Since the TV is no longer tossing a huge portion of the light it creates, you can get the same light output with less power, or even greater brightness with the same power as before. Nanosys, a quantum dot manufacturer, expects a 3x increase in efficiency or brightness with this layout. There are also potential improvements to viewing angle.
Right now the expectation is to use the same or similar blue LED backlight, and red and green QDs. But it's possible to use OLED as the light source. Since
current implementation of OLED requires color filters, this isn't beyond the realm of possibility. If they're working on it though, they're not saying.
We might see this tech in LCDs within the next year or so.
Direct-view quantum dot: The potential OLED killer
As cool as that is, there's still an issue: The LCD. Massive amounts of engineering and hard work has been done over the last few decades to overcome the inherent limitations of liquid crystal displays. Sure they've gotten pretty good, but they still have significant issues compared to OLED.
The next step for quantum dots is to ditch the liquid crystal entirely: Direct-view quantum dot displays. Instead of photoluminescence, the next-next generation of QD displays will be electroluminescent.
Instead of blue LEDs supplying light to excite the QDs into emitting their light, this next-gen display will use electricity directly. Though QD manufacturers probably wouldn't love the analogy, this would be similar to how OLED works. A material, either OLED or QD, would get tiny amounts of current to glow a certain brightness. Cut off that current, the pixel goes dark. Send a lot, and it's bright.
As you can guess, this means insane contrast ratios. More than that, it potentially means better brightness as well. Quantum dots are exceptionally efficient, so a smaller amount of current can result in a lot of light. So potentially these direct-view quantum dot TVs could be brighter than OLED, with the same black level, and with better color and longer life. That's the theory anyway.
As I mentioned at the top, since
has already started using "QLED" in their marketing for their current-gen LCD TVs with quantum dots, that perfect name for this new, direct-view QD tech is off the table. So what do we call them?
"QDED" sounds cool, but perhaps a bit too metal. Nanosys is calling the tech QDEL, opening up lots of marketing opportunities for "Dude, you're getting a QDEL." On second thought, maybe just QDTV is simple enough.
The future is dots
If I seem excited about quantum dots, it's because I am. This is a fascinating and cool technology that could radically improve the picture quality of TVs. Beyond Samsung, other TV manufacturers like TCL and Hisense sell quantum dot models now, and Sony, LG and others have sold them in the past. I expect the trend to continue in the future. The major quantum dot makers have moved to cadmium-free QDs, so that toxic material isn't in TVs going forward (and can't be, due to EU law).