In the before times, there was CRT. Then came plasma and LCD. More recently, we got OLED. Each of these technological advancements improved picture quality in some ways and kept others the same. Each had its own weaknesses as well, but the overall progression was for the better.
A few years ago quantum dots entered the scene, augmenting the available technologies. These microscopic particles boosted the performance of both LED, LCDs and OLEDs, making them brighter and more colorful. These glowing dots didn’t create the image, though. The image was created by the LCD or OLED pixels, which were either directly or indirectly improved by quantum dots.
While quantum dots were a big step in performance, they were still constrained by the older technologies around them. The core drawbacks inherent in LCD and OLED were still there. The next step, the “holy grail” of quantum dots, were direct-view quantum dots, aka nanoLED. These would be displays that only used quantum dots — no LCD or OLED, and theoretically offering even better picture quality with few or none of the drawbacks of previous technologies. It’s looking like that future tech is almost part of our present. Here’s why nanoLED is potentially so cool.
The potential range of uses of OLED vs. QD-augmented technologies, vs EL-QD.
Quantum what?
It will help to first explain quantum dots. We’ve written about them a lot in the past, but the short version is, they’re tiny particles that glow when you hit them with energy. That energy, for the last few years, has been light. Typically, blue light is created by an LED or OLED, and that blue light excites red and green quantum dots. Together, they create all the light you need to create an image.
Two methods of adding quantum dots to LED LCD displays.
These are called photoluminescent quantum dots. “Photo” as in light, and “luminescent” as in “glowy.” The most common use for quantum dots has been as a layer in the sandwich that makes up a modern television. This “color conversion layer” can be combined with other layers, but for our purposes you can just think of it as a thin layer of yellowish-looking plastic that helps a TV or other display create lots of color.
Because quantum dots have near-perfect efficiency, they’re able to improve the brightness, or decrease the energy usage, of a TV with basically no other changes. Compare this to the most common way of creating color on older LCDs: color filters. Basically, a color filter would block every “color” of light except either red, green or blue. All the other colors were still created by the white backlight, which meant a lot of light was wasted that was being blocked by the color filter. Or to put it another way, for every red pixel, the TV was still creating green, blue and everything in between. You were just seeing red; the rest was wasted energy.
How quantum dots are added to QD-OLED and microLED displays. In the case of the former, the whole panel is essentially blue OLED pixels, some are converted using QD to be red or green. In the case of the latter, QDs are incorporated into the microLEDs themselves.
Switching to quantum dots instead of traditional color filters, nearly all the energy used by the TV to create light is sent out to your eyeballs (essentially). Typically a blue LED or OLED creates nothing but blue light. That’s the blue you see with blue pixels. Quantum dots convert that blue almost perfectly into red and green as well. Basically nothing is wasted, so the TV can be more efficient. That means a brighter TV, one that uses less energy, and often both. This is a big reason why TVs are capable of such impressive light outputs and wide colors these days.
Quantum now
Direct view, electroluminescent “nanoLED” quantum dot displays. The pixels are just quantum dots, no OLED or liquid crystal materials. Note the far fewer layers, which theoretically should mean lower production costs and other benefits.
Until now, quantum dots were the Robin to OLED and LCD’s Batman. They helped, but they weren’t the star of the show. What’s different with nanoLED is how the quantum dots create light. Instead of being photoluminescent, these direct-view quantum dots are electroluminescent. Electro, as in electricity. Zap a pixel that’s only quantum dots with some fraction of a volt, and it glows. Put enough of these pixels close together, program a way to access each of them, and you’ve got a display going.
Nanosys, one of the main manufacturers of quantum dots, has been working on this technology for years. A few months ago I got to see a prototype in person, and a short time later, a behind-the-scenes look at their factory where they make quantum dots. (It looks like a microbrewery.) Nanosys calls electroluminescent quantum dots “nanoLED,” though they’re also called EL-QD and QD-LED.
Interestingly and surprisingly, according to Nanosys, there isn’t a huge difference in the overall makeup of photo- and electroluminescent quantum dots. They’re not interchangeable exactly, but more similar than not. The difficulty largely isn’t the quantum dots themselves, it’s everything around them. Supplying just the right amount of electricity at just the right time to enable a bunch of quantum dots to resemble your favorite TV show is the challenge. Currently, multiple companies are experimenting with different manufacturing methods including inkjet printing and photolithography. Both these methods have potential positives and negatives, but conveniently, they’re similar to how modern displays are currently made. It’s less about inventing a new wheel than it is figuring out how to get the current wheels to fit on a new car.
The evolution of quantum dots in TVs.
The quantum potential pros and cons
No technology is perfect, which is doubly true of new technologies. Since there are no publicly viewable and certainly no commercial nanoLED displays, we have to make some educated guesses about what these new displays might look like.
Potential pros
- Contrast: Since each pixel can be deactivated, we can expect contrast ratios similar to or better than OLED.
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Even thinner displays: With fewer layers needed to create an image, TVs and other displays can be even thinner. That could mean wafer-thin TVs, thinner phones, lighter VR headsets and more.
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Printable: Theoretically, inkjet and other manufacturing techniques could create nanoLEDs on just about any flat or curved surface, cheaply.
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Color: Similar, or even better, color than what’s currently found in QD-enhanced LCDs and OLEDs.
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Scalable: Using technology similar to how LCDs are manufactured, nanoLED displays could, theoretically, be available in the same range of sizes and resolutions as LCDs. So everything from smartwatches to wall-size TVs.
Both inkjet and photolithography are common in TV manufacturing. Adapting them to work with nanoLED is one of the current challenges.
Potential cons
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Cost: It’s a new tech, so the first few generations are likely to be expensive.
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Resistance: There’s a lot of money invested in making LCDs and OLEDs. Companies wanting a return on the money spent on those factories, and not wanting to spend more money converting them, and this could delay nanoLED’s widespread use.
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Performance: Theoretically they’ll offer incredible contrast ratios, but will nanoLED be as bright as QD-enhanced LEDs and OLEDs?
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‘Theoretically:’ The inkjet and photolithography manufacturing methods for nanoLED that will unlock its potential are as yet unproven at scale.
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Lifespan and reliability: Most likely nanoLED won’t have OLED’s potential burn-in issues, and current red nanoLEDs have the potential of longer lifespans than LED LCDs. Green and blue nanoLEDs as yet don’t have that longevity, but this is a key focus of research.
Quantum when?
I saw my first nanoLED display at CES 2023, but I’d heard Nanosys talk about the technology for years. It also seemed like the logical next step when I first learned about quantum dots. However, it was always “a few years away.” That said, Nanosys’ quantum dots timeline from almost a decade ago has matched the particle’s actual use in TVs surprisingly well. So when the company says “a few years,” I’d be surprised if that wasn’t close. The manufacturer expects to see it used in smaller displays, like phones and tablets first, then larger displays like monitors and TVs.
Nanosys is not the only company working on nanoLED either. Multiple companies, including BOE, Samsung Display, Sharp and TCL are all experimenting with this quantum dot tech. These are some of the heaviest hitters in the display manufacturing world, and the fact that they’ve all gotten prototypes working, and they’re all interested in the technology, is reason enough we all should be curious about it.
That said, it will certainly be a while before you can choose between a QD-OLED and a nanoLED display at your local Best Buy. At that point I’d bet LED LCDs with quantum dots will be relegated to the mid- and lower end of the market. Though perhaps some mini-LED might be holding its own in there (which, incidentally, can also use quantum dots). Regardless, that’s a future filled with a lot of great looking TVs.
As well as covering TV and other display tech, Geoff does photo tours of cool museums and locations around the world, including nuclear submarines, massive aircraft carriers, medieval castles, epic 10,000-mile road trips, and more. Check out Tech Treks for all his tours and adventures.
He wrote a bestselling sci-fi novel about city-size submarines and a sequel. You can follow his adventures on Instagram and his YouTube channel.
Source: CNET
