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Quantum Dots + OLED = Your Next TV

Formerly rival technologies will come together in new Samsung displays

3 min read
Photo illustration of 2 display monitors facing each other connected by a rainbow
Edmon de Haro
Blue

For more than a decade now, OLED (organic light-emitting diode) displays have set the bar for screen quality, albeit at a price. That’s because they produce deep blacks, offer wide viewing angles, and have a broad color range. Meanwhile, QD (quantum dot) technologies have done a lot to improve the color purity and brightness of the more wallet-friendly LCD TVs.

In 2022, these two rival technologies will merge. The name of the resulting hybrid is still evolving, but QD-OLED seems to make sense, so I’ll use it here, although Samsung has begun to call its version of the technology QD Display.


To understand why this combination is so appealing, you have to know the basic principles behind each of these approaches to displaying a moving image.

In an LCD TV, the LED backlight, or at least a big section of it, is on all at once. The picture is created by filtering this light at the many individual pixels. Unfortunately, that filtering process isn’t perfect, and in areas that should appear black some light gets through.

In OLED displays, the red, green, and blue diodes that comprise each pixel emit light and are turned on only when they are needed. So black pixels appear truly black, while bright pixels can be run at full power, allowing unsurpassed levels of contrast.

But there’s a drawback. The colored diodes in an OLED TV degrade over time, causing what’s called “burn-in.” And with these changes happening at different rates for the red, green, and blue diodes, the degradation affects the overall ability of a display to reproduce colors accurately as it ages and also causes “ghost” images to appear where static content is frequently displayed.

Adding QDs into the mix shifts this equation. Quantum dots—nanoparticles of semiconductor material—absorb photons and then use that energy to emit light of a different wavelength. In a QD-OLED display, all the diodes emit blue light. To get red and green, the appropriate diodes are covered with red or green QDs. The result is a paper-thin display with a broad range of colors that remain accurate over time. These screens also have excellent black levels, wide viewing angles, and improved power efficiency over both OLED and LCD displays.

Samsung is the driving force behind the technology, having sunk billions into retrofitting an LCD fab in Tangjeong, South Korea, for making QD-OLED displays While other companies have published articles and demonstrated similar approaches, only

Samsung has committed to manufacturing these displays, which makes sense because it holds all of the required technology in house. Having both the OLED fab and QD expertise under one roof gives Samsung a big leg up on other QD-display manufacturers.,

Samsung first announced QD-OLED plans in 2019, then pushed out the release date a few times. It now seems likely that we will see public demos in early 2022 followed by commercial products later in the year, once the company has geared up for high-volume production. At this point, Samsung can produce a maximum of 30,000 QD-OLED panels a month; these will be used in its own products. In the grand scheme of things, that’s not that much.

Unfortunately, as with any new display technology, there are challenges associated with development and commercialization.

For one, patterning the quantum-dot layers and protecting them is complicated. Unlike QD-enabled LCD displays (commonly referred to as QLED) where red and green QDs are dispersed uniformly in a polymer film, QD-OLED requires the QD layers to be patterned and aligned with the OLEDs behind them. And that’s tricky to do. Samsung is expected to employ inkjet printing, an approach that reduces the waste of QD material.

Another issue is the leakage of blue light through the red and green QD layers. Leakage of only a few percent would have a significant effect on the viewing experience, resulting in washed-out colors. If the red and green QD layers don’t do a good job absorbing all of the blue light impinging on them, an additional blue-blocking layer would be required on top, adding to the cost and complexity.

Another challenge is that blue OLEDs degrade faster than red or green ones do. With all three colors relying on blue OLEDs in a QD-OLED design, this degradation isn’t expected to cause as severe color shifts as with traditional OLED displays, but it does decrease brightness over the life of the display.

Today, OLED TVs are typically the most expensive option on retail shelves. And while the process for making QD-OLED simplifies the OLED layer somewhat (because you need only blue diodes), it does not make the display any less expensive. In fact, due to the large number of quantum dots used, the patterning steps, and the special filtering required, QD-OLED displays are likely to be more expensive than traditional OLED ones—and way more expensive than LCD TVs with quantum-dot color purification. Early adopters may pay about US $5,000 for the first QD-OLED displays when they begin selling later this year. Those buyers will no doubt complain about the prices—while enjoying a viewing experience far better than anything they’ve had before.

Update 5 January 2022: At CES 2022, the annual consumer electronics show held in Las Vegas, three companies announced products incorporating QD-OLED technology, all using Samsung’s display hardware. Samsung unveiled a 65-inch QD-Display TV. Alienware introduced a gaming monitor. And Sony’s launched two Bravia XR A95K TVs. None of these companies have yet announced pricing.

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Legged Robots Learn to Hike Harsh Terrain

ANYmal demonstrates locomotion performance that’s slightly superhuman

5 min read
A bright orange four legged robotic dog stands on a grave patch at the top of a mountain with Swiss countryside in the background

Robots, like humans, generally use two different sensory modalities when interacting with the world. There’s exteroceptive perception (or exteroception), which comes from external sensing systems like lidar, cameras, and eyeballs. And then there’s proprioceptive perception (or proprioception), which is internal sensing, involving things like touch, and force sensing. Generally, we humans use both of these sensing modalities at once to move around, with exteroception helping us plan ahead and proprioception kicking in when things get tricky. You use proprioception in the dark, for example, where movement is still totally possible—you just do it slowly and carefully, relying on balance and feeling your way around.

For legged robots, exteroception is what enables them to do all the cool stuff—with really good external sensing and the time (and compute) to do some awesome motion planning, robots can move dynamically and fast. Legged robots are much less comfortable in the dark, however, or really under any circumstances where the exteroception they need either doesn’t come through (because a sensor is not functional for whatever reason) or just totally sucks because of robot-unfriendly things like reflective surfaces or thick undergrowth or whatever. This is a problem because the real world is frustratingly full of robot-unfriendly things.

The research that the Robotic Systems Lab at ETH Zürich has published in Science Robotics showcases a control system that allows a legged robot to evaluate how reliable the exteroceptive information that it’s getting is. When the data are good, the robot plans ahead and moves quickly. But when the data set seems to be incomplete, noisy, or misleading, the controller gracefully degrades to proprioceptive locomotion instead. This means that the robot keeps moving—maybe more slowly and carefully, but it keeps moving—and eventually, it’ll get to the point where it can rely on exteroceptive sensing again. It’s a technique that humans and animals use, and now robots can use it too, combining speed and efficiency with safety and reliability to handle almost any kind of challenging terrain.

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A Transistor for Sound Points Toward Whole New Electronics

“Topological” acoustic transistor suggests circuits with dissipationless flow of electricity or light

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Model of a honeycomb lattice that serves as the basis for a "transistor" of sound waves—whose design suggests new kinds of transistors of light and electricity, made from so-called topological materials. Electrons in a topological transistor, it is suspected, would flow without any resistance.

Hoffman Lab/Harvard SEAS

Potential future transistors that consume far less energy than current devices may rely on exotic materials called "topological insulators" in which electricity flows across only surfaces and edges, with virtually no dissipation of energy. In research that may help pave the way for such electronic topological transistors, scientists at Harvard have now invented and simulated the first acoustic topological transistors, which operate with sound waves instead of electrons.

Topology is the branch of mathematics that explores the nature of shapes independent of deformation. For instance, an object shaped like a doughnut can be deformed into the shape of a mug, so that the doughnut's hole becomes the hole in the cup's handle. However, the object couldn't lose the hole without changing into a fundamentally different shape.

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