A Quantum Leap In Display Quality From Quantum Dots: 3 Players Set to Dominate Emerging Markets

Q Dot Displays 1415226538155Quantum dots are improving screens worldwide, but their cadmium content worries some

Long the object of ivory tower fascination, quantum dots are entering the commercial realm. Factories that manufacture the nanomaterials are opening, and popular consumer products that use them are hitting the market.

Behind the gee-whiz technology are three companies with three different approaches to producing and delivering quantum dots. The firms—Nanosys, QD Vision, and Dow Chemical (Nanoco) — are racing to capture a share of the emerging market, but there may not be a place for everyone at the finish line.

Developed at Bell Labs in the 1980s, quantum dots are semiconducting inorganic particles small enough to force the quantum confinement of electrons. Ranging in size from 2 to 6 nm, the dots emit light after electrons are excited and return to the ground state. Larger ones emit red light, medium-sized ones emit green, and smaller ones emit blue.

Quantum dots have been proposed for all sorts of applications, including lighting and medical diagnostics, but the market that is taking off now is enhancing liquid-crystal displays (LCDs).

According to Yoosung Chung, an analyst who follows the quantum dot business for the consulting firm NPD DisplaySearch, last year saw the introduction of the first commercial display products to incorporate quantum dots: Bravia brand televisions from Sony and the Kindle Fire HDX tablet from Amazon. This year, the Chinese company TCL introduced a quantum-dot-containing TV and Taiwan’s Asus shipped a quantum dot laptop.

What quantum dots bring to displays is more vibrant colors generated with less energy. The liquid crystals in conventional LCD screens create colors by selectively filtering white light emitted by a light-emitting diode (LED) backlight, which typically runs along one edge of the screen. But that white light is broad spectrum and not optimal for producing the highly saturated reds, greens, and blues needed for lifelike images.

Jeff Yurek, a marketing manager at Nanosys, says the color performance of LCDs is only 70% of what is provided by more expensive organic light-emitting diode (OLED) displays.

Q Dot Displays 1415226538155

Quantum-dot-enabled displays incorporate a backlight that gives off blue light, some of which the dots convert into pure red and green. The three colors combine into an improved white light that the LCDs draw on to create pictures that are almost as vivid as those achieved with OLEDs.

Moreover, because no light is wasted, energy costs are lowered. That’s important, according to Yurek, because the display accounts for half of the power consumed in a mobile device. By incorporating Nanosys’s quantum dots in its new HDX tablet, Amazon was able to cut display power consumption by 20%, he claims.

“Going from the HD to the HDX, they made a thinner, lighter, higher resolution, more colorful display with longer battery life,” Yurek says.

On the strength of demand from companies such as Amazon, Nanosys has been investing in its quantum dot plant in Milpitas, Calif. According to Yurek, the company is now completing an expansion that will more than double its output. Soon, he says, the firm will have the capacity to supply dots for 250 million 10-inch tablet devices a year.

Also expanding is QD Vision, a Lexington, Mass.-based firm founded on chemistry developed at Massachusetts Institute of Technology. Its dots can be found in Sony’s Bravia line and are set to appear in TVs made by TCL, which is the third-largest TV maker after Samsung and LG.

Seth Coe-Sullivan, QD Vision’s chief technology officer and cofounder, explains that his firm and Nanosys use the same basic manufacturing technique: They decompose organocadmium and other compounds at high heat in the presence of surfactants and solvents. The resulting monomers nucleate and form nanocrystals. Size can be controlled stoichiometrically or by thermally quenching the growing crystals.

Where the two firms differ is the way in which they embed quantum dots in a consumer product. Nanosys works with companies such as 3M to create quantum-dot-containing films that are placed between the LED backlight and the LCDs in tablets and other displays. For example, the Asus quantum-dot-containing laptop, known as the NX500 Notebook PC, incorporates the 3M/Nanosys film.

QD Vision, in contrast, encapsulates its quantum dots in a polymer matrix inside a glass tube that is placed directly against the LED backlight. It’s a hot environment but one that the dots can withstand, Coe-Sullivan says, because of how they are synthesized and packaged.

QD Vision manufactures its dots in Lexington and ships them to a contractor in Asia to be packaged in the tubes. The contractor is in the process of quadrupling capacity to 4 million tubes per month, which is enough, Coe-Sullivan says, to supply a quarter of the world’s TV industry.

The display in Amazon’s Kindle Fire HDX tablet is enhanced with quantum dots.
Credit: Amazon


He argues that his firm’s tube approach is suited to TVs and other large displays, whereas a film works better with smaller tablets and laptops. So far, marketplace adoption bears this contention out. “I honestly don’t feel our products compete with each other,” Coe-Sullivan says.

Dow, however, is throwing down the gauntlet against both approaches. Using technology licensed from the British firm Nanoco, Dow is developing cadmium-free quantum dots. It is betting that the display industry is uneasy with the cadmium content of dots from Nanosys and QD Vision and that it will flock to a cadmium-free alternative.

In September, Dow announced that it will use the Nanoco technology to build the world’s first large-scale, cadmium-free quantum dot plant at its site in Cheonan, South Korea. When the plant opens in the first half of 2015, Dow says, it will enable the manufacture of millions of quantum dot TVs and other display devices.

Dow and Nanoco haven’t disclosed the active material in their quantum dots and declined an interview with C&EN. They acknowledge that the dots contain indium but insist that they aren’t indium phosphide, as their competitors claim.

The use of one heavy metal versus another might not seem to make a big difference environmentally. But in the European Union, cadmium is one of six substances regulated by the Restriction of Hazardous Substances, or RoHS, directive. Cadmium cannot be present in electronics at levels above 100 ppm without an exemption.

Larger amounts of cadmium are allowed in LED-containing displays under an exemption that expired on July 1. Late last year, in a consultation process moderated by Oeko-Institut (Institute for Applied Ecology), a German nonprofit, the major quantum dot players made their cases for why the expiring exemption should or shouldn’t be extended.

Nanosys, QD Vision, 3M, and others lobbied for extension to at least 2019, arguing that the benefits of cadmium-based quantum dots outweigh any potential harm. One big reason is that they lower energy consumption by devices, meaning less use of coal in power plants and fewer of the cadmium emissions that can come from burning coal.

In April, Oeko recommended to the EU that the exemption be extended—but only to July 1, 2017, in light of emerging technology that could reduce or eliminate the need for cadmium quantum dots. Industry executives expect the EU to adopt the recommendation by the end of the year.

In their submissions to the consultation process, Dow and Nanoco argued that no extension is necessary because cadmium-free dots are already here. In fact, the Korea Times recently reported that LG and Samsung plan to launch cadmium-free TVs in 2015 with quantum dots from Dow.

Coe-Sullivan says he’ll believe it when he sees it. “The idea that the product is just around the corner has been around for a long time,” he observes. Cadmium-free displays from LG and Samsung were expected to appear at the recent IFA electronics trade show in Berlin, he says, but ended up being a no-show.

The reason, according to cadmium dot proponents, is that indium-based dots have about half the energy efficiency and a narrower color range. “Cad-free today does not have the same performance as cadmium-containing quantum dots,” Coe-Sullivan says. QD Vision and Nanosys also contend that indium-containing quantum dots aren’t environmentally superior, pointing to indium phosphide’s presence on a list of substances being considered for inclusion in RoHS.

Meanwhile, Coe-Sullivan notes, QD Vision has moved away from the metal-alkyl precursors and phosphorus-containing solvents that can make quantum dot manufacturing hazardous. It now uses metal-carboxylate precursors and more benign alkane solvents. Last month, the shift won it one of the Environmental Protection Agency’s Presidential Green Chemistry Challenge Awards.

Chung, the DisplaySearch analyst, is watching the jousting between the cadmium and cadmium-free camps with interest, although he isn’t ready to predict a winner yet. Display makers are concerned about cadmium, he notes, yet they also have qualms about the lower efficiency of cadmium-free quantum dots.

Chung may not know which technology will prevail, but he is sure about one thing. “Now is the time for quantum dots to penetrate the market,” he says.  

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2015 American Chemical Society

What Are Quantum Dots, and Why Do I Want Them in My TV?

Quantum dots glow a specific color when they are hit with any kind of light. Here, a vial of green quantum dots are activated by a blue LED backlight system.

Quantum dots glow a specific color when they are hit with any kind of light. Here, a vial of green quantum dots are activated by a blue LED backlight system.

If you look at the CES 2015 word cloud—a neon blob of buzz radiating from the Nevada desert, visible from space—much of it is a retweet of last year’s list. Wearables. 4K. The Internet of Things, still unbowed by its stupid name. Connected cars. HDR. Curved everything. It’s the same-old, same-old, huddled together for their annual #usie at the butt-end of a selfie stick.

But there at the margin, ready to photobomb the shot, is the new kid: quantum dot. It goes by other names, too, which is confusing, and we’ll get to that in a minute. Regardless of what you call it, QD was all over CES this year, rubbing shoulders with the 4K crowd. You may have heard people say it’s all hype. Those people can go pound sand. Quantum dot is gonna be the next big thing in TVs‎, bringing better image quality to cheaper sets.

A Quantum-Dot TV Is an LCD TV

The first thing to know is quantum-dot televisions are a new type of LED-backlit LCD TV. The image is created just like it is on an LCD screen, but quantum-dot technology enhances the color.

On an LCD TV, you have a backlight system, which is a bank of LEDs mounted at the edge of the screen or immediately behind it. That light is diffused, directed by a light-guide plate and beamed through a polarized filter. The photons then hit a layer of liquid crystals that either block the light or allow it to pass through a second polarized filter.

Where a Nanosys quantum-dot film sheet (QDEF) fits into an LCD display.

Before it gets to that second polarizer, light passes through a layer of red, blue, and green (and sometimes yellow) color filters. These are the subpixels. Electrical charges applied to the subpixels moderate the blend of colored light visible on the other side. This light cocktail creates the color value of each pixel on the screen.

With a quantum-dot set, there are no major changes to that process. The same pros and cons cited for LCD TVs also apply. You can have full-array backlit quantum-dot sets with local-dimming technology (Translation: good for image uniformity and deeper blacks). There can be edge-lit quantum-dot sets with no local dimming (Translation: thinner, but you may see light banding and grayer blacks). You can have 1080p quantum-dot sets, but you’re more likely to see only 4K quantum-dot sets because of the industry’s big push toward UltraHD/4K resolution.

But a Quantum-Dot TV Is Different

In a quantum-dot set, the changes start with the color of the backlight. The LEDs in most LCD TVs emit white light, but those in quantum-dot televisions emit blue light. Both types actually use blue LEDs, but they’re coated with yellow phosphor in normal LCD televisions and therefore emit white light.

Quantum dots can be arranged along the entire back of the display in a film insert or in a "quantum rail" alongside an edge-lit system. This is QD Vision's quantum rail insert alongside a TCL TV.

Here’s where the quantum dots come in. The blue LED light drives the blue hues of the picture, but red and green light is created by the quantum dots. The quantum dots are either arranged in a tube—a “quantum rail”—adjacent to the LEDs or in a sheet of film atop the light-guide plate.

Quantum dots have one job, and that is to emit one color. They excel at this. When a quantum dot is struck by light, it glows with a very specific color that can be finely tuned. When those blue LEDs shine on the quantum dots, the dots glow with the intensity of angry fireflies.

“Blue is an important part of the spectrum, and it’s the highest-energy portion—greater than red or green,” explains John Volkmann, chief marketing officer at QD Vision, which makes quantum dots for several TVs and monitors. “You start with high energy light and refract it to a lower energy state to create red or green… Starting with red or green would be pushing a rock uphill.”

Quantum dots are tiny, and their size determines their color. There are two sizes of dots in these TVs. The “big” ones glow red, and they have a diameter of about 50 atoms. The smaller ones, which glow green, have a diameter of about 30 atoms. There are billions of them in a quantum-dot TV.

This is a batch of red quantum dots being prepared in a 70-liter vat. It's lit with an ultraviolet flashlight, which is what makes the dots glow red.

If you observed quantum-dot light with a spectrometer, you would see a very sharp and narrow emission peak. Translation: Pure red and pure green light, which travels with the blue light through the polarizers, liquid crystals, and color filters.

Because that colored light is the good stuff, quantum dots have an advantage over traditional LCD TVs when it comes to vivid hues and color gamut. In a normal LCD, white light produced by the LEDs has a wider spectrum. It’s kind of dirty, with a lot of light falling in a color range unusable by the set’s color filters.

“A filter is a very lossy thing,” says Nanosys President and CEO Jason Hartlove. Nanosys makes film-based quantum-dot systems for several products. “When you purify the color using a color filter, then you will get practically no transmission through the filter. The purer the color you start with, the more relaxed the filter function can be. That translates directly to efficiency.”

So with a quantum-dot set, there is very little wasted light. You can get brighter, more-saturated, and more-accurate colors. The sets I saw in person at CES 2015 certainly looked punchier than your average LCD.

That Sounds Expensive

There’s no doubt that quantum-dot TVs will cost more than normal LCDs—especially because they’re likely to be 4K sets. But quantum-dot is getting a lot of buzz because its cheaper than OLED.

In most peoples’ eyes, OLED TVs are the best tech available. But they’re expensive to build and expensive to buy—you’re looking at $3,500 to as much as $20,000—and the manufacturing process differs in several key ways. That’s a big reason LG is the only company putting big money into building them.

Conversely, quantum-dot sets don’t require overhauling the LCD fabrication process, and they produce a much wider color gamut than traditional LCDs. They’re closer to OLED in color performance, and they also can get brighter. That’s important for HDR video.

“The attraction to the OEM is that this is a pure drop-in solution,” says Nanoco CEO Michael Edelman, whose company makes quantum-dot film in a licensing deal with Dow Chemical. “They remove a diffuser sheet in front of the light-guide plate and replace it with quantum-dot film. Nothing in the supply chain gets changed, nothing in the factory gets changed. They get, in some cases, better than OLED-type color at a fraction of the cost.”

As you’d expect, companies making film-based and tube-based solutions are touting each approach as superior. QD Vision claims its tube-based approach is easier and cheaper to implement, and it can boost the color performance of cheaper edge-lit LCD sets. According to QD Vision, the oxygen-barrier film needed for film-based dots is costly, which explains why Nanoco and Nanosys are partnering with Dow and 3M for that film.

Film-based suppliers say their method has the upper hand due to “light coupling,” or the ability to feed all that quantum-dot light directly into a light-guide plate. The film layer also purportedly works better with full-array backlight systems, which will be used in a lot of UHD and HDR TVs.

Super! So This Is OLED for Less Money?

Not entirely. Color gamut is important, but it’s only one aspect of picture quality. Because these are LCD sets, they won’t have the blackest blacks, super-wide viewing angles, and amazing contrast of OLED. And while the extra brightness and saturation makes onscreen colors really pop, all that luminance may create light bleeding.

Here's a sheet of quantum-dot film on top of a blue LED backlight system. The red and green quantum dots combine with blue light to produce a "pure" white that can be efficiently channeled by the set's color filters.

Some quantum dots also contain cadmium, which is toxic at high levels—think “factory emission” levels rather than “sealed tube or film in your TV” levels. Still, there are health and environmental concerns, especially if a bunch of quantum-dot TVs end up in landfills. The European Union restricts the use of cadmium in household appliances. Some quantum-dot producers are marketing their product as cadmium-free. QD Vision, which supplies quantum dots for TCL’s new flagship 4K TV, Sony’s well-reviewed 2013 Triluminos sets, and Philips and AOC monitors, still uses cadmium.

“There are only a couple of materials that deliver on the promise of quantum dots,” says QD Vision’s Volkmann. “The other is based on indium. Cadmium is superior with respect to delivering higher-quality color, meaning a broader color gamut. But also much more energy-efficient at converting blue light to other forms of light that allow you to fill out that spectrum. The folks making indium-based solutions like to paint cadmium as the bad guy… Cadmium is under observation by different regulatory agencies around the world, but it turns out indium is too.”

Nanosys, which produces both cadmium and cadmium-free quantum dots, agrees that cadmium-based dots are more efficient.

“Cadmium-based materials have a narrower spectral width,” says Nanosys’s Hartlove. “More pure color. And what that means is the other things the system has to do in order to keep that color pure, the burden on the rest of the system is reduced.”

Hartlove also says that cadmium may be a greener solution. The cad selenide crystal used in quantum dots isn’t as toxic as pure metallic cadmium, and the efficiency of their color-producing ways has benefits.

“The type of power we generate in the US from coal-based power plants throws cadmium into the atmosphere,” says Hartlove. “That’s one of the byproducts of burning coal. And you look at the net cadmium content over this whole lifecycle, and it turns out that cadmium sequestration is actually net better for the environment.”

Why Isn’t Everybody Calling It “Quantum Dot”?

Each manufacturer with a quantum-dot TV set seemingly has a different name for the technology. Samsung likes “nano-crystal semiconductors.” Sony has new Triluminos TVs that “incorporate the same benefits as quantum dots.” LG, TCL, Hisense, and Changhong are actually calling it quantum dot, which is nice.

“The term quantum dot is generic,” says Hartlove. “Each company kind of wants to grab this for their own and brand it their own way. That will probably lead to some consumer confusion… but I think most of the industry will converge on a way to describe this technology.”

There are slight differences between the technologies everyone’s using, but they’re variations on a theme. The differences center on whether the TVs are edge-lit or back-lit with quantum dots, and whether the systems use cadmium- or indium-based quantum dots.

Who Is Making Quantum Dots?

At this stage, three companies are the big players in the quantum-dot TV landscape.

QD Vision specializes in glass-tube “edge-lit” components, and its systems will be found in TCL TVs and monitors from Philips and AOC. It supplied the quantum-dot component for Sony’s 2013 Triluminos sets, but Sony recently ditched the company in favor of another.

Nanoco focuses on cadmium-free, film-based quantum dot systems. They have a licensing deal with Dow Chemical, and Dow is currently building a factory in South Korea to ramp up production of quantum-dot film. Nanoco’s cadmium-free technology will be found in LG’s quantum-dot TVs in 2015.

Nanosys is another film-based producer that has partnered with 3M on the film-sheet tech. It makes both cadmium-based and cadmium-free quantum dots. They are the company behind Amazon’s HDX 7 display and the Asus Zenbook NX500, and Samsung licenses the cadmium-free quantum-dot tech in its new SUHD 4K sets from Nanosys. Nanosys is also working with Panasonic, Hisense, TCL, Changhong, and Skyworth on future TVs.

When Can I Get One, and What Will It Cost?

The new TVs showcased at CES each year usually start hitting stores in the spring, but some higher-end models don’t arrive until the fall. That’s a little bit of a wait, but it’s probably for the best—there are UltraHD content-delivery complications to work out, anyway.

The TV we know the most about in terms of pricing is TCL’s 55-inch H9700, and we still don’t know much. It’s already available in China for around $2,000 U.S., and TCL representatives at CES hinted that it will be close to that mark when it hits the U.S.

Expect that to be at the low end of the quantum-dot price bracket; LG, Samsung, and Sony generally have pricy TVs, and similar 4K LCDs from last year—minus the quantum dots—went in the $2,000 to $3,000 range for a 55-incher. For this initial wave of quantum-dot TVs, most MSRPs will probably fall between $2,500 to $4,000 for a 55-inch 4K set.

Dow Chemical and NANOCO Enter Into Agreement for Quantum Dots

Dow to sell, market and manufacture cadmium-free quantum dots for LCD displays

QDOTS imagesCAKXSY1K 823/01/2013 Manchester

Philadelphia, PA and Manchester, UK,January 23, 2013 – Dow Electronic Materials, a business unit of The Dow Chemical Company (NYSE: DOW) and Nanoco Group plc (AIM: NANO) today announced they have entered into a global licensing agreement for Nanoco’s cadmium-free quantum dot technology. Under the terms of the agreement, Dow Electronic Materials will have exclusive worldwide rights for the sale, marketing and manufacture of Nanoco’s cadmium-free quantum dots for use in electronic displays.

The agreement brings together Nanoco’s world-leading technology with Dow’s large-scale manufacturing capability and well-established sales, marketing and distribution network. Dow Electronic Materials is already a major supplier of critical electronic materials to the global display industry.

The financial details of the agreement are not being disclosed though Nanoco will receive royalty payments related to Dow’s sales of cadmium-free quantum dots. Nanoco will continue to provide any technology advances to its cadmium-free quantum dot technology throughout the lifetime of the agreement and participate with Dow in the marketing and technical support of these materials.

Dow intends to build production capacity in Asia where it has extensive manufacturing capabilities to supply high-performance materials to its customers in the display and semiconductor-related segments. Full commercial production is expected to begin in the first half of 2014.

“We believe that Nanoco’s cadmium-free quantum dots will become a new standard in the display industry owing to their ability to significantly improve the color performance of LCD displays both cost-effectively and by avoiding the use of heavy metals,” said C.G. Park, Global Business Director, Dow Electronic Materials. “When coupled with Nanoco’s technology, Dow’s deep technical, engineering and industry knowledge in films, LCD, LED, and OLED display segments brings our customers an unmatched portfolio of materials solutions.”

Michael Edelman, Nanoco’s Chief Executive Officer, commented: “We are delighted to sign this agreement with Dow Electronic Materials. This agreement is transformational for the quantum dot industry and a significant endorsement of Nanoco’s cadmium-free quantum dot technology. With Dow’s production expertise and deep customer relationships, display makers can begin to plan their quantum dot production requirements with further confidence.”