Materials and Other Game Changers
Quantum dots, OLEDs, phosphors, e-paper, glass, and films represented significant materials developments on display in Los Angeles.
by Ken Werner
Unless you are one of the engineers who builds display panels from primary
materials and components, you probably think “quantum dots vs. OLEDs” when you see the phrase “display materials.” That’s fair enough, and we saw lots of dots and OLEDs at the Society for Information Display’s Display Week event at the Los Angeles Convention Center, May 21–25 of this year. But the situation is becoming increasingly complicated, and some of the truths we thought we knew are changing. In addition, there is a lot more to the field of display materials than quantum dots and OLEDs, including phosphors, e-paper, and glass and films.
With the recent acquisition of QD Vision by Samsung, Nanosys has been the only company making QDs in commercial quantities and licensing its technology for customers to manufacture in volume. All other players have struggled to reach commercial success while polishing their technologies and looking for revenue streams. Nanosys continues its march from strength to strength, but some of the other companies have announced developments that are keeping them in the game.
At Display Week, Nanosys was vigorously promoting its Hyperion quantum-dot material set, which contains a little cadmium, but so little that it falls below the restriction of hazardous substances (RoHS) limit without requiring an exception. Hitachi is mass producing the film, which is currently being used by Hisense and AUO. Hisense previously used Nanosys cadmium-based dots in 3M quantum-dot enhancement film (QDEF) before switching to the Hyperion/Hitachi product. AUO is making panels for Vizio. Nanosys was not focusing on its other quantum-dot technology, which it licenses to Samsung for the QLED QDs that go into Samsung’s Q family of super-premium LCD TVs.
Nanosys CEO Jason Hartlove described his company’s plans regarding opto-emissive technology – this is the term Nanosys uses to describe quantum dots used to replace the conventional matrix color filter (MCF) in LCDs. “Customers say they are on track for TV intros with opto-emissive technology in 2018,” he said. Sets using the technology were shown privately at CES 2017 and will probably be shown publicly at CES 2018, if not before.
Hartlove continued, “Customers say the internal polarizer fabrication and assembly process is proceeding on schedule. The opto-emissive approach should cut power consumption by 50 percent [compared to MCFs] unless some compensation films are needed; then, it will be a bit less. The opto-emissive system puts the QD ‘sources’ on the surface, so the appearance and viewing angle are very much like those of an OLED but much brighter.” Hartlove noted that one TV maker might sneak in with an opto-emissive set at the very end of 2017.
In other developments, Hartlove confirmed that Nanosys is working with microLED developers, and is thinking about how they can become part of the supply chain for direct-emissive devices.
3M to Retire QDEF
3M had a lot to show and talk about in its Display Week booth (see the discussion of several new films toward the end of this article), but the company’s industry-changing QDEF was noticeably absent both from the booth and from 3M’s pre-show press releases. Given the importance of QDEF to 3M and to the LCD panel industry, this was curious to say the least.
Following the show, I dug into my contact list and wound up speaking with Marketing Specialist Mary Auvin in 3M’s Display Materials & Systems Division. She said 3M is indeed retiring from the QDEF business, though it will be produced and supported with customers through 2018. By phone, she suggested that the panel industry’s growing reluctance to use cadmium-based quantum dots was a factor in the decision. But 3M could presumably use cadmium-free QDs in a replacement film. Could it be that 3M thinks that QDEF will soon become a low-priced commodity, with the high-value part of the business going to opto-emissive quantum dots?
I discussed these issues with Jeff Yurek, director of marketing and investor relations for Nanosys. He wouldn’t comment on what his customer 3M is doing, but he did comment on Nanosys’s view of the situation.
“We definitely see both QDEF and photo-emissive quantum dots coexisting in the market for a long time to come. QDEF offers important benefits to LCDs in terms of color volume and HDR performance. The massive installed base of LCD manufacturing capacity is not going anywhere any time soon, so there will be a place for QDEF.
“In fact, I think it’s likely that we’ll see all three generations, including electroluminescent quantum dots, in the market at some point in the not-too-distant future. The three QD implementations offer benefits that display makers will find attractive for different applications and market segments.
“Nanosys continues to sign QDEF coating partners to expand the supply of QDEF to the market in addition to the announced partners that you already know of. This is probably the best signal that I can give you for the continued and increasing demand we see for QDEF.”
Nanoco Receives First Commercial Order
At Display Week, Nanoco focused on a new, somewhat puzzling collaboration with OLED-maker Kyulux. (See the OLED section of this article.) And a month after the show, the company announced the receipt of its first commercial order from Wah Hong Industrial Corp., a manufacturer of optical films and sheets for the display industry. The order is for resins containing Nanoco’s cadmium-free quantum dots (CFQDs).
The CFQD resin products will be produced in Nanoco’s plant in Runcorn, UK, and delivered to Wah Hong for conversion into films, which will be supplied to an OEM for use in TV and monitor products. This first order is for initial production, which is expected to ramp up over the next few months. Nanoco and Wah Hong expect products to appear in the display market during 2017.
Wah Hong seems to be taking the initiative seriously. Said Wah Hong President C. P. Yeh, “We are pleased to announce our first orders for Nanoco’s CFQD resin following an extensive trial sampling program performed over recent months. As a business, we recently invested in a new, wider coating line that will enable films large enough to fit 100-in. TVs to be produced and we remain on track to commence production of CFQD films for our customers during the second half of 2017.”
After a several years-old agreement with Dow Chemical that produced a plant in Korea to make QDs that were apparently never ordered in significant quantities, and a recent licensing and manufacturing agreement with Merck that seems to have led nowhere after being enthusiastically promoted in 2016, this order from Wah Hong feels like an important one for Nanosys.
QMC Focuses on Continuous Production Line
In the closing hours of Display Week, we had an exclusive interview with QMC Senior Director of Business Development
Toshi Ando. Ando said partner Uniglobe Kisco is buying sample quantities of QMC’s cadmium-free OLED materials. QMC is shipping small quantities and is
transitioning to the large reactor, Ando said.
QDs with low or no cadmium are clearly what panel makers and their customers are looking for, but everybody knows that and all suppliers have them. So cadmium-free is no longer a differentiator. Several analysts, including this one, have suggested that QMC’s continuous production reactor, which permits in-line rather than batch manufacturing, could be QMC’s greatest asset. Ando said that facilities for in-line manufacturing are relatively inexpensive and permit materials to be fabricated at low cost. Since the process can be tuned in real time, it is easier to optimize the production process and obtain consistent characteristics. Specifically, Ando said, the output spectra (designated by the measured full width of the peak at half of its maximum value (full width at half maximum, or FWHM) are
During Display Week, QMC announced that the United States Patent Office had granted a patent (#9,577,149) “for the continuous synthesis of high quantum yield InP/ZnS nanocrystals.”
Prior to Display Week, QMC had announced a Chinese investment to support
manufacturing and applications facilities in Chengde and Beijing. The land with pre-existing buildings has been purchased and equipment has been
ordered, said Ando. Equipment installation should take six months, and process optimization two to three months. Ando said the company expected to
be shipping samples to prospective customers from the end of Q2 ’17, and to start shipping in volume Q2 ’18.
Ando also said that QMC has been working on dot-on-chip. The most recent data show no degradation for four hours at 150 C.
Other Materials Makers
• Avantama AG (Zurich) was promoting its perovskite-type QDs (Fig. 1) at Display Week. The technology is well developed and a pilot line is under development, a company rep said. Materials sampling will follow.
• We first became interested in StoreDot a couple of years ago at CES, when the company showed organic molecules that have properties similar to those of quantum dots. This year, the Israeli company had a booth at Display Week, where it was showing but not pushing its quantum emitters for displays. A spate of recent news stories focused on the other main application of StoreDot’s technology, fast-charging batteries. The company’s FlashBattery system uses a super-capacitor architecture and its own chemistry, StoreDot says, to recharge either mobile-device or automotive batteries in 5 minutes, while providing more energy density than Li-Ion batteries and supporting a large number of charge-discharge cycles, despite the rapid charging.
• Crystalplex, to the best of my knowledge the only quantum-dot company in Pittsburgh, exhibited at Display Week for the first time in 2017, showing its sapphire-passivated QDs. A year ago, the company received a key US patent (#9,425,253) for the fabrication of sapphire-passivated quantum dots that are environmentally stable without additional protection against moisture and oxygen – i.e., environmental stability withoutadditional barrier layer protection. Another key technology is the method for producing its alloy gradient core, which changes the effective size ofthe quantum well by gradient of a transition in the chemical composition rather than physical size. Thus, the exterior diameter of the QDs isapproximately 8 nm, independent of the color each is designed to produce. It is possible that the consistent dot size could make fabrication of opto-emissive films somewhat easier.
Fig. 1: Avantama showed a green emitter at its booth in Los Angeles. All photos by Ken Werner.
LG Display showed an automotive transparent OLED with a transmissivity of 60 percent. The company’s signage OLED display is still at 45 percent. The increase to 60 percent for the automotive OLED is significant because the US National Highway Traffic Safety Administration requires 70 percent transmissivity for an optical element that is placed between a driver and his view of the road, and one of LGD’s use cases is a direct-view HUD sitting on the dash between the driver and the windshield. We were not permitted to photograph this display’s predecessor at CES, but that restriction was relaxed for Display Week (Fig. 2). An LGD rep said the transparent signage display is ready for customers.
Fig. 2: LG Display’s transparent OLED display for automotive applications features a transmissivity of 60 percent.
Nanoco and Kyulux
During Display Week, British QD developer Nanoco and German thermally activated delayed fluorescence (TADF) OLED developer Kyulux announced a collaboration and joint development agreement. Both are development-stage companies, although Nanoco may be graduating from that position. (See accompanying entry in the earlier quantum-dot section of this article.)
TADF is a technology through which the high efficiency of phosphorescent OLEDs (for which the essential IP is controlled by Universal Display Corp.) can be realized with certain fluorescent OLEDs. UDC has very good red, green, and yellow phosphorescent emitters, so in this arena, it would seem that the biggest potential advantage of TADF would be a blue emitter that combines the necessary lifetime, efficiency, color coordinates, and emission width. That full combination has not yet been demonstrated, although Kyulux competitor Cynora says it’s close. (See below.)
One possible synergy in combining the talents of a company that makes OLEDs (light sources) with a company that makes down-converting devices (quantum dots) that change the color of incoming light to a light of lower wavelength is that if you can’t make an emitter for a crucial color, you might want to use a down-converter to make the color you need. In the Innovation Zone (I-Zone) on the show floor, Kyulux showed its “hyperfluorescence” materials, the company’s name for its fourth-gen TADF. A company said a yellow emitter will be available for customer sampling by the end of the year. But QDs can only down-convert; that is, convert to colors with a longer wavelength than the wavelength of the incoming photon. So you could produce orange and red from Kyulux yellow, but not blue and green. And a deep, efficient, long-lived blue is where the need lies.
At his presentation at the SID/DSCC Business Conference, Cynora CMO Andreas Haldi promised his company would produce a high-efficiency blue TADF OLED in 2017, and commented, “We are very happy that OLEDs are not still perfect.” (For more from Haldi, see ID’s Q&A with him in the November/December 2016 issue.)
As evidence of the “booming market” in OLEDs, he cited the following:
1. Samsung Display plans to supply 72 million flexible OLED panels to Apple this year;
2. Google has offered at least $880 million to LG Display for OLED investment; and
3. LG Display is directing 70 percent of its capital expenditure to OLED production.
He also cited projections from UBI Research that revenues from OLED panels will approximately triple from 2017 to 2021 and that revenues from OLED materials will more than triple. He noted that while high-efficiency red-and-green OLED emitters are commercially available, “an efficient blue emitter is still missing.” Therefore, Cynora’s top priority is to “bring a first efficient commercial blue material to the market.”
Haldi announced what Cynora called “record results for high-efficiency blue OLED emitters,” including a 15 percent external quantum efficiency at 1,000 nits with an emission peak at less than 470 nm and a lifetime of greater than 90 hours at 700 nits to 97 percent of initial luminance (LT97) on a device level. Haldi also said the color purity is 62 nm, which presumably refers to the FWHM of the emission curve. He said that these numbers are “close to customer specifications,” and that the company will now focus on moving the emission peak toward 460 nm. (The blue LED commonly used in quantum-dot LCD sets emits at approximately 450 nm.) The company expects to commercialize this high-efficiency blue TADF emitter by the end of 2017, with green in 2018, and red in 2019.
Electrophoretic display company E Ink showed a developmental foldable E Ink display with a 7.5-mm bend radius, pixel density of 227 ppi, and diagonal of 10.3 inches. (At 7.5 mm, the “fold” is a gentle one – Fig. 3.)
Fig. 3: E Ink’s prototype foldable display has a 7.5-mm bending radius.
E Ink is talking to customers about this innovation now and expects to start manufacturing foldable displays in 2018.
At last year’s exhibit, we thought it was remarkable that the color panel E Ink was showing could produce 30K colors with a 10-second-update, cycle-driving waveform. This year the capability was increased to 50K colors with a 10-second waveform, or 30K colors in 4 seconds. And this year, the company’s full-color EPD panels measure 20 inches on the diagonal vs. 32 inches last year, incorporate improved chemistry, and, according to an industry source, demonstrate a “vastly improved lifetime.” Production will come in late 2018, E Ink said. And it promised a 32-in. full-color panel will be shown later this year.
An E Ink rep said there is room for further update cycle-driving waveform improvement, as each new chemical formulation changes the interaction with waveform and colors. High voltage produces much better colors, he said, but current electronics won’t produce the necessary waveforms at the required voltages.
The two-year-old Dutch company Color CNTRL, which was built with the people and IP of the now-defunct IREX, showed its transparent and reflective e-papeolor techngy (Fig. 4).
Fig. 4: Color CNTRL showed its transparent and reflective e-paper technology at Display Week.
The CMY technology delivers a 22:1 contrast ratio, representatives said. The technology is ready for manufacturing, and Color CNTRL is looking for a manufacturing partner. The company is also looking for smart windows and smaller applications. The films are UV and IR stable, and have an operating temperature range of –20 to +50 C. The display is very transparent and is designed to produce intense colors, using highly stable automotive pigments. The company is looking for a pilot line, and in the next six months, will develop thin-film transistor versions of its displays, said Director of Displays Hans Hermann.
In the I-Zone, the South China Academy of Advanced Optoelectronics of South China Normal University showed a three-layer color subtractive display using an electro-fluidic approach similar to that developed by Liquavista. Researchers have constructed a Gen 2.5 manufacturing facility and are focusing on relatively large pixels for outdoor displays. There seemed to me no concern about possible IP conflicts with Amazon, which purchased the Liquavista technology.
We first saw CLEARink in its suite during last year’s Display Week, and were impressed by its technology for creating a high-speed EPD. CLEARink features a clever implementation of electrophoresis that uses an optical plate and lenslets combined with the traditional moving black-ink particles. In the white state, incoming light experiences total internal reflection (TIR) and returns to the viewer. Lurking behind the optical plate is an “ink” containing black particles that are moved toward or away from the plate. When the particles touch the plate (actually, when they get close enough to interfere with the evanescent light wave), the TIR is defeated and light at that point is absorbed. This approach requires the particles to move only a very small distance (~0.5 microns) and therefore can enable update rates compatible with video images. This year, the company earned a Best in Show Award from SID, with an exhibit that included several impressive hand-built prototypes (Fig. 5).
CLEARink’s Steven Gou said the company is working with a large display maker on a pilot line to produce units for sampling.
Fig. 5: CLEARink’s display features 80+ percent white reflectance, 212-dpi XGA, and text and video on the same page.
General Electric showed its RadiantRed TriGain red phosphor, which is intended to be used within an LED package. The phosphor consists of potassium silicon fluoride (PSF) doped with Mn4+, which produces a sharp emission centered at 631 nm.
In contrast, “typical red nitride phosphors produce a broad red spectrum, resulting in a slight orange tint or significant spillage into the infrared,” according to GE’s literature. Thus, according to GE, RadiantRed produces “the truest red available in LCDs without compromise.” In 2014, GE licensed Nichia and Sharp to make LEDs using the phosphor for display backlighting applications, and now has more than 10 announced licensees, including Toyoda Gosei, Citizen, and Samsung.
Glass and Films
As usual, Corning had an extensive booth with knowledgeable people eager to tell the glassmaker’s story. One part of that story is that Lotus NXT high-dimensional-stability glass is being used as the carrier glass for making the flexible OLED Infinity displays Samsung uses in Galaxy S8 and S8+ smartphones. A major focus was Lotus Iris glass, a thin glass intended to replace polymer for use as a light-guide plate (LGP). Compared with polymer, Iris glass offers less thickness, less color shift, better light transmission, more stability, and greater heat tolerance, according to Corning.
With many premium TV sets using edge lighting for 1D local dimming, Corning was stressing the superior local dimming index of Iris glass. The index refers to minimizing the lateral dispersion of the light from each LED in the edge light. A high index results in less light bleeding into adjacent local zones that should be dark or black, thus producing higher dynamic range, or less cross-talk for more exacting calibration of the regions. Corning is working to justify the greater base cost of Iris glass (over polymers) by lowering overall system cost. LEDs, for example, can be closer to the LGP for better coupling (hence less light loss and greater efficiency), according to Bob Quinn, commercial director for advanced glass innovations. Corning said that using Iris glass for the LGP can improve luminance by 5 to 10 percent, as well as delivering a local dimming index greater than 80 percent.
Another major focus was the use of Gorilla Glass as the cover glass for automotive interiors. Even complex three-dimensional shapes can nowbe cold-formed, which will produce parts that are cheaper and lighter, said Christie McCarthy, Corning’s director of commercial operations forauto interiors.
Over at Asahi Glass Company’s booth, the main draw for visitors was a cartoon-like digital concierge, but more interesting to dyed-in-the-wool display geeks was AGC’s new flexible cover glass intended for foldable smartphones, rollable PCs, and “seamless design PCs,” in which the display and keyboard are on a continuously curved substrate. The glass has a radius of curvature of 2.7 mm at 70-µm thickness, and has been tested to more than 100,000 bending cycles. Surface hardness is greater than 9H.
Bendable and Free-Form LCDs
Among the many things Merck representatives were happy to discuss at their Display Week booth was the continuing development of bendable and free-form LCDs. Two weeks before the show, Merck had announced a collaboration with FlexEnable from the UK, “to accelerate the development of free-form displays, following a recent breakthrough by FlexEnable with conformable, large-area, full-color and video-rate organic [LCDs] on plastic. With a bend radius that can go below 30 millimeters, organic LCDs can satisfy market needs for new use cases; for example, in automotive applications. In the near future, organic LCDs can be curved around even more complex surfaces and shapes by combining FlexEnable’s high-performance organic thin-film transistors with the innovative polymer-wall LC technology from Merck KGaA, Darmstadt, Germany,” which was described in a paper at last year’s Display Week.
Merck doesn’t want the industry to forget that it is also very serious about OLEDs. Last year, the company opened a new production facility inDarmstadt that allows production capacity to be increased by a factor of five. The capacity of a Korean application lab is to be doubled this year.
Merck/EMD’s Bob Miller said the company’s plans to produce guest-host liquid-crystal architectural glass are on schedule. The manufacturingplant should be completed by the end of 2017, and production should start early in 2018. Whether the initial production will focus on privacymode or solar control will depend on the initial customer. All Miller would say about that customer is that it will be in Europe.
• Among much else, AUO was showing a 3.5-in. flexible LCD, which the company called the “world’s smallest bending radius flexible transmissive TFT-LCD.” The colorless polyimide substrate was carrier coated and removed with laser lift-off technology. The “chip-on-glass” was direct-bonded onto the plastic film, which presumably makes it “chip-on-plastic.”
• The folding radius is 20 mm; contrast ratio, 1,000:1; pixel dimensions, 320 × 480; luminance, 300 nits; thickness without backlight, less than 110 µm; and total thickness, 1.5 mm. AUO is targeting applications such as bendable, conformable, and instrument-cluster displays.
• In the I-Zone, Ngomad was showing an aftermarket anti-reflection film that uses a slow-sputtered titanium dioxide (TiO2). The company said the film reduces reflectivity from 4.5 percent to 0.7 percent and is available now.
• Among the many optical films 3M showed in its booth at Display Week was an optimized phone film stack. The conventional stack comprises a silver reflector below the light-guide plate and a diffusor and two prism films above the LGP and below the LCD sandwich. The thickness of this stack (excluding the LGP and the LCD) is 252 µm. 3M’s optimized stack consists of a 3M ESR-80v2 reflector under the LGP and a diffusor, 3M ASOC3-106 (24), and 3M APF film between the LGP and the LCD. The thickness of this stack is 254 µm, but the center brightness of the testbed phone was 390 nits, compared to 230 nits for the conventional stack. There’s an even thinner stack consisting of 3M ASR-80, diffusor, 3M ASOC4-LS-82 LH (24), and 3M APF-QWP, which totals 231 µm, with an axial center brightness of 420 nits at the cost of a modest reduction of the brightness cone to 52/57 FWHM.
• 3M also presented its new dual-brightness enhancement film (DBEF-PVOH), which acts as both an absorbing and reflecting polarizer, and introduced what it called a new concept in light control film (LCF). The conventional film-based way to control light from automotive dashboard instruments is to apply a film that contains, literally or effectively, louvers that allow the light to reach drivers’ eyes, but block light that would otherwise reflect off the windshield. 3M’s new approach is to replace the louvers with an “engineered refractive structure.” Claimed benefits are improved zone luminance, a 20 to 30 percent increase in efficiency, sharp cut-off, and wide viewing angle.
A Lively Evolution
Innovations in materials and processes are at the core of non-trivial improvements in displays and modules. At Display Week 2017, we saw materials developments that guarantee a lively display evolution over the next few years. •
Ken Werner is principal of Nutmeg Consultants, specializing in the display industry, manufacturing, technology, and applications, including mobile devices and television. He consults for attorneys, investment analysts, and companies re-positioning themselves within the display industry or using displays in their products. He is the 2017 recipient of the Society for Information Display’s Lewis and Beatrice Winner Award. You can reach him at firstname.lastname@example.org.