Is QDOG the Future of LCD TV?

Published December 4, 2017

DSCC has learned that the product plans of TV makers and display makers are working at making a combination of two intriguing technologies to improve LCD TV: Quantum Dots and Glass Light Guide Plates (LGP). Last month quantum dot supplier Nanosys filed with the US Commissioner for Trademarks for a trademark on the name “QDOG”. The filing information gives no detail about Nanosys’ intended use of the trademark or any other information about its intended meaning, but lists Nanosys’ Director of Marketing Jeff Yurek as the Signatory. While it’s amusing to think that QDOG is Nanosys’ new mascot (like the RCA dog Nipper) or Mr. Yurek’s gangsta rapper name, DSCC believes that QDOG stands for Quantum Dot On Glass, which may be the next best thing in the TV world.

DSCC has previously reported on glass LGP products, which have been promoted by Corning and Asahi as replacements to plastic or PMMA LGPs, and we have also reported on the development of Quantum Dots. Does the combination of these two great things bring something even better, like chocolate and peanut butter in a Reese’s candy, or something worse, like the combination of chocolate and beer? Our initial assessment suggests that this dog can hunt.

While Quantum Dots have shown great promise to bring advanced performance to LCD TVs, and have been promoted, especially by Samsung, under the moniker QLED TVs, sales this year have been disappointing, and the take-up of QLED and quantum dots by other TV brands has been slow. One of the reasons for this disappointing performance in the marketplace is the expense of the Quantum Dot Enhancement Film (QDEF, see Figure #1), which serves as a replacement for the Brightness Enhancement Film (BEF) in a traditional LCD TV. QDEFs have been supplied by 3M, Hitachi and Chinese maker Exciton (“Nanosys Adds Exciton as 3rd Film Supplier for Quantum Dots”, DSCM 03.17.2017), although 3M has discontinued its production of the films.

Figure 1: ​Schematic of 3-layer QDEF Film, QDEF in LCD Module

The problem with the QDEF is the cost of the barrier film, which is required to protect the quantum dot material from oxygen and water. Out of a total estimated cost for QDEF of about $30 per square meter, at least half of the cost is the two barrier films. While quantum dot suppliers have been working on ways to make QDs more robust, so they don’t require such protection, this demand competes with other priorities like improving performance and cost, and moving away from cadmium-based materials. Therefore, a method to use quantum dots which did not require barrier films could help QDs gain greater marketplace acceptance.

That’s where glass comes in. In my years at Corning, I learned that glass is the best encapsulation material available (whether this is true or not regarding all possible materials, it is the accepted wisdom at Corning). This factoid from Corning’s web site highlights its use as a protective layer:

Glass has been used for millennia as a container because of its effectiveness at keeping contents (such as a liquid or a gas or even a high vacuum) completely isolated and protected from contamination by the surrounding environment. A molecule of oxygen, for example, takes about two weeks to pass through 1mm thickness of polycarbonate polymer (a common “high tech” plastic). The same oxygen molecule would take 30 billion years to pass through 1mm of silica glass!

So perhaps it was only a matter of time before someone paired the great need of QDs for encapsulation with the great ability of glass to encapsulate, but now it’s happening. DSCC sources in the industry have related the structure of QDOG as shown in Figure #2:

Figure 2: Schematic of Quantum Dot on Glass (QDOG)

Our understanding is that QDOG is being driven not by TV set brands, but by Samsung’s Display division. In SDC’s approach, they are taking Glass LGPs provided by Corning and Asahi at a substrate level, rather than at a panel size level, and depositing the QD layer on the substrate, then covering the QD with an inexpensive encapsulation layer of SiNx, which is only used to protect the QDs during a few process steps before the LGP-QD is cut to panel size and laminated onto the LC cell. Thus, the QD processes become an added part of the LC cell fabrication, giving a sort of “QDOG panel cell” which captures a much higher value content than a typical LC cell.

The downside of this approach, of course, is the cost of the LGP. DSCC estimates that a glass LGP adds $40 to the cost of a 55” TV panel, when considering both the raw glass and the light extraction patterning required. This extra cost has limited the adoption of glass LGP to a few small brands and selected models. A big part of this cost is a function of the small volumes of this product, but that chicken-and-egg problem does not have an easy answer.

Figure #3 shows DSCC’s estimate of the Backlight Unit (BLU) cost for 55” UHD TV panels with QDEF and QDOG, in comparison to conventional TV panels with edge LED backlight and PMMA LGPs. We estimate that in 2018 the BLU for a QDOG panel will cost $46 more than for a conventional panel.

Figure 3: Estimated Backlight Costs for Glass LGP and QD Products on 55” UHD TV

In their presentation during SID DisplayWeek, Corning claimed that because of the advantages of glass in light coupling and mechanical strength, at a total TV set cost glass LGP can be equal to or even lower than PMMA. A major driver of Corning’s analysis involves improved light coupling: Corning claims that by positioning the LEDs closer to the glass LGP (which is not possible with PMMA because of the thermal expansion and warp of plastic), a 15% improvement in light coupling can be obtained. Such an improvement can allow fewer LEDs, a lower-cost power supply, and fewer heat sinks, all of which save cost.

DSCC’s cross checks did not confirm the 15% light coupling improvement; on the contrary, one panel maker claimed that light coupling was worse with glass LGPs, and therefore more LEDs were required. Corning’s response to this claim was that the improved light coupling is enabled by a design which brings the LED strip closer to the LGP, and if the design of the LED strip-to-LGP gap does not change, then the benefit may not be realized.

By coupling glass LGP with quantum dots, though, it’s possible that QDOG represents a major advance on bringing both quantum dots and glass LGPs to a virtuous cycle whereby a profitable premium product gains market share and higher volumes, which allows for the economies of scale that drive lower costs, which drives yet higher adoption, and so on.

Our checks with TV brands and panel makers indicate that 2018 will be a breakthrough year for QDOG, with SDC’s business plan to build 1 million quantum dot on glass LGP panels, to be sold to TCL and other brands. We’ve heard a few points about this business plan that seem to be at odds. On the one hand, we understand that 65” would be a prime product for QDOG, but 65” is not an efficient cut on Gen 8.5, so SDC’s product line is more likely to include 55” and 49”. It’s possible that 65” could be made at SDC through an MMG approach, but this would make the product even more costly. It’s also possible that TCL could purchase 65” panels for this product from another vendor in 2018, as they prepare to start their Gen 10.5 fab in early 2019. With Gen 10.5, TCL would be well positioned to build 65” and 75” QDOG panels with Asahi’s XCV glass LGP at a substrate level.

Aside from the obvious goal of new revenue generation, one of the goals of Corning’s and Asahi’s efforts to push glass LGPs is to make use of idle or underutilized glass melting capacity. As long as the glass industry has some idle capacity, the ability of glassmakers to disrupt the pattern of continuous price decreases is constrained.

The current outlook on QDOG suggests that glass LGP can have a small but meaningful impact on overall glass supply. Assuming an average glass consumption of 1 square meter per panel (55” on Gen 8.5 at 91.7% yield would be exactly 1 square meter) and an average thickness of 2mm, glass LGPs would consume the equivalent of 4 million square meters of display glass melting capacity, or about 2% of the overall demand in 2018. While that’s not enough to change the overall dynamic of glass supply/demand, especially since Corning is adding new capacity for BOE’s Gen 10.5 fab in Hefei, it may be enough to tighten things up a bit.

With QDOG, LCD TV has yet another approach to fend off the threat of OLED in the TV market. We are looking forward to seeing the first QDOG products at the CES show this January.

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Written by

Bob O'Brien