The Rise And Potential Fall Of The Magnificent OLED

In March 2023 ‘JOLED’ filed for bankruptcy protection marking yet another chapter in the troubled tale of using OLED technology for high quality displays.

Anyone who’s in the market for a TV or video display in 2023 would probably prefer that it was an OLED. They’re expensive, because they’re rare, and they’re rare because they’re hard to make, but - compare jewellery-grade diamonds. They’re also expensive because they’re rare, though they actually do very little but sparkle attractively. The industrial diamonds used in cutting equipment are more useful, but not nearly as pretty. OLED displays, on the other hand, are certainly good and laudable and do useful work, as is clear to anyone who’s stood in one of those blacked-out trade show booths and compared an OLED to anything less than the very best dual layer LCDs.

The problem is that OLED display panels have long been testing the mettle of almost everyone who’s been involved in manufacturing them. The problem is somewhat specific to large sized displays suitable for monitors. Low-resolution displays for simple menus on electronic devices have long been common, and so are OLEDs for cell phones.

Until recently, though, LG was the only company which had managed to bring panels suitable for TVs to mass production in what seemed to be a financially sustainable manner. LG’s design relies on a white subpixel to achieve enough brightness for reasonable HDR, an approach that’s very effective for domestic viewing but less than ideal for HDR reference displays as it invariably leads to somewhat desaturated highlights on bright material. They’re probably the best TVs ever made, but the design isn’t really intended to satisfy the market for precision reference monitors.

Compare Sony’s no-compromise approach to OLED panels for applications such as its BVM-X300, which achieved HDR brightness with only RGB subpixels. Fantastic as that was, the thousand-nit output required the panel to be driven at a fairly taxing power level, with reports of alarmingly limited lifespan (especially for such a thoroughbred display). Let’s not forget, Sony was also the company which showed the little XEL-1 television, with a small, eleven-inch, 960 by 540 pixel OLED panel, at every relevant trade show for years. During those years there was much speculation about why the technology seemed so difficult to bring to market, and there was no great surprise when it turned out to be tricky.

Reports of Sony exiting the consumer OLED market began in the early 2010s, which quickly made the XEL-1 a collector’s item (people now make YouTube videos about them). By 2012, Sony and Panasonic had joined forces, perhaps recognizing the difficulty of manufacturing OLED panels, with the specific idea of creating inkjet-style printing processes which might make them easier to build. This, too, had been abandoned by the end of 2013. About six months later, Panasonic and Sony joined forces with Japan Display, itself a joint project involving Hitachi and Toshiba, to create another company, JOLED, to manufacture OLED panels.

Even with this sort of combined industrial might, it wasn’t until 2017 that Sony returned to building OLED TVs under its Bravia moniker. The surprise was that it did so using LG’s panels, and that’s how things remained until relatively recently, when Samsung began using quantum dot technology to build pure RGB panels for the consumer market. This was a new development, relying on a single OLED emitter type to drive red, green and blue quantum dot coatings, effectively converting short-wavelength (blue) light to longer-wavelength light like a phosphor-converted LED.

In the meantime, JOLED seemed to be doing well, with companies including Eizo creating high-performance monitors using its panels. It also supplied large numbers of smaller panels for laptops, tablets and phones. The company had built plants in Nomi and Chiba after attracting hundreds of millions in investment from organizations with an interest in making OLED work. The future looked - well - bright.

Then, in March this year, just as SmallHD had almost completed development on a monitor using a 32-inch JOLED panel, JOLED itself filed for bankruptcy protection. Readers will be forgiven for frowning at the realization that this was something like the third generation of companies which had rationalized, consolidated or outright failed because OLED, while potentially spectacular, is difficult to build - really, properly, tremendously difficult.

It’s not yet clear what interest there is in keeping JOLED’s technology alive. Clearly, we’d all prefer someone found a way to avoid throwing away the enormously expensive manufacturing plants and to keep the research and development work going. It seems, though, that was the entire purpose of JOLED in the first place: to ensure that expensively-accrued OLED know-how had a home, then it failed. This starts to sound like a cyclical problem, and at some point, it seems reasonable to expect that investors will begin to ask awkward questions regarding the sheer practicality of high-performance OLED.

Meanwhile, the mature technology of LCD goes from strength to strength. At the high end, it’s plausible to wonder whether displays based on increasingly tightly-packed LEDs might begin to compete too. The densest LED displays shown at NAB this year was Planar’s 0.6mm option, and at that scale, a 4K display need be less than two and a half meters (about eight feet) across. The guide price for such a display is apparently about US$85,000, so yes, we’ve found a rare way to make Sony’s finest BVM-series reference displays look comparatively affordable. Cost is one reason most theatrical exhibition spaces have been resistant to LED video walls (other reasons include weight, maintainability, and problems with placing loudspeakers). Nonetheless, it’s hard to argue with the performance of LED video walls. They’re possibly becoming practical for high-end grading suites.

OLED is beginning to show overtones of the situation which existed with plasma displays. There was much to like about them. Even so, they were a nuisance to make (less of a nuisance than OLED, but still), and they existed in the context of ever-better LCDs. The next big thing not only needs to be better than the incumbent, it also has to advance at a rate which allows it to stay better than the incumbent, and it has to stay better and cheaper than new challengers. LCD beat plasma. Might it ultimately ward off OLED in the same way?

Well, possibly. There are no signs of superlative dual-layer LCDs, as used in things like the BVM-HX3110, finding their way into consumer-priced options. Matrix backlights are effective but not ideal, and there seems to be no other approach to improving the old bugbear of LCD black levels. If there’s a single technology that at least claims to be solution to all these problems, it’s microLED. MicroLEDs are exactly what they sound like: devices based on the same physics as the on-light on your keyboard, just much smaller. The trick has been figuring out how to make very dense arrays of them for video display, without them being scattered in dead pixels.

Some of the very high density video wall panels sold by Sony and Samsung have been referred to as microLED, and advancement has been rapid. Sony’s Crystal LED Display line included a 1080-line display at 55 inches in 2012, and by 2019 Samsung showed a 75-inch 4K microLED display. Though ostensibly consumer-oriented, those are luxury displays at a luxury price, perhaps more likely to be found in the boardroom of an ambitious startup than in a domestic lounge. High densities have made more modestly-sized display panels possible, and AU Optronics showed a 12-inch panel in 2019.

Then, in February this year, MIT announced a big leap in microLED: resolution of 5,000 DPI, or a spacing of just over 0.005mm in the numbers used by conventional LED panel manufacturers. That’s an entirely different level of resolution to conventional LED video wall panels, and certainly capable of replacing things like LCD. Actually doing that means figuring out how to mass-produce microLED displays, though there are signs that microLED displays need not end up suffering the manufacturability issues of OLED.

MicroLEDs have a lot of the advantages of OLED: speed, contrast, resolution and colorimetry all measure well, but crucially, conventional, non-organic LEDs are more robust, and less prone to slow decay in use. The MIT team has even figured out how to stack them vertically (which formed the core of the February announcement) meaning that a single location can include red, green and blue elements. That in itself multiples the pixel density by three, at least in one axis. Let’s not get too excited; brightness can be a concern and microLED is currently a rare and expensive technology. It, too, has missed deadlines (AU claimed it was “one or two years” from being fully commercialized in 2019, and it still isn’t, though credit should be given for the pandemic).

Still, microLED might have a chance to steal a march on the competition. A dazzling future in which all displays are bright, affordable and OLED seems perpetually stuck behind practical problems which have resisted solution for decades. Research into the electroluminescent materials involved stretches back to the mid twentieth century. One research project at the Cavendish Laboratory at Cambridge in 1989 resulted in the company Cambridge Display Technology, which exists to this day as a subsidiary of Sumitomo Chemical. By the late 1990s organizations including Kodak were producing small displays. Now, 25 years later, it could be argued we’re still struggling to make big ones feasible.

OLED is a wonderful technology, though incumbent LCD designs continue to evolve and improve, and there is at least one plausible contender in microLED which may emerge soon. It’s unclear where this might end, although the benefit is that no matter which technology we’re using, it’ll inevitably end up creating better displays for everyone.

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