Shedding Light on OLED Displays

Sony XEL-1

Sony XEL-1’s 11-inch screen is a mere 3 mm thick and features a 1,000,000:1 contrast ratio.

What exactly are "organic light-emitting diodes," who's making them, and what challenges does this new technology face?


Mar. 11, 2008 — by .(JavaScript must be enabled to view this email address)

Crowds are as common at the annual Consumer Electronics Show (CES) as dirty faces are at an elementary school ice cream party. The same goes for shoving and line-cutting. But the elbowing and jockeying for prime position that took place at Sony’s massive display during the 2007 show exceeded the norm.

All of the jostling at a show that for several consecutive years had championed a “bigger-is-better” approach was to get a glimpse of a tiny Sony television. But this one was special. It was a TV whose 11-inch display used OLED (organic light-emitting diode) technology; a set that wound up being a prototype of a model whose sales launch Sony announced a year later at CES 2008.

The excitement over Sony’s OLED TV, now officially called the XEL-1, makes sense once you see it. The display is a marvel – both for its diminutive physical dimensions and the picture it displays. Ignoring its elegant and appropriately futuristic stand, the display itself is just 3 mm (just over one-tenth inch) thick. By contrast, Vizio’s recently discontinued 13-inch LCD TV is 2.5 inches thick. The difference between the Sony XEL-1’s picture quality and conventional LCD displays is equally dramatic, thanks to its 1million:1 contrast ratio, extensive color spectrum, and nearly limitless viewing angle.

Sony deserves kudos for being the first to market with an OLED TV. But the inherent advantages of OLED technology ensure it won’t be the last. Samsung already has demonstrated a 40-inch OLED TV. And although they haven’t publicly announced it, you can be sure other manufacturers are working feverishly to get OLED televisions into production.

That’s because the advantages of OLED compared to other commonly used television technology – particularly the most popular one, LCD – can be striking. But like any new technology, manufacturers face a formidable challenge of making OLED technology affordable for it to become commonplace. For example, Samsung, generally considered the largest TV maker in the world, is on record as saying it won’t put OLED sets into production until they can be sold for around the same price as TVs based on other technologies. Sony, on the other hand, obviously believes that there are at least some consumers willing to pay a premium—$2,500 for its 11-incher, which is more than the street price of some very good 55-inch plasma models – to have the latest and greatest TV technology.

And there’s little doubt that OLED is the latest and greatest current display technology available. So much so that if production costs become competitive and no other viable technology emerges, every TV made a few years from now could be OLED. Here’s why:

Better Picture
OLED displays offer higher contrast, brighter images, wider color spectrum, and better viewing angles than LCD displays. Other than that, they’re nothing special. Kidding aside, the OLED technology edge comes from its design technology (see sidebar). Unlike LCD displays, which require an always-on backlight and create black by partially obscuring that light, the pixels that make up an OLED display are naturally black. That leads to remarkable contrast by today’s TV standards. The brighter images and broader color spectrum (around 16 million colors versus 260,000 for a typical LCD, according to Kodak) are characteristics of the technology. So is OLED’s 178-degree viewing angle, which means its picture looks great from anywhere in front of the display. And OLEDs will be unbeatable when it comes to reproducing rapid motion because their pixel response time is virtually instantaneous. By contrast, the fastest LCD TV refresh rates are typically around six milliseconds. 

Less Costly
Although OLED production costs are high now, economies of scale and the development of production facilities should ultimately bring it down to prices that LCDs won’t be able to match. That’s because the materials and manufacturing requirements of OLED displays are inherently less expensive than those of LCD or plasma flat panels. Operating costs will also be significantly lower for OLEDs because they use less electricity. They require absolutely no backlight, which is where most of an LCD’s power consumption goes. 

More Versatile Form Factors
In addition to being substantially thinner and lighter than plasma and LCD flat panels, OLEDs displays can be delivered in an almost unimaginable variety of form factors. Because they can be manufactured on flexible substrates and don’t require the hard glass panels of LCDs or plasmas, they can be turned screens that can be rolled up like the morning newspaper, applied to clothing, and even turned into semi-transparent heads-up displays. The flexibility of their substrates also make them inherently more durable than current display technologies. Finally, once manufacturers begin producing OLED displays in great quantities, there will be no practical or economical limit to screen size.

If it sounds as though OLED technology makes for the ideal TV, you’re close. But there are a few shortcomings, although two of them should be fairly easy to resolve. The first is that OLEDs are extremely susceptible to water damage, which might limit their applications until unbreechable sealing techniques are developed. That will probably happen when CE companies overcome the second problem of developing the manufacturing infrastructure to mass produce OLED displays cost effectively.

The third problem is more serious and more challenging: Although the red and green OLED elements have lifespans comparable to LCD and plasma TVs, the blue elements currently last a maximum of about 14,000 hours in flat panel display applications. LCD and plasma displays have lifespans nearly five times that. But 14,000 hours is also three times as long as blue OLED elements lasted just a couple of years ago, so progress definitely is being made. Unless an even newer, cheaper, and better technology emerges in the very near term – and right now that doesn’t seem likely – the next big-screen TV you buy may very well be a stunning OLED display.

Sidebar: A Simplification of OLED Technology
Kodak scientists are credited with inventing OLED technology in 1987, and the company still holds patents on it. That means OLED television makers may have to pay licensing fees to Kodak to use the technology.

Although there are several variations of OLED display technology, all of them rely on the same fundamental design and principles. The display is comprised of two adjacent layers of organic molecules sandwiched by a cathode and an anode layer. This sandwich rests on a substrate, or base, material.

An electrical current is sent from the cathode to the anode layer, causing molecules in both layers to react. The reaction is primarily a movement of electrons that ultimately results in some of them replacing others and emitting light as a byproduct.




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