Why Is OLED Different And What Makes It So Great?

Why Is OLED Different and What Makes It So Great?

I have seen the future of high definition displays and lo, it is glorious. Not to mention rollable, foldable, and clearly superior to LCD/LED — really every other panel technology available today.

What is OLED and how does it work?

OLED, or Organic Light Emitting Diodes, are an offshoot of existing conventional LED technology. LEDs are semiconducting light sources that function through electroluminescence — that is, they produce photons (aka light) by plopping electrons into little electron holes within the device's emissive layer. Basically, electricity goes in and light comes out thanks to a semiconductuctive material, rather than a white-hot metal filament like an old-school lightbulb.

OLED technology, first successfully implemented in 1987 by Kodak researchers Ching W. Tang and Steven Van Slyke, takes this same idea as LED, but flattens it. Rather than an array of individual LED bulbs, OLED uses a series of thin, light emitting films. This allows the OLED array to produce brighter light while using less energy than existing LCD/LED technologies. And since these light-emitting films are composed of hydrocarbon chains, rather than semiconductors laden with heavy metals like gallium arsenide phosphide, they get that "O" for "organic" in their name.

An OLED panel is typically composed of four primary layers: The substrate, which acts as the structural framework; the anode, which draws electrons; the cathode, which provides electrons; and the organic layer between. That organic layer is further divided into a conducting layer — which provides the "electron holes" that the electrons flowing through layer can snap into, shedding energy in the process — and an emissive layer where the light is actually produced. And if you want to start messing with producing actual colour, it's just a matter of adding red-, green-, and blue-tinted plastic layers to the substrate.

There are additional flavours of OLEDs that are better for different kinds of devices. When a device only needs to display a static pattern with relatively slow refreshes — like the LCD readout of a calculator or e-ink displays of the Kindle Paperwhite — you can use something called a passive matrix OLED (or a PMOLED). These work by turning on voltage to specific areas of the film and leaving them on until the device refreshes its instructions.

Then there's active matrix OLEDs, like the AMOLEDs you might find in a smart phone. These are for high-definition applications that demand fast refresh rates, such as smartphone screens or HD televisions. AMOLED displays require a thin film transistor back-plane to actually drive each of the individual pixels, but this layer is just as flexible as the others, allowing for the development of rollable, foldable, transparent display panel prototypes.

Why's it so great?

The LEDs in today's LED televisions are actually used only to provide a white back light, which then shines through a rapidly-refreshing LCD shutter array which tints the emanating light. OLEDs, on the other hand, operate as both light source and colour array simultaneously. This may not sound like a big difference, but does offer a wide range of benefits including:

  • Lower power consumption - An OLED display doesn't need any of the electronics and circuitry used to drive the LED back light and LCD shutter from a LED display, which makes OLEDs more efficient. LED screens produce black simply by fully closing the pixel shutter — the back light is still shining (it never actually turns off) but the light itself is being blocked. An OLED instead turns the pixel off entirely to produce the colour black, saving energy in the process.
  • Better picture quality - Since OLEDs incorporate their own colour filters, they can produce deeper blacks and a wider gamut array. The lack of a permanently-on backlight promotes higher contrast ratios (the difference between the brightest and darkest pixels on the screen). And thanks to the lack of a shutter array, OLED displays can have refresh rates that are an order magnitude faster than those of LCD/LED sets. We're talking a boost from 480 Hz to 100,000 Hz — theoretically, at least. On top of that, OLEDs offer an impressively wide viewing angle — nearing 90 degrees off center for many panels — without the colour and clarity losses seen in traditional LEDs.
  • Better durability and lighter weight - Ditching the back light and shutter arrays also means manufacturers can replace the heavier, shatter-prone glass substrates often used in LED displays with lighter, stronger plastic substrates. And with the advent of injet-based printable OLEDs, these light producing compounds can be applied to more exotic and malleable surfaces. Additionally, the OLED films themselves are quite durable and can withstand a wider operating temperature range than regular LEDs without failing.
  • The price is only going down from here - The ability to simply print out OLEDs as you would a term paper or silk-screened t-shirt holds incredible technological potential. It's also ludicrously expensive at present — look to spend about triple for an OLED set than a conventional LCD/LED these days — but once roll-to-roll production capabilities are scaled up sufficiently, the cost of spitting out an OLED panel should drop below what we're paying to make current generation LEDs.

It's not perfect but it's close

OLED technology isn't without its drawbacks and shortcomings. The biggest issue facing OLED right now is the fact that the material used to produce blue light degrades at a much faster rate than the other hues, which eventually throws off the colour balance and reduces the overall brightness of the display.

This forces manufacturers to compensate by, say, drastically increasing the size of the blue sub-pixel to as much as double the green and red, or requiring the consumer to continually fiddle with the calibration. Luckily, a great deal of research has been made into improving the efficiency and lifespan of blue OLED, culminating in a recent breakthrough that has brought the hue up to par with its other subpixels.

To be clear, the composition of the display panel — whether it's a CRT, plasma, LED, or OLED — has very little to do with the resolution of the screen. The terms, HD, 4K, and UltraHD all refer to the number of pixels the manufacturer can pack into a panel, not what those pixels are made of or how they work. This is why you can find sets like Sony's flagship 4K XBR-65X950B using LCD/LED panels and 1080p sets like the LG EC 9300 sporting OLED displays.

If you're currently in the market for a TV that is both future-proof and offers a superior image, you're going to be paying through the nose for something like LG's latest 4K OLEDs. Conversely, you could split the difference, depending on how soon you think you'll be buying your next set, and either opt for a 4K LCD/LED or a 1080p OLED. Just don't waste your cash on a 1080p LED; that tech is already in the past, replaced by a bright and glorious future. [OLED Info - Wiki 1, 2 - How Stuff Works - Explain that Stuff - PC Mag - Cornell University]


Comments

    Guess I will get my old VT50 repaired afterall

    I bought an LG 55EC930T (in Australia) OLED TV two weeks ago and it is amazing. I have never seen such amazing contrast and colour in movies. The out of the box cinema settings were very close to the settings I took from my go to calibration site Flatpanelshd.com and 4K doesn't even matter at 55 inchs at the correct viewing distance. The curve is ever so slight, no where near as harsh as on the current Samsung's and WebOS makes the smart TV good. Again, I cant explain how good all 1080p movies look, its like looking though a window. The only slight flaw is you need to enable some very light motion flow and de-judder as 24fps isn't quite smooth enough or I am too sensitive to it, I also see flickering in white when at the cinema. Gaming is also good, you need to use game mode and set the input as PC, once you have done that it gets down to about 32ms and looks so awesome. I know I'm waxing lyrical about this set but everyone that has seen it has been blown away by how good it is. One of my biggest complaints while watching Interstellar at the Imax last night was the blacks looked rubbish after watching Gravity, Empire, Batman, anything on an OLED. Even my wife thinks its good!!!!!!

    Last edited 07/11/14 11:29 am

    Yup... Gonna wait for a 65" OLED 4K to come down close to current LCD prices and then jump... On a more techy note though, I read in Phys.org awhile back that they are developing, from memory, cos I can't find the actual article, either atomic, or molecular sized light sources..! :)

    Last edited 07/11/14 12:22 pm

    Two words:
    Burn In

    The current gen OLEDs all suffer from burn in. A big drawback if you want to use it for regular TV or Games...or anything other than just Movies really.
    Also while OLED technology uses less power than conventional LCD/LEDs the current TVS actually consume MORE power.

    Still looking forward to the future of OLED but right now? Not a chance. Don't pay extra to be a beta tester.

      yup. OLED sounds good, but needs many more years of testing and R & D before its really for the consumer !

      Hey. I have yet to see any symptoms of burn in (so far) and have been watching letterbox, 4.3 and have enjoyed multiple hours of gaming on mine. From what I have read, LG have developed an algorithm that purges the screen to eliminate image retention. I guess its the same as plasma and the risk of burn in didn't stop me wanting the best picture when I bought into that 12 years ago. I'm happy to be a beta tester for new tech. If no one bought in at the ground level, there would be no new products for everyone else.

      Last edited 07/11/14 1:46 pm

      Remember that phones have been using OLED screens and displaying static images for years without problems. The only one I saw with burn in was a demo unit at Dick Smith that had been displaying the same image for more than a year, and it went away after playing with the screen for a while.

      I use OLED monitors every day for work and some of them are on for many days straight with the same image on the screen and no noticeable burn in at all. The monitors we use are Sonys BVM and PVM broadcast/professional range. TV broadcast in Australia has been using OLED for about 3-4 years now.

      The only problem i find with Sonys OLED is when viewing them off centre the colour can change quite dramatically.

    Sadness.. i just bought a LG 60LB7500, and here you tell me it's a crap TV.... sigh...

    I wonder how many years it will take apple to adopt it. Maybe never because they would have to pay someone royalties to use it and apple would rather their customers suffer than to pay royalties to other companies.

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