What is OLED?

By now you've probably heard about OLED or organic light-emitting diodes. LG and Samsung both revealed potential models at this year's Consumer Electronics Show, with the LG winning CNET's Best of CES Award.

Make no mistake, this is the most important advancement in TV technology in over a decade and a vast improvement over both LCD and plasma.

Here's why.

How does it work?

You only need red, green and blue light to create a TV image. OLEDs work by putting electricity through certain materials that glow these specific colours. No other TV technology creates light directly like this.

LCD (liquid crystal display) TVs use colour filters and light-blocking liquid crystals above a light-creating backlight. Plasmas use UV light created by igniting pockets of gas to excite red, green and blue phosphors.

What does this mean?

Well, OLED TVs will be thinner, lighter, more efficient and better performing than any current television technology. Each pixel can be shut off, for an absolute black — no other tech can do this, except for the now virtually extinct CRT (cathode ray tube). This means an actual infinite contrast ratio, not just marketing hype.

For example, LG's 55-inch OLED unveiled at CES weighs 3.4 kilograms and is about as deep as a pencil (0.78mm).

It's hard not to be excited about OLED, as it ticks all the boxes of a dream television: incredible contrast, impossibly thin, extremely energy efficient.

LED vs. OLED

As we've discussed before, current televisions marketed as "LED TVs" aren't actually LED TVs. They're LCD TVs that use LEDs for the backlight. While LED LCDs are energy efficient compared with "regular" LCDs and plasmas, they're still not as energy efficient as OLED.

As far as the difference between LEDs and OLEDs, the latter uses materials that include carbon ("organic") to create light when supplied a current. In an extremely oversimplified and generalised explanation, LEDs are like tiny light bulbs, while OLEDs are light-emitting areas or surfaces.

The only real LED TV, as in a TV that used LEDs for the image itself, was Sony's Crystal LED prototype shown at CES. If this technology moves past the prototype stage, we'll report on it more fully.

RGB OLED vs. "White" OLED

The current OLED TV technology can be split in two camps: RGB OLED and "White" OLED. RGB OLED is similar to how plasma TVs work, with separate red, green and blue OLED sub-pixels.

White OLED is rather different and a bit confusing at first. The red, green and blue OLED materials are sandwiched together, and when powered, these create a white light. This white light passes through a colour filter, to create the red, green and blue sub-pixels.

It looks something like this:

How White OLED works

A side view of LG's White OLED structure. The front of the TV screen is at the top, with the back of the TV at the bottom. A sandwich of red, green and blue OLED layers (1) together produce white light (2). Colour filters (3) allow a specific colour through toward the screen (4).
A clear filter (right) allows the white light to pass through, increasing overall brightness. As shown, this pixel would appear white. Turn off the OLED behind the blue filter, and the pixel would appear yellow. Turn off the OLED behind the blue and red filters, the pixel will appear green and so on.
(Credit: Geoffrey Morrison/CNET)

This image above represents one solitary pixel. There are just over 2 million of these on each full HD (1920x1080) TV. In the LG design, pictured above, there is an additional white sub-pixel, which adds additional brightness, helping efficiency.

This seems weird, right? After all, if you've got all three colours there already, why make white just to then turn it back into specific colour? Well, it turns out "White" OLED (WOLED) has several benefits. There are some claims that this white sandwich has longer life and less chance of colour shift versus utilising R, G and B OLEDs separately. LG wouldn't commit to a lifespan claim when we asked it directly, however, saying only that while "long-life testing is still under way, we believe our WOLED will perform quite well vis-à-vis other displays".

What they did say, and this is very important, is at this stage it's easier to manufacture. That translates to "cheaper". And we're in the camp that thinks anything that gets OLED to market sooner is a good thing.

Lastly, and this could be where "White" OLED wins out, it's easier to scale to different screen sizes, which means bigger (or smaller) OLED TVs sooner. That also means it's easier to scale to 4K resolutions. This writer is on record saying 4K TVs are stupid, but will admit that it's inevitable.

We know some of you are thinking: "urgh, colour filters!" what kind of LCD-esque step back is this horror hybrid? At first, we were in this camp as well, but the more we've researched things, "White" OLED offers a lot of advantages, separate from the "pure performance" aspect. Could RGB OLED be slightly more efficient or have slightly better performance? Maybe, but at this stage, it doesn't matter. If "White" is easier to make, that's the road we're on.

OLED needs to come to market before we can argue the potential benefits of one version of the technology over another. OLED, regardless of the specific flavour, is going to perform better and be more energy efficient than any current television.

Inevitably, future versions of this technology will perform better. We can fixate on that pixel by pixel when we come to it.

AMOLED vs. OLED

Mobile phones and other small portable devices often specify that their screens are AMOLED instead of just OLED. The AM stands for active matrix, which is how the screen is addressed by the electronics of the device. It is just a different way of running an OLED screen, one that's better for motion, like video. Each pixel can be addressed individually, which is what you want in a television.

Those of you with long memories will remember the days when LCD monitors were called TFT LCD or active-matrix LCD. You hardly ever see that clarification made nowadays because every LCD screen you're now likely to come in contact with — be they in either phones, tablets or TVs — is active matrix. Same idea here. OLED TVs will be some kind of active matrix.

When is this all happening?

Like any new technology, OLED TVs will be expensive at first. Don't forget it wasn't too long ago that big-screen LCDs and plasma were well beyond the means of us mere mortals. Let the one percenters buy these first-generation panels (estimates say US$8000 or AU$10,000), driving down the cost for the rest of us. Within a few years of launch, expect to see OLEDs as a significant, but reasonable, step up over LED LCDs and plasmas.

In the meantime, you can check out what OLED looks like now. Many mobile phones, including Samsung and HTC models, feature OLED screens. Samsung has released a new tablet with a 7.7-inch OLED and the just released Sony PlayStation Vita has a 5-inch OLED screen.

In the future, OLED has few limitations on size or resolution. Wall-size OLED screens have been hypothesised. Flexible OLED, still many years off, fulfils the sci-fi promise of screens you can roll up like a magazine.

Excited yet?

Via CNET



Add Your Comment 2


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DamienC1 posted a comment   
Australia

Didn't Sony bring this to the market years ago with a tv the thickness of a credit card, or am I thinking of something else?
If they did, why are they not leading the pack in this area instead of LG and Samsung?

 

alexeiw123 posted a comment   
Australia

great article!




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