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What is OLED? Black levels, burn-in, and contrast ratios explained

What is OLED?
LG WX OLED (2020) (Image credit: LG)

What is OLED technology? Well, OLED stands for Organic Light Emitting Diode (more on that later) and it’s become a common TV panel technology in recent years. That’s because you’ll find it in both OLED TVs and high-end smartphones like the iPhone 11 Pro.

But even though it’s cropping up in lots of places, you might still be struggling to make head or tail of what those four letters really mean for you as a consumer – and whether investing in something with an OLED label on it is worth it in the long-run. 

We get it. The TV market is full of difficult acronyms and some of them are much more useful than others. (Oh and don't get us started on model names. TX-55GZ1500 doesn't exactly roll off the tongue, does it?)

Although we don’t think you need to get to grips with every acronym, OLED is an important term to familiarise yourself with if you're on the lookout for a new smart TV, or just looking to understand the latest chatter around today's best TVs to buy right now. That's because so many of the latest and greatest televisions have OLED panels, with only Samsung's QLED panels really offering a rival of any kind.

So, back to that Organic Light Emitting Diode. The OLED acronym describes a type of panel used in TVs, including LED-LCD, plasma or CRT. For a long time we might have said OLED was the next big thing in home entertainment – but it's now well and truly here. 

But just because it's (almost) everywhere, doesn't mean it isn't worth shouting about. Compared to its predecessors – and most of the LCDs currently on the market – OLED TVs offer better image quality (think blacker blacks and brighter whites), reduced power consumption, and faster response times.

Not everyone owns an OLED TV, of course, because of a pretty steep price barrier. That's slowly changing, largely thanks to more affordable models like the LG B9, scaled up production, and a smaller 48-inch size for the CX OLED and Sony A9G OLED.

The big question is: should we believe the OLED hype? We've run you through everything you need to know about the big screen buzzword in the guide below.

Don't have time to read a whole article? Watch our quick OLED explainer video below:

FAQ

OLED FAQ: quick questions answered

  • Is OLED better than LED? They're different. OLED excels in some areas, such as contrast, color accuracy, and black levels – though the low brightness might rub you the wrong way.
  • Is OLED better than 4K? OLED TVs tend to have a crisp 4K resolution, but most 4K TVs don't have OLED panels. Pick and choose as you like!
  • Is OLED better for my eyes? OLED panels emit around half the amount of blue light than equivalent LCD sets, which should reduce the likelihood of damage to your eyes and stop the evening's programming keeping you up at night. You should get those benefits for OLED smartphones too.
  • Why is OLED so expensive? They're expensive and difficult to produce, with a lot of models suffering breakages while on the factory line. (Only the working ones make it to retail, of course.)
  • What's the lifespan of an OLED TV? Any OLED TV should last you years of use. Back in 2016 The Korea Times reported that LG OLED TVs had a lifespan of over 100,000 hours (11 years of constant use).
  • Should I worry about OLED burn-in? Probably not. Image retention isn't a widespread problem, and you're unlikely to be affected – though we have more information on this below.

OLED explained

What is OLED, and how is it different?

What is OLED?

Most OLED TVs offer exceptional picture quality, though they need to be paired with a high-spec processor to really do sources justice (Image credit: Panasonic)

OLED stands for Organic Light-Emitting Diode, with "organic" referring to the carbon film that sits inside the panel before the glass screen. 

OLED panels emit their own light when an electric current is passed through, whereas cells in a LCD-LED display require an external light source, like a giant backlight, for brightness.

This backlight is what separated LCD screens from their LED variants. A traditional LCD screen has a backlight (called a cold-cathode fluorescent light, or CCFL) which is uniform across the entire back of the screen.

This means that whether the image is black or white, it is being lit by exactly the same brightness across the panel. This reduces what we call "hotspots," or areas of super bright light, because the actual light source illuminating them is uniform.

This all started a few years back when engineers at companies like Samsung and Sony introduced an array of LEDs as a backlight, which meant that if a certain part of the screen was black then those LEDs behind that portion could be turned off to make it appear blacker.

This is a better solution than a CCFL backlight, but it still has its problems. Since it's a light behind the LCD producing the illumination rather than the LCD layer itself, the illumination is not entirely in-sync with the pixel in front of it. The result is an effect called 'blooming', whereby LED light from bright portions of the image bleeds over into areas of blackness.

This is what separates OLEDs from LCD/LED displays. In an OLED TV display, the pixels themselves are the things producing the light, and so when they need to be black they are able to turn off completely, rather than relying on a backlight to turn off on their behalf.

What are the advantages of OLED?

What is OLED?

Philips TVs combine OLED panels and Ambilight projection to great effect – and the first Philips OLED is making its way to the US too (Image credit: Future)

The result is remarkably dark blacks in an image, and when you combine this with the bright whites of an OLED panel, you're left with a fantastically vibrant image.

LG and Panasonic, pretty much the most consistent producers of OLED televisions on the planet, like to use the term "infinite contrast" to describe how the self-lighting pixels switch off completely when reproducing black giving it an "absolute" black color instead of a "relative" black that only describes how dark one pixel can get compared to the brightest pixel on the screen.

For years there was a question mark about longevity of OLED panels, while production lines have been impossible to make profitable due to high failure rates. 

But as companies like LG invest billions in development of OLED – with the likes of Philips and Sony joining the fray – its affordability is improving, even if it's still more expensive than competing technologies. Current production issues for LG's most recently-opened TV factory won't be helping that price drop come quicker, either.

The advantages of OLED go beyond simple static image quality, though, to the responsiveness and smoothness of the display itself, meaning gamers and home cinema aficionados are going to absolutely love OLED TV. 

OLED panels are capable of a refresh rate of as low as 0.001ms, which for reference, is around 1,000 times faster than a standard LED-backlit LCD panel, while also being superior to the now-discontinued plasma tech, too.

And, because the lighting source they use is so tiny, the depth of screen sizes has shrunk at the same rate. That means OLED TVs have awesomely deep blacks and bright, peak whites, improved color accuracy as well as smooth responsive motion - and all from a form factor that's just a few millimeters in depth and much lighter than standard TVs.

TVs

Which OLED TVs are out now?

LG 2020 TV lineup

LG has a whole host of new OLED televisions for 2020 (Image credit: LG)

OLED TVs have been on the market since 2012, and a variety of manufacturers have tackled the technology over the years. It used to be the case that OLEDs were produced by just Samsung and LG.

But Samsung dropped the technology over its cost and how difficult it was to produce, and has no intention of restarting production any time soon. More recently, Hisense ditched its OLED focus too.

LG, on the other hand, has been releasing OLED sets consistently over the last few years. The 2020 LG TV line-up has seen a new LG CX Series OLED, an LG GX ‘Gallery’ Series OLED to replace the old LG E9, an LG Signature ZX 8K OLED, as well as many others.

If you're not big into LG TVs, there are plenty more OLED TVs to look forward to in 2020 too. The Panasonic 2020 TV line-up includes the high-end Panasonic HZ2000 OLED, while more mid-range OLED sets like the Philips 55OLED754 continue to perform well in our tests.

You can also head to our best OLED TVs guide to see the top five OLEDs we've had the pleasure of reviewing on the site.

How much do OLED TVs cost?

OLED TVs are definitely getting cheaper, but they're still a long way from what we'd call affordable. The prices of new LG TVs start at $1,600 in the US and £1,500 in the UK, and Panasonic's are more expensive still.

The scarcity of OLED TVs on the market means that those small number of players in the market are more or less free to charge exactly what they want. An increase in competition, though, is helping to change that, as is the introduction of a new 48-inch panel size and a scaling up of production.

It's significantly cheaper to buy a 2019 OLED right now, with the budget LG B9 costing just $1,300 / £1,100 – not cheap compared to some LCD sets, but still the cheapest way to get a decent OLED into your home.

Burn-in

Do I need to worry about OLED burn-in?

What is OLED burn-in? Burn in, or image retention, is when an image or sequence is played so often and continuously on a television set that it leaves a permanent mark on the panel – obviously not ideal for a home television.

You don't particularly need to worry, as it largely happens only when displaying a static image or sequence on repeat, as with a display unit in a showroom or retail store. You should get several years warranty, anyhow, and we don't see many home cinema fans using their OLED TV in this way.

What is OLED?

Burn-in shouldn't worry you, thanks  (Image credit: Toshiba)

TV makers like LG are also working to limit the risk of this, with screen saver features, a Screen Shift function that "moves the screen slightly at regular intervals to preserve image quality", and "Logo Luminance Adjustment, which can detect static logos on the screen and reduce brightness to help decrease permanent image retention" (via LG.com).

But if you're planning on leaving your TV for countless hours at a time – say, to parent the children in your absence, or to play the same looping video over and over – then OLED may not be the right panel technology for you.

What's next?

What's the future for OLED TV?

OLED is an expensive panel technology that has finally managed to gain traction – after spending so long as an outlier than we wrote an opinion piece in 2014 about how the technology might be dead.

Obviously that didn't turn out to be the case, and we're seeing plenty of stunning OLED models hitting the market, even if price points are still taking an age to drop within reach of regular consumers.

But just because OLED isn't affordable yet doesn't mean it's not getting better. An $1,600 / £1,200 price tag isn't what we'd consider budget, but it's a great deal cheaper than what OLED was retailing for even just a year ago.

That trend is always going to be good news for the consumer, though manufacturers may have other things in mind. 

Samsung is one of several TV makers looking to develop what's called QD-OLED: a new type of OLED panel that uses quantum dot emitters to improve brightness. The tech is very much in development, but when it arrives, it could meld the competing QLED and OLED technologies and render previous methods of production obsolete.

Those are obviously grand claims, and we're yet to see these new hypothetical panels put to use – but we'll be sure to keep you in the loop as it does / doesn't happen.

Original reporting in this article was by Jamie Carter.

  • Convinced? Head to our round-up of the best OLED TVs you can buy right now