OLED TV is the epitome of 21st century display technology with its super-thin panels, big screen sizes and Ultra HD images, so it might surprise you to discover the underlying concepts and materials were first developed in the 1960s.
The first practical OLED display was built in 1987, but it wasn’t until the 2000s that manufacturing capabilities made mass-produced OLED TVs a reality. Sony was a major OLED pioneer in the early days, but the first big-screen OLED TVs were launched by Samsung and LG in 2013.
These initial OLEDs used 55in Full HD panels, were limited to Standard Dynamic Range (SDR), and came with a hefty price tag. The Samsung and LG models also used differing approaches to producing an image, and, for reasons discussed later, Samsung dropped out of the OLED market the following year. This left LG as the main OLED panel supplier, and no company has invested as much in the technology or done more to promote OLED TVs to consumers. So, no matter which brand of OLED 4K TV you buy, the chances are the panel itself is manufactured by LG.
But what is an OLED, what are its strengths and weaknesses, why are manufacturers putting quantum dots on them, and should you buy an OLED TV? Read on to find out.
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What is OLED?
OLED stands for Organic Light-Emitting Diode, but since that probably doesn’t help much we’ll break it down further. A diode is simply a component that conducts electricity, and if you combine it with an organic compound that glows when a charge is passed through it, you can create light.
The compound itself is composed of carbon-based materials that are electroluminescent, so when an electrical charge is applied, they glow. This makes OLED self-emitting, and means a backlight is not required to generate the image, which is particularly useful for TV display technology.
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How does an OLED TV work?
A traditional Liquid Crystal Display (LCD) TV uses a panel composed of up to six layers, with a backlight, glass substrates containing a liquid crystal layer and then polarising filters. As a result, the panel has to be reasonably deep to accommodate all these layers and components. The adoption of LED backlights has made designs thinner, but the light still has to pass through the liquid crystal layer, making it difficult for an LCD TV to deliver deep blacks.
An OLED TV on the other hand, is simply composed of the previously-mentioned organic compound layer sandwiched between a thin-film transistor and a filter, which is why they’re so incredibly thin. This isn’t the only advantage, because the self-emissive nature of OLED means when you switch off the current to an individual pixel it simply stops glowing, and as a result the blacks are completely black with no light spill or afterglow.
The first commercially available OLED TVs used red, green and blue (RGB) subpixels, and while the images produced were excellent there was an issue – the organic material that produces blue light decays faster than the materials used for red and green. Samsung’s first OLED TV used this approach, and the company decided it wasn’t commercially viable and pulled out of the market.
While Sony continued to manufacture RGB OLED panels for professional-grade monitors, LG developed its WRGB technology for mass production. This design uses a compound that produces white light, and then applies filters to create the red, green and blue subpixels. This bypasses the issue of blue decay, thus increasing the lifespan and brightness of a TV.
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What are the advantages of an OLED TV?
The obvious advantage of an OLED TV is the thinner panel allowing for some very sleek and contemporary designs, although space is still required for electronics, connections, and speakers. In recent years, LCD TVs have made significant gains in narrowing the panel depth through the use of LEDs and more recently Mini LEDs.
Since the light generated by an OLED panel doesn’t have to pass through an LCD matrix, the optimal viewing angles are also significantly wider. An OLED TV doesn’t suffer from a drop-off in contrast or colour when viewed at extreme angles (both horizontally and vertically), which means no matter where you’re sitting in the room, you’ll get the best picture.
The other big advantage of an OLED TV is its black levels and shadow definition just above black. The self-emissive nature of OLED gives it an inherent advantage over LCD in this area, and while the latter has tried to emulate OLED using dimmable zones, even if it has thousands of these, it can’t hope to compete with the precision offered by a 4K OLED TV’s eight million pixels.
An OLED TV’s ability to control each pixel individually is also very useful when it comes to High Dynamic Range (HDR), allowing it to deliver precise specular highlights. When you combine the deep blacks with these precise highlights, you get a huge dynamic range and superior contrast performance. In addition, an OLED can produce a wide colour gamut, with most capable of hitting 100% of DCI-P3.
OLED TV’s also have very fast response times, allowing them to refresh each image quicker than competing LCD TVs. This not only allows for support of higher frame rates of up to 120Hz, but also incredibly low input lags that are often less than 10ms. This makes OLED TVs great for gamers looking for superior image quality and responsiveness.
What are the disadvantages of an OLED TV?
The self-emissive nature of OLED means it can potentially suffer from image retention and even screen burn. This is where a static image like a heads-up display in a game is temporarily, or in the worst cases permanently, burnt into the screen. Thankfully, manufacturers have introduced features to successfully mitigate the issue in recent years, but it’s still something potential buyers should be aware of, especially if they’re big gamers.
LCD TV manufacturers often point to the limited brightness of an OLED TV when it comes to HDR, but in reality, this is less of an issue than it might first appear. Most OLED TVs can reach around 700cd/m2 on a 10% window, and advanced models can hit up to 1,000cd/m2 by using a rear sink to dissipate the extra heat generated. Once you combine the deep blacks with pixel-precise highlights and effective tone mapping, the resulting HDR performance is generally very impressive.
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However, the one area where an OLED TV has limitations is in reproducing a bright overall image with HDR. This is because an OLED will struggle to energise its entire panel, and under these conditions, the TV’s automatic brightness limiter kicks in. As a result, a full-field white pattern on an OLED won’t reach more than about 200cd/m2, whereas an LCD TV can easily hit 400 to 500cd/m2.
Finally, if you’re a fan of 8K you’ll need deep pockets for an OLED that supports this resolution. The complexities of manufacturing OLED panels with over 33 million pixels makes 8K OLED TVs very large, while the limited production yields mean they’re also very expensive. Prices will undoubtedly drop over time, but for now 8K OLED is purely for the high-end market.
What is QD-OLED?
LG has dominated OLED panel manufacture for the last decade, but in 2022 it will be facing some competition from an unexpected quarter. Samsung has developed a new Quantum Dot or QD-OLED panel, with TVs from Samsung (S95B) and Sony (A95K) being released this year. But what is QD-OLED, and how does it work?
A QD-OLED panel is manufactured using multiple layers of blue OLED material, which eliminates the issue of inconsistent decay. Each pixel is composed of three subpixels: a blue subpixel consisting of the original blue light, and red and green subpixels created using quantum dots.