Fans of TV gear love to debate the merits of the two leading flat-panel technologies: Quantum Dot LED (or QLED TV as it’s most commonly known) and Organic LED, otherwise known as OLED TV. Each has its advantages, but also its weaknesses. But just over the horizon — and getting closer every day — is a new display technology called Quantum Dot OLED or QD-OLED. As the name suggests, it’s a hybrid of QLED and OLED, and if it lives up to its promises, it might just be the best display technology we’ve ever seen.
But what exactly is QD-OLED, why does it have the potential to be a picture quality game-changer, and which companies are using it to make new TV models? Let’s take a deep dive into the details of QD-OLED and find out.
What is QD-OLED?
Simply put, QD-OLED is a hybrid display technology that aims to take the already very impressive qualities of OLED TV and improve on brightness and color through the use of quantum dots.
The result, according to experts, should be a TV that exhibits the stunning levels of contrast and perfect blacks of OLED while delivering brightness levels that we’ve traditionally only seen on QLED TVs. In short, it should give us the best of both worlds.
It’s also possible that over time, QD-OLED TVs may prove less expensive to buy than similarly sized OLED TVs. We’ll discuss this in more detail later.
How does QD-OLED work?
To understand the inner workings of QD-OLED, we need to quickly explain the differences between QLED and OLED.
QLED TV uses four main elements to produce its pictures: An LED backlight, a layer of quantum dots, an LCD matrix, and a color filter.
The LED backlight produces all of the brightness you see — and modern LED backlights can produce a lot of brightness, far more than OLED light sources. But achieving that brightness while maintaining a full-spectrum white, is difficult.
The solution: Start with a really bright blue LED light source, then use red and green quantum dots to balance the blue into a full spectrum of white. Because quantum dots can be tuned to emit specific colors and, amazingly, can do this at a nearly 100% efficiency level, QLED TVs get a much-needed improvement to their color accuracy without sacrificing any brightness or needing to use more energy.
From there, the purified white light passes through the LCD matrix (which is responsible for the images you see, and how bright or dark areas of the screen are) and, finally, through the color filter, which converts the white light into the right amounts of red, green, and blue so that we see true color images.
Samsung Q90T 4K HDR QLED TV Dan Baker
It’s a good system that produces bright and very colorful images. It’s also quite affordable to produce because, with the exception of the quantum dots, all of the components have been around for decades, and are now “cheap” to make.
But it has drawbacks, too. No matter how hard the LCD matrix tries, it can’t block 100% of the light from coming through in dark scenes, so you never get that perfect, inky black that you see on an OLED TV. The LCD matrix also creates problems for off-angle viewing because it tends to “tunnel” light straight outward from the screen.
QLED also has to use more energy to create the brightness you see because the combination of the LCD matrix and the color filter diminishes the light the LED backlight generates. This makes QLED TVs less energy efficient than OLED TVs.
Finally, and this may only matter to decor-oriented TV buyers, all of those elements add up to a thicker overall TV panel.
OLED TV uses an OLED light source and a color filter to produce its image.
That sounds remarkably simple compared to QLED TV, and it is. Thanks to the emissive nature of the basic element of OLED TV — the OLED pixel — this one ingredient can take care of brightness and image creation, essentially fulfilling the roles of both the LED backlight and the LCD matrix in QLED TV.
Without an LCD matrix, viewing angles with OLED TV are as near-perfect as we’ve ever seen. You can sit wherever you like and still see the same levels of brightness, contrast, and color.
And as we’ve already hinted at, because OLED pixels can be shut off completely when an image calls for perfect blackness, that’s exactly what you get: No light being emitted at all.
But OLED TV isn’t perfect either. You can only derive so much brightness from an OLED pixel. It’s excellent in low-light conditions, but it simply can’t compete with QLED’s dedicated LED backlight in brighter environments. If you’ve ever looked at a QLED and OLED TV side by side in a brightly lit Costco warehouse and found the QLED TV more appealing, it’s probably due to its superior brightness.
LG CX OLED TV Dan Baker/Digital Trends
OLED TV brightness is lower than QLED for two main reasons. First, and most importantly, each OLED pixel creates its own light. But the more power you drive through an OLED pixel, the more you shorten its lifespan. So OLED TVs could probably get brighter than they do today, but few buyers would be OK with a TV that only lasted half as long. The LEDs used in a QLED TV’s backlight are far less susceptible to this kind of aging and can continue to produce lots of light for a long time.
Second, no matter how much light an OLED pixel can create, some of that light will be absorbed by the color filter.
OLED panels are also susceptible to something known as burn-in. If you display the same kind of content on an OLED TV for tons of consecutive hours — say a lower info banner on a news channel, or a control panel in a video game — it can cause those pixels to age at a faster rate than the pixels that are constantly displaying different images.
The residual “shadow” of that static content is called burn-in, and once it happens, it’s usually permanent.
Finally, because the large-format OLED panel market is effectively a monopoly, with just one company — LG Display — manufacturing and selling them to companies like LG, Sony, Philips, and Vizio, it will remain more expensive than QLED for some time to come.
QD-OLED: Busting the brightness barrier
So the question that faces the TV world is, how can you hold on to all of OLED’s many benefits and improve on its weaknesses?
The favored solution right now is QD-OLED.
Quantum Dot OLED significantly increases the overall brightness of OLED — and even improves its already superb color — by optimizing how much light a single OLED pixel can emit and eliminating the color filter.
Here’s how it works.
Why start with white?
At the moment, OLED TVs create their light and color starting point with white light. They do this by combining blue and yellow OLED material to create a blend that comes very close to pure white. Why do this instead of using red, green, and blue OLED material? The answer has to do with the complexities of manufacturing OLED panels at the 50-inch to 88-inch sizes of today’s TVs while keeping costs as low as possible.
To give you a sense of just how expensive a true RGB OLED panel is, Sony makes a 4K, 55-inch monitor for the broadcast and film industries that use this technology. It costs nearly $28,000.
But when you start with white light, you need a way to separate the individual red, green, and blue portions of the spectrum. A color filter does this admirably, but color filters, as we mentioned above, reduce brightness.
Sony A8H OLED Dan Baker/Digital Trends
LG’s technique for regaining some of the brightness lost to the color filter involves the use of a white subpixel that bypasses the color filter.
When you’re watching standard dynamic range (SDR) content, the use of that white subpixel is moderate. OLED TVs can easily get bright enough to meet the full specification for SDR without relying heavily on the brightness of the white subpixel.
“Displays of all types that use this architecture are able to achieve color accuracy at relatively lower luminance,” said Jeff Yurek, director of marketing and investor relations at Nanosys, a company that develops quantum dot technology. But HDR material is a bit trickier.
When viewing HDR content, the panels turbocharge these white subpixels to deliver HDR’s higher brightness. But there’s a limit to how hard you can drive those white subpixels. Push them too far and not only do you reduce the panel’s life, but that extra brightness can also wash out the color of the other subpixels, something that is especially noticeable when displaying small features like text, which can often look less crisp.
Back to blue
To deal with the technical hurdles of OLED brightness, Q