QLED Versus OLED, What To Expect From Samsung’s 4K And 8K TVs
We will start at the beginning with a basic LED LCD display. Virtually everyone has encountered one of these displays at some point in their life as they make up the majority of the market. These use a white LED backlight to shine through tiny red, green, and blue filters to create the image we see. The filters can be opened and closed on demand and to varying extents thanks to liquid crystals -- the LC in LCD. Older non-LED LCD displays worked in similar manner, only they employed cold-cathode fluorescent lamp (CCFL) backlights instead which were bulkier and more expensive to produce.
There are, of course, a number of shortcomings with traditional LED LCD displays. For one, these displays are prone to light "bleeding" through closed filters, resulting in blacks that are more of a glowing dark gray. Even when displaying an all-black image, the screen still glows more than it would if the display were powered off. The LED backlighting can also be inconsistent across the panel which is most noticeable in dark scenes.
Another issue stems from LED technology itself: pure white LEDs do not really exist. A true white light would contain the full spectrum of frequencies and produce a rainbow when shown through a prism. LEDs are much more limited in the frequencies they produce. To get "white" LEDs for the backlight, manufacturers start with a blue LED and apply a yellowing phosphor-coat to warm up the light to a neutral white.
This pseudo-white light is still deficient in certain wavelengths -- particularly reds. The impact here is that the resulting brightness of the display has to be tempered to the peak brightness of the dullest color for best results. This further reduces the amount of color space a display can reproduce. Keep in mind, both display brightness and color space are major components of HDR display certification.
OLED TV Technology
We will note that some OLED variants, including LG's, work differently by stacking the red, green, and blue sub-pixel layers to produce a white light that is then filtered back to red, green, or blue like and LCD display. These displays are often dubbed WRGB as in "white, red, green, and blue". Compared to blue-yellow LED LCD displays, the white light produced by a WRGB OLED covers more of the spectrum and retains better color after being filtered while also retaining the ability to selectively turn off pixels. The subpixel stacking also virtually eliminates the effects of pixel burn-out OLEDs face with static images because all the pixels wear at the same rate regardless of color.
OLED has been the gold standard for television displays for a few years now thanks to its impressive image quality, but remains expensive to produce for large panels and peak brightness still lags behind LED displays. To shore up LED's weaknesses, Samsung has been investing heavily into QLED technologies.
To OLED Or QLED - That Is The QuestionSo, are the newest QLED offerings good enough to dethrone OLED? It is certainly going to depend on how you watch your television. Let's break things down into a few categories: brightness, black levels, viewing angles, response time, power efficiency, longevity, and price.
As alluded to earlier, OLED panels tend to struggle with brightness output. That is not to say they are dim by any measure, however. The HDR specifications do not point to any particular brightness value to qualify, but the general consensus is around 1,000 nits with a good portion of HDR content being mastered with this level in mind. While OLED panels can meet this threshold, bright pixels do wear faster, but more on that later. QLED panels, on the other hand, are able to produce tremendously bright pictures with ease. Samsung's new Q900R, for instance, claims a peak brightness of 4,000 nits.
Conversely, OLED panels are unmatched for black levels. Samsung has made improvements to their QLED tech including the addition of an anti-reflective layer, but improving the filters to block more backlight still cannot compete with turning pixels off. This advantage really helps OLED TVs pop in dark rooms in a way no backlit solution can.
OLED TVs also have the upper-hand with odd viewing angles. Since the OLED pixels are directly emissive, they can be seen from just about any angle without degrading the image. QLED and other LED backlit panels are best viewed dead-on. Off-axis angles reveal a loss of contrast and color shift which tends to worsen the further from center you move. As with black levels, Samsung has made improvements here with their anti-reflective coating to minimize glare so it is at least less of a concern than it used to be.
An often overlooked metric for displays, response times measure how long it takes a pixel to change colors. These response times typically track the time it takes a pixel to turn and off or else from one gray level to another. Faster response times reduce artifacting, ghosting, and motion blur. Once again, OLED takes the crown here, thanks to its individual control over pixels. QLED panels still rely on local dimming which impacts regions of pixels, resulting in a slower response time. We will add that this is a different phenomena than input lag, but input lag varies too much from model to model to really pin down on display technology alone.
For what it is worth, QLED panels are more environmentally friendly than their OLED competition. Eliminating the need for large backlights seems like it would reduce power consumption on paper, but OLED televisions end up consuming more power to light up pixels individually. The gap does narrow as screen size increases, but for most practical display sizes -- 45" to 65" -- QLED panels are simply more efficient. For example, the 65" Sony Q90R is rated at 115W of typical power draw with a peak of 255W while Sony's 65" A9F OLED TV pulls in a whopping at 500W. Rtings.com also has a handy calculator to estimate consumption differences at various sizes.
Longevity is another area where OLED panels stumble. Make no mistake, modern OLED displays are significantly more resilient than they used to be. Many newer models are rated for tens, if not hundreds, of thousands of hours of continuous operation before dimming down noticeably. HDR content with high peak brightness does have the potential to accelerate this clock, but we do not think it is a serious concern for even the most avid movie fanatics. Regardless, QLED's Quantum Dots are effectively stable over time enough to not degrade in any meaningful way, which gives them the edge here.
While it looks like OLED retains the picture quality lead for now, do you think Samsung's QLED models are attractive enough to save some cost?