OLED TVs and QLED TVs generally occupy the top spot in premium TV comparaisons. Abyssal blacks are characteristic of OLED TVs, while QLED TVs offer very high peak brightness. The two technologies are sometimes confused, but there are fundamental differences between the two that influence the image.
When choosing between an OLED or QLED TV, it is good to know the advantages of each of these display technologies to select the one best suited to your needs.
OLED & QLED: how do they work?
An OLED (Organic Light-Emitting Diode) is an electronic component capable of producing light using an organic compound that lights up when an electric current flows through it. The panel of an OLED TV has several million of them. Each pixel is actually made up of 4 subpixels (one Red, one Green, one Blue and one White) which are each materialized by an OLED that emits its own light. These are called auto-emissive pixels.
A film transistor that transmits an electrical current to turn each individual subpixel on and off covers both sides of the OLED panel (the film on the front is transparent). This design, which does not require any backlighting, makes it possible to produce ultra-thin and very light OLED panels.
LCD LED and QLED TV screens, on the other hand, consist of an LED backlight system, several filters and a monochrome LCD matrix with pixels that can be made opaque to allow more or less light to pass through.
A QLED television is an LCD TV equipped with a LED backlight system combined with a quantum dot filter that is inserted between the backlight and the LCD panel. This quantum dot filter utilizes the optical properties of cadmium selenide nanocrystals. The nanocrystals emit a light whose wavelength (therefore color) is defined by their shape and size when subjected to a light source.
The quantum box filter of QLED televisions is calibrated to enhance the purity and luminosity of red and green, the Achilles’ heel of LCD TVs with standard backlighting. The colors generated are more intense and higher brightness peaks are possible.
OLED advantages and disadvantages
True blacks = perfect contrast
Because every pixel in an OLED television generates its own light, a true black dot is created when a pixel is turned off, unlike LCD technology where residual light can pass through an opaque pixel. OLED TVs display true blacks and offer more variations of brightness in the darker areas of the image. The image contrast is the main beneficiary, with stunningly realistic HDR images. This is even more obvious when the room is dark: blacks are actually black and not dark gray or faded.
Almost instant response time
Latency is the time that it takes for a pixel to go from black to white and back to black again. High latency can generate artifacts (motion blur, ghosting and jitter). OLED TVs have a response time of 0.1 ms, compared to 2 to 5 ms for the best QLED TVs. Consequently, OLED technology displays smoother images and provides better definition on moving images, without any blurring. This is particularly important when watching sport on TV.
Wide viewing angles
OLED technology allows very wide viewing angles. With an OLED television, it doesn’t matter whether the viewer is seated opposite the screen, to the side, or if they are higher or lower, they benefit from the same image quality, with no loss of brightness or color alteration.
Lower brightness peaks
Although OLED is capable of providing true blacks, it is more limited than QLED in terms of maximum image brightness. Except for a few very high-end models such as the Panasonic GZ2000s, which can reach almost 1000 nits, most OLED TVs peak somewhere between 700 and 800 nits. QLED TVs on the other hand can reach 2000 nits and even 4000 nits for high-end models. With HDR content, OLED technology is therefore somewhat disadvantaged when it comes to highlights. Ideally, an OLED TV should be installed in a room that isn’t too bright.
Reflections on the screen
To maintain their brightness and contrast, OLED TVs aren’t equipped with an anti-reflective filter and have a shiny screen. This isn’t a problem when watching a movie in a dark or dimly lit room, but it can be an obstacle in bright rooms or if the TV is placed opposite a window, which will be reflected on the screen.
Limited choice of screen sizes
The high cost and technical restrictions of OLED panel production limit the number of different screen sizes available. Until 2019, only OLED televisions with a diameter of 55” (139cm), 65” (164cm) and 77” (195cm) were available. It wasn’t until 2020 that an OLED TV with a diameter of 48” (122cm) was produced by LG (the LG OLED48CX), and very large sizes (2 meters and above) are not currently available.
Very high brightness peaks
With brightness peaks typically exceeding 1000 nits, QLED TVs are particularly good at displaying HDR images with high contrast. They offer a lot of variation in brightness, even in the middle of the day in a brightly lit room.
Effective anti-reflective filters
The high brightness of QLED televisions means that they can be equipped with a very effective anti-reflective filter without fear of losing too much luminous intensity. QLED TVs are therefore less affected by glare on the screen when watching a show in the middle of the day in a well-lit room.
More choice in screen sizes
As QLED TVs use LCD panels, which are available in many different sizes, there is a lot more choice when it comes to screen dimensions, with models ranging from 43” (108cm) to 85” (214cm).
Colors that can sometimes be too vivid
This is often the drawback to using quantum dot filters and sometimes perfectible screen calibration. Colors are too saturated and can even be garish, with images that don’t look natural. This flaw isn’t as frequent on most high-end models and can be corrected with a custom setting or by using the television’s Cinema mode, which is usually more accurately calibrated than the standard mode. The Filmmaker mode is another solution when watching compatible movies that provides colors and calibration that are true to the director’s vision.
Blacks that aren’t always true blacks
LCD display technology that requires backlighting can sometimes suffer from residual light leakage. The light generated by the LEDs behind the LCD panel can bleed into or be filtered through an opaque pixel. This makes it very difficult if not impossible to achieve true blacks. While the blacks of a QLED TV may seem very deep during the day, as soon as you watch a program in the dark, the blacks are at best a very dark gray.
The importance of backlighting
Like classic LCD LED TVs, QLED TVs require a backlighting system to work. The quality and working principle of this system directly impacts the image quality. The best system remains Direct LED or Full LED backlighting (a multitude of diodes distributed across the back of the display) which provides the possibility of modulating the luminosity (dimming) and controlling the backlighting of individual zones (local dimming).
QLED TVs with Edge LED backlighting or no local dimming provide inferior contrast and may suffer from blooming around bright objects and subtitles.
Why choose an OLED TV?
Cinematographic atmosphere with movies and series
OLED TVs are sought after by movie lovers because of their true blacks that allow them to produce images with excellent contrast, especially when watching programs in the dark or in a dimly lit room.
Despite a lower peak brightness than QLED TVs, OLED TVs are also recommended for watching HDR content as they provide great legibility during dark scenes. In addition, the moderate brightness peaks of OLED TVs are actually an advantage when watching content in the evening or at night. The experience is more comfortable and the highlights are less dazzling than with a QLED TV.
Sports fans will be delighted by the responsiveness of OLED TVs, which follow the players’ every movement on the pitch without any jitter and provide realistic colors (grass on football pitches, the clay court at Roland Garros, the color of the jerseys and the landscapes during the Tour de France…).
Finally, gamers can now consider using a G-Sync/FreeSync compatible OLED TV, as the input lag on some models is as good as that of Samsung QLED televisions. You just have to be careful to avoid screen burn-in by varying the types of games played and by not leaving the OLED screen on 24/7 so that the data of the HUD doesn’t leave marks.
Why choose a QLED TV?
Watching TV shows, movies and series during the day
QLED TVs are particularly suitable for watching TV shows, movies and series (including HDR) when the room isn’t dark or dimly lit. Their high peak brightness and the generally very effective anti-reflective filter allow you to enjoy nuanced and highly legible images, even in a room that is bathed in summer sunlight.
Another advantage of QLED TVs, especially models from Samsung, is their very low input lag which makes them particularly suitable for video games. Gamers should therefore opt for a QLED TV, even though OLED TVs have made a lot of progress in this respect.