Over the past few years, this has been the greatest battle in high-end televisions. When QLED technology from Samsung, introduced in 2017, replaced S-UHD, it had the same: competing with OLED televisions.
Let’s analyze the advantages and disadvantages of QLED versus OLED displays to clarify which option to choose when buying a new TV.
The Main Difference Between QLED and OLED
OLED (Organic Light-Emitting Diode) arrays have self-illuminating cells, unlike LCD panels in conventional LED televisions. QLED televisions, on the other hand, are in the group of LCD panels and require an external light source to generate the image. Typically, this illumination is located on the back or side of the panel.
In essence, QLED (Quantum Dot Light-Emitting Diode) panels also need an external light source and are an evolution of LCDs and Quantum Dot or nanocrystal technology. You can think of them as enhanced LED panels.
So, what sets them apart from “normal” LED panels? QLED panels can activate pixels more precisely using quantum dots, small semiconductor crystals between 2 and 10 nm. This allows them to play much better with contrast, resembling OLED in its main advantage (better contrast for deeper blacks).
Structure of an organic light-emitting diode (OLED). In the middle, between the ETL and HIL, we can see the emission and conduction layers of the organic material. | Image: Tech Briefs
One of the most important qualities of OLED panels is their ability to emit light without the need for an external light source, unlike LCD panels. This is possible because they use organic diodes, which are semiconductor electronic components that allow and control the passage of electric current in a single direction.
Unlike conventional diodes, those using organic material have the ability to react to electrical stimulation by emitting light, making OLED technology self-emissive.
There’s no difference between the OLED panels manufactured by LG and those being produced by Samsung so far. However, if we look at the strategy used to reproduce colors, the first significant difference between the two technologies becomes apparent. The OLED panels manufactured by LG Display are W-OLED (White OLED), so the light emitted by each of the panel’s self-emissive cells is white.
The issue is that in order to create a color image, you need to capture the three primary RGB colors (red, green, and blue). This requires placing an RGB color filter on top of the organic diode array.
It’s interesting to note that LG didn’t originally develop this technology. For many years, Kodak was at the forefront of OLED technology development. In 2004, Kodak made a surprising announcement: The company had successfully addressed the main drawback of RGB OLED panels, which was the premature degradation of the blue subpixels. Its solution also enabled the production of larger OLED panels at a lower cost.
Kodak’s implemented technology was White OLED, which it patented. However, due to financial difficulties, including the decline of the film photography market in the 1990s, Kodak’s innovation faced challenges at the time.
These circumstances led the company’s management to decide to stop working on OLED technology. In 2009, LG purchased this technology and the associated patents from Kodak for $100 million. As they say, the rest is history.
White OLED panels produced by LG Display have a major advantage over traditional RGB OLEDs: They don’t suffer from premature blue subpixel degradation. Additionally, they’re easier and cheaper to manufacture and allow for larger panel sizes. However, there are also some disadvantages to consider.
As we mentioned before, W-OLED technology requires the placement of an RGB color filter on top of the organic diode matrix to reproduce the three basic colors. However, this filter absorbs light and reduces the brightness delivery capacity of W-OLED panels compared to RGB OLED panels. Additionally, its color reproduction capability is inferior to that of RGB OLED technology.
The reason why going through the differences between QLED and OLED is important is that Samsung has developed QD-OLED technology to solve the shortcomings of W-OLED while maintaining its advantages over RGB OLED. Samsung’s proposal is to replace the RGB filter in W-OLED panels with a matrix of nanocrystals, or quantum dots, responsible for color reproduction.
The removal of the RGB filter should, in theory, enable the panel to achieve better brightness levels for both average and peak measurements. Moreover, the nanocrystals should be capable of reproducing a much wider color range compared to the RGB color filter.
However, Samsung’s proposed changes in its technology compared to W-OLED not only involve the elimination of the RGB filter but also the use of blue pixels instead of white pixels. With this change, the nanocrystals will modify the blue light to produce the other primary colors, red and green.
This transformation is possible due to the unique property of nanocrystals, which allows them to alter the wavelength of light, simultaneously enabling them to manipulate blue light to generate red and green light.
Quantum dots are a type of nanocrystal made of semiconductor materials with intriguing properties. Due to their minuscule size, their behavior is described by the laws of quantum mechanics rather than classical mechanics.
The electronic characteristics of quantum dots are determined by their size and shape, making them useful for various applications such as photovoltaic technology, biological labeling, and pollutant removal, alongside their application in electronics, of course.
For its part, LG introduced Nano Cell technology, aiming to enhance the image quality of traditional LED panels, similar to Samsung’s QLED technology. Sony also focuses on improving LED panels, referring to technologies such as X-tended Dynamic Range PRO for managing the backlight panel. Ultimately, the goal is to enhance LED panels by controlling pixel activation precisely.
Now, let’s compare the advantages and disadvantages (on paper) of QLED and OLED.
Advantages of QLED Over OLED
Higher brightness levels. QLED is an advancement of nanocrystal technology, which already offered higher brightness levels compared to OLEDs. Samsung’s new QLEDs boast brightness figures of up to 4,000 nits, exceeding the 1,000 to 2,000 nits typically offered by OLED panels. This extra brightness enhances image clarity, particularly in bright environments.
Better durability. It’s challenging to make a direct comparison since OLED TVs have only been around for about a decade and QLED models also have a limited lifespan. However, OLED TVs, being organic, are more susceptible to image degradation and retention.
Lower cost. Although the cost of OLED TVs has been decreasing, it’s still an expensive product because it requires a complex evaporation system. As such, QLED TVs generally come with a lower price tag compared to OLED TVs, particularly in larger sizes. Today, it’s common to find QLED models priced below $1,000.
Disadvantages of QLED Over OLED
QLED technology is currently unable to achieve pure black. In this regard, OLED has no rival for now: It doesn’t need an external light source, so it can achieve pure black. Although it has improved in the last few years, QLED still relies on external light, making it more complicated to achieve pure black compared to OLED.
By definition, the contrast in OLEDs is infinite because it turns off each pixel individually. | Image: RTings
Response time. QLED varies between 2 and 8 ms, while OLED has a response time of 0.1 ms. Input lag differences between the two technologies are minimal, but some QLED models have very low input lag, making them suitable for gamers.
Better viewing angles. While QLED’s flexible feedback system improves viewing angles, OLED technology provides superior viewing angles even without this feature.
Design. OLED panels don’t require external illumination, so they can always be slimmer than QLEDs, which need space for a light source. As a result, OLED TVs still remain the thinnest on the market.
The choice between OLED and QLED depends on how you plan to use the TV. On paper, QLED TVs offer higher brightness, longer lifespan, larger sizes, and competitive pricing. On the other hand, OLED excels in excellent contrast, making it ideal for watching TV in the dark.
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