Burn-in effects on Samsung’s QD-OLEDs

In the past, noticeable burn-in effects could sometimes be observed on TVs with OLED displays. On the other hand, these hardly ever occur on newer devices, which is also due to various countermeasures by the manufacturers.

However, if you watch videos on the TV with the same, high-contrast image content, i.e. logos or, for example, tagesschau24 with scroll bars displayed at the bottom, you will probably also observe burn-in damage on newer OLED TVs after a while: Shadows appear in those places in the picture , which previously had the logo or the bright scroll bars for a long time. The culprit is the increased wear and tear of the organic layer in these very places. However, there is a key difference between LG Display’s WOLEDs and Samsung Display’s QD-OLEDs.

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More from c't magazine

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With LG’s WOLEDs, the “white” light is created by stacking organic layers that glow red, blue, green, and yellow-green, resulting in white overall. Color filters on this layer structure that glows white bring color back: for the red sub-pixels, for example, the blue and green components are filtered out of the white light so that red remains.

The white light in the WOLED is generated by stacked red, green, blue and yellow-green glowing organic layers. The color filters in turn filter red, green and blue from the white light for the RGB sub-pixels.

If a window or a logo stays on the screen for a longer period of time, the organic layers at this point will wear away, to varying degrees depending on the colour. Therefore, the burned-in area not only becomes a little darker, but also gets a color cast.

In its new QD-OLEDs, Samsung only uses blue-glowing organic layers. The light only becomes multicolored through the additional layer of quantum dots: The nanoparticles contained therein are so-called photoluminescence sources, which produce red and green light when irradiated with blue light. So nothing is filtered out here, but converted, which is why the QD-OLEDs should also shine brighter in principle. The color locus of the red and green sub-pixels is determined solely by the quantum dots, the light intensity (brightness) of the display solely by the light intensity of the blue-glowing organic layer.

The QD-OLED contains organic layers that glow blue, from which the quantum dots generate red and green light for the RGB sub-pixels.

If a logo or a bright frame stays in the picture for a longer period of time, this puts a strain on the organic layer, as with WOLED. The QD-OLED also wears out, but there is no color cast, only a slightly lower brightness. This partially declining light intensity can be compensated for relatively easily by applying more current to the affected areas. In the OLEDs, it is constantly recorded for each pixel how long and how brightly it shines and then adjusted accordingly with an algorithm – those who had to shine particularly brightly for a particularly long time are supplied with more power.

Such calculations already existed in the days of plasma displays, where the phosphor layer also wore out due to the constant bombardment. LG also uses such algorithms in its WOLEDs, but can only eliminate the decreasing brightness, not any color casts.

The wear and tear of the organic layer affects the lifetime of the displays in both WOLEDs and QD-OLEDs. However, the service life, at least for WOLEDs, is now significantly longer than in the early days of large OLED TVs. Most TV manufacturers today offer a multi-year guarantee for their devices without worrying.

They are also able to do this because they do not operate the displays at the limit, so that any wear and tear on the organic layer can be easily compensated for with more power. The so-called cleaning measures also contribute to a longer service life. Incidentally, they use the algorithms mentioned above, among other things.

Read here what you can do to reduce the risk of burn-in:

Due to a lack of experience, we don’t yet know how the QD-OLEDs behave in terms of service life. But one can assume that the world’s largest TV manufacturer will not jeopardize its reputation because of a new display technology. Therefore, the QD-OLED TVs will probably also have a long service life.

The first device with Samsung’s new QD-OLED technology is the Alienware AW3423DW from Dell. c’t 3003 shows the strengths and weaknesses of the gaming monitor AW3423DW in the video.


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