This is why Quantum Dots aren’t quite as good as OLED in 4K TVs

by on January 12, 2015

Stephan Jukic – January 12, 2015

As we’ve already covered on more than one occasion, quantum dots are making a big splash in the world of 4K TV displays and with good reason. As this article explains, the new technology does some wonderful things with the color quality that users will be able to get from the 4K TVs that have quantum dots built into them.

Some have even gone as far as to compare quantum dots to the OLED displays that LG came out with last year and is building more of in 2015. However, even though the dots do give OLED a run for its money in terms of color quality, there is one crucial way in which they definitely underperform OLED.

Just before we get down to that, a quick rundown of how QD technology works: Quantum dots are extremely tiny atomic crystals that glow with different colors when LED light is shined on them. The number of atoms in a QD crystal (something which can be fairly precisely controlled) determines what color it shines with and because the structure of these crystals is very stable, they can stably keep their color for a very long time.

TVs with QD technology have a sheet of film filled with quantum dots of different colors spread in front of their LED arrays and this sheet of QD film then causes the light from the LEDs to take on much more precise tones as it hits the LCD panel itself, thus causing the LCD screen to create much more accurate representations of all the colors your TV screen shows.

In this regard –color representation—quantum dots create a color gamut that is pretty much as beautiful as that seen in OLED TVs, at least as far as a normal persons eyes are concerned.

A diagram which explains how quantum dot particles are applied to a film that goes inside LCD LED displays in 4K TVs

A diagram which explains how quantum dot particles are applied to a film that goes inside LCD LED displays in 4K TVs

However, where QD technology still falls way behind OLED is in how it represents black. In this, OLED truly shines and does so by not shining at all.

LCD screens with conventional LED panels providing their backlight create black by blocking out the LED light that goes to specific pixels with a tiny little shutter inside the individual pixel spaces on the LCD panel. Since the LEDs behind this stay lit, some of their light still leaks through and thus the resulting black is more of a dark grey instead of a pure dark color. Whether a TV uses quantum dots or not, this is the case with LED displays of any type.

OLED TVs on the other hand, use organic light emitting diodes which can individually be completely shut off with the right electrical signal. Thus, when your TV wants to show black, it literally turns off the light behind it on the screen, thus producing a deep, truly dark black color. For creating truly vivid visuals, this is an extremely important quality that injects an amazing level of color contrast in many scenes from entertainment content.

Thus, while QD TVs produce beautifully rendered, realistic colors that compare favorably to OLED, they fail at creating a perfect black that OLED absolutely excels at generating by literally going dark.

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