In the current world that we live in, we’re all chronically online and constantly stare at a screen – either it’s our phone, tablet, laptop, desktop monitor, or a TV. They’re all screens, but they’re probably made out of a different display technology. We’ve heard of all of these types of panels before:
- TN
- IPS
- VA
- Mini LED
- Micro LED
- OLED
- QLED
- and there’s something new called QD-LED
So recently, during the Society of Information Display (SID) 2024, Samsung showed off a QD-LED display – also known as Quantum Dot Light Emitting Diode Display. The name itself, even though very confusing and similar to many other terms used while describing TVs nowadays – is very important. We’ll get into it later in a second.
Samsung’s QD-LED demo display is rather interesting. It’s an 18.2-inch screen that has an impressive resolution of 3200×1800 pixels, resulting in about 202ppi with a FW brightness 250 nits. I’m not sure if they mean the full-width half maximum value, but either way that’s the value they provided. The panel is also printed using inkjet. However, we don’t know about the refresh rate or the pixel response time. But it’s still in the demo phase anyway.
What’s the difference between quantum dot and OLED?
I told John, my colleague about it, and he asked me one question – what’s the difference between quantum dot and OLED?
Well, I immediately responded that quantum dots do not have burn-in issues that plague OLEDs. Quantum dots are inorganic, unlike OLED. The O in OLED stands for “organic”.
Then I continued to ramble on about how quantum dots work. It needs an external light source to excite its electron into a higher level, reaching a metastable state. Then, that electron will drop its electron back down into a stable state. And to lose that amount of energy is by emitting a photon – or light, in a particular frequency.
In a way, it’s similar to lasers but they both do different things.
Then John told asked me, let’s say if it requires a backlight, then does that mean we can’t get true blacks and per-pixel dimming zone like OLEDs have? Technically, that’s what the current QLED TVs are experiencing. You see, the QLED TVs that we can go out and buy right now use a blue light source to excite the quantum dots into a higher level of energy, then let them go back into a steady state by emitting a certain frequency of light.
I found this excellent YouTube video where they took apart a TV and used a spectrometer to test it layer by layer, and we can see what each of the layers does. For this TV in particular, a blue light source is used to excite the quantum dots and those quantum dots convert that blue light into green and red colors.
To achieve better contrast ratios, TVs use a technique called dimming zones. The array of backlight LEDs will have varying brightness levels depending on what image is shown on the screen. It is better than having the backlight turned on at a constant brightness level but will create a halo effect on the screen. The most prominent is when we’re looking at white subtitles on a black background.
To eliminate the use of a backlight, there is another technology called QD-OLED. It’s essentially replacing the backlight with another layer of OLED and get the best of both worlds since OLED has fantastic contrast levels and super deep black levels, while QLED has vibrant colors and better brightness levels. But since OLEDs are involved, burn-in is inevitable.
And that’s where Samsung’s latest QD-LED comes into play. It’s the same as the current QD-OLED screen technology that we have, but without the organic part – hence it won’t have any burn-in issues.
It can emit light on its own without the need for a backlight and Samsung’s demo is a full-fledged screen with RGB quantum dots arranged in an array. However, there are no other additional information provided at this point in time. I presume that the QD-LED is a step forward of the existing QD-OLED displays by eliminating the organic part.
From what I can find out, the QD-LED is using cadmium-free quantum dots but I can’t find that information on Samsung’s website.
I’m really not sure what technologies QD-LEDs use to be able to achieve self-emissive quantum dots. They are probably using electroluminescent quantum dots – which means feeding it with electricity and light will come out of it. It’s basically the same idea as an LED, hence the name QD-LED.
The future of QD-LED
If QD-LED is going to be a thing, then I think it will be the absolute best display we can get. It will have the best of everything – great brightness, magnificent colors, deep blacks, and most importantly – no burn-in. In theory, the pixel response time should be great as well since it does not need the LCD layer to control which pixel should be lit or turned off.
Currently, there is no roadmap on when QD-LED displays will be available to purchase, but maybe in a few years if things play out nicely.
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