Quantum dots explained: How this nanotechnology could give OLED TVs a run for the money
Since this discussion is related to using quantum dots in TVs, you might think the nanotech is replacing the LCDs and OLEDs used to generate color on today’s flat panels. Nope. Someday maybe, but for the moment they are being employed solely as LED backlight filters.
Look carefully and critically at an LED-backlit LCD TV (often referred to as an LED TV), and you’ll notice that the picture looks a bit cool, perhaps even washed out. It’s difficult to do in the absence of something better to compare, so you’ll have to trust me on this one. The reason for this phenomena (the coolness, not the trust-me factor) is thatthe light today’s TV LEDs produce is heavily skewed towards the blue end of the spectrum. Blue, as in icy and cold.
LED backlighting remains popular partially because it’s more energy efficient overall than the preceding CCFL (cold cathode fluorescent lamp) backlight technology. On higher-end TVs, LEDs can be spread across the entire panel and controlled individually (a feature known as local dimming), enabling the TV to produce darker blacks. LED backlights are also much smaller than CCFLs, enabling the ultra-thin profiles that are in vogue today. Thin is in—and it’s likely to stay so.
If color gamut is a concern, you can always buy an OLED TV with its super rich colors and deep blacks. But the prices for OLED start at $2000 for 1080p resolution and only get absurd from there. With UHD (3820 by 2160 resolution, opportunistically marketed as 4K, even though it’s only twice the resolution of 1080p) LCD TVs starting at $600 in smaller sizes, getting consumers to pay several times that for an OLED TV is tough—superior image or not. And to be perfectly honest, even without quantum dots, an LED/LCD TV offers a pretty nice picture.
So here comes the easily producible quantum dot, which seems to be just about the ideal solution for improving the color gamut of the everyday LED/LCD TV and low-balling OLED out of existence. Just filter that harsh white LED light with richly-radiating quantum dots and voila!
Alas, it hasn’t worked out that way so far. Quantum dots seem to be showing up only in pricier TVs. Vendors want to steal some thunder from OLED at the top-end rather than improve the color spackes of their entire range. At least that was the case as this article published—just about a month before the vast majority of 2016 models are announced.
Case in point: the misleading SUHD monikerSamsung sticks on its high-end models. You might think SUHD is a new resolution higher than UHD. It’s not, it’s just a marketing term for the addition of quantum dot filtering and some tweaking. I say just, but Samsung’s SUHD models deliver noticeably better color reproduction compared to its less-expensive TVs. The same is true of Sony’s Triluminos brand and the Color IQ label (belonging toQD Vision) that’s behind several quantum-dot efforts. TVs that use quantum dots come very to close to OLED on every score except black. Quantum dot technology works.
Alas, one reason that quantum dots have been largely ignored to date (they’re been around for decades) is that they’re largely produced from cadmium—a somewhat toxic element that’s on the hit list of just about every environmental agency you’d care to name. The European Union’s RoHS (Restriction of the use of certain Hazardous Substances)severely limits the use of cadmium, with an exemption for light-producing products (that restriction is currently under review).
If a group of researchers at Oregon State University are correct, the way around this problem is to use the less-toxic copper indium diselenide, which they say they’ve used to economically produce quantum dots. There’s also a company called Nanoco touting CF (cadmium-free) quantum dots. So the cadmium problem could be short lived.
Quantum dots have applications beyond TVs, including deployments in computer monitors. After all, the most significant difference between a computer display and a TV is the absence of a TV tuner. And for anyone who uses a computer to edit photographs or to publish color documents, such as print magazines, color gamut is key. Philips just announced a quantum dot 27-inch display that it says delivers 99 percent of the Adobe RGB color space. The average flat-panelcomputer display doesn’t come anywhere near that.
Scientists from the Berkeley Lab and University of Illinois have used quantum dots to fabricate photovoltaic cells that are up to 30 times more efficient than today’s technology can deliver. Basically, if I read it correctly, light is gathered and concentrated, then steered to a quantum dot which focuses it directly into the solar cell.You can find the research here.
There’s even talk of using the technology to turn ordinary windows into solar panels.
So should you be looking for quantum dots in your next LED/LCD TV Yes, if you have money, but not UHD-OLED kind of money. Those of us in the working class should stick with the older 1080p TV for a year or two, or until quantum dots are pervasive, OLED has finally come down in price, or some other whiz-bang solution has rendered both technologies moot.