MIT Develops Quantum-Dot OLEDs

deglr6328 writes "Researchers at MIT have developed a new type of Organic Light emitting Diode (OLED) using Cadmium Selenium Quantum Dots as the electron-hole recombination layer. It is widely believed that the next generation of flexible flat panel display technologies will be self luminous (non-backlit) organic light emitting diodes. However, the efficiency and lifespan of both small molecule and polymer type OLEDs, to date, has been poor for small wavelength emitting compounds. Using quantum dots as the emissive layer in OLEDs potentially solves both of these problems since they are inorganic and won't degrade, and they have a theoretical maximum quantum efficiency of near 100%. Mmmmm ... can't wait to buy my first roll-up display!"

Comments

Cool... but when?

[httpamphibio.us]

Haven't roll-up displays been "two years away" for about seven years now?

I love the concept... but really, shouldn't we have at least one low quality, high priced, first generation consumer product by now?

Keep waiting

[nesneros]

I remember being a freshman in college, and making a dork of myself by telling all my friends how these things would be out in a year and how massively cool they would be. Oh, and electronic paper too. And those things had prototypes and everything. And even if they didn't, in 5 years or so a plasma display would only cost as much as a CRT.

Let's fast-forward 7 years to the present and there's an announcement that a lab has created a device, and we translate this to mean that functional products are just around the corner.

Excuse me for being such a cynic, but until something hits store shelves at an affordable price, its pretty pointless to get excited.

Short lifespan

[BESTouff]

However, the efficiency and lifespan of both small molecule and polymer type OLEDs, to date, has been poor for small wavelength emitting compounds

Apparently these displays would have a short lifespan. We would then have disposable screens. That seems a perfect consumer target: cheap, glowing, quickly obsolete.

Re:Short lifespan

[Emperor Shaddam IV]

We would then have disposable screens

With Cadium. Wonderful for the water supply and growing plants. My liver and kidneys can hardly wait. I could always use some more heavy metals in my diet.

mmm, high resolution

[briancnorton]

My roommates in grad school were working on this type of thing, and they were promising resolutions over 300 DPI. That makes me salivate, but I find it funny that for once display technology will be more advanced than image generation technology. (video cards) A 300 DPI, 17" widescreen would be a resolution of something like 4500x2500, or 11 million pixels, compared to 1 or 2 million pixels in a high-res display today. AGP 32X anyone?

A step in the right direction but...

[Drakula]

using quantum dots does not solve the total efficiency problem. The overall efficiency of a LED is the product of the injection efficiency, the extraction efficiency, and the internal quantum efficiency. The inorganic quantum dots will make the internal quantum efficiency large, this is how well the device converts the injected electrons into light. However, the big stumbling block is the injection effeciency, how well the injected current is converted to electron-hole pairs for generating light. When this efficiency is low, a large amount of the applied power is lost to heat. This will need to be overcome as well before OLEDs of any type make as a commercial technology.

Also the cadmium selenide system is known to have lifetime issues. These, and related, materials were the first candidates for blue/green LEDs and lasers but suffered from horrible lifetimes.

Cadmium? No thank you

[freshwat]

We're finally getting rid of extremely toxic cadmium in batteries and now this? Don't these guys learn? They have to engineer over the whole like cycle, including disposal.

For those miss the point

[akincisor]

The point of the article is that they have managed to use an inorganic layer in between just two organic layers and produce a magnitude of light equivalent to earlier efforts with 20 layers. These things have 25 times(!) the power efficiency. This might also be the first commercial application of quantum dots.

Money answer?

[swb]

I wonder sometimes if "the powers that be" aren't just holding back on some of the new LCD-like display technologies because they've got a lot of money tied up in LCD technology that's just starting to show a return on investment.

And there's the whole recession thing, which has limited sales and maybe curtailed manufacturers' desire to invest in converting plants and equipment to make the new displays.

I know it seems a little conspiratorial, and the answer probably that the technology isn't reliable or mass producable yet, but I still can't help but wonder if the economy picks up we'll see from Apple or someone else not afraid to roll out an expensive 1st gen product and then see it approach commodity levels a couple of years later.

Although I keep asking myself why a 13" LCD TV sells for $800 and a 17" LCD monitor is $500. That's a market contrast I *don't* get, and the explanations I've been given about the cost of tuners and IR control logic don't add up, especially when a tube 20" is $170.

Near 100% efficiency?

[atcurtis]

Maybe every electron-hole combination generates a photon of light but IIRC the direction in which the photon of light travels is random.

That means that at least 50% of the photons are travelling the wrong direction... Perhaps the most optimistic view is that 40% are travelling forwards from the OLED screen, the remainder are absorbed back into the substrate and turned into heat.

Maybe someone would like to correct me...

ttfn