Commercial LEDs consist of a semiconductor material that is electrically injected with positive and negative charges, which produce light when they meet. Typically, two contact points are used in a semiconductor-based light emitting device; one for injecting negatively charged particles and one injecting positively charged particles.
Isn't that a bit too simplified?
That said it sounds like very cool technology although hard to see how electrical wires to each pixel would be as invisible at wall-sized scales.
ITO isn't really transparent... it's pretty yellow (80-95% transmission) and it doesn't carry current well (20-100ohm/sq). You'd be better off with a metal mesh with large pitch electrodes. You're going to need some wires to address the display as well (whether active or passive matrix).
With a large pitch Cu or Al conductors you can do 5ohm/sq with good transparency. That will let you do 200nits (candela/m2) with the efficiency of these thin LEDs. ITO would be 10x lower conductance and only works in LCDs because they are inverting voltage light valves (not light sources).
If everything worked out you could reasonably view thin LEDs in a dim office environment. That's not really interesting unless it's 3D.
Seems to be bendable so maybe breaking it is harder than current screens.
> “The materials are so thin and flexible that the device can be made transparent and can conform to curved surfaces,” said Der-Hsien Lien, a postdoctoral fellow at UC Berkeley and a co-first author
Maybe, maybe not. Flat flexible circuits are established technology. LG already have a flexible display, although apparently it has a dead pixel problem. http://www.bbc.co.uk/news/technology-35230043
Wouldn’t a rigid, curved glass surface be less prone to breakage than a flat piece of glass, since the full force of an impact is more likely to be deflected?
> By laying the semiconductor monolayer on an insulator and placing electrodes on the monolayer and underneath the insulator, the researchers could apply an AC signal across the insulator. During the moment when the AC signal switches its polarity from positive to negative (and vice versa), both positive and negative charges are present at the same time in the semiconductor, creating light.
This is highly simplified, but essentially the LED is now capacitively coupled to its supply on one side, through the insulator*. As a result it has to be driven with AC. Neat trick.
That's similar to how electroluminescent displays work. Except those use an insulating layer and electrode layer on both sides of the light producing layer instead of just one.
If you can layer enough of such invisible screens, you could make a nice 3d display, although I'm not sure if it would actually look nice (you could probably see through objects).
At a guess, being able to easily augment sunlight in parts of the world that get few hours of sunlight during local winter.
Sun shines through when it's there, LED takes over when not.
However in practice I don't think this would be useful - they're considerably less efficient than existing LEDs (currently 1% vs 25-30%) and I think that efficiency is more of a problem than transparency.
The standard showcase for such things are usually transparent displays. While looking cool, they would be pretty annoying: There's always interference with the background. That's also why no one uses transparent whiteboards as seen in movies.
But of course, it would also be neat to just have displays on surfaces where not visible when turned off.
They’re the only option available because tiny mobile keyboards were pretty damned annoying, too, while also carrying the cost of dozens of potential points of failure, taking up a considerable amount of real estate regardless of how long the keyboard is actually used, and forcing a particular key layout on the user. I honestly don’t think I’d buy a phone with a hard keyboard, even if there were decent options for one.
I had a Blackberry Torch [1] for a while in the early 2010's. The keyboard was great, and you could use a touchscreen keyboard as well (it would seamlessly switch the app to fullscreen if you slide it open). It was thicker and heavier than most comparable phones, but with modern tech that would be less of an issue.
The biggest problem with it at the time was it was running Blackberry OS, which was a reasonable e-mail client, mediocre (and later, noticeably outdated) browser, and abysmal app store and selection of 3rd party apps.
I remember saying it would have been a great phone if they had dropped their own OS and went to Android (and spent their software dev time making their version of Android better and building their e-mail client etc on top).
My next phone was an Android something or other, and by then, I was more than happy to give up the physical keyboard to get something more useful than an e-mail interface brick in my pocket.
They were pretty annoying for the first week, and then we all got used to them. At this point everyone is pretty adept at thumb touch keyboards. I know I fly on my iPhone. Apple was correct, physical keyboards are a useless waste of space on a mobile phone.
Miniaturizing a QWERTY keyboard is a waste of space. Physical buttons do, however, add a lot of value to a phone.
Apple was not correct about key input, just as they were not correct to remove the TRRS audio jack. They make a lot of decisions that force the market towards where they want it to be, and then people put up with it because they feel they have no viable alternatives. Those who say they like what Apple does might just be loving the one they're with, because they can't have what they love.
Or plastic, it doesn't matter. I wrote whiteboard to convey the meaning: Something you write on to visualize thoughts, often for collaboration. Not sure if there's another word than whiteboard for it.
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[ 3.5 ms ] story [ 142 ms ] threadCommercial LEDs consist of a semiconductor material that is electrically injected with positive and negative charges, which produce light when they meet. Typically, two contact points are used in a semiconductor-based light emitting device; one for injecting negatively charged particles and one injecting positively charged particles.
Isn't that a bit too simplified?
That said it sounds like very cool technology although hard to see how electrical wires to each pixel would be as invisible at wall-sized scales.
https://en.wikipedia.org/wiki/Indium_tin_oxide
With a large pitch Cu or Al conductors you can do 5ohm/sq with good transparency. That will let you do 200nits (candela/m2) with the efficiency of these thin LEDs. ITO would be 10x lower conductance and only works in LCDs because they are inverting voltage light valves (not light sources).
If everything worked out you could reasonably view thin LEDs in a dim office environment. That's not really interesting unless it's 3D.
> “The materials are so thin and flexible that the device can be made transparent and can conform to curved surfaces,” said Der-Hsien Lien, a postdoctoral fellow at UC Berkeley and a co-first author
This is highly simplified, but essentially the LED is now capacitively coupled to its supply on one side, through the insulator*. As a result it has to be driven with AC. Neat trick.
Tiny thin LEDs are necessarily not going to have a huge power output. If the substrate is glass it will have decent thermal conductivity.
However in practice I don't think this would be useful - they're considerably less efficient than existing LEDs (currently 1% vs 25-30%) and I think that efficiency is more of a problem than transparency.
I think you can make background dark (from transparent) by using good old LCD technology. Because that's basically what LCD is about.
But of course, it would also be neat to just have displays on surfaces where not visible when turned off.
The biggest problem with it at the time was it was running Blackberry OS, which was a reasonable e-mail client, mediocre (and later, noticeably outdated) browser, and abysmal app store and selection of 3rd party apps. I remember saying it would have been a great phone if they had dropped their own OS and went to Android (and spent their software dev time making their version of Android better and building their e-mail client etc on top).
My next phone was an Android something or other, and by then, I was more than happy to give up the physical keyboard to get something more useful than an e-mail interface brick in my pocket.
[1] https://en.wikipedia.org/wiki/BlackBerry_Torch_9800
The problem with physical phone keyboards is that they still tried to be like desktop keyboards. They needed to be more like console controllers.
Apple was not correct about key input, just as they were not correct to remove the TRRS audio jack. They make a lot of decisions that force the market towards where they want it to be, and then people put up with it because they feel they have no viable alternatives. Those who say they like what Apple does might just be loving the one they're with, because they can't have what they love.
You mean glass?
Not sure if that would actually be useful for anything besides a density increase, but it could make color vector displays feasible.
https://www.youtube.com/watch?v=IJQzPrkkH6A https://www.youtube.com/watch?v=Lv46YU-X9Xs
I'm confuzzled by the 'news', although the AC drive, vice DC is interesting I suppose.