> 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.<p>This is highly simplified, but essentially the LED is now capacitively coupled to its supply on one side, <i>through</i> the insulator*. As a result it has to be driven with AC. Neat trick.
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.<p>But of course, it would also be neat to just have displays on surfaces where not visible when turned off.
Some more pictures from the article itself: <a href="https://www.nature.com/articles/s41467-018-03218-8/figures/4" rel="nofollow">https://www.nature.com/articles/s41467-018-03218-8/figures/4</a>
Float-in-the-air 3D displays/images are in the labs already! <a href="https://www.nature.com/articles/d41586-018-01125-y" rel="nofollow">https://www.nature.com/articles/d41586-018-01125-y</a>
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).
This did not inspire confidence:<p><i>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.</i><p>Isn't that a bit too simplified?<p>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.
Isn't heat a current major concern with LEDs? If so wouldn't this have to be hooked up to a heatsink in practice making the transparency irrelevant?
Transparent OLEDs (TOLEDs), Transparent Quantum Dot LEDs (QD-LEDs), Transparent Inorganic LEDs, have all been around for a long time now:<p><a href="https://www.youtube.com/watch?v=IJQzPrkkH6A" rel="nofollow">https://www.youtube.com/watch?v=IJQzPrkkH6A</a>
<a href="https://www.youtube.com/watch?v=Lv46YU-X9Xs" rel="nofollow">https://www.youtube.com/watch?v=Lv46YU-X9Xs</a><p>I'm confuzzled by the 'news', although the AC drive, vice DC is interesting I suppose.