Flexible displays are a fairly mature technology at this point, but a research team from UCLA is taking the idea of a flexible display one step further. The display technology created by Qibing Pei and his team doesn’t just bend — it can be repeatedly folded, twisted, and stretched without being damaged. Even being stretched to more than double its normal size, the material remains lit and goes right back to normal when released. This could have a myriad of uses, not the least of which as the basis for a new class of smartphone screens.

As with most flexible display solutions, this one is based on organic light-emitting diode (OLED) technology. These displays don’t need a backlight because the pixels themselves produce all the light. If you’re making a stretching display, it really isn’t workable to fasten a strip of LEDs to it. When not lit, the material is almost completely transparent, opening up a number of additional uses beyond mobile devices.

Durability was an essential component of the UCLA team’s work on stretchable OLEDs from the beginning — the team wanted to create a material that was more than just a tech demo. They stretched the OLED display 30% past its original size 1000 times and found it still went back to normal when released and continued to work as intended. The maximum stretching tolerance is around double normal size. It can also be bent through 180 degrees with no ill effects — that means you can fold it up like a piece of paper and it pops right back.

The material functions in this way thanks to a novel layered construction. The light comes from a single layer of electroluminescent polymer, which is held between two transparent elastic composite electrode layers. The electrodes themselves are a notable advancement. A lack of stretchable electrodes has been one of the problems holding this kind of display back.

It may look like the final product is just a single block of light-emitting material, but it has been designed to have individual pixels, just like boring old non-foldable screens. The key to this is in the electrodes. They are composed of a network of silver nanowires combined with an insulating polymer. The layers are rotated 90 degrees from each other, forming a crosshatch pattern when viewed from above. Each intersection acts as a single pixel in the display.

Probably the most interesting potential application for this technology is in mobile devices. Imagine having a phone or tablet with a screen that could change size or be folded up for storage. Maybe the two devices will even be the same thing — simply stretch out your phone when you need a bigger screen. The versatility of this material could also make it trivially easy to put a screen on any surface in your home. As a bonus, you’ll still be able to see through it when it’s off. This screen tech is still in its early stages, but it could be the first of its kind to make it past the trade show demo stage.

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Research paper: doi:10.1038/nphoton.2013.242 – “Elastomeric polymer light-emitting devices and displays” (paywall)