Stretchable OLEDs

Researchers from Kyung Hee University in Korea have designed highly efficient stretchable OLED devices by incorporating the prestretched elastomer with optical adhesive film.

The researchers say that the so-called Geometrical Stretchable OLED (GSOLED) device enhances the efficiency of the OLEDs with the light extraction phenomenon brought by nanowavy corrugated structures. Furthermore, GSOLED shows stability in stretchable conditions and displays narrower emission spectrum with improved color purity.

Researchers from Korea's KAIST, in collaboration with Dong-a University and ETRI have developed a new stretchable OLED structure that is made from 3D rigid islands, or bumps. These so-called 3D-Pop islands remain unchanged as the display itself stretches and so maintain excellent performance.

The OLED islands are connected with parts that are curved in shape (similar to a horseshoe) that can be deformed while still operating normally, even at 500% tension. The whole structure can simultaneously utilize hinge-type rotation and tension of the bending connection connector, and is so not limited to a 2D plane. Even at 40% elasticity, the light emitting area remains at 85%. 

Researchers from Korea's Yonsei University developed a new highly-promising stretchable OLED device by sequential coating technique. The new device can stretch up to 70% and maintain 80% brightness after 300 cycles at 40% strain. The OLED offers a maximum brightness of 3,151 nits and a total current efficiency of 5.4 cd/A.

The researchers say that standard stretchable OLEDs (what they refer to as intrinsically-stretchable OLEDs, or is-OLED) suffer from reduced performance due to orthogonal solvent problem and also the standard lamination process may cause defects and delamination. The new technique overcomes these issues.

Researchers from Korea's KAIST, ETRI, and Dong-A University propose a new stretchable OLED display architecture, based on a 3D form that includes hidden sections that act both as active emitting areas and interconnectors. The idea is that as the OLED display is stretched, these areas pop into place and add to the emitting area of the OLED. The areas are basically hidden pixels that are only used when the display stretches.

To create this OLED device, the researchers attached ultrathin OLED films to a 3D rigid island array structure through quadaxial stretching, enabling precise, deformation-free alignment. The researchers explain that a portion of the ultrathin OLED is concealed by letting it ‘fold in’ between the adjacent islands in the initial, non-stretched condition and gradually surfaces to the top upon stretching. 

LG Display demonstrated several exciting OLED display prototypes at Display Week 2023.

First up was the company's 77" 8K Meta (microlens-array) panel - this has been commercialized already, but it is always a wonder to watch this particular display which offers an extraordinary image quality.

Researchers at the University of Chicago, led by Sihong Wang (above) and Juan de Pablo, developed a stretchable OLED device that uses TADF emitters to enable high efficiency and high stretchability.

The researchers say that this is the highest-efficiency stretchable display demonstrated to date, as all previous designs used fluorescent OLED emitters. The TADF stretchable device achieves 10% EQE and a stretchability of 125%. The substrate of this new device is a newly synthesized polymer.

LG Display has demonstrated a 12" 100 PPI full-color stretchable MicroLED display. The display can stretch up to 20% (to create a 14" display).

The display is said to be "close to commercialization" - as it is highly flexible, durable, and reliable. LGD says that it is the world's first full-color high-resolution stretchable display that was ever produced. But we do know that companies have demonstrated stretchable OLED displays in the past, for example Samsung with its 13" stretchable display shown in 2021.

TCL CSoT says that it has developed a new hinged-pixel design that can enable uniform stretchable displays.

The idea is to connect adjacent pixels with flexible hinges, so that when the display is stretched, the hinges make sure the pixels retain a fixed distance between them. The company says that this design can remain uniform for up to 40% expansion.

Panasonic announced a new thermoset stretchable film for printed electronics, called Beyolex. Panasonic targets several applications for its new film, including OLED substrates and encapsulation film.

Beyolex is based on a proprietary non-silicone thermoset polymer chemistry developed by Panasonic researchers at the company's Electronic Materials laboratory in Osaka, Japan. The film features softness, conformability, high temperature resistance, and ultra-low permanent deformation after stretching.

Samsung Display has demonstrated a new stretchable AMOLED display. The 13-inch panel (we do not know the resolution) was shown in a unique 3D demo.

The idea behind the demo is that the panel reacts to the video content (flowing lava), so it changes the height of parts of the screens to make the experience more realistic, a sort of volumetric display.