Flexible Displays? UCLA Demonstrate First Fully Stretchable OLED

Advanced Materials

In the past, stretchable electronics featured at least one brittle element. The overall pliability of the electronic device was therefore only as robust as its most rigid component. The researchers at UCLA solved the problem using organic compounds and stretchable polymers to create the stretchable OLED said Qibing Pei, professor of materials science and engineering at UCLA and principal investigator of the project.

"To make a stretchable electronic device you must find materials for the different purposes that are stretchable. We did that here with carbon nanotubes and a polymer electrode infused into the carbon nanotube coatings to preserve conductance," Pei said.

Polymer light-emitting electrochemical cells sustain up to 45 percent linear strain.

Pei says implications for stretchable OLEDs range from multimedia-enhanced clothing to flexible display technology. He added that flexible display technology would have the potential to change the way mobile hardware is designed.

"Right now smart phone dimensions are determined by the screen size. If the display could roll out or stretch when needed, the form factor decisions around smart phones would change," said Pei.

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The working prototype built at UCLA emits blue light in a one centimeter square area and stretches up to 45 percent. With enough monetary investment in the research, Pei suspects a flexible display is 3 to 5 years in the future, or whenever the packaging problem is solved.

"The biggest barrier is the packaging. The polymer we use is sensitive to air and moisture. If you take the device out in the air it won't last long," Pei said. "The current encapsulation technology is plastic and rigid. So either we have to develop a stretchable encapsulation material or improve the polymer so you don't have to protect it from air."

Pei said the research, funded by the National Science Foundation, began about a year ago and future goals include building a stretchable transistor, the semiconductor devices used to amplify and switch electronic signals.