A material developed by Assistant Professor Sihong Wang and Proffesor Juan de Pablo can stretch more than twice its original length without disrupting its ability to emit light and display a clear image. (Image: Wang Group)

Imagine a thin, digital display so flexible that you can wrap it around your wrist, fold it in any direction, or even curve it over your car’s steering wheel. Well, imagine no more — researchers at the Pritzker School of Molecular Engineering (PME) at the University of Chicago have designed such a material; it can even bend in half or stretch to more than twice its original length — and still emit a fluorescent pattern.

The material, described in Nature Materials, has a wide range of applications, from wearable electronics and health sensors to foldable computer screens.

“One of the most important components of nearly every consumer electronic we use today is a display, and we’ve combined knowledge from many different fields to create an entirely new display technology,” said Sihong Wang, Assistant Professor of Molecular Engineering, who led the research with Juan de Pablo, Liew Family Professor of Molecular Engineering.

“This is the class of material you need to finally be able to develop truly flexible screens,” said de Pablo. “This work is really foundational and I expect it to allow many technologies that we haven’t even thought of yet.”

The displays on most high-end smart-phones, as well as a growing number of televisions, use OLED — organic light-emitting diode — technology, which sandwiches small organic molecules between conductors. When an electrical current is switched on, the small molecules emit a bright light. The technology is more energy-efficient than older LED and LCD displays and known for its sharp pictures. However, the molecular building blocks of OLEDs have tight chemical bonds and stiff structures.

“The materials currently used in these state-of-the-art OLED displays are very brittle; they don’t have any stretchability,” said Wang. “Our goal was to create something that maintained the electroluminescence of OLED but with stretchable polymers.”

The pair knew what it takes to imbue stretchability into materials — long polymers with bendable molecular chains — and also knew what molecular structures were necessary for an organic material to emit light very efficiently. They set out to create new polymers that integrated both properties.

“We have been able to develop atomic models of the new polymers of interest and, with these models, we simulated what happens to these molecules when you pull on them and try to bend them,” said de Pablo. “Now that we understand these properties at a molecular level, we have a framework to engineer new materials where flexibility and luminescence are optimized.”

Armed with computational predictions for new flexible electroluminescent polymers, they built several prototypes. Just as the model had predicted, the materials were flexible, stretchable, bright, durable, and energy efficient.

A key feature in their design was the use of “thermally activated delayed fluorescence,” which let the materials convert electrical energy into light, in a highly efficient way. This third-generation mechanism for organic emitters can provide materials with performance on par with commercial OLED technologies.

“My overall dream is to make all the essential components for a full system of wearable electronics, from sensing to processing to displaying information,” said Wang. “Having this stretchable light-emitting material is another step toward that dream.”

The team is planning to develop new iterations of the display in the future, integrating additional colors into the fluorescence and improving the efficiency and performance.

“The goal is to eventually get to the same level of performance that existing commercial technologies have,” said Wang.

For more information, contact Colleen Mastony at This email address is being protected from spambots. You need JavaScript enabled to view it..