Researchers have developed a highly flexible and stretchable digital display that emits a fluorescent pattern. The material, which can be bent in half and stretched to more than twice its original length, has potential applications in wearable electronics, health sensors and foldable computer screens. This new class of materials was created by combining information from different fields, such as atomic models of new polymers and thermally activated delayed fluorescence, which provides highly efficient light emission. Researchers are working on further enhancements, including additional colors and improved efficiency and performance.

Imagine a thin digital display that’s flexible enough to wrap around your wrist, fold in any direction, or tilt over your car’s steering wheel. Researchers at the Pritzker School of Molecular Engineering (PME) at the University of Chicago have developed a material that can bend exactly in half, or stretch to more than twice its original length, yet still emit a fluorescent pattern.

Material described in a scientific journal Nature Supplies It has a wide range of applications, from wearable electronics and health sensors to advanced computer displays.

“One of the most important components of almost every consumer electronics we use today is the display, and we combined knowledge from many different fields to create an entirely new display technology,” said Sihong Wang, professor of molecular engineering, who led the research. With Juan de Pablo, Liv Family Professor of Molecular Engineering.

“This is the grade of material you need so that you can finally design truly flexible displays,” De Pablo added. “This work is truly eye-opening and I hope it will enable many technologies that we haven’t even thought of yet.”

Production of flexible, glossy polymers

The screens of most high-end smartphones and an increasing number of televisions use OLED (organic light-emitting diode) technology, which inserts small organic molecules between conductors. When an electric current is turned on, the small molecules emit a bright light. This technology is more energy efficient than older LED and LCD displays and is praised for its sharp images. However, the molecular building blocks of OLEDs have close chemical bonds and a rigid structure.

“The materials currently used in these state-of-the-art OLED displays are very fragile; they do not stretch,” Wang said. “Our goal was to create something that retains the electroluminescence of OLEDs, but with flexible polymers.”

Wang and de Pablo knew what was needed to impart stretchability to materials—long polymers with flexible molecular chains—and they also knew what molecular structures were needed to make the organic material emit light very efficiently. They decided to create new polymers that would combine both properties.

“We were able to develop atomic models of interesting new polymers, and with these models, we model what happens to these molecules when you try to pull and bend them,” De Pablo said. “Now that we understand these properties at the molecular level, we have a framework for developing new materials where flexibility and gloss are optimized.”

University of Chicago scientists have developed a flexible, stretchable digital display material that can emit a fluorescent pattern that could potentially be used in wearable electronics and foldable displays. Credit: Image courtesy of Wang Group

Armed with computational predictions for the new flexible electroluminescent polymers, they created several prototypes. As predicted by the model, the materials were flexible, elastic, shiny, durable and energy efficient.

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