The stretchable display is all the more surprising since the organic materials that current OLED displays are composed of are usually quite stiff.
“The materials currently used in these state-of-the-art OLED displays are very brittle; they don’t have any stretchability,” said Sihong Wang, co-corresponding author of the study. “Our goal was to create something that maintained the electroluminescence of OLED but with stretchable polymers.”
The researchers used computational predictions to develop their new, stretchier OLED polymers.
After experimenting with several prototypes, the researchers found a solution that used thermally activated delayed fluorescence (TADF), an efficient way of allowing organic material to convert electricity into light.
The team embedded alkyls – organic chemicals composed of carbon and hydrogen atoms – in the polymer between TADF units. Through this method the softness and flexibility of the material was enhanced.
The researchers found that the prototype OLED display could be stretched to more than twice its original length without impacting its light-emitting abilities or the clarity of the display image.
“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 Juan de Pablo, co-corresponding author of the study. “Now that we understand these properties at a molecular level, we have a framework to engineer new materials where flexibility and luminescence are optimized.”
The Chicago team are not the only researchers developing stretchable displays. In 2021, Samsung announced a wearable health-monitoring display capable of stretching up to 30 percent of its original length.
Meanwhile, last November LG revealed a microLED stretchable display that could stretch up to 20 percent.