A plastic-softening chemical that has been used for decades in everyday products such as vinyl flooring and plastic wrap could help create a new generation of brighter, more flexible electronic displays.
Researchers at the University of Chicago Pritzker School of Molecular Engineering have discovered that adding a common plasticizer to special light-emitting polymers makes them much more stretchable while also significantly improving how efficiently they produce light.
The findings, published in Nature Communications, could help advance wearable electronics, soft medical devices, flexible robots and future 3D display technologies.
Stretchable organic light-emitting diodes, or OLEDs, have attracted growing interest because they could be built into clothing, skin-like patches or robotic systems that bend and move without breaking.
However, designing materials that are both soft and bright has proven difficult. Materials that stretch well often lose some of their light-emitting performance, while highly efficient light emitters are usually too rigid.
Professor Sihong Wang and his research team believed there might be a much simpler solution than creating entirely new materials. Instead of redesigning the light-emitting polymers, they wondered whether adding a widely available plastic softener could improve both flexibility and brightness at the same time.
The team focused on thermally activated delayed fluorescence (TADF) polymers, a highly efficient class of light-emitting materials. When these polymers are packed too closely together, they interfere with one another. Instead of releasing energy as light, much of that energy is lost through a process known as concentration quenching.
The researchers thought that adding a plasticizer could gently separate the polymer chains. This extra space would reduce interference between neighboring molecules while also allowing the material to stretch more easily.
To test the idea, undergraduate researcher Glingna Wang added dioctyl phthalate (DOP), a plasticizer commonly used to soften plastics, to the polymer films.
The results exceeded the researchers’ expectations. The treated films became both much brighter and much more flexible. The light-emitting efficiency increased from about 60 percent to nearly 100 percent, approaching the theoretical maximum. At the same time, the material’s ability to stretch before cracking increased dramatically, from just 5 percent strain to more than 110 percent strain.
The team also tested the same approach on four other types of TADF polymers with different chemical structures. In every case, the materials became both more efficient and more stretchable, suggesting that the technique could work across a wide range of light-emitting polymers instead of being limited to a single material.
When incorporated into working OLED devices, the plasticized films improved device efficiency by around 35 percent compared with untreated versions.
The project was led by undergraduate student Glingna Wang, who has since begun a Ph.D. at Northwestern University. She said the opportunity to lead an independent research project during her undergraduate studies gave her valuable experience for graduate research.
The research team is now working to integrate the improved materials into complete stretchable display arrays. They are also exploring their use in biomedical technologies, including wearable light-based therapies and flexible medical devices that could one day interact directly with the human body.
The study was published in Nature Communications.
