Common plastic additive unlocks brighter, stretchier OLED displays for wearables

A material science team at the University of Chicago has found an unlikely solution to one of the stubborn problems in flexible electronics: they borrowed a trick from the plastic wrap in your kitchen drawer. The discovery centers on dioctyl phthalate, a plasticizer that has softened vinyl flooring and cling film for decades. When mixed into light-emitting polymers, the same additive that makes everyday plastics pliable also makes them glow brighter and stretch farther—a finding that could reshape how wearable displays are engineered.

The work emerged from a larger ambition. Sihong Wang, an associate professor of molecular engineering at UChicago, envisions a future where electronics live directly on or inside the human body, sensing vital signs and displaying information without the bulk of conventional devices. Stretchable OLED displays are a critical piece of that vision. But the field has been stuck on a fundamental trade-off: materials that emit light efficiently tend to be rigid, while materials that stretch tend to dim. Wang's lab had been developing stretchable TADF polymers—thermally activated delayed fluorescence materials that outperform conventional emitters—but they ran into a wall. When the polymers pack tightly together in a film, neighboring units interfere with each other's light emission. The phenomenon, called concentration quenching, causes their energies to cancel out before any photons escape.

The insight came from a simple observation: if you could push the polymer chains slightly apart, they might stop interfering with each other. The same physical separation that reduces quenching could also let the chains slide past each other more easily when stretched—much the way plasticizers allow rigid polymers to bend. An undergraduate researcher named Glingna Wang decided to test whether dioctyl phthalate, a plasticizer already approved for use in consumer products, could work in light-emitting materials. No one had tried it before.

The results exceeded expectations. When DOP was added to the TADF films, efficiency jumped from 60 percent to nearly 100 percent—approaching the theoretical maximum. Simultaneously, the material's stretchability improved dramatically, from a crack-onset strain of just 5 percent to more than 110 percent. The effect was not confined to a single polymer type. When the team tested DOP with four other TADF polymers of different chemical structures, all showed substantial gains in both brightness and elasticity. In working OLED devices, the plasticized films delivered a 35 percent improvement in efficiency compared to devices made without the additive.

What distinguishes this approach is its simplicity and breadth. Most advances in stretchable electronics require custom chemical synthesis tailored to each new material. This method is different: mix two things together, one of them commercially available and used for decades, and you get results that work across multiple polymer families. "We found a potentially broadly applicable physical method that could work across different types of polymer-based emitters," Wang said. The discovery sidesteps the need for elaborate new chemistry, which typically takes years to develop and scale.

Glingna Wang, who led the experimental work as an undergraduate, has moved on to a PhD program at Northwestern University, where she plans to continue studying biomedical applications of flexible electronics. She arrived at the lab without expecting to become the first author on a Nature Communications paper. The experience, she reflected, taught her how to tackle research problems independently and prepared her for graduate work. Her contribution underscores how sometimes the most elegant solutions come not from inventing something new, but from recognizing that something old might work in an unexpected place. The next phase will be scaling the approach and testing how these brighter, stretchier displays perform in actual wearable devices and robotic applications.