UChicago PME Uses Dioctyl Phthalate to Boost Stretchable OLED Brightness

The quest for skin-compatible electronics has long been stalled by a stubborn trade-off: materials that are soft enough to stretch often lose the ability to emit light efficiently. Researchers at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) have bypassed this hurdle using a chemical additive already found in vinyl flooring and plastic wrap.

By blending dioctyl phthalate (DOP) into thermally activated delayed fluorescence (TADF) polymers, the team created films that are both more elastic and more luminous. The discovery, published in Nature Communications, suggests that a simple physical adjustment can outperform complex chemical synthesis.

Solving Concentration Quenching with Dioctyl Phthalate

The primary obstacle in stretchable OLEDs is concentration quenching. When light-emitting polymers are packed too tightly, neighboring units interfere with one another, canceling out energy before light can be released. The UChicago team hypothesized that creating tiny pockets of physical space between these polymer chains would stop this interference.

DOP acts as a plasticizer, pushing the polymer chains apart. This does two things simultaneously: it prevents quenching to boost brightness and allows the chains to slide past each other during mechanical stretching. This approach is distinct because it doesn’t require a custom chemical structure for every new material.

“In the past, we’d been trying to come up with all kinds of complicated, new chemical structures for stretchable emitters,” said Sihong Wang, an associate professor of molecular engineering at UChicago PME and senior author of the new study published in Nature Communications. “But this method is really simple; you just mix two things together, and one of them is a commercially available additive that people have used for decades to soften everyday plastics.”

Sihong Wang, associate professor of molecular engineering at UChicago PME

Measurable Gains in Efficiency and Elasticity

The data from the study shows a dramatic shift in performance. The efficiency of the TADF films climbed from 60% in untreated versions to nearly 100%, which is close to the theoretical maximum. The mechanical durability saw an even sharper jump, with the crack-onset strain increasing from 5% to more than 110%.

These improvements weren’t limited to a single material. When the team applied DOP to four other TADF polymers with different chemical structures, all exhibited substantial gains.

Metric	Untreated Film	DOP-Enhanced Film
Fluorescence Efficiency	60%	Nearly 100%
Crack-Onset Strain	5%	More than 110%

Undergraduate Leadership in the Wang Lab

The research was led by Glingna Wang, a UChicago PME undergraduate in the class of 2025 who is now starting a PhD at Northwestern University. While other research groups had used plasticizers to improve stretchability, Glingna Wang noted that no one had tested the use of plasticizers in light-emitting polymers before.

“But with the great trust and guidance of Professor Wang, and the supportive environment in the Wang group, I gradually learned to tackle problems and face actual research issues on my own.”

Glingna Wang, first author of the study

Parallel Breakthroughs in MXene Electrodes

While the UChicago team focused on the light-emitting layer, separate research from Seoul National University and Drexel University has targeted the electrodes. Traditional OLEDs use indium tin oxide (ITO), which is brittle and cracks under pressure. To solve this, researchers replaced ITO with MXenes—ultrathin, highly conductive materials made of layered carbides and nitrides.

This redesigned OLED combines a flexible phosphorescent polymer layer with MXene nanomaterial electrodes. This allows the display to stretch up to 1.6 times its original length. These MXene-powered displays achieved an external quantum efficiency of 17%, and researchers stated this is a record for stretchable OLED displays; they also achieved 200 percent stretching without losing performance.

The team also utilized an exciplex-assisted phosphorescent (ExciPh) layer, which converts more than 57% of excitons into light, compared to 12-22% for the polymer-based emissive layers commonly used in today’s OLEDs.

The Path to Body-Compatible Electronics

These two distinct paths—simplifying the emitter chemistry with plasticizers and replacing brittle electrodes with MXenes—converge on a single goal: electronics that integrate seamlessly with the human body. For Sihong Wang, these displays are a critical piece of a larger vision for devices that can sense, compute, and communicate directly on or inside the body.

Yury Gogotsi, a materials scientist at Drexel University, suggests that this technology could move displays from desktops and pockets to the sleeve of a jacket or rolled into a tube. The potential applications for these developments lie in skin-mounted electronics, soft robotics, and flexible consumer devices.