Thanks to modern LED bulbs, light is cheaper than ever to make—except for one particular kind.
Three University of Chicago scientists have announced an innovative way to create infrared light, which has long been a more difficult task than making visible light due to the different materials required.
The new method, which uses quantum dots, performs as well as or better than current infrared light sources while being much simpler to make. The scientists hope the breakthrough could lead to cheaper and more efficient infrared technology—which is used in everything from medicine to vehicle emissions tests.
“The configuration improves the power conversion efficiency by about 100-fold,” said study coauthor Philippe Guyot-Sionnest, professor of physics and chemistry at UChicago and member of the James Frank Institute, “leading to possibly the most efficient mid-infrared LEDs made so far with any materials.”
The results are published Feb. 24 in Nature Photonics.
The ins and outs of infrared
Our eyes can see much of the world, but we’re unable to perceive any light that shines in the infrared spectrum, which means we’re missing out on a lot.
For example, the moths you might dismiss as drab are secretly beautiful—it’s just that their patterns and colors show up only in the infrared, which our sorry human eyes cannot perceive. Similarly, salmon use infrared light to navigate streams; snakes use it to hunt at night; and plants use it to attract pollinators.
But for humans to see and use this light, we must create devices. The trouble is that the energy of infrared light makes it more difficult to create and capture than visible light.
Guyot-Sionnest’s laboratory specializes in quantum dots—particles so tiny that you would need to pile trillions of them together to make a single visible speck. The lab had previously created a new technique to make these particles emit light in the infrared spectrum, but they wanted to make the method even more efficient.
Former UChicago graduate student Xingyu Shen, PhD’25, now at the University of Wisconsin-Madison, had developed an ink that could be used to “print” high-quality quantum dots on a surface. Meanwhile, postdoc Augustin Caillas began tinkering with the geometry of the devices themselves.
The researchers figured they could try a decades-old trick in physics. If they could funnel the electrons and the electromagnetic field of the light into the same tiny spot, that would create the conditions for them to fluoresce faster—creating a brighter light.
The ideal geometry turned out to be a circuit that looks like an extremely miniature bow tie. Two gold triangles meet at one point in the middle, with an infinitesimally small gap in between. The whole setup is just 60 nanometers thick, which is about how long your fingernails grow in one minute.
When the researchers run a current across the device, the electrons shuffle along towards the tip, where they “fall” down energy levels from dot to dot, and emit light as they go.
The team tested the devices and found a 100-fold improvement in efficiency over their previous versions.
“The performance was really quite good right away—it was striking,” said Caillas.
The method to make the devices is much simpler than the infrared light sources used in devices you might buy at the store today. Those are all made with a technique known as molecular epitaxy, which involves evaporating semiconductors in a special ultra-high vacuum and condensing it into many atomically-thin layers, which is expensive both in time and fabrication tools. The team hopes their work could make infrared light LEDs, lasers, and cameras more readily available.
Infrared light has many uses. It is what you see in night-vision cameras that detect body heat, but it’s also used in sensors (such as breathalyzers), fiber optics, and environmental monitoring. Doctors are also investigating how it can be used in medicine, including wound healing, arthritis and cancer care.
The new technique could be especially useful for sensors, Shen explained.
“Right now, you cannot make infrared devices that emit different colors on the same chip, which means you cannot test for multiple wavelengths using the same chip,” she said. “But with our method, you can easily print the dots on any area.”
To make the devices, Caillas used the Pritzker Nanofabrication Facility, a specialized research facility at UChicago that supports advanced lithography techniques.
Citation: “Purcell enhanced mid-IR cascade LEDs.” Caillas, Shen, and Guyot-Sionnest, Nature Photonics, Feb. 24, 2026.
Funding: U.S. Army Research Office, National Science Foundation, Martha Ann & Joseph A. Chenicek Fellowship.