Bayram wins prestigious ARPA-E OPEN grant to develop novel green LEDs

2/14/2022 12:29:58 PM Jenny Applequist for HMNTL

Imagine you’re part of a nomadic band of early humans, frequently on the move in pursuit of needed resources. Your survival may depend on whether someone’s eye can pick out tiny specks of green on the horizon—telltale signs of the presence of life and water. It isn’t an easy way to live, but a hidden power gives you a leg up: the human visual system has evolved to amplify the color green.

Can Bayram
Can Bayram, UIUC

Lifestyles have changed quite a bit since then, but HMNTL and ECE associate professor Can Bayram is preparing to demonstrate that our amplification of green can still offer a valuable advantage. He just received a prestigious ARPA-E “OPEN” grant to support his development of novel green LED lights that, among other benefits, will be able to generate the same human-perceived level of brightness as today’s blue LED lamps, but with significantly less energy consumption and associated carbon emissions. They will also avoid the health concerns associated with today’s LEDs.

“If you have three different color lights with the same optical power—blue, green, and red—green will always look brighter to us,” explains Bayram, “because our eyes are more sensitive to green.” When a white light source lacks a green component, it needs to compensate by consuming more energy to achieve the same apparent brightness.

The new project’s goal is to enable a “true” white light LED, which might have triple the efficiency of today’s LEDs. This true white light would be achieved through the means of color-mixed lights that include red and blue LED components plus the green LED that Bayram will develop.

Today, the LED bulbs that create white light are made by coating blue LEDs with phosphors; the blue light is converted into a broader emission spectrum when it passes through the phosphors. Unfortunately, the phosphor particles tend to degrade and rearrange themselves, eventually emitting different wavelengths that skew towards blue. It isn’t merely an aesthetic problem, but a health issue. There are concerns about everything from retinal injury, to sleep and attention disorders, to damaging effects on the behavioral patterns of wildlife, as humans aren’t the only ones that are thrown off by the unnatural light.

That problematic phosphor coating won’t be needed in Bayram’s new color-mixed design.

Novel Green LEDs for the Ultimate Solid-State Lighting
Novel Green LEDs for the Ultimate Solid-State Lighting. Credit: Richard Liu.

“With our technology, hopefully [in] three years, we will close the gap between having high-efficiency, unhealthy light versus low-efficiency, healthy light,” he says. “So hopefully we will push this up so that we can all have both energy savings and environmental savings, as well as health benefits.”

The U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) routinely offers funding opportunities that address specific topics, but about every three years, they offer an “OPEN” opportunity whose mission is “to support the development of potentially disruptive new technologies across the full spectrum of energy applications.” Anyone can apply—not just academic researchers, but people from industry or elsewhere—and applicants can propose any kind of energy-related technology research they want. Thousands of applications pour in, but following multiple rounds of review, just a few dozen will be funded. In the 2021 cycle, Bayram’s proposal was one of 68 winners.

The proposal likely stood out, in part, because of its potentially enormous real-world benefits. Lighting accounts for 15% of global electricity consumption, and as the population continues to grow, lighting needs will expand as well. Accelerating the transition to energy-efficient lighting is therefore seen as a critical way to improve both the global economy and climate conditions. If the Department of Energy’s 2035 goals for solid-state lighting (SSL), such as LEDs, can be met, lighting-related energy needs and greenhouse gas emissions will be reduced by approximately 55%.

Bayram’s project could thus offer huge energy and environmental benefits, so is a good fit for the OPEN program’s goal of supporting high-risk, high-reward projects. Entitled “Green Light Emitting Diodes for the Ultimate Solid-State Lighting,” it will run for three years.