Researcher Finds Better Energy Efficiency With LEDs Inspired By Fireflies
Say what?! It’s true! A research team in the electrical engineering department at Penn State has found improved energy efficiency for LEDs that mimic fireflies (or lightning bugs).
Why is this so important? Aren’t LEDs efficient enough? Well, yes, and no. Compared to incandescent light bulbs, LEDs are super efficient, using 75% less energy and lasting 25 times longer than incandescents. But when we talk about commercial settings, some LED fixtures are at around 50% efficient for the light they produce, which leaves a lot of room for more improvement.
What Does LED Efficiency Really Mean?
For lighting, when we talk about LED efficiency, we are talking about how much light is actually being emitted/produced, known also as light extraction efficiency. Incandescents are known for producing more heat than light (90% heat, and only 10% light). That’s crazy!
How The Body of Fireflies Inspired Better Efficiency
A student in the electrical engineering department at Penn State noticed that the lantern on a firefly has asymmetrical structures:
“Later I noticed not only do fireflies have these asymmetric microstructures on their lanterns, but a kind of glowing cockroach was also reported to have similar structures on their glowing spots. This is where I tried to go a little deeper into the study of light extraction efficiency using asymmetric structures.” – Chang-Jiang Chen, student in electrical engineering at Penn State University.
To test this theory, the research team used computer-based simulations to demonstrate that the asymmetric surface could improve light extraction. With an asymmetrical pyramid structural pattern on the surface, the researchers found that LED light extraction efficiency improved to about 90 percent!
According to Stuart (Shizhuo) Yin, professor in the electrical engineering department at Penn State, this asymmetrical micro-structural pattern improves light extraction in two different ways:
- Greater surface area of the asymmetric pyramids allows greater interaction of light with the surface, trapping less light.
- When light hits the two different slopes of the asymmetric pyramid, there is a greater randomization effect of the reflections, which gives light another chance to escape.
The researchers then demonstrated this by using a nanoscale 3D printer, creating asymmetric surfaces, which allowed the release of more light then of symmetrical surfaces, as expected.
Once the team has the patent for their discovery which they have already filed for, they hope to go to manufacturers to commercialize the technology.