According to the findings in Optik, LED made with firefly-mimicking structures could improve efficiency. The new type of LED bulb could one day light homes while reducing power bills.
"LED light bulbs play a key role in clean energy," says Stuart Yin, professor of electrical engineering at Penn State. "Overall commercial LED efficiency is currently only about 50 percent. One of the major concerns is how to improve the so-called light extraction efficiency of the LEDs. Our research focuses on how to get light out of the LED."
Fireflies and LEDs face similar challenges in releasing the light they produce because the light can reflect backwards and get lost. One solution for LEDs is to texture the surface with microstructures—microscopic projections—that allow more light to escape. In most LEDs these projections are symmetrical, with identical slopes on each side.
Fireflies' lanterns also have these microstructures, but with asymmetric sides that slant at different angles, giving a lopsided appearance. Using asymmetrical pyramids to create microstructured surfaces, the team found that they could improve light extraction efficiency to around 90 percent.
The LED-based lighting market is growing rapidly as the demand for clean energy increases, and is estimated to reach $85 billion by 2024. "Ten years ago, you go to Walmart or Lowes, LEDs are only a small portion (of their lighting stock)," says Yin. "Now, when people buy light bulbs, most people buy LEDs." LEDs are more environmentally friendly than traditional incandescent or fluorescent light bulbs because they are longer-lasting and more energy efficient.
Two processes contribute to the overall efficiency of LEDs. The first is the production of light—the quantum efficiency—which scientists measure using how many electrons convert to light when energy passes through the LED material. Scientists have already optimized this part in commercial LEDs. The second process is getting the light out of the LED—called the light extraction efficiency.
The researchers have filed for a patent on this research. Once they obtain the patent, they are considering collaborating with manufacturers in the field to commercialize this technology.
Source: Futurity: Research News, Fireflies inspire new energy-saving LED light bulbs, Feb 20. 2019