Learning Fireflies To Improve LED Emitting Efficiency? The U.S. Research Team Has Already Done So.

- Feb 25, 2019-

Researchers at Pennsylvania State University in the United States have found that the luminous efficiency of LEDs can be improved by imitating the luminous structure of fireflies.


Stuart (Shizhuo) Yin, an electronic engineering expert at Pennsylvania State University, points out that most commercial LEDs have only about 50% luminous efficiency at present. How to improve the so-called efficiency of LED light extraction is one of the keys of the research. They focus on how to extract light from LED.


The team found that light disappears when it reflects backwards, so fireflies and LEDs face similar challenges in releasing light. For LEDs, one solution is to create micro-structures on their surfaces to texture them and emit more light. However, the microstructures of most LED surfaces are symmetrical, with the same tilt angle on each side.


Fireflies'lanterns also have microstructures. However, the researchers found that these microstructures are asymmetric, with one side tilting at different angles. They also found that other glowing insects had similar structures. In view of this, they decided to try to create a similar asymmetric structure on the surface of the LED.


Sapphire Substrate with Asymmetric Micro-pyramid Structure


Researchers have successfully created an asymmetric micro-pyramid structure on the surface of LED, which improves the efficiency of light extraction in two ways. Firstly, the asymmetric pyramid structure has a larger surface area, which promotes more interaction between light and surface, and makes less light absorbed. Later, when light encounters two different inclined angles of the asymmetric pyramid structure, the light reflection has greater randomness, which means that the light reflects more.


Comparison of luminescence efficiency between symmetric and asymmetric structures


By using this method, the extraction efficiency of LED light can be improved to 90%. The research team applied for a patent for the study and said they were seeking to work with relevant manufacturers to promote the commercialization of the technology.


It is reported that the results of this study have been published in Optik magazine.