All LED materials suffer an internal reflection problem. Much of the light generated is reflected back into the material itself and is lost as heat. Light travel slower inside the LED than in the air. When it come to the LED/air interface it will encounter an internal reflection. This is like having a semi-transparent mirror at the interface that permits some light to escape and some reflect back into the material. The result is lower light output and heat removal problem.
Researchers at the University of Namur, Belgium, has drawn inspiration from firefly to solve the internal reflection problem. They make a LED overlayer pattern that mimicked the unique surface geometry of firefly's cuticles. They deposited a layer of light-sensitive material on top of the LED and then exposed sections with laser to create triangular factory-roof profile. The researchers adjusted the dimensions of the protrusions to a height and width of 5 micrometers to maximize the light extraction. This has improved the LED light output by 55%.
The researchers think that the technology should be able to be commercialized within the next couple of years. This new research was recently published in the Optical Society’s (OSA) open-access journal Optics Express.