Fred Schubert, professor of physics and electrical, computer, and systems engineering at RPI and one of the authors of the study, says that the material stops reflections from nearly all the colors of the visible spectrum, as well as some infrared light, and it also reduces reflections from light coming from more directions than conventional coatings do. In contrast, conventional antireflective coatings work best only for specific colors, which is why, for example, eyeglasses with such coatings still show faint red or green reflections.
The researchers showed that they can prevent almost all reflection of a wide range of wavelengths of light by “growing” nanoscale rods projected at specific angles from a surface. Such coatings could improve many optical devices. The bluish tinge is because the coating allows more blue light to reflect. A new antireflective coating on the lower piece reduces reflection to about 0.1 percent. The piece at the top reflects 12 percent of the light. Seeing no reflection: Two pieces of aluminum nitride, a semiconducting material that can be used in light-emitting devices, reflect different amounts of light. The work is published in the current issue of Nature Photonics. Now researchers at Rensselaer Polytechnic Institute (RPI), in Troy, NY, and semiconductor maker Crystal IS, in Green Island, NY, have developed a new type of nanostructured coating that can virtually eliminate reflections, potentially leading to dramatic improvements in optical devices. In solar cells, for example, reflections mean less light that can be converted into electricity.
Unwanted reflections limit the performance of light-based technologies, such as solar cells, camera lenses, and light-emitting diodes (LEDs).
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