Harvesting light using nanostructured surfaces (inspired by the eyes of moths)

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http://www.amolf.nl/news/detailpage/back_to/news/article/harvesting-light-using-nanostructured-surfaces//0dab14f845/

Harvesting light using nanostructured surfaces

Category: News, Nano Wire Photonics
January 27, 2009

Researchers from the FOM Institute for Atomic and Molecular Physics (AMOLF), located at the High Tech Campus in Eindhoven, and Philips Research developed a method to drastically reduce the reflection of light at the interface between a high refractive index semiconductor and air. The researchers were inspired by the eyes of moths that are covered by tapered nanostructures. Thanks to these nanostructures, night moths are capable of seeing very well in the dark. The results of the research have recently been published in the prestigious journal Advanced Materials.

Light travels as a straight beam in homogeneous media. The direction of the light beam changes when it arrives at an interface between two different media. A fraction of light is reflected into the first medium and the rest is refracted into the second medium. At large angles of incidence at an interface between air and a solid material such as a semiconductor, nearly 100 % of the light is reflected. Interfaces which reduce this reflection exist in nature. For example, the eyes of a moth are covered with tapered nanostructures, which increase the eye sight of the moth in the dark by allowing more light to enter the eyes.

Inspired by these biostructures, researchers from AMOLF and Philips Research developed a method which drastically reduces the reflection between air and a semiconductor. This method consists of the growth of nanowires with different lengths or with the same length, but conically shaped. Using this method, a gradual change from air to semiconductor is achieved, which leads to an efficient coupling of light into the semiconductor and minimizes the reflection. These layers show a large reduction of the reflection over a broad range of colors and angles of incidence. The reduction of the reflection is of importance for different applications. A low reflection can not only increase the sensitivity of a light detector, it can also increase the efficiency of solar cells and LEDs. The results of this research are published in the prestigious journal Advanced Materials.

This work is part of the research program of the Foundation for Fundamental Research on Matter (FOM), which is financially supported by the Netherlands Organisation for Scientific Research (NWO) and is part of an industrial partnership program between Philips and FOM.

More information: Silke Diedenhofen and/or Jaime Gómez Rivas, FOM Institute for Atomic and Molecular Physics AMOLF, c/o Philips Research Laboratories Eindhoven, High Tech Campus 4, 5656 AE Eindhoven, Tel. [phone] or 040 27 42349

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[Demeter]

1. Fascinating!

(To coin a phrase). Thanks for the post!