New Alloys Key to Efficient Solar Energy and Lighting

Monday, March 22 2010

A recent advance by Arizona State University researchers in developing nanowires could lead to more efficient photovoltaic cells as well as better LEDs. ASU electrical engineers are working to improve quaternary alloy semiconductor nanowire materials.

Nanowires are tens of nanometers in diameter and tens of microns in length. Quaternary alloys are made of semiconductors with four elements, often made by alloying two or more compound semiconductors. Semiconductors are the material basis for technologies such as solar cells, high-efficiency LEDs for lighting, and for visible and infrared detectors.

One of the most critical parameters of semiconductors that determine the feasibility for these technologies is the band gap. The band gap of a semiconductor determines, for example, if a given wavelength of sun light is absorbed or left unchanged by the semiconductor in a solar cell. Band gap also determines what color of light an LED emits. To make solar cells more efficient, it’s necessary to increase the range of band gaps.

Ideally, the highest solar cell efficiency is achieved by having a wide range of band gaps that matches the entire solar spectrum, said Cun-Zheng Ning, a professor in the School of Electrical, Computer, and Energy Engineering.