Usually solar cells are made from ultrapure single crystal silicon wafers that have a minimum thickness to maximize how much sunlight is trapped. A scientific team led by Berkeley Lab chemist Peidong Yang essentially made arrays from nanowires and gave them a radial orientation that achieves better performance than a wafer. The nanowires are each eight micrometers thick--which is about one-thousandth of a human hair wide--and several microns long. That's less silicon than a standard 100-micrometer thick wafer. Their findings were published recently (full article) in the journal Nano Letters.
Not only does the technique require less silicon than conventional wafers, but it works with metallurgical grade silicon, also referred to as "dirty" silicon, which could mean an additional price reduction. Because of their orientation, each nanowire behaves like a separate solar cell. Currently silicon photovoltaics with 20 percent efficiencies exist, but Yang's approach increases the ability of the solar cells to trap light by a factor of 73, according to the lab.
Another advantage is that Yang's technique is relatively simple and scalable so it could be incorporated into solar manufacturing processes right away. I applaud advancements that make solar power more feasible, but can't wait until we can buy some photovoltaic "paint" at the hardware store and draw power from all sorts of surfaces.
Photo: Yang's photovoltaic cell has arrays of silicon nanowires. Credit: Peidong Yang, Berkeley Lab.
Tags: Alternative Power Sources, Green Tech, Nanomaterials, Nanotech, Solar Power
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