The Secret to a Better Solar Cell? A Trillion Holes
Black Silicon allows for Cheaper & More Efficient Solar Cell
At its most basic, solar cell technology relies on the ability of the solar cell to capture the sun’s light and convert it to electricity. The operative word here is ‘capture’. The better the solar cell is at capturing rather than reflecting light, the more efficient the solar cell is likely to be. This makes a new, inexpensive silicon etching technology developed by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) of particular interest to solar cell manufacturers.
NREL’s chloroauric acid etching process can create a trillion holes in a compact disc-sized silicon wafer. These holes cause the silicon to appear black - a product known as black silicon - which makes it highly light-absorbent. This light-absorbency is critical in efficiently using the sun’s wavelengths to convert solar photons into the electrons needed for solar energy. If this new silicon material could be integrated into a solar cell, the cell could potentially be more efficient and cost-effective than traditional solar cells.
After experimenting with the sizes of the holes in the silicon wafer, NREL researchers came up with a workable silicon solar cell that is just slightly less efficient than the current record of 16.8 percent efficiency. However, the inexpensive solar cell manufacturing process would offset the minor reduction in efficiency.
NREL plans to continue research because even small gains in solar cell efficiency translate into significant market advantage.