While the reflective and shiny solar panels that researchers have been making thus far look pretty, they’re no match for the National Renewable Energy Laboratory’s (NREL) recently discovered black silicon solar cell. The scientists at NREL discovered that etching thousands of tiny holes into a silicon wafer causes it to be almost black and thus able to absorb almost all of the sun’s rays, and more absorbent solar cells mean more efficient panels.
We recently reported on researchers that are using off the shelf dyes to help solar cells absorb a wider range of light but this experiment goes even further. No color can stand up to black when it comes to absorbing . Black doesn’t bounce anything back – it hoards all photons for itself. The researchers got the idea from a team in Munich that had carefully placed a thin layer of gold and some fancy chemicals on their silicon to turn it black.
By mixing gold and chemicals into a cocktail and spraying it on silicon, they were able to create a black silicon wafer in under 3 minutes at room temperature. At 100 degrees Fahrenheit they can do it in less than a minute — this bodes well for mass manufacturing. They call their black silicon wet-etched, because the chemical and gold mixture is wet when applied and etches holes into the substance. Their next effort — and its a big one — is engineering a workable solar panel around their etched silicon.