Today’s solar cells are designed to be non-reflective because solar efficiency depends on the photons being absorbed and not bouncing back into the atmosphere.

To create these non-reflective surfaces, crystalline solar cells, or wafers, are treated in some fashion to create a textured surface, which allows the photons to bounce around and strike multiple surfaces before “losing” their energy. Uncoated wafers, by contrast, absorb only 67.4 percent of the light striking them.

These treatments, or coatings are a good solution to energy efficiency, and can increase absorption rates up to 96.21 percent, but because they are sometimes almost prohibitively expensive in terms of raw materials, the financial advantages of adding coatings (in terms of efficiency) can sometimes be outweighed by their cost.

Now, the National Renewable Energy Laboratory, or NREL, says it has devised a simple chemical “bath”, or treatment, that could potentially replace these pricey, antireflective coatings. The process consists of dipping wafers into a water-based fluid containing hydrogen peroxide, hydrofluoric acid and chlorauric acid – the latter comprised of hydrogen, chlorine and a minute amount of gold, which acts as a catalyst and can be used again and again.

The single dip process can be done at room temperature and normal pressure using equipment common to solar panel manufacturing facilities. After three minutes at room temperature, the silicon wafer is transformed into a cell with a black, highly absorbent surface which contains miniscule tunnels of varying depths. Because there are no sharp edges inside the tunnels to reflect light, and because their depth varies so widely, each tunnel absorbs a different wavelength of light, leading to broad-spectrum solar cell efficiencies.

According to NREL’s chief materials scientist Howard Branz, the monocrystalline silicon cells treated reflect almost no light, and convert 16.8 percent of the light that reaches them into electricity, which is a remarkably high efficiency rating considering that the previous record for black silicon cells was 13.9 percent.

The bath, using no specialized equipment, could be used to replace the vacuum deposition process currently employed to “roughen” the surfaces of silicon wafers and create tunneling effects before their inclusion in solar panels, according to Branz, who added that baths currently used in today’s solar cell manufacturing process to clean wafers between etching steps could also be used to create the coating, reducing costs even further.

NREL has applied for patents on the process, which will likely inspire a startup to prove that solar photovoltaic electricity can achieve cost parity with conventional fossil fuels in the near future.