"Black Silicon" Allows Solar Cell Efficiency to Spike

Researchers have developed a simple one-step system to help boost the efficiency of pre-existing solar cell technology at minimal cost.

According to Rice University, a team of graduate students have determined that to spike solar cell efficiency, you simply have to literally spike a silicon surface.

Traditional solar cell panels already let a significantly amount of light through, which is then promptly converted into electricity. However, to achieve this, past advances in technology have focused on "anti-reflection" layers, forcing the absorption of some light while still reflecting certain spectrums. These layers are often crafted in an expensive two-phase technique that requires metal deposition and electrosis chemical etching.

Rice lab chemist Andre Barron aimed to simplify this process using an inexpensive chemical bath.

A stew of copper nitrate, phosphorous acid, hydrogen fluoride and water was found to etch nanoscale spikes into silicon in a relatively efficient and speedy process. These spikes are large enough to eliminate the reflective properties of a surface by 99 percent, gathering all but one percent of directed light.

Although the silicon is not black, the team coined the new silicon layer "black silicon," as it reflects very little light back to the human eye and thus appears dark.

Improving upon this process, the team has managed to make black silicon layers with spikes and pores only 590 nanometers large.

What's most remarkable about this technique is that traditional silicon reflects nearly 100 percent of light that hits it.

Still, the researchers are quick to admit that an additional protective coating is needed if this silicon surface is to weather the elements, just like current solar paneling. Unfortunately, these protective layers don't absorb 100 percent of the light that hits them. Otherwise, solar panels wouldn't gleam in the midday sun.

Still, it's a step forward, adding to a bevy of solar cell enhancements seen in the last few months.

The study detailing this technique was published in the Journal of Materials Chemistry A on June 4.