Solar cell efficiency can be significantly increased by making the cells a bit duller, according to two recent research efforts.

In one effort, a group of Harvard University researchers discovered something dubbed black silicon, which gets its name from its appearance.

Black silicon is produced by exposing silicon wafers to very short duration femtosecond laser pulses in the presence of sulfur hexafluoride gas. This process turns the silicon dark to the human eye, hence the name.

But more important than its appearance, the process essentially roughs up the surface of the material creating tiny cone structures infused with sulfur. This rough surface can capture much more of the sun’s light than a traditional photovoltaic solar cell.

Specifically, while traditional solar cells only convert visible light into electricity, a cell of black silicon could be made to absorb a wider swath of the sun’s emissions including visible and infrared. The group claims it has seen a 100 to 500 times increase in sensitivity to light with the material compared to conventional silicon.

(Harvard has licensed the technology to produce black silicon exclusively to SiOnyx, a Massachusetts technology startup.)

In another effort late last year, researchers in the University of South Wales, ARC Photovoltaic Centre of Excellence, reported the first silicon solar cell to achieve the milestone of 25 per cent efficiency – a world record. According to a NewScientist article, the record “was in part due to their [the solar cell’s] dullness. An anti-reflective surface cuts reflection to 3% across most of both the visible and infrared spectrums, helping them to convert 25% of light energy into electricity.”

Naturally, these and other promising technologies will need to be commercialized for improved efficiency benefits to be fully realized.