Hello,

We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Martin LaMonica

A View from Martin LaMonica

Black Silicon Solar Cells to Capture More Light

Researchers at Fraunhofer modify lasers to improve the efficiency of converting infrared light to electricity with solar cells.

  • October 11, 2012

In the quest to generate more power from solar cells, many scientists have their eye on infrared light.

Blasting a specially tuned laser in the presence of sulfur gas alters the texture of solar cells to absorb infrared light. Credit: Fraunhofer

About one quarter of the energy in sunlight is essentially lost on solar cells because they can’t convert light in the infrared spectrum into electricity. That has led to an active field of research in so-called black silicon, in which the surface of silicon solar cells is modified to absorb rather than reflect infrared light.

German research institute Fraunhofer says it has developed a way to double the efficiency of black silicon. If incorporated into existing photovoltaic manufacturing, the technique could improve silicon cell efficiency, which averages around 17 percent, by 1 percent. Depending on the cost the technology would add, that could help lower the cost of solar power.

Black silicon is made by striking solar cells with lasers in the presence of sulfur gas to change the cells’ texture. “This structures the surface and integrates sulfur atoms into the silicon lattice, making the treated material appear black,” Stefan Kontermann, who heads the Nanomaterials for Energy Conversion research group at the Fraunhofer Institute, explains in a statement.

Fraunhofer researchers improved the efficiency of black silicon by controlling the laser pulse that drives the sulfur atoms into the silicon cell. Changing the position of the sulfur reduces the amount of infrared energy needed to excite electrons so that they are converted into electricity. It effectively creates an intermediate energy level where more infrared light is able to produce electricity. “We used the laser pulses to alter the embedded sulfur in order to maximize the number of electrons that can climb up while minimizing the number that can go back down,” Kontermann says.

Researchers have made a prototype device and hope to develop an algorithm to best determine how laser pulses should be modified to change the energy level of the sulfur. Fraunhofer said it intends to create a spinoff company to commercialize the research so that manufacturers can make tandem solar cells with normal and black silicon. 

The National Renewable Energy Laboratory in Colorado has developed a chemical treatment to improve black silicon performance, which has been licensed by Natcore Technology (see “Black Silicon Makes Solar Cells Cheaper”).

Want to go ad free? No ad blockers needed.

Become an Insider
Already an Insider? Log in.

Uh oh–you've read all of your free articles for this month.

Insider Premium
$179.95/yr US PRICE

More from Sustainable Energy

Can we sustainably provide food, water, and energy to a growing population during a climate crisis?

Want more award-winning journalism? Subscribe and become an Insider.
  • Insider Premium {! insider.prices.premium !}*

    {! insider.display.menuOptionsLabel !}

    Our award winning magazine, unlimited access to our story archive, special discounts to MIT Technology Review Events, and exclusive content.

    See details+

    What's Included

    Bimonthly magazine delivery and unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Access to the magazine PDF archive—thousands of articles going back to 1899 at your fingertips

    Special discounts to select partner offerings

    Discount to MIT Technology Review events

    Ad-free web experience

    First Look: exclusive early access to important stories, before they’re available to anyone else

    Insider Conversations: listen in on in-depth calls between our editors and today’s thought leaders

  • Insider Plus {! insider.prices.plus !}* Best Value

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus ad-free web experience, select discounts to partner offerings and MIT Technology Review events

    See details+

    What's Included

    Bimonthly magazine delivery and unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Access to the magazine PDF archive—thousands of articles going back to 1899 at your fingertips

    Special discounts to select partner offerings

    Discount to MIT Technology Review events

    Ad-free web experience

  • Insider Basic {! insider.prices.basic !}*

    {! insider.display.menuOptionsLabel !}

    Six issues of our award winning magazine and daily delivery of The Download, our newsletter of what’s important in technology and innovation.

    See details+

    What's Included

    Bimonthly magazine delivery and unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

/
You've read all of your free articles this month. This is your last free article this month. You've read of free articles this month. or  for unlimited online access.