New tech can make solar cells less 'shiny', more efficient

Scientists, including one of Indian-origin, have come out with a new technology that can boost the efficiency and lower the cost of solar cells.

A solar cell is basically a semiconductor, which converts sunlight into electricity, sandwiched between metal contacts that carry the electrical current. But this widely used design has a flaw: The shiny metal on top of the cell actually reflects sunlight away from the semiconductor where electricity is produced, reducing the cell's efficiency.

Now, Stanford University scientists have discovered how to hide the reflective upper contact and funnel light directly to the semiconductor below. Their findings could lead to a new paradigm in the design and fabrication of solar cells.

Using nanotechnology, researchers have developed a novel way to make the upper metal contact nearly invisible to incoming light, said lead author Vijay Narasimhan, adding that the new technique could significantly improve the efficiency and thereby lower the cost of solar cells.

The solution: Create nanosized pillars of silicon that "tower" above the gold film and redirect the sunlight before it hits the metallic surface. Creating silicon nanopillars turned out to be a one-step chemical process.

Besides gold, the nanopillar architecture will also work with contacts made of silver, platinum, nickel and other metals, said graduate student and co-author Ruby Lai.

The study is published in the journal ACS Nano.