Researchers design nano-crystals for high efficiency solar cells

February 17 2009 / by Garry Golden
Category: Energy   Year: Beyond   Rating: 4 Hot

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Researchers at US Los Alamos National Laboratory (LLNL) have confirmed a unique energy phenomena known as 'carrier multiplication' via nanoscale sized semiconductor crystals that could improve the efficiency of solar cells by squeezing more energy out of inbound photons.

Traditional solar cells absorb a photon of light that releases an electron to generate an electrical current. Any excess energy from the photon reaction is wasted as heat or vibration.  The notion of 'carrier multiplciation' rests on the idea that we can get multiple electrons released from a single photon by forcing electrons into a more confined space.

Carrier multiplication was observed several years ago, but has been criticized as a phantom phenomena via a process known as 'photoionization'.  But now a research team led by Victor Klimov has confirmed that semiconductor crystals designed at the nanoscale (billionth of a meter) can channel this excess photon energy into a group of tightly packed electrons, leading to a more efficient solar cell.

The team did not release statements about commercialization or scalable efficiencies.  “Researchers still have a lot of work to do,” Klimov cautioned. “One important challenge is to figure out how to design a material in which the energetic cost to create an extra electron can approach the limit defined by a semiconductor band gap. Such a material could raise the fundamental power conversion limit of a solar cell from 31 percent to above 40 percent.”

via Azano.com

LLNL Press Release

 

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