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Geek-Up[1.28.2011]: Neutron Scattering and Full-Spectrum Solar Cells

January 28, 2011 - 5:11pm


Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL

Detector tanks for the new SANS instruments at the High Flux Isotope Reactor. The Bio-SANS detector is on the right. Source: ORNL

Oak Ridge National Lab and North Carolina State University scientists are helping to develop medicines that will block the spread of viruses. Using the Bio-SANS instrument at ORNL’s High Flux Isotope Reactor, these researchers are studying how viruses change their structure as they move between different host species. Through small angle neutron scattering they were able to compare the structural details of viruses from mammalian and insect cells.

The differences? Mammalian-grown viruses have larger diameters, higher levels of cholesterol and a different distribution of genetic material.

ORNL researcher Flora Meilleur explains, “These results suggest that structural changes are likely to be important in transmission between hosts. The chemical environment of the host cell appears to affect how the virus assembles itself.”

Find out how neutron scattering’s unique properties furthered this medical advance here >

Scientists at Lawrence Berkeley National Lab have made major steps towards full-spectrum solar cells manufactured at a consumer-friendly price.

A little background: solar cells are made from semiconductors which respond to light depending on their band gaps, and no single semiconductor has a band gap that can respond to sunlight’s full range from low-energy infrared to high-energy ultraviolet.

A illustration of how the band gaps impact semiconductors’ ability to respond to light. On the left, wide band gaps respond to shorter wavelengths with higher energies. On the right, multiple band gaps can respond to a range of energies. Source: LBNL

The solution: Wladek Walukiewicz, who leads LBNL’s Solar Energy Materials Research Group, and his team created a multiband semiconductor made from a highly mismatched alloy (HMA) – gallium arsenide nitride. Similar to one of the most familiar semiconductors, gallium arsenide, this HMA replaces some of its arsenic atoms with nitrogen. This method creates a third, intermediate energy band for the semiconductor which can now span the full solar spectrum.

There’s one piece of the puzzle left – how to make this commercially viable. Team Walukiewicz’s solution can be made through a common method for fabricating compound semiconductors – metalorganic chemical vapor deposition (MOCVD).

Check out how LBNL scientists made a full-spectrum solar cell here >