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In this issue:
Effects of Thermal Annealing on Organic Solar Cells
Astrophysics Colloquium with NASA's John Mather March 17

SLAC Today

Tuesday - March 1, 2011

Effects of Thermal Annealing on Organic Solar Cells

Architecture of an organic photovoltaic device. The negative electrode is aluminum; indium tin oxide (ITO) is a common transparent electrode; and the substrate is glass. The structure of the active layer is critical to the performance of the solar device. (Image courtesy Eric Verploegen.)

Organic solar cells, which use organic polymers or small organic molecules to convert sunlight into a useable form of energy, are a promising new tool for providing inexpensive, environmentally friendly energy. To date organic solar cells have demonstrated comparatively low rates of efficiency, stability and strength. However, there is much room for improvement before the theoretical efficiency limits are reached.

In a recent X-ray scattering study undertaken at Beamline 11-3 of the Stanford Synchrotron Radiation Lightsource, a team of Stanford and SLAC researchers studied the effects of a heating process used during manufacturing on the molecular arrangement of the two components that often make up the active layer of an organic solar cell—the polymer that absorbs photons and converts them into an electric charge, and the "fullerene," a carbon-based material that accepts this charge and transports it out of the solar cell. The effects of the heating process on these materials in turn affects the finished solar cell's efficiency.

The study reveals that, in one of the most popular blends, the heating process can cause significant rearrangements of the active layer's structure, including the formation and rearrangement of crystals. By manipulating the layers' structures, the authors conclude, it may be possible to develop improve the performance of organic solar cell devices.

This work was published in the October 22, 2010 edition of Advanced Functional Materials.

To learn more about this research see the full scientific highlight.

(Photo - John Mather)
Nobel Laureate John Mather.

Astrophysics Colloquium with NASA's John Mather March 17

On Thursday, March 17, Nobel Laureate John Mather, NASA scientist and principal investigator for the James Webb Space Telescope, will present an Astrophysics Colloquium, "The James Webb Space Telescope—Science Opportunities and Mission Progress."

(Image - James Webb Space Telescope)
Artist's conception of the James Webb Space Telescope. (Image: NASA.)

The James Webb Space Telescope—the planned successor for the Hubble Space Telescope—is well on its way to being ready for launch. In this KIPAC Astrophysics Colloquium, Mather will describe the likely scientific programs of the telescope, ranging from the first objects to form after the Big Bang, through the assembly of galaxies and the formation of stars, to the potential detection of planetary systems capable of supporting life. Mather will also discuss the remaining work for the project, including testing the telescope and instrument package end-to-end at the gigantic vacuum chamber at Johnson Space Center, and developing and testing the deployable sunshield.

This Astrophysics Colloquium will be held in Kavli Auditorium at 4:15 p.m. All are invited to attend.




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