10-10/11 :: October/November 2010

nanotimes News in Brief

For the second time in history a research organiza- tion is rewarded with the EARTO Innovation Price. The awarded research was done by a team of sci- entists at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg. Dr. Andreas Bett and his colleagues developed concentrator solar cells with almost double the efficiency levels of conventional silicon-based cells. This was possible by stacking three different solar cells monolithically on top of each other, thus using almost the entire solar spec- trum for energy production. The unique cells have established a new benchmark. A spin-out of ISE – Concentrix Solar GmbH – produces the concen- trator systems that, for example, feed solar power into the grid from a solar park in Spain with 25% system efficiency. For the development of metamor- phic triple-junction solar cells, the team has been closely collaborating for years with AZUR Space Solar Power in Heilbronn, the leading European manufacturer of solar cells for space. This partner is aiming to bring the highly efficient solar cells to the market by 2011. http://www.concentrix-solar.de

Researchers at the University of California, Los Angeles, USA, published in PNAS an article to a simple and scalable film fabrication technique that allows reproducible control of thickness, and morphological homogeneity at the nanoscale. They demonstrate that under the proper conditions of volume, doping, and polymer concentration, films consisting of monolayers of conducting poly- mer nanofibers such as polyaniline, polythiophene, and poly(3-hexylthiophene) can be produced in a matter of seconds. A thermodynamically driven solution-based process leads to the growth of trans-

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parent thin films of interfacially adsorbed nanofi- bers. High quality transparent thin films are deposi- ted at ambient conditions on virtually any substrate. This inexpensive process uses solutions that are recyclable and affords a new technique in the field of conducting polymers for coating large substrate areas. © PNAS

Julio M. D’Arcy, Henry D. Tran, Vincent C. Tung, Ale- xander K. Tucker-Schwartz, Rain P. Wong, Yang Yang, Richard B. Kanera: Versatile solution for growing thin films of conducting polymers, In: PNAS Early Edition, November 1, 2010, DOI: 10.1073/pnas.1008595107: http://dx.doi.org/10.1073/pnas.1008595107

The research group around R. Wiesendanger at Institute of Applied Physics, Hamburg University, Germany, show electrical excitation and read- out of a spin associated with a single magnetic dopant in a semiconductor host. They use spin-re- solved scanning tunnelling spectroscopy to measure the spin excitations and the magnetization curve of individual iron surface-dopants embedded within a two-dimensional electron gas confined to an indium antimonide (110) surface. The dopants act like iso- lated quantum spins the states of which are gover- ned by a substantial magnetic anisotropy that forces the spin to lie in the surface plane.

A. A. Khajetoorians, B. Chilian, J. Wiebe, S. Schuwalow, F. Lechermann, and R. Wiesendanger: Detecting excitati- on and magnetization of individual dopants in a semicon- ductor, In: Nature, Vol. 467(2010), Pages 1084-1087, DOI:10.1038/nature09519: http://dx.doi.org/10.1038/nature09519