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to harvest a greater fraction of the solar spectrum. They found that by employing the interconnecting gold-nanoparticle layer, they were able to enhance power conversion by as much as 20%. The gold nanoparticles create a strong electromagnetic field inside the thin organic photovoltaic layers by a plas- monic effect, which concentrates light so that much more of it can be absorbed by the subcells.

The team is the first to report a plasmonic-enhan- ced polymer tandem solar cell, having overcome the difficulties involved in incorporating metal na- nostructures into the overall device structure.

“We have successfully demonstrated a highly effici- ent plasmonic polymer tandem solar cell by simply incorporating gold nanoparticles layer between two subcells,” Yang said. “The plasmonic effect happe- ning in the middle of the interconnecting layer can enhance both the top and bottom subcells simul- taneously – a ‘sweet spot‘ – leading to an impro- vement in the power conversion efficiency of the tandem solar cell from 5.22% to 6.24%. The enhan- cement ratio is as high as 20%.”

Experimental and theoretical results demonstrate that the enhancement effect was attained from local near-field enhancement of the gold nanoparticles. The results show that the plasmonic effect has great potential for the future development of polymer solar cells. The team‘s proposed interlayer structures as an open platform can be applied to various poly- mer materials, opening up opportunities for highly efficient, multi-stacked tandem solar cells.

Jun Yang, Jingbi You, Chun-Chao Chen, Wan-Ching Hsu, Hai-ren Tan, Xing Wang Zhang, Ziruo Hong, and Yang

11-08 :: August 2011

Yang: Plasmonic Polymer Tandem Solar Cell, In: ACS Nano, Vol. 5, Issue 8, August 23, 2011, Pages 6210- 6217, DOI:10.1021/nn202144b: http://dx.doi.org/10.1021/nn202144b

An international team of scientists has developed a novel X-ray technique for imaging atomic displace- ments in materials with unprecedented accuracy. They have applied their technique to determine how a recently discovered class of exotic materials – multiferroics – can be simultaneously both magne- tically and electrically ordered.

H.C. Walker, F. Fabrizi, L. Paolasini, F. de Bergevin, J. Herrero-Martin, A.T. Boothroyd, D. Prabhakaran & D.F. McMorrow: Femtoscale Magnetically Induced Lattice Distortions in Multiferroic TbMnO3, In: Science, Vol. 333(2011), No. 6047, September 02, 2011, Pages 1273- 1276, DOI:10.1126/science.1208085: http://dx.doi.org/10.1126/science.1208085

http://www.esrf.eu/news/general/atomic-displace- ments/index_html/

For the first time, scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have demonstrated a microscale device made of graphene – the remarkable form of carbon that’s only one atom thick – whose strong response to light at terahertz frequencies can be tuned with