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w 12 | Live from the Labs cnrs I international magazine The Hidden Subspecies of Ehux Organic Solar Cells by Eddy Delcher w Simple organic molecules could in the future become a cheaper and far greener alternative to silicon for producing solar panels,1,2 reveals a recent study by CNRS researchers.3 “Using a triarylaminebased family of molecules, we are able to synthesize simple organic compounds that provide good energy conversion levels,” explains Jean Roncali, who headed the study. “More importantly, we are working on making our product viable on an industrial scale, putting cost efficiency at the heart of our research.” Organic molecules that display efficient photovoltaic properties—like conjugated polymers and complex soluble chemical compounds—have been described in recent years. But these have important drawbacks: the former consist of large molecular chains of varying lengths that affect the reproducibility of their electronic properties, while producing the latter requires multi-step syntheses with low overall yield, making the process incompatible with industrial use. Roncali’s team uses simpler organic molecules like triphenylamine, a compound with good electrical conductivity, as well as the electron-withdrawing molecule dicyanovinyl. “We play Lego with these basic building blocks to create photovoltaic cells, while limiting the production of chemical waste,” explains Roncali. Compared with silicon panels, which have a heavy carbon footprint, organic solar cells are cheaper and greener to produce, although their power conversion efficiency is two to three times lower so far. “We must optimize our material’s performance while preserving our cost advantage. Organic solar cells have already found niche applications, like mobile phone chargers, but years of research are still needed before they can supplant silicon,” foresees Roncali. 01. A. Leliège et al., “Small D-π-A systems with o-phenylene-bridged accepting units as active material for organic photovoltaics,” Chemistry, 2013. 19: 9948-60. 02. D. Demeter et al., “Tuning of the Photovoltaic Parameters of Molecular Donors by Covalent Bridging,” Adv. Funct. Mater., 2013. doi: 10.1002/adfm.201300427. 03. Institut des sciences et technologies moléculaires d’Angers (Moltech-Anjou, CNRS / Université d’Angers). Physics Marine Biology By Clémentine Wallace w How can some ocean microorganisms be found practically all over the planet, thriving in drastically different environments? A study recently published in Nature1 provides an answer for at least one type of organism: the phytoplankton Emiliania huxleyi (Ehux), which populates both tropical and subarctic waters and forms an important part of the sea plankton in spring and in summer, when it blooms. “Ehux’s ability to adjust to such a broad range of environments is due to the incredible variability of its genome,” explains Jean-Michel Claverie, one of the scientists who participated in the study.2 To understand the surprising ubiquity of this tiny unicellular alga—five thousandths of a millimeter in size— the researchers sequenced and compared the genomes of 14 strains collected from waters throughout the world. Their analysis revealed that while all the strains possess about 30,000 genes, each contains a genome that varies widely from that of the others. “We therefore realized that Ehux is not one single organism with an incredible capacity to adapt, but a plethora of subspecies very similar in appearance, yet very different genetically,” says Claverie. Indeed, while sharing a core set of genes—technically known as a “pan-genome”—each strain contains 20 to 30% of genes specifically suited to its habitat. “Pan-genomes were known to exist among bacteria, but this is the first time we see this model in algae,” concludes Claverie. The scientists will further investigate whether this unexpected phenomenon can explain the ubiquity of other microalgae. 01. B.A. Read et al., “Pan genome of the phytoplankton Emiliania underpins its global distribution,” Nature, 2013. 499: 209–13. 02. Information génomique et structurale (CNRS / Aix-Marseille Université). Contact information: IGS, Marseille. Jean-Michel Claverie > Jean-Michel.Claverie@igs.cnrs-mrs.fr Contact information: Moltech-Anjou, Angers. Jean Roncali > jeanroncali@gmail.com q Electron scanning microscope image showing the various levels of calcification found in the different subspecies of Ehux. qOrganic solar cell in a glove box. © Kyoko Ha gino-Tomioka © c. frésill on/CNRS Photothèque Marseille Angers A full report on this research can be viewed on the online version of the magazine. > http://www.cnrs.fr/cnrsmagazine


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