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nanotimes News in Brief
10-07/08 :: July/August 2010
Solar Cells // Empa Grows “Sea-Urchin” Shaped Structures
Laboratory have succeeded in growing sea-urchin shaped nanostructures from minute balls of polysty- rene beads using a simple electrochemical process. The spines of the “sea urchin” consist of zinc oxide nanowires.
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The structured surface should help increasing the efficiency of photovoltaic devices.
They used polystyrene spheres as a sort of scaffol- ding to create three-dimensional nanostructures of semiconducting zinc oxide on various substrates. The two scientists are convinced that the (nanostructured) “rough” but regularly-structured surfaces they have produced this way can be exploited in a range of electronic and optoelectronic devices such as solar cells and also short wave lasers, light emitting diodes and field emission displays.
The principle behind the process is quite simple. Little spheres of polystyrene a few micrometers in diameter are placed on an electrically conducting surface where they orient themselves in regular pat- terns.
The tiny balls of polystyrene anchored in this way form the template on which the nanowires are des-
Images: “Sea-urchins” made of tiny polystyrene balls, with zinc oxide nanowire “spines” are created using a simple electrochemical process. © EMPA, Switzerland
amil Elias and Laetitia Philippe of Empa’s Mechanics of Materials and Nanostructures
posited. Jamil Elias has succeeded in using an elec- trochemical method which himself has developed to vary the conductivity and electrolytic properties of the polystyrene balls in such way that the zinc oxide is deposited on the surface of the microspheres. Over time regular nanowires grow from this surface, and when this process is complete the polystyrene is removed, leaving behind hollow spherical structures with spines – little sea-urchins, as it were! Tightly packed on the underlying substrate, the sea-urchins
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