November 05, 2009 | 0 Comments
Researchers at Georgia Tech have developed nanostructures on optical fibers in a dye-sensitized solar cell with eventual 7%-8% efficiency, enough for "practical energy harvesting" applications hidden away from rooftops.
by John Toon, manager of research news and publications office, Georgia Institute of Technology
November 5, 2009 - Using zinc oxide nanostructures grown on optical fibers and coated with dye-sensitized solar cell materials, researchers at the Georgia Institute of Technology have developed a new type of three-dimensional photovoltaic system. The approach could allow PV systems to be hidden from view and located away from traditional locations such as rooftops.
"Using this technology, we can make photovoltaic generators that are foldable, concealed and mobile," said Zhong Lin Wang, a Regents professor in the Georgia Tech School of Materials Science and Engineering. "Optical fiber could conduct sunlight into a building's walls where the nanostructures would convert it to electricity. This is truly a three dimensional solar cell."
Details of the research were published Oct. 22 in the early view of the journal Angewandte Chemie International. The work was sponsored by the Defense Advanced Research Projects Agency (DARPA), the KAUST Global Research Partnership and the National Science Foundation (NSF).
|Design and principle of a three-dimensional DSSC. The cross-section of the fiber can be cylindrical or rectangular. a) The 3D DSSC is composed of optical fibers and ZnO NWs are grown vertically on the fiber surface. The top segment of the bundled optical fibers utilizes conventional optical fibers and allows for remote transmission of light. The bottom segment consists of the 3D DSSC for solar power generation at a remote/concealed location. b) Detailed structure of the 3D DSSC.|
Dye-sensitized solar cells, which use a photochemical system to generate electricity, are inexpensive to manufacture, flexible, and mechanically robust -- but their tradeoff for lower cost is conversion efficiency lower than that of silicon-based cells. However, using nanostructure arrays to increase the surface area available to convert light could help reduce the efficiency disadvantage, while giving architects and designers new options for incorporating PV into buildings, vehicles, and even military equipment.
Fabrication of the new Georgia Tech PV system begins with optical fiber of the type used by the telecommunications industry to transport data. First, the researchers remove the cladding layer, then apply a conductive coating to the surface of the fiber before seeding the surface with zinc oxide (ZnO). Next, they use established solution-based techniques to grow aligned zinc oxide nanowires around the fiber much like the bristles of a bottle brush. The nanowires are then coated with the dye-sensitized materials that convert light to electricity.
|SEM images of ZnO nanowires grown on the surfaces of a rectangular fiber, showing uniform coating around its surfaces. The nanowires are well aligned with diameters of 50-100nm and heights 4μm, both of which can be controlled experimentally. (Source: Angewandte Chemie International)|
|(A) Optical image of a rectangular fiber with ZnO NWs grown on the surface. (B) Optical image of a fiber after dye loading on NW surfaces. (C) SEM image of the fiber with NWs grown on surface before dye loading. (Source: Angewandte Chemie International)|
|Close-up shows the brown light-absorbing material for the three-dimensional solar cell grown on optical fiber by researchers at the Georgia Institute of Technology. (Credit: Georgia Institute of Technology)|
This article was originally published by RenewableEnergyWorld.com and was reprinted with permission.