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November 3rd, 2009

Georgia Tech group creates 3D photovoltaic system

Published on November 3rd, 2009 | Edited by: Peter Wray

Dye-sensitized nanowires cover the outer surface of a optical fiber to optimize photon collection. (Credit: Angewandte Chemie International.)

What if there was a way to create a material covered with tiny 3D solar collectors instead of the typical 2D flat photovoltaic systems (and in this context flexible PV sheets still count as two-dimensional)? And, what if you could “feed” these collectors with sunlight via optical fibers? Then you might be able to tuck these systems (architecturally speaking) into out-of-the-way locations or sites less obvious than rooftops.

That was some of the thinking motivating a group of researchers at Georgia Tech whose work is reported on in a new paper in Angewandte Chemie International.

The GT group figured out a way to improve upon existing dye-sensitized solar cell technology by growing nanostructures (on the optical fibers) that effectively increase the surface area of a collector. Compared to other approaches, DSSCs, generally speaking, are at a disadvantage because they relatively inefficient. On the other hand, the manufacturing costs of dye-sensitized cells are low. They also tend to be able to take more mechanical abuse.

The group grows the nanostructures by replacing in one section the outer layer of quartz optical fiber with a conductive coating. They then seed the surface with zinc oxide followed by solution-based techniques that grow aligned zinc oxide nanowires that radiate outward around the fiber. Finally, the nanowire–optical fiber is given a dye-sensitized materials coating. Groups of these nanowire-coated fibers are immersed in an electrolyte to harvest electrons. Length improves efficiency and the group has been able to make nanowire sections as long as 20 cm.

Closeup of single nanowire-coated fiber. (Credit: Georgia Tech and Gary Meek.)

According the the GT group, this internal axial illumination in this hybrid system multiplies six-fold the energy conversion efficiency of the DSSC nanowire array. “In each reflection within the fiber, the light has the opportunity to interact with the nanostructures that are coated with the dye molecules,” explains Z.L. Wang, who led the group. “You have multiple light reflections within the fiber, and multiple reflections within the nanostructures. These interactions increase the likelihood that the light will interact with the dye molecules, and that increases the efficiency.”

The team says it has reached an efficiency of 3.3 percent and think efficiencies of 7 to 8 percent are in reach if they make further modifications, such as using a better method for collecting the charges and a titanium oxide surface coating.

These efficiencies are still a long way off of current 2D PV units. But Wang says there would be several advantages to the group’s hybrid DSSC system. The already low production cost could be driven lower by using polymer fibers. The optical fibers used to feed the nanowire fibers could be placed fairly freely, providing a larger area for gathering light, and lenses could also be employed to focus the incoming light.

Another advantage is that it gives building designers new options. “This will really provide some new options for photovoltaic systems,” Wang said. “We could eliminate the aesthetic issues of PV arrays on building. We can also envision PV systems for providing energy to parked vehicles, and for charging mobile military equipment where traditional arrays aren’t practical or you wouldn’t want to use them.”


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2 Responses to Georgia Tech group creates 3D photovoltaic system

  1. CitizenKane says:

    Hey Guys,

    Just saw this. You know there are already several issued patents on fiber photovoltaics as well as a company based on these patents. These have been in development since before 2003!!! I always find is surprising that folks can come along and copy what has been in literature for some time, and get news releases like it is new…

    Just thought you should know. Nothing new here except the audacity of copying.

  2. Dear Sir or Madam,
    it is right, in the Gerogia Institute of Techgnology 3D solar cell was developed and applied for a patent in May, 2008.

    However, this is nothing new, because I have differently developed than the researchers from Georgia not the only fiberglass, but equally whole 3D solar cells system and have introduced this already on my web page since June, 2009. The system is to be found at the following web address:

    http://sites.google.com/site/sunrydz/

    I am an autodidact and Prof. Wang has so expressed himself on my development in the 11/5/2009:

    “Dear Mr. Dzikowski
    thank you for the information. We did the work ourselves independently and did it experimentally rather than just cartoon drawing. Have you published your data in a professional journal? just releasing in a personal website is not good enough to warranty the originality. BTW, I didnot take any thing from your website, I never
    knew its existence.
    With regards
    ZL Wang”

    Best regards

    Ryszard Dzikowski

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