Technological developments
design. have created a new way to make “dye- creating a thin film that acts as the
Initial company plans include sensitized” solar cells, in which photons semiconductor for the dye-sensitized solar
production of a 7% efficient, 106 W bounce around like they were in a cell device. Steps that had been difficult
single-junction amorphous silicon module pinball machine, striking these dyes and to accomplish with conventional methods
at the company’s 35 MW solar module producing electricity. This technology have been made easy through the use of
factory, under construction in Charlotte, may be slightly more expensive than some these natural biological systems, using
NC. Future plans include development existing approaches to make dye-sensitized simple and inexpensive materials.
of a second-generation tandem junction solar cells, but can potentially triple the “Conventional thin-film, photo-
module with a targeted stabilized efficiency electrical output. synthesizing dyes also take photons
over 11%. This will increase manufacturing “Most existing solar cell technology is from sunlight and transfer it to titanium
capacity to 50 MW without the purchase based on silicon and is nearing the limits dioxide, creating electricity,” Rorrer said.
of additional equipment. of what we may be able to accomplish with “But in this system the photons bounce
Solar cell performance was that,” said Greg Rorrer, an OSU professor around more inside the pores of the
independently confirmed by The of chemical engineering. “There’s an diatom shell, making it more efficient.”
University of Delaware’s Institute of enormous opportunity to develop different The physics of this process, Rorrer
Energy Conversion, designated in 1992 types of solar energy technology, and it’s said, are not fully understood – but it
a University Center of Excellence for likely that several forms will ultimately all clearly works. More so than materials in a
Photovoltaic Research and Education by find uses, depending on the situation.” simple flat layer, the tiny holes in diatom
the Department of Energy. Dye-sensitized technology, for instance, shells appear to increase the interaction
uses environmentally benign materials between photons and the dye to promote
ancient diatoms lead to new and works well in lower light conditions. the conversion of light to electricity, and
technology for solar energy And the new findings offer advances in improve energy production in the process.
Engineers at Oregon State University have manufacturing simplicity and efficiency. The insertion of nanoscale tinanium
discovered a way to use an ancient life form “Dye-sensitized solar cells already oxide layers into the diatom shell has been
to create one of the newest technologies exist,” Rorrer said. “What’s different in reported in ACS Nano, a publication
for solar energy, in systems that may be our approach are the steps we take to of the American Chemical Society, and
surprisingly simple to build compared to make these devices, and the potential the Journal of Materials Research, a
existing silicon-based solar cells. improvements they offer.” publication of the Materials Research
The secret: diatoms. The new system is based on living Society. The integration of this material
These tiny, single-celled marine life diatoms, which are extremely small, single- into a dye-sensitized solar cell device was
forms have existed for at least 100 million celled algae, which already have shells also recently described at the fourth annual
years and are the basis for much of the with the nanostructure that is needed. Greener Nanoscience Conference.
life in the oceans, but they also have rigid They are allowed to settle on a transparent
shells that can be used to create order in conductive glass surface, and then the ecN achieves world-record
a natural way at the extraordinarily small living organic material is removed, leaving efficiency for innovative solar
level of nanotechnology. behind the tiny skeletons of the diatoms to module
By using biology instead of form a template. Researchers of the Energy research Centre
conventional semiconductor A biological agent is then used to of the Netherlands (ECN) have achieved
manufacturing approaches, researchers precipitate soluble titanium into very a premium conversion efficiency of
at OSU and Portland State University tiny “nanoparticles” of titanium dioxide, 16.4% (aperture area) on a full-size solar
module, a new world-record efficiency for
photovoltaic modules with multicrystalline
silicon solar cells. The previous world-
record was held by Sandia National
Laboratory (USA), at 15.5% aperture-area
efficiency.
Several modules with aperture-
area efficiencies beyond 16% were
manufactured with high-efficiency cells
made from wafers supplied by REC Wafer
Norway and Deutsche Solar.
The efficiency was achieved
using industrial-scale equipment for
interconnection and encapsulation of rear-
contact cells. This equipment is provided
by the Dutch equipment builder Eurotron.
The Dutch solar cell manufacturer
Solland Solar will be the first to use the
world-record technology in commercial
production, later this year. The research
and development has been financed by the
European Commission within the project
Diatoms are abundant oceanic plankton (Source: NOAA)
CrystalClear and by the Dutch government
22 – Global Solar Technology – May/June 2009
www.globalsolartechnology.com
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