DuPont's colorless polyimide film, a revolutionary new material currently in development for use as a flexible superstrate for cadmium telluride (CdTe) thin film photovoltaic modules, has reached a new world record for solar cell conversion efficiency.
Empa, a leading research institute for material sciences and technology development, based in Dübendorf, Switzerland, has demonstrated a conversion efficiency of 13.8 percent using the new Kapton colorless film, leapfrogging their previous world record of 12.6 percent and nearing that of glass.
Because the film is over 100 times thinner and 200 times lighter than the weight of glass typically used for PV, there are inherent advantages in transitioning to flexible, film-based vs. rigid glass CdTe systems. High speed and low cost roll-to-roll deposition technologies can be applied for high throughput manufacturing of flexible solar cells on polymer film as substrates.
It potentially enables significantly thinner and lighter-weight flexible modules that are easier to handle and less expensive to install, making them ideal for applications including Building Integrated Photovoltaics.
"Rather than transporting heavy, fragile glass modules on large trucks and lifting them by crane onto rooftop PV installations, one could imagine lightweight, flexible film-based modules that could simply be rolled up for transport, and easily carried up stairs," said Robert G. Schmidt, new business development manager, Photovoltaics - DuPont Circuit & Packaging Materials. "With record-setting efficiency already established through Empa, we're confident this flexible, lightweight and durable material has the potential to revolutionize the industry by enabling flexible design and lowering balance of system costs."
Empa's Laboratory for Thin Films and Photovoltaics is involved in the research and development of high-efficiency thin film solar cells with emphasis on novel concepts for enhancing the performance of solar cells, simplifying the fabrication processes, and advancing device structures for next generation of more efficient and low-cost devices.
They have been doing groundbreaking work in developing and optimizing a low deposition temperature (< 450 degrees Celsius) process for high-efficiency CdTe solar cells on glass (15.6% efficiency) and polymer film (12.6% efficiency). Although they established the previous world record in the area of flexible CdTe, they have continued to explore materials that would enable further advances.
"Finding a film that could both be transparent and withstand high-processing temperatures was a challenge initially, but the new film had both the tolerance for high temperatures needed, and higher light transmittance due to its transparency that allowed it to exceed our previous world record in conversion efficiency of flexible CdTe solar cell," said Prof. Dr. Ayodhya N. Tiwari, head of the laboratory - Empa. "As we continue to raise the standards for PV efficiency, materials make a distinct difference in the progress we make toward achieving grid parity. Of course, further development is needed for addressing cost and stability issues."
Three new Kapton® PV9100 series films were introduced for the thin film PV market in 2010, including offerings for Amorphous Silicon (a-Si) modules and Copper Indium Gallium Selenide (CIGS) photovoltaic applications.
DuPont is currently accepting requests for evaluation samples of its new polyimide film for flexible CdTe superstrate constructions and intends commercialization in 2012.
DuPont www.dupont.com is a science-based products and services company. Operating in more than 90 countries, DuPont offers a wide range of innovative products and services for markets including agriculture and food; building and construction; communications; and transportation.
Image: New DuPont™ Kapton® colorless polyimide film currently in development enables lightweight, flexible CdTe solar modules that recently delivered a new world-record for conversion efficiency.Photo courtesy of Empa.
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