Printable organic photovoltaic solar cells with 9.2% efficiency

From a Phillips66 press release:
HOUSTON, August 21, 2012 – Phillips 66 (NYSE:PSX) South China University of Technology (SCUT), and Solarmer Energy, Inc. have successfully set a new world record in power conversion efficiency for polymer-based organic photovoltaic (OPV) cells. The 9.31 percent efficiency was certified by the Newport Technology & Application Center’s Photovoltaic Lab in Long Beach, Calif.

“The breakthrough in efficiency offers a good opportunity for the commercialization of the organic photovoltaic technology,” said Dr. Byron Johnson, manager of Sustainability Technologies at Phillips 66. “This marks an important milestone for the industry and has the potential to deliver truly low cost energy for the world.”

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As a bonus, the researchers also demonstrated that the design works for making semi-transparent inverted PSCs, which might be used in windows, curtains, and invisible electronic circuits. Further, the researchers have calculated that their new design could reach the 10% target by making some reasonable improvements. By collaborating with Phillips 66 and Solarmer, they hope to bring the first OPV products to the market some time next year.

From PhysOrg Although silicon solar cells have efficiencies climbing above 20%, the researchers emphasize that OPV's low-cost production will make them competitive with the more expensive silicon cells. However, the plastic-based OPVs have had to overcome another problem in order to attract commercial interest: low stability that leads to short lifetimes. This problem stems in part from the cathode, which is often made of a reactive metal that easily oxidizes in air. Although encapsulating the cathode can minimize degradation, researchers have discovered that they can completely eliminate the need for this reactive metal by inverting the device architecture. In an inverted cell, the electric charges exit the device in the opposite direction as in a normal device. This happens because the positive and negative electrodes (which absorb the negative and positive charges, respectively) are reversed. Inverting the device architecture allows researchers to make the cathode out of a more suitable material; in this case, the researchers used indium tin oxide (ITO) modified with the polymer PFN.