Silver nanoparticles boost polymer solar cells' commercial potential

10-May-13

The fate of polymer solar cells in the marketplace has been tied to three main factors: Lifespan in outdoor environments, the cost of materials that make up the modules (namely indium tin oxide, or ITO), and power-conversion efficiency. These three issues remain the keys to unlocking the commercial potential of polymer solar cells to being someday rolled out like plastic tarps to power our homes cheaply and reliably. Nanotechnology has been trying to address all three of these issues, but perhaps none of them more than improving the power-conversion efficiency, which has lingered at around 5-7%. Now researchers at the Ulsan National Institute of Science and Technology (UNIST) in Korea have used metal nanoparticles to achieve the highest yet reported power conversion efficiency for plasmonic polymer solar cells, reaching 8.92%. While polymer solar cells have been reported as high as 10.6% for polymer solar cells with more than one p-n junction, the UNIST researchers believe that their device, which reached nearly 9% using a single junction, could exceed 10% in commercial products. The research, which was published in the ACS journal Nanoletters focused on polymer solar cells enhanced by plasmonics. Plasmonics exploits the phenomenon of "photons striking small, metallic structures to create plasmons, which are oscillations of electron density in the metal," as per Neil Savage. The Korean researchers were able achieve high light absorption despite thinning out the films that make up the active layer of the solar cell by using silver nanoparticles. These nanoparticles provided the metal in the material that allowed for the exploitation of the surface plasmon resonance effect.