TOKYO—Researchers at the RIKEN Center for Emergent Matter Science and Kyoto University’s Department of Polymer Chemistry have developed a new polymer that can minimize energy loss when used in solar cells. This would enable the cheaper polymer cells to become as efficient as silicon-based solar cells when converting photon energy from sunlight to electricity. In solar cells, photons from the sun strike electrons and move them into a position where they can create an electric current. Photon energy loss—the amount of energy lost when converting photon energy from sunlight into electric power—has typically been much greater in polymer-based solar cells than in silicon-based ones. “Since this new polymer greatly reduces photon energy loss, it has allowed us to achieve a superb power conversion efficiency of nearly 9% with a very high open-circuit voltage in plastic solar cells,” said study coauthor Itaru Osaka. An efficiency of 15% is considered the breakthrough level that will allow polymer-based cells to be commercialized. The study is published in the journal Nature Communications.