Helmholtz-Zentrum Berlin für Materialien und Energie

A natural limit exists at around 30 percent, partly because solar cells do not absorb light containing energy below a materialspecific threshold. In laboratory experiments scientists at the University of Sydney and the Helmholtz-Zentrum Berlin (HZB) have now developed a solar cell “turbo booster” known as photochemical upconversion. In the process two low-energy photons that are normally not absorbed in the cell are combined to form a high-energy photon that can generate charge carriers that contribute to current flow within the cell. The photochemical turbo booster utilises organic molecules to merge low-energy red photons to form high-energy yellow photons. “We were able to demonstrate that the efficiency of a solar cell can be increased using photochemical upconversion,” says project leader Dr. Klaus Lips from the HZB’s Institute for Silicon Photovoltaics. The improvement in efficiency is still small, but further research could potentially boost it far beyond the 30-percent mark.

HZB/Red.