Thin Films Yield High-Efficiency Solar Cell

A polycrystalline photovoltaic cell described in the October 1999 issue of Progress in Photovoltaics: Research and Applications exhibits an efficiency of 12.8 percent. Its developers, a team of researchers from the Thin Film Physics Group at the Swiss Federal Institute of Technology in Zurich, expect to fabricate cells with 15 percent efficiency, competitive with the industry average.

The thin-film, Cu(In,Ga)Se₂-based solar cell is flexible and lightweight, with the potential to produce 1.5 kW/kg. Its thickness, including the polymer substrate, is less than 25 µm. Physical vapor deposition of the 2-µm-thick absorber layer was performed at a substrate temperature of approximately 450 °C.

The Fraunhofer Institute of Solar Energy Systems, an authorized certification center in Freiburg, Germany, performed the efficiency measurements under air mass 1.5 global illumination.