Physicist, engineer and educator. Pioneer in solar cells, solar energy systems, and solid state physics. Received diploma in physics in 1949 from Humboldt University, Berlin; member of faculty there until 1961. Director of the laboratory for dielectric breakdown at the German Academie der Wissenschaften, Berlin, from 1955 to 1961. Came to University of Delaware in 1962 as professor of physics; became professor of physics and engineering in 1972 until retirement in 1994, when he was named Distinguished Professor Emeritus of Physics and Solar Energy. Fellow of the American Physical Society (1965), the American Solar Energy Society (2000), and the Institute of Electrical Engineers (2001). In 1973 founded and directed the Institute of Energy Conversion.