Uwe Rau

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Uwe Rau is a German physicist who has made important advances in understanding how solar cells work, especially thin-film solar cells. He helped explain energy losses in these devices and developed the use of electroluminescence measurements to characterize solar cells, turning this technique into a standard tool in research and industry.

Rau studied physics at the University of Tübingen and in Lyon, France. He earned his diploma in 1987 and his PhD in 1991 in the group of Huebener at Tübingen, researching how germanium behaves under high magnetic fields and how charges move in semiconductors. He then worked at the Max Planck Institute for Solid State Research in Stuttgart on crystalline silicon solar cells. In 1995 he moved to Bayreuth to focus on Cu(In,Ga)Se2 solar cells. In 1997 he returned to Stuttgart to work at the Institute of Physical Electronics, led by Jürgen Werner, where he continued his Si and CIGS research and began exploring dye-sensitized and organic solar cells and the basic luminescence of solar cells. He earned his habilitation in 2002 from the University of Oldenburg for his work on electrical transport properties of semiconductors and interfaces for photovoltaics.

Since 2007 Rau has been a full professor at RWTH Aachen and the Director of the Institute for Energy and Climate Research at Forschungszentrum Jülich. From 2011 he has also directed the HITEC graduate school at Jülich. He is the director of JARA-Energy, which coordinates renewable energy research between Forschungszentrum Jülich and RWTH Aachen.

Rau is best known for his 2007 paper on the reciprocity between a solar cell’s ability to generate electricity and its light-emitting response when driven by electricity. This work uses the principle of detailed balance to link the photovoltaic and light-emitting modes of a semiconductor diode and has greatly influenced how researchers study solar cells with luminescence methods. He also contributed to key ideas about thin-film solar cells, including the effects of disorder and potential fluctuations, how cells age and repair themselves, passivation of grain boundaries, and how light trapping can limit efficiency.