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Welcome to the Solar Energy – Materials and Technology grout at the Institute of Physics, University of Freiburg

 

The research of the group is closely linked to research activities conducted in laboratories at Fraunhofer ISE (www.ise.fraunhofer.de). The aim of the research is to enhance the utilization of the solar energy. To be successful on system integration level it is essential to investigate the basic physical and structural properties of materials. The focus of our work is devoted to modelling, design, fabrication and improvement of photovoltaic materials to achieve better economics and conversion efficiency of solar or laser light into electricity. This includes classical semiconductors as Silicon or III-V-based compounds but also organic semiconductors or organic-inorganic perovskites. Structural, physical and electrical properties are investigated by optical and electrical methods (photoluminescence, electroluminescence, ellipsometry, spectral metric, light- and dark IV-measurement, XRD-analysis, Hall-measurement, ECV, REM, EDX…). The combination of material and solar cell characterization with advanced modelling allows us to understand absorption and electrical carrier dynamics inside the devices structure and focus our work on overcoming the most important losses.

A special focus is put on organic and Perovsikte materials. Dr. Uli Würfel is heading this research group, please see: https://www.fmf.uni-freiburg.de/de/projekte/materialien-fuer-energiespeicherung-und-konversion-1/organische-und-perowskit-solarzellen

 

On device level, tandem or multi-junction solar cells are the path to increase the power conversion efficiency up to 50%. The monolithic combination of materials with different lattice constants like Silicon and GaAs places challenges and required new manufacturing tools or growth and deposition methods. Developing multi-junction solar cells with highest efficiency has always been a focus of the III-V group at Fraunhofer ISE.

 

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Figure: Scanning electron microscope image of a GaInP/GaInAs/Si triple-junction solar cell overlayed with an EDX analysis of the elements inside the structure. The Silicon bottom cell has a thickness of 120 µm whereas the III-V top cells only have an overall thickness of < 2.5 µm.