Stefan Glunz was born in Dortmund, Germany in 1966. He received his diploma in physics in 1992 and his PhD in 1995 from University Freiburg. After his PhD he started working as a scientist in the research group for high-efficiency silicon solar cells at the Fraunhofer Institute for Solar Energy Systems (ISE), Freiburg. Currently he heads the division “Photovoltaics – Research” at Fraunhofer ISE. His division at Fraunhofer ISE consists of 180 members including 25 PhD students and is focused on high-efficiency silicon solar cells, characterization and emerging photovoltaics. He has extensive experience in managing of both industry and public financed projects including several large European projects. His research interests include the design, fabrication, and analysis of high-efficiency silicon solar cells. His work include the detailed characterization of the Si-SiO2 interface and other dielectric passivation layers as Al2O3, the analysis of the metastable defect in Czochralski silicon and of fundamental semiconductor parameters as Auger recombination in silicon, and the development of new technologies for the cost-efficient fabrication of high-efficiency silicon solar cells as laser-fired contacts and passivated contacts (TOPCon). His group at Fraunhofer ISE has set several international records including the highest efficiency for multicrystalline silicon solar cells (22.3%). Beyond pure silicon photovoltaics he is especially interested in silicon-based tandem cells. Recently a team of silicon and III-V specialists in his division at Fraunhofer ISE have managed to achieve an efficiency of 33.3% for a monolithical III-V/silicon tandem cell.
Since 2015 Stefan Glunz is full professor at the Albert Ludwig University of Freiburg, Germany. He is one of the founding professors of the new Institute for Sustainable Systems Engineering (INATECH) at the Technical Faculty. The research of INATECH is dedicated to Energy Systems, Sustainable Materials and Resilience. A new master programme was started in 2015 focussing on these topics in which he is responsible for courses as “Solar Energy” and “Photovoltaic Laboratory”. His research at the university focusses on emerging PV technologies as perovskite solar cells and tandem cells.
Prof. Glunz is the author/coauthor of more than 100 journal and 250 conference papers and founding editor of the IEEE Journal of Photovoltaics. In 2008 he received the Eni Award for the promotion of science and technology in the field of renewable energies. In 2014 he received the European Becquerel Prize for outstanding merits in photovoltaics. He is a scientific committee member for several conferences and workshops in the field of photovoltaics and has initiated an international conference on crystalline silicon photovoltaics (SiliconPV).
Title and Abstract of the Speech:
Carrier-selective contacts for high-efficiency silicon solar cells
Head of Division Solar Cells – Development and Characterization
Fraunhofer Institute for Solar Energy Systems
79110 Freiburg, Germany
Traditional crystalline solar cells feature doped junctions like diffused phosphorus emitters or alloyed aluminum back surface fields. Such technologies are well-understood and robust in mass production. However, since the increased doping level within the silicon absorber increases the level of intrinsic charge carrier recombination, i.e. Auger recombination, this technology limits inherently the efficiency potential. Therefore, to allow cell efficiencies closer to the theoretical limit, it is beneficial to spatially separate the carrier separation from carrier generation. This concept is known as carrier-selective or passivated contacts. The best known example is the a-Si/c-Si heterojunction as used by Sanyo/Panasonic or Kaneka successfully for their record cells. Also the highly efficient interdigitated back contact solar cells fabricated by SunPower are utilizing passivated concepts. At Fraunhofer ISE the TOPCon technology based on a thin tunnel oxide and a heavily doped recrystallized PECVD-deposited silicon layer has led to efficiencies of 25.8% and 22.3% on mono- and multicrystalline silicon, respectively. Recently, “silicon-free” approaches based on metal oxide layers like MoOx have shown a very high potential. This talk will give an overview over the different available technologies.