Karl Leo

Karl Leo (born 10 July 1960 in Freiburg im Breisgau, Baden-Württemberg, Germany) is a German physicist. He holds the chair of optoelectronics at the Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) of TU Dresden and is a leading researcher on organic semiconductors. He is known for the controlled electrical doping of organic thin films and the resulting highly efficient organic light-emitting diodes (OLEDs) and organic solar cells, and for the first experimental generation and detection of Bloch oscillations in a semiconductor superlattice. Leo has co-founded several technology spin-off companies based upon his research, among them Novaled[1] and Heliatek.[2][3] His honours include the Gottfried Wilhelm Leibniz Prize (2002),[4] the Deutscher Zukunftspreis (2011),[5] the Blaise Pascal Medal in Physics (2021)[6] and the Order of Merit of the Free State of Saxony (2025).[7]

Education and Career

After his Abitur in 1979 in St. Georgen im Schwarzwald and military service in 1980, Leo studied physics at the Albert-Ludwigs-Universität Freiburg, graduating in 1985 with a diploma thesis on solar cells carried out at the Fraunhofer Institute for Solar Energy Systems under Adolf Goetzberger. In 1986 he moved to the Max Planck Institute for Solid State Research in Stuttgart, where he received his doctorate from the University of Stuttgart in 1988 under Hans-Joachim Queisser, with work on ultrafast spectroscopy of semiconductors.[8]

From 1989 to 1991 Leo was an Otto Hahn fellow and postdoctoral researcher at AT&T Bell Laboratories in Holmdel, New Jersey. He then joined RWTH Aachen as an assistant professor and completed his habilitation in 1993.[9] Since the 1993/94 winter term he has held a full professorship for optoelectronics at the Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) of TU Dresden, which he has headed (with an interruption from 2003 to 2006). In parallel he worked for the Fraunhofer Society from 2001 to 2013, first as a department head at the Fraunhofer Institute for Photonic Microsystems (IPMS)[10] and, from 2008, as director of its organic-electronics division, which became Fraunhofer COMEDD in 2012. He has also held visiting professorships at Tohoku University (2009) and at King Abdullah University of Science and Technology[11] (KAUST, 2013–2014).

Research focus

Leo works in semiconductor optics and the physics of thin organic films. In 1992 he achieved the first generation and detection of Bloch oscillations in a semiconductor superlattice, an effect long considered impossible to observe.[3] Much of his later work concerns the controlled electrical doping of organic semiconductors, which enabled p–i–n device architectures and organic light-emitting diodes with very low operating voltages and record power efficiencies; in 2009 his group reported a white OLED reaching the luminous efficiency of a fluorescent tube.[12] His work on organic solar cells produced some of the highest reported efficiencies, later commercialised through the spin-off Heliatek. Further topics include organic permeable-base transistors, near-infrared organic photodetectors and organic bioelectronics. Leo has published more than 700 peer-reviewed papers and is co-inventor of around 60 patent families.

Awards

References

  1. ↑ "News & Press". NOVALED | Creating the OLED Revolution. Retrieved 2026-07-20.
  2. ↑ "Spin-offs". TU Dresden. Retrieved 2026-07-20.
  3. 1 2 "Karl Leo: Seltene Doppelbegabung - brand eins online". www.brandeins.de (in German). Retrieved 2026-07-20.
  4. ↑ "DFG - Wissenschaftliche Preise". www.dfg.de. Archived from the original on 2007-09-29. Retrieved 2026-07-20.
  5. ↑ "Preisträger 2011". Deutscher Zukunftspreis (in German). Archived from the original on 2019-08-24. Retrieved 2026-07-20.
  6. ↑ "Karl Leo receives Blaise Pascal Medal of the European Academy of Sciences". TU Dresden. Retrieved 2026-07-20.
  7. ↑ Mundus, Jana. "Der Erfinder der Oleds: Forscher Karl Leo erhält Sachsens Verdienstorden". SZ - Sächsische Zeitung (in German). Archived from the original on 2025-06-23. Retrieved 2026-07-20.
  8. ↑ Leo, Karl (1988). "Untersuchung der Ultrakurzzeit-Dynamik von heißen Ladungsträgern in GaAs". Doktorarbeit, Universität Stuttgart.
  9. ↑ Leo, Karl (1993). "Optische und elektronische Eigenschaften von Halbleiter-Übergittern und organischen Dünnschichten". Habilitationsschrift, RWTH Aachen.
  10. ↑ "Willkommen - Fraunhofer IPMS - Fraunhofer IPMS". www.ipms.fraunhofer.de (in German). Retrieved 2026-07-20.
  11. ↑ "KAUST | A top research university in the Middle East". KAUST. Retrieved 2026-07-20.
  12. ↑ Reineke, Sebastian; Lindner, Frank; Schwartz, Gregor; Seidler, Nico; Walzer, Karsten; Lüssem, Björn; Leo, Karl (2009). "White organic light-emitting diodes with fluorescent tube efficiency". Nature. 459 (7244): 234–238. doi:10.1038/nature08003. ISSN 0028-0836.
  13. ↑ "DFG - Wissenschaftliche Preise". www.dfg.de. Archived from the original on 2007-09-29. Retrieved 2026-07-20.
  14. ↑ Hector Fellow Academy / www.hector-fellow-academy.de / info@hector-fellow-academy.de. "2014". www.hector-fellow-academy.de (in German). Archived from the original on 2021-12-01. Retrieved 2026-07-20.
  15. ↑ "Prof. Karl Leo zum acatech-Mitglied gewählt". TU Dresden. Retrieved 2026-07-20.
  16. ↑ Öffentlichkeitsarbeit, Referat Kommunikation und; Klimaschutz, Sächsisches Staatsministerium für Wirtschaft, Arbeit, Energie und. "futureSAX-Innovationskonferenz 2019 – Wirtschaftsminister Martin Dulig prämiert die Gewinner der Sächsischen Gründer-, Transfer- und Innovationspreise". www.medienservice.sachsen.de (in German). Retrieved 2026-07-20.{{cite web}}: CS1 maint: multiple names: authors list (link)
  17. ↑ "Karl Leo erhält Blaise-Pascal-Medaille der European Academy of Sciences". TU Dresden. Retrieved 2026-07-20.
  18. ↑ "OLED-Pionier Karl Leo erhält Europäischen Erfinderpreis". pro-physik.de (in German). Retrieved 2026-07-20.
  19. ↑ Office, European Patent. "European Patent Office announces winners of the European Inventor Award 2021". www.epo.org. Archived from the original on 2023-03-31. Retrieved 2026-07-20.
  20. ↑ "Prestigious UNIPRENEURS Founders Award for Prof. Karl Leo". TU Dresden. Retrieved 2026-07-20.
  21. ↑ "Outstanding achievements in research and transfer: TUD scientist Karl Leo honored with Order of Merit of the Free State of Saxony". TU Dresden. Retrieved 2026-07-20.
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