Aarhus University Seal / Aarhus Universitets segl

Upconversion of light: a method for increasing the efficiency of existing and future solar cells

PhD defence, Tuesday 21 January 2020. Jeppe Hedelund Christiansen.

2020.01.21 | Sunitha Satkunam

Jeppe Hedelund Christiansen

During his studies, Jeppe Hedelund Christiansen has researched the optical properties of erbium ions doped into thin films of the glas material titanium dioxide. Jeppe has especially focused on the process photon upconversion, in which, two or more particles of light (photons) are combined to one of higher energy.

Jeppe has studied photon upconversion of 1500 nm to 980 nm light which has applications in increasing the efficiency of existing and future silicon-based solar cells. This is, because silicon cannot absorb part of the long-waved light from the sun - among other light with wavelength of 1500 nm, but it can absorb light with wavelength around 980 nm. Placing an erbium-based upconverter in front of the solar cell will thus increase its efficiency. The results of Jeppe’s research have led to a greater theoretical understanding of the upconversion process in erbium ions and the required properties of the upconverting unit, before such a device will become relevant for real-world applications. 

The PhD degree was completed at the Department of Physics and Astronomy, Faculty of Natural Sciences, Aarhus University.

This résumé was prepared by the PhD student.

Time: Tuesday 21 January 2020 at 13.15 
Place: Building 1525, room 318, “Fysisk auditorium”, Department of Physics and Astronomy, Aarhus University
Title of PhD thesis: Photon upconversion in trivalent erbium ions
Contact information: Jeppe Hedelund Christiansen, e-mail: jdc@phys.au.dk, tel.: +45 26 21 73 49
Members of the assessment committee:
Senior Researcher, Rita Rizzoli, Institute for Microelectronics and Microsystems, National Research Council of Italy
Professor Bryce S. Richards, Institute for Microstructure Technology, Karlsruhe Institute of Technology
Professor Steen Hannestad (chair),  Department of Physics and Astronomy, Aarhus University
Main supervisor:
Associate Professor Brian Julsgaard, Department of Physics and Astronomy, Aarhus University
Language: The PhD thesis will be defended in English


The defence is public.
The PhD thesis is available for reading at the Graduate School of Science and Technology/GSST, Ny Munkegade 120, building 1521, 8000 Aarhus C.

PhD defence
12183 / i43