TU Braunschweig - Institute for High Frequency Technology

The group of Prof. Wolfgang Kowalsky (Institute for High Frequency Technology, TU Braunschweig) at InnovationLab researches in the field of analytics. It cooperates with groups from the University of Heidelberg and TU Darmstadt.

The main focus of our research is the correlation between structure and function in organic (opto)electronic devices. We investigate

  • fundamental properties of doped organic semiconductors,
  • organic solar cells, and
  • surface modifications for applications in organic electronics.

Our main experimental tools are advanced electron microscopy and scanning probe microscopy and combinations thereof. You can find further details under methods.

Our homepage gives a brief overview of our ongoing research. For more detailed information please take a look at our list of publications. In case you are interested in working in our team or collaborating with us, please contact us directly.

Doped Organic Semiconductors

How does the morphology of a host dopant system affect its doping efficiency? We are working on finding an answer to this and related questions in close collaboration with our partners from Heidelberg University (Prof. Annemarie Pucci, Prof. Rasmus Schröder) and TU Darmstadt (Prof. Wolfram Jaegermann). We investigate in particular the model system CBP:MoO3.
Our activities in the field of doped organic semiconductors are funded by the Federal Ministry of Education and Research (BMBF) within the project InterPhase (FKZ 13N13656).

Interface Modifications for Organic Electronics

Surfaces and interfaces have a tremendous influence on the performance of electronic devices. This might apply more to organic electronics than to silicon-based technologies. Thus, the controlled modification of organic/inorganic and organic/organic interfaces is of high importance. One approach we are pursuing in this direction is making use of self-assembled monolayers to control the barrier height and wettability of organic/inorganic interfaces.
Our activities in the field of interface modifications are funded by the BMBF within the project InterPhase (FKZ 13N13656).


Correlated Electron and Scanning Probe Microscopy

We have an integrated SEM-AFM system (BRR by Zeiss/DME) that combines a Crossbeam Auriga electron microscope (SEM and FIB, Zeiss) with a scanning probe microscope (DME). This combination enables us to perform experiments that would be impossible using the components separately.


Scanning Probe Microscopy (SPM)

Besides the SPM incorporated in the SEM, we have two further SPMs for measurements in UHV and ambient. All SPMs are equipped for a variety of scanning probe techniques (e.g. scanning Kelvin probe microscopy), giving us not only morphological but also electronic information on our samples with high spatial resolution.


Analytical Transmission Electron Microscopy (TEM)

We use our TEM (Zeiss Kronos) in close collaboration with the group of Prof. Rasmus Schröder (Heidelberg University) to study the structure-function relationship in organic and hybrid solar cells. Using spectroscopic imaging, we are also able to distinguish even different organic materials based on their respective electron energy loss spectra.

Electrical and Optical Characterization

We use the following instruments that are accessible at iL for electrical and optical characterization of our samples:

  • UV/VIS ellipsometer and absorption spectrometer
  • solar simulator
  • Kelvin-Probe
  • Photo-CELIV
  • temperature-dependent electrical transport measurements

PhD Students

Marc-Michael Barf

PhD student
Contact via Email
Room: E 4.06

Phone: +49 (0) 6221 54 19 123 (iL)

Paul Heimel

PhD student
Contact via Email
Room: F 4.15

Phone: +49 (0) 6221 54 19 139 (iL)

Xiaokun Huang

PhD student
Contact via Email
Room: E 4.06

Phone: +49 (0) 6221 54 19 123 (iL)

Master & Bachelor


  • Israr Ahmed (Master thesis, 2017)
  • Jakob Bombsch (Bachelor & Master theses, 2017)
  • Stefan Brackmann (Master thesis, 2016)
  • Ramos Bwalya (Bachelor & Master theses, 2017)
  • Dominik Daume (Master thesis, 2012)
  • Dr. Daniela Donhauser (PhD thesis, 2013)
  • Helge Eggers (Master thesis, 2017)
  • Bernd Epding (Bachelor & Master theses, 2016)
  • Florian Friedrich (Bachelor thesis, 2016)
  • Martin Gebhardt (Master thesis, 2016)
  • Markus Gölz (Master thesis, 2013)
  • Dr. Sebastian Hietzschold (Bachelor, Master & PhD theses, 2017)
  • Tim Helder (Bachelor thesis, 2016)
  • Tobias Jenne (Master thesis, 2014)
  • Dr. Michael Kröger
  • Carsten Leinweber (Master thesis, 2013)
  • Benjamin Martini (Master thesis, 2012)
  • Dr. Christian Müller (Master & PhD theses, 2017)
  • Dr. Lars Müller (Bachelor, Master & PhD theses, 2018)
  • Alexander Müller-Brandt (Master thesis, 2013)
  • Dr. Diana Nanova (Master & PhD theses, 2015)
  • Marcel Plogmeyer (Bachelor thesis, 2015)
  • Viola Rädle (Bachelor thesis, 2016)
  • Seon-Young Rhim (Master thesis, 2017)
  • Dr. Rebecca Saive (PhD thesis, 2014)
  • Felix Schell (Master thesis, 2014)
  • Dr. Michael Scherer (Master & PhD theses, 2016)
  • Dr. Janusz Schinke (PhD thesis, 2014)
  • Dr. Ilja Vladimirov (Master & PhD theses, 2016)
  • Dongxiang Wang (Master thesis, 2016)
  • Christian Willig (Bachelor & Master theses, 2017)