Nanocharacterization for Advanced Functional Materials


Oana Cojocaru-Mirédin


+49 241 80 20270


  research topics atomprobe Picture showing the correlation between chemical, structural, and electrical properties applied for advanced functional materials.

Functional Materials are often characterized by particular inherited functions such as energy storage, optical and electrical data storage, ferroelectricity, etc. which makes them to become a central focus of investigation in material science, physics, and chemistry. Moreover, the performance of these materials is strongly linked to their chemical, structural, and electrical/optical properties.

Therefore, the aim of this group of the I. Institute of Physics (IA) is to understand and design complex functional materials through advanced nanocharacterization methods such as atom probe tomography, transmission electron microscopy, electron backscatter diffraction and electron beam induced current as shown in the picture below. Atom probe tomography is a modern and powerful tool able to map the position and identity of the atoms in 3D. It is believed that APT combined with other (nano)characterization tools will help in technological advances, i.e. in the development of novel energy and data storage materials.

Current research topics in the group:

  • Designing novel thermoelectric and phase-change materials by controlling the microstructure and the composition;
  • Designing better and environmentally friendly buffer layers for Cu(In,Ga)Se2 thin-film solar cells;
  • Understanding the relationship between misorientation and impurity segregation at the grain boundaries in the absorber of a Cu(In,Ga)Se2 thin-film solar cell;
  • Understanding the relationship between recombination activity, grain boundary structure, and chemistry in multicrystalline Silicon solar cells;


Abou-Ras, D.; Schmidt, S.S.; Schäfer, N.; Kavalakkatt, J.; Rissom, T.; Unold, T.; Mainz, R.; Weber, A.; Kirchartz, T.; Simsek Sanli, E.; van Aken P. A.; Ramasse, Q.M.; Kleebe, H.-J.; Azulay, D.; Balberg, I.; Millo, O.; Cojocaru-Mirédin, O.; Barragan-Yani, D.; Albe, K.; Haarstrich, J.; Ronning, C.
Compositional and electrical properties of line and planar defects in Cu(In,Ga)Se 2 thin films for solar cells – a review.
Phys. Status Solidi RRL 10(5), 363–375 (2016)​

Cojocaru-Mirédin, O.; Fu, Y.; Kostka, A.; Sáez-Araoz, R.; Beyer, A.; Knaub, N.; Volz, K.; Fischer, C.-H.; Raabe, D. Interface engineering and characterization at the atomic-scale of pure and mixed ion layer gas reaction buffer layers in chalcopyrite thin-film solar cells.
Progress in Photovoltaics: Research and Applications 23 (6), pp. 705-716 (2015).

Stoffers, A.; Cojocaru-Mirédin, O.; Seifert, W.; Zaefferer, S.; Riepe, S.; Raabe, D.
Grain boundary segregation in multicrystalline silicon: correlative characterization by EBSD, EBIC, and atom probe tomography.
Progress in Photovoltaics: Research and Applications 23 (6) 2015 (online published)

Cojocaru-Mirédin, O.; Schwarz, T.; Choi, P.; Herbig, M.; Würz, R.; Raabe, D.
Atom Probe Tomography Studies on the Cu(In,Ga)Se2 Grain Boundaries.
Journal of Visualized Experiments 74 (2013)

Schwarz, T.; Cojocaru-Mirédin, O.; Choi, P.; Mousel, M.; Redinger, A.; Siebentritt, S.; Raabe, D.
Atom probe study of Cu2ZnSnSe4 thin-films prepared by co-evaporation and post-deposition annealing.
Applied Physics Letters 102, pp. 1-4 (2013)

A. Stoffers, B. Ziebarth, J. Barthel, O. Cojocaru-Mirédin, C. Elsässer, and D. Raabe
Complex Nanotwin Substructure of an Asymmetric Σ9 Tilt Grain Boundary in a Silicon Polycrystal
Physical Review Letters 115 (2015) 235502.