Dr. Ilka Hermes

Group Leader Correlative Atomic Force Microscopy
at the Leibniz-Institut für Polymerforschung Dresden e.V.

Hohe Str. 6
01069 Dresden

Phone: +49 (0)351 4658-539
Fax: +49 (0)351 4658-284
Email: hermes@ipfdd.de

We are working to resolve nanoscale surface properties of functional materials under application of external stimuli via correlative electrical and nanomechanical atomic force microscopy (AFM).

Atomic force microscopy (AFM) scans samples with a nanometer-sized tip attached to a cantilever. From the deflection of the cantilever caused by interaction forces, the surface structure can be reconstructed in real space with a spatial resolution down to sub-nanometer. The potential of AFM lies not only in high-resolution imaging of sample topographies, but also in the method’s unique ability to additionally capture electrical, mechanical, piezoelectric and magnetic surface properties. Our work aims at the holistic characterization of functional materials using different AFM methods and further (macroscopic) measurement techniques. In particular, we are interested in in-situ measurements of responsive materials during the application of external stimuli like an electrical bias, illumination and/or mechanical stress. Among others, we are employing Kelvin probe AFM to resolve charging processes, conductive AFM to image local conductivities, as well as nano- and electromechanical AFM.

• Hermes, I. M.; Best, A.; Winkelmann, L.; Mars, J.; Vorpahl, S.M.; Mezger, M.; Collins, L.; Butt, H.-J.; Ginger, D.S.; Koynov, K.; Weber, S.A.L., Anisotropic carrier diffusion in single MAPbI3 grains correlates to their twin domains, Energy Environ. Sci., 2020, 13, 11, 4168-4177.
  https://doi.org/10.1039/D0EE01016B
• Hermes, I. M.; Bretschneider, S.A.; Bergmann, V.W.; Li, D.; Klasen, A.; Mars, J.; Tremel, W.; Laquai, F.; Butt, H.-J.; Mezger, M.; Berger, R.; Rodriguez, B.J.; Weber, S.A.L., Ferroelastic Fingerprints in Methylammonium Lead Iodide Perovskite, J. Phys. Chem. C, 2016, 120, 10, 5724-5731.
  https://doi.org/10.1021/acs.jpcc.5b11469
• Hermes, I. M.; Hou, Y.; Bergmann, V.W.; Brabec, C.J.; Weber, S.A.L., The Interplay of Contact Layers: How the Electron Transport Layer Influences Interfacial Recombination and Hole Extraction in Perovskite Solar Cells, J. Phys. Chem. Lett., 2018, 9, 21, 6249-6256.
  https://doi.org/10.1021/acs.jpclett.8b02824
• Weber, S.A.L., Hermes, I. M.; Turren-Cruz, S.-H.; Gort, C.; Bergmann, V.W.; Gilson, L.; Hagfeldt, A.; Graetzel, M.; Tress, W.; Berger, R., How the formation of interfacial charge causes hysteresis in perovskite solar cells, Energy Environ. Sci., 2018, 11, 9, 2404-2413.
  https://doi.org/10.1039/C8EE01447G
• Axt, A.; Hermes, I. M.; Bergmann, V.W.; Tausendpfund, N.; Weber, S.A.L., Know your full potential: Quantitative Kelvin probe force microscopy on nanoscale electrical devices, Beilstein J. Nanotechnol., 2018, 9, 1, 1809-1819.
  https://doi.org/10.3762/bjnano.9.172