Theoretical Soft X-ray Spectroscopy of Adsorbed Systems
Theoretical computation of soft x-ray spectra of organic molecules in complex environments like on surfaces or in supermolecular architectures in close collaboration with experimental groups. The theoretical approach is crucial to correctly describe the electronic structure which determines the charge transfer, the molecule surface interaction and the magnetic structures. We explore ab initio and hybrid DFT based methods, including van der Waals approaches and the Hubbard U method.
In the study of organic molecule magnets, like phthalocyanines and porphyrins with a 3d metal ion in the center, the aim is to find reversible and feasible mechanisms to affect the molecular spin, that can successively be used in devices. The soft x-ray spectra give unique insights into the interaction of the molecules with their environment and how this affects their electronic structure.
We apply the same methods to investigate organic molecules in polymer solar cells, and in particular we want to understand how the molecules degrade during the operation, affecting the lifetime of the cells. In addition the theoretical modeling of soft x-ray spectra can be used as a guideline to determine the presence of adsorbates on a molecule, or even to fingerprint intermediates in chemical reactions, like for example in the electrochemical reactions for the production of solar fuels.
- Brena et al., Valence-Band Electronic Structure of Iron Phthalocyanine: an Experimental and Theoretical Photoelectron Spectroscopy Study J. Chem. Phys. 134, 074312 (2011).
- Brena et al., InSb–TiOPc interfaces: Band alignment, ordering and structure dependent HOMO splitting Surf. Sci. 306, 3160 (2009).
- Brena and Ojamäe, Surface effects and quantum confinement in nanosized GaN clusters: Theoretical predictions J. Phys. Chem. C 112, 13516 (2008).
Magnetic Molecules and Adsorption
Organic Polymer Solar Cells