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Organic semiconductors, unlike inorganic semiconductors, are not held together by electronic bonds but by comparatively weak van der Waals interactions between the molecular building blocks. This has important implications for the resulting band structure, optical properties, and transport of charge carriers or excitons. For many systems, however, it is not clear to which extent coherent phenomena or local processes govern the optical properties.
It becomes particularly exciting when two different semiconductor materials are brought together. Can excitations migrate from one layer to the other? Do we possibly even observe new signatures that can be assigned to the interface? And what do such signatures tell us about the nature of the interface? Resolving such questions is of great importance in assessing the potential of new materials for use in semiconductor devices.
Moreover, semiconductors are not perfect. Structural disorder or defects can greatly affect and degrade opto-electronic properties. Luminescence spectroscopy is particularly sensitive to the influences of defects and compositional disorder, as it reveals non-radiative processes or the signatures of defects in low-temperature spectra. Of particular interest here is the relationship between luminescence properties and the micro- or nanostructure of a semiconductor sample.
Furthermore, our methodology is of course not limited to semiconductors. We aim to further develop imaging luminescence methods. For example, we are currently investigating the extent to which imaging photoluminescence excitation spectroscopy is suitable for the spectroscopic identification of microplastic particles.
Current projects
Collaborative research centre CRC 1083: „Structure and Dynamics of internal interfaces”, Subproject B10: “Dynamics of Charge Transfer Excitons at organic/organic and hybrid organic/anorganic interfaces”
LOEWE Exploration: „Spectroscopic identification of microplastics through photoluminescence excitation spectroscopy“