GRK 2818:  Optical excitations in organic and inorganic semiconductors: Understanding and control through external stimuli

• Subject Area: Condensed Matter Physics ; Polymer Research
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464648186

Semiconductor materials are undoubtedly the cornerstone of modern electronics and of central importance for sustainable economic growth. In order to meet the technical requirements of modern electronics, the computer chip industry has advanced the structuring of traditional, inorganic semiconductors to ever smaller length scales, so that by now the expansion of an excited state in the semiconductor is limited by its nanostructure. This changes the laws governing such photoexcitations. Conversely, it is now possible to arrange molecules selectively in supramolecular architectures and to control the order in molecular semiconductor films so that photoexcitations normally confined to one molecule spread coherently over several molecules. As a result of these developments, researchers studying nanostructured inorganic semiconductors and researchers devoted to organic semiconductor materials often address similar questions, but without benefiting from each other's insights. On the contrary, due to lack of communication, significant misunderstandings often occur. This is a scientific problem that the IRTG aims to address both in its research and in its qualification program. A focus in both communities is how we can change the function and purpose of a semiconductor. Traditionally, this has been defined and determined by its building blocks. To enable different functions such as light emission, sensing, signaling or energy harvesting, chemically different building blocks had to be used. Here we want to use a radically different approach inspired by nature. Nature achieves different functions and purposes in light-active systems by adapting the local environment of the "semiconductor." A classic example of this are bacteria that perform photosynthesis. In them, the embedding of light-collecting proteins is adapted so that the charge and energy generation is modified. We want to apply a similar approach to our organic and inorganic artificial photoactive systems. Our goal is to use external stimuli to define the functionality of the semiconductor without changing its chemical composition. As external stimuli, we will use light, local electromagnetic fields, and self-assembly processes to adapt the local environment. In this way, we aim to better understand and control the interaction between light and matter, across different classes of materials and with respect to technologically relevant applications.

• DFG Programme: International Research Training Groups
• International Connection: Australia
• Applicant Institution: Universität Bayreuth
• IRTG-Partner Institution: Monash University; The University of Melbourne
• Spokesperson: Professorin Dr. Anna Köhler
• Participating Researchers: Professor Dr. Georg Herink; Professorin Dr. Eva M. Herzig; Professor Dr. Jürgen Köhler; Professor Dr. Stephan Kümmel; Professor Dr. Markus Lippitz; Professor Dr. Harald Oberhofer; Dr. Fabian Panzer; Professor Dr. Markus Retsch; Professor Dr. Mukundan Thelakkat
• IRTG-Partner: Spokesperson: Professor Dr. Paul Mulvaney