Experimental Physics VI

    Research Interests

    Quantum Sensors and Microwave Emitters

    In recent years, wide-bandgap semiconductors, such as silicon carbide (SiC) attracted a lot of interest as a technologically perspective platform for quantum spintronics with the ability for single spin engineering and control. Our group is interested in atomic scale color centers in SiC, particularly silicon vacancies, which combine resonant optical addressability using near-infrared light and long spin coherence times.

    Spins in Organic Semiconductors

    Organic semiconductors are a promising class of materials for the next generation of light emitting diodes (OLED) and solar cells (OPV). Several phenomena in these semiconductors are related to the spin properties of triplet excitons and charge transfer states that are optically or electrically generated in device active layers and can influence the charge carrier generation and radiative recombination quantum efficiency. In other words, spin is a crucial parameter controlling the physical limits of device quantum efficiency.

    Photovoltaic Materials and Devices

    Our research activities are focused on the physics of organic and, more recently, hybrid perovskite photovoltaics. Perovskite photovoltaics is a relatively new type of thin-film PV technology, which experienced a tremendous increase in power conversion efficiency from 3.8 % to above 22 % within the last 10 years.

    Organic Electronics

    Our research in the field of Organic Electronics is concentrated on electronic excitations in molecular single crystals, crystalline thin films as well as single molecules and their interplay with the structural and electronic characteristics on nanometer length scale. Disclosing the fundamental processes together with their dependence on morphology and temperature allows for a fundamental understanding and, thus, improvement of the device performance of organic field-effect transistors (OFETs), organic photovoltaics (OPVs) as well as OLEDs.

    Organic Thermoelectrics

    Upon primary energy consumption a significant amount of waste heat at moderate temperatures of around 100°C is generated. Regarding recent efforts on sustainable, environmental-friendly energy sources it is thus of utmost importance to take advantage of these losses by means of thermoelectric generators (TEGs) which directly recover waste heat into electric power. In contrast to well-established inorganic TEGs, mainly based on doped Bi2Te3, organic van-der-Waals bound semiconductors constitute a promising alternative material class for next-generation, low-cost and green-technology TEGs.

    Metal-Organic Hybrid Structures

    Metal-organic hybrid structures offer unique possibilities for application in already existing devices, such as photo-detectors or organic light-emitting diodes (OLEDs), as well as in novel photonic architectures. Furthermore, the coupling between the electronic excitations of a molecular thin film and the local plasmonic resonances of a metallic nanopattern in close proximity can tune the optical properties of the organic layer or even generate new plasmon-polaritonic states, also called plexcitons.