Future Directions

With the achievement of an efficient single-layer blue organic light-emitting diode with 100% internal quantum efficiency the next step will be the improvement of the operational stability, which requires understanding of the degradation processes on a molecular level. With a simplified device architecture in place, the number of materials and layers that contribute to degradation is drastically reduced, allowing for a detailed investigation of the key molecular degradation processes in OLEDs. Understanding of the degradation mechanism will serve a guideline for the design and synthesis of new emitters. Furthermore, the aim is to develop fully solution-processed OLEDs, for which the recently obtained simplified OLED structure is an excellent starting point. With regard to semiconducting perovskites we will develop novel molecules for 2D Perovskites used in transistors. 

With regard to device physics the focus will be on OLED efficiency improvements as a result of increased optical outcoupling, which is now the only limiting factor in the efficiency of the single-layer OLEDs, with current losses in the 70-80% range. Improvements are expected both by adjusting the internal device architecture, as well as by using external outcoupling strategies to extract light from the substrate modes. Furthermore, with regard to the fundamental understanding of photophysical properties of organic semiconductors we will focus on kinetic processes and their relation towards molecular structure and how these properties impact the performance of optoelectronic devices, including light-emitting diodes. In the organic transistor field, we will couple electrical characterization with a tunable light source in inert atmosphere, enabling the development of OFET-based light-gated devices and circuits. For wearable and on-skin electronics inkjet-printed and stretchable OECTs will be developed, where the focus lies on the fundamental understanding of strain-induced changes in morphology as well as electronic and ionic transport. 

To further enhance our understanding of the morphology formation we will continue on the dual research track of modeling phase transitions in thin film processing and life science, based on materials science and statistical mechanics. Our current thermodynamic and kinetic models will form the basis for simulating the development of crystal grain morphologies in, in particular, solution-processed metal halide perovskite films, as used in thin film PV and transistors. The second track concerns cellular phase transitions, in particular the formation of the biomolecular condensates that compartmentalize and organize the cytoplasm and the nucleoplasm into so-called “membraneless organelles” (MLOs). These condensates play pivotal roles in, e.g. cellular stress response, signaling and the development of neurodegenerative diseases. Experimentally, the self-assembly and unidirectional crystallization of organic and perovskite semiconductors as well as peptides using meniscus guided coating will be studied. The ability to obtain highly ordered thin films of semiconductors or biomolecules films will allow fabrication of high mobility field-effect transistors and directed cell growth, respectively, the latter as a first step towards a functional biocomputer. The new HR-MAS probe at the recently upgraded 850 MHz NMR system opens the possibility to study these molecular processes in situ via NMR studies of sample series with increasing concentration.  Although, the possibility of temperature variation at the HR-MAS setup is limited to 0° - 70°C, in-situ studies of the thermal influence on the molecular pre-organization are feasible. This is most relevant for the deposition of oligo peptides, were remarkable changes in the local molecular organization can be observed in this temperature range.  

In the field of bioelectronics hybrid devices will be developed for emulating the signaling processes of the biological building blocks, namely the neurons and synapses. These biomimetic devices will be based on electrochemical devices and synthetic lipid membranes. The synthetic membranes will be multi-responsive allowing for multimodal communication between the electrochemical device and the membranes. This research line will allow the emulation of biological functions in a well-controlled context and with minimum biological waste. With respect to biosensors, in the short-term, the sensitivity of OECTs for COVID-19 detection will be improved by implementing the current-driven OECT-configuration, which has proven to be a powerful strategy for monitoring cell layer integrity.