Interplay of structural and electronic properties and their impact on thin films of metal-free organic radicals (Final report on DFG funded projects, reference number: CA852/11-1 and CA852/11-3, Project number: 394233453)

The project and its extension concentrate on radical thin films. I have identified and refined the growth protocols for various radicals and multi-radicals, enabling their evaporation while pre-serving their radical nature. Additionally, I have explored the influence of different functional groups on thin film properties. During these years, I have addressed a variety of aspects, demonstrating the feasibility of using radicals in fields ranging from quantum technologies to spintronics. By using primarily X-ray-based techniques, including at synchrotron facilities, I have linked structural, electronic, and magnetic properties. I have also examined how the interaction strength between the (multi-)radicals and the substrate affects the interface formation, growth modes, and film processes of the radical thin films. Furthermore, I have focused on evaluating film stability, which is crucial for understanding their chemistry when exposed to air prior to performing electron spin resonance (ESR) spectroscopy—a traditional (ex-situ) technique used for radicals—and for determining film stability in environments simulating working devic-es. I have developed a protocol to study the effects of air exposure on radical thin films and utilized this method. Finally, I have conducted and interpreted X-ray magnetic circular dichro-ism (XMCD) investigations, revealing the interplay between structure and magnetic behavior in radical thin films.