Spatially resolved electronic circular dichroism of chiral π-conjugated materials in thin film

In recent years, organic π-conjugated semiconductors started to replace the more classical inorganic semiconductors for optical and electronic applications, thanks to their benefits: lower processing costs, low-impact disposal, remarkable tunability. In this context, chirality opens the possibility of fabricating organic optoelectronic devices with enhanced performances, thanks to the ability of modulating the optoelectronic properties through guiding the supramolecular aggregation of π-conjugated materials constituting the active layers. Moreover, it allows the development of technologically advanced applications for the detection or the production of circularly polarized (CP) light. Nowadays, obtaining materials characterized by high discrimination of CP-light in absorption (electronic circular dichroism, ECD) or emission (circularly polarized luminescence, CPL) is fundamental. However, device performances are ultimately affected also by active layers homogeneity. When considering the spatial distribution of different chiral supramolecular orders, the only techniques able to provide useful information are spatially resolved chiroptical spectroscopies. This doctoral work shows progresses in chiral π-conjugated systems, which aggregate in supramolecular structures, dedicating a particular attention to their ECD properties in thin film. A most advanced experimental tool is ECD spatial distribution with synchrotron radiation, also known as synchrotron radiation ECD imaging (SR-ECDi), which is available at Diamond Light Source with B23 beamline, where this thesis was carried out. Furthermore, the development of a new microscopy technique able to reveal the spatially resolved ECD of thin films with high dichroic ratios is illustrated through its application on a material characterized by a complex domains-like ECD texture in thin film. Further than just considering only the ECD of the thin film samples, in some cases also all the other polarization properties are discussed by the determination of the so-called Mueller matrix. Such study is, again, performed as a spatially resolved technique, known as synchrotron radiation Mueller matrix polarimetry imaging (SR-MMPi), available at Diamond Light Source B23 beamline.