Spatially Addressed Supramolecular Nanowires: A Full Structural Characterization by GIWAXS

Supramolecular nanowiring rests on the precise interconnection of nano- or microelectronic circuit elements with electroactive 1D supramolecular polymers. It represents a unique opportunity to access miniaturized organic electronic devices. The bottom-up construction of such integrated nanowires can be in principle generated by addressing the supramolecular polymerization process with a spatial precision that cannot be accessed by top-down approaches. However, most analytical techniques fail to access the fine structural and orientational features of such nanowires within electronic circuits at that scale. Even grazing-incidence wide-angle X-ray scattering (GIWAXS) poses major hurdles for the practical investigation due to beam path obstruction for most in-plane orientation of the samples. To overcome these limitations, we have implemented here a sensing modality based on GIWAXS collection for unique sample orientation and spot shape analysis in the reciprocal space allowing the entire film morphology to be accessed. In this case study involving triarylamine-based nanowires, we determine in a single experiment the packing structure of the supramolecular polymers interconnecting microelectrodes, together with their 3D and 2D orientational order parameters (S3D ≈ 0.986 and S2D ≈ 0.91). Our investigation demonstrates that the nanowires lie flat along the substrate and align along the normal to the electrodes. This alignment occurs with a coherence length of more than 100 nm, representing more than 200 molecules along the nanowire axis. Overall, this work highlights the great potential of GIWAXS to become a reference method for the full characterization of nanowiring processes with supramolecular polymers and self-assemblies integrated in complex device geometries.