Supramolecular order of solution-processed perylenediimide thin films: High-performance small-channel n-type organic transistors

N,N′-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN ₂), a soluble and air stable n-type molecule, undergoes significant reorganization upon thermal annealing after solution deposition on several substrates with different surface energies. Interestingly, this system exhibits an exceptional edge-on orientation regardless of the substrate chemistry. This preferential orientation is rationalized in terms of strong intermolecular interactions between the PDIF-CN₂ molecules. The presence of a pronounced π-π stacking is confirmed by combining near-edge X-ray absorption fine structure spectroscopy (NEXAFS), dynamic scanning force microscopy (SFM) and surface energy measurements. The remarkable charge carrier mobility measured in field-effect transistors, using both bottom- and top-contact (bottom-gate) configurations, underlines the importance of strong intermolecular interactions for the realization of high performing devices.