Crystallization of organic semiconductor molecules in nanosized cavities: Mechanism of polymorphs formation studied by in situ XRD

The crystallization of an organic semiconductor, viz., tetrahexil-sexithiophene (H4T6) molecules, confined into nanosized cavities of a self-organized polystyrene beads template, has been investigated by means of in situ grazing incidence X-ray diffraction measurements, during the solvent evaporation. Thanks to these real time experiments, the phase content and the crystalline domain orientation of H4T6 have been determined, from the onset of the first crystalline molecular assembly to the stable system. The correlation between the bead size dependent crystallization mechanism in this complex system and the enhanced transistor performance has been established. These results, which can be extended to a wide range of organic materials, are useful for developing an attractive sustainable process for fabrication of organic devices with enhanced performance.