Morphological transformation of pyrazine-based acene-type molecules after blending with semiconducting polymers: from fibers to quadrilateral crystals

Abstract

Micron-sized fibers of n-type pyrazine-based acene-type molecule (PBA) spin-coated films were formed after solvent vapor annealing (SVA). PBA fibers dramatically transformed into quadrilateral crystals after blending with semiconducting polymers under identical post-treatment procedures. For polymer blended systems, a much longer post-treatment time was needed to achieve the nucleation of PBA molecules. Furthermore, the orientation of PBA molecules in the quadrilateral crystals became much more ordered. There are two prerequisites for choosing the blended polymers: good compatibility with PBA molecules and comparatively strong crystallinity. Even though the blended polymers suppress the PBA nucleation process because of interpenetrating polymer networks, the self-organization of semiconducting polymers may control the diffusion rate of PBA molecules in the mixture and finally facilitate PBA self-assembly into perfect ordered aggregates.