Epitaxial Growth of Highly Oriented Fibers of Semiconducting Polymers with a Shish‐Kebab‐Like Superstructure

Highly oriented fibers of regioregular poly(3‐alkylthiophene)s (P3ATs) showing a “shish‐kebab” morphology are prepared by oriented epitaxial crystallization in a mixture of 1,3,5‐trichlorobenzene (TCB) and pyridine. The superstructure of the P3AT fibers consists of an oriented thread‐like core several hundreds of micrometers long, the “shish”, onto which lateral crystalline fibrils made of folded polymer chains, the “kebabs”, are connected in a periodic way with a periodicity in the range 18–30 nm. The P3AT‐chain axis is oriented parallel to the fiber axis whereas the π‐stacking direction is oriented perpendicular to it. The oriented character of the shish‐kebab fibers results in polarized optical absorption and photoluminescence. The formation of oriented precursors by epitaxial orientation of polymer chains onto long needles of a molecular crystal—TCB in the present case—appears to be an original alternative to the crystallization usually performed under external flow conditions. Highly oriented and nanostructured crystalline fibers of conjugated polymers, namely regioregular poly(3‐alkylthiophene)s, are obtained by an epitaxial growth process. The P3AT fibers show a so‐called “shish‐kebab” superstructure (see figure). Such highly oriented and nanostructured P3AT fibers exhibit polarized light absorption and photoluminescence.