Crystallization and OFET Performance of a Hydrogen-Bonded Quaterthiophene

Crystalline thin films of π-conjugated molecules are relevant as the active layers in organic electronic devices. Therefore, materials with enhanced control over the supramolecular arrangement, crystallinity, and thin film morphology are desirable. Here, we report that hydrogen-bonded substituents serve as additional structure-directing elements that positively affect crystallization, thin film morphology, and device performance of p-type organic semiconductors. We observed that a quaterthiophene diacetamide exhibited a denser packing than other quaterthiophenes in the single-crystal structure and, as a result, displayed enhanced intermolecular electronic interactions. This feature was preserved in crystalline thin films that exhibited a layer-by-layer morphology with large domain sizes and high internal order. As a result, organic field-effect transistors of these polycrystalline thin films showed mobilities in the range of the best mobilities values reported for single-crystalline quaterthiophenes. The use of hydrogen-bonded groups may, thus, provide an avenue for organic semiconducting materials with improved morphology and performance.