Perfluoroarene units in distyryl-oligothiophene analogues: An efficient electron density confinement preventing n-type transport in organic thin film transistors

Solid-state properties of two perfluoroarene-containing analogues of distyryl-oligothiophenes (DFSnT, n = 2, 4) are presented. High vacuum evaporated thin films were implemented as semiconducting layers into organic thin film transistors (OTFTs). Morphology of thin films has been studied by atomic force microscopy (AFM). OTFT measurements performed under high vacuum show that these compounds behave as only p-channel semiconductors. By using a controlled low evaporation rate together with a fine control of the substrate temperature, highly interconnected μm-long rodlike crystallites were obtained. However, analysis of these materials reveal a direct impact of the molecular structure where the presence of the two double bonds may affect the final transport properties by confining the electrons in such molecular segments and hampering electron delocalization in perfluoroarene units.

► Organic thin film transistors based on small organic semiconductors (DFS2T and DFS4T).
► Highly oriented polycrystalline thin films formed by vapor-deposition.
► Direct impact of the molecular structure on the final transport properties.
► Confinement of electrons at specific segments of the molecular backbone.