In this paper we report polycyclic, fully-conjugated, heteroaromatic compounds 1–5, two of them having a helical shape (tetrathia--helicenes 1 and 2), and explore their potential use as p-type semiconductors for organic thin-film transistors (OTFTs). Furthermore, we describe their optical absorption, emission, and electrochemical properties. In addition, the single crystal X-ray diffraction structure for compound 3 is reported. Thin films of all compounds were fabricated on several substrates at different temperatures by physical vapor deposition, and were characterized by optical spectroscopy, wide-angle X-ray diffraction, atomic force microscopy, and TFT measurements. The AFM images of compound 1 exhibit an interesting tubular morphology for films deposited at room temperature. This is the first observation of a compound with a helical shape leading to a nanowire-like morphology. In agreement with the molecular structure/morphology, only compound 4 is a ptype semiconductor with good carrier mobility.
Synthesis, characterization, and transistor response of tetrathia--helicene precursors and derivatives / KIM CHOONGIK; MARKS TOBIN J; FACCHETTI ANTONIO; SCHIAVO MICHELE; BOSSI ALBERTO; MAIORANA STEFANO; LICANDRO EMANUELA; TODESCATO FRANCESCO; TOFFANIN STEFANO; MUCCINI MICHELE; GRAIFF CLAUDIA; TIRIPICCHIO A.. - In: ORGANIC ELECTRONICS. - ISSN 1566-1199. - 10(2009), pp. 1511-1520. [10.1016/j.orgel.2009.08.018]