Electron-withdrawing substituted tetrathiafulvalenes as ambipolar semiconductors

The synthesis of four new TTF derivatives bearing phthalimides and fluorinated alkyl moieties as potential ambipolar semiconductors is described. The presence of such electron-withdrawing groups permits the stabilization of the energy of HOMO and LUMO orbitals. The solid-state structures of these novel molecules have been characterized by X-ray diffraction techniques. The potential of these materials as hole and electron conductors has been estimated under theoretical considerations by evaluating the position of the frontier energy levels as well as their charge carrier mobilities. Preparation of solution-processed single crystal organic field-effect transistors (OFETs) has resulted in hole mobilities of up to 0.33 cm² V^-1 s ^-1 for compound 1. On the other hand, electrical time of flight (EToF) measurements on single crystals of compound 3 demonstrated ambipolar transport, reaching very high mobility values around 2.0 cm² V ^-1 s^-1 for both types of charges.