Three new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB‐TTF) central core and a 2,1,3‐chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB‐TTF, have been synthesised as active materials for organic field‐effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron‐withdrawing 2,1,3‐chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material. The solution‐processed single‐crystal transistors exhibit high performance with a hole mobility up to 0.04 cm2 V−1 s−1 as well as good ambient stability. Fused flat: Rigid electron donor–acceptor conjugates with tetrathiafulvalene (TTF) as an electron donor and 2,1,3‐benzochalcogendiazole as an electron acceptor have been prepared (see figure). Together with tetramethoxy‐substituted dibenzo‐TTF, a detailed study of their electronic properties is described. The solution‐processed single‐crystal transistors based on these π‐extended TTF derivatives exhibit high performance as well as good ambient stability.