Extension of N-Heteroacenes through a Four-Membered Ring.

The synthesis of novel π-extended N-heteroacenes, which have a large tetraazaacene subunit and a quinoxaline subunit connected through a four-membered ring, is reported. They were studied with experimental and computational methods in comparison to the corresponding tetraazaacenes. As found from the DFT calculation, the four-membered ring is a better linker than a five-membered ring or a C-C single bond to extend N-heteroacenes for a new design of n-type semiconductors in terms of the spatial delocalization and energy level of LUMO as well as the reorganization energy. In solution-processed thin film transistors, the π-extended N-heteroacenes are found to function as n-type semiconductors with field effect mobility of up to 0.02 cm(2)  V(-1)  s(-1) under ambient conditions.