n-Type Azaacenes Containing B <- N Units

We disclose a novel strategy to design n-type acenes through the introduction of boron-nitrogen coordination bonds (B <- N). We synthesized two azaacenes composed of two B <- N units and six/eight linearly annelated rings. The B <- N unit significantly perturbed the electronic structures of the azaacenes: Unique LUMOs delocalized over the entire acene skeletons and decreased aromaticity of the B <- N-adjacent rings. Most importantly, these B <- N-containing azaacenes exhibited low-lying LUMO energy levels and high electron affinities, thus leading to n-type character. The solution-processed organic field-effect transistor based on one such azaacene exhibited unipolar n-type characteristics with an electron mobility of 0.21 cm(2) V-1 s(-1).