A dendritic oligoarylamine-substituted benzimidazole derivative as a useful n-type dopant

4-(N,N-Dimethylamino)phenyl-substituted 1,3-dimethyl-2,3-dihydro-1H-benzimidazole (N-DMBI-H) has been reported as a useful solution-processable n-type dopant to control electrical conductivity over a wide range in PCBM ([6,6]-phenyl-C₆₁-butyric acid methyl ester) thin films. An approach for increasing the chemical stability of the DMBI-H dopant molecule in solution phase by attachment of dendritic oligoarylamine at the 2-position of the benzimidazole ring (N3-DMBI-H) has been explored in this study, and moreover the efficacy of the solution-processable n-type dopant has been clarified together with the electronic properties of N3-DMBI-H. On the basis of electrochemical, spectroelectrochemical, and quantum chemical calculations, it has been deduced that one-electron-oxidized species for N3-DMBI-H as well as N-DMBI-H are readily converted into diamagnetic cationic species by releasing a hydrogen atom.