High optical transparency in all redox states: Synthesis and characterization of benzimidazole and thieno[3,2-b]thiophene containing conjugated polymers

The synthesis of a novel monomer based on benzimidazole and thieno[3,2-b]thiophene moieties, 4′-tert-butyl-4,7-di(thieno[3,2-b]thiophen-2-yl)spiro[benzo[d]imidazole-2,1′-cyclohexane] (TTBI), and its electrochemical polymerization are reported. Electrochemical and spectroelectrochemical studies of the polymer were investigated. The high optical transparency and low coloration efficiency during oxidation and reduction processes make the polymer a great candidate for hole-injection layers in light-emitting diodes and photovoltaic devices as well as counter electrodes for electrochromic devices.