Low-potential electrosynthesis of a novel nitrogen analog of PEDOT in an ionic liquid and its optoelectronic properties

• The low-potential polymerization of N-methyl-3,4-dihydrothieno[3,4-b][1,4]oxazine into PMDTO was reported.
• PMDTO had favorable electroactive, good thermal stability, and excellent electrochemical stability.
• PMDTO provided an optical band gap of about 1.6 eV.
• PMDTO switching from slight blue (oxidized) to dark blue (reduced) and with good optical contrast (24.0%).

ABSTRACTIn this study, the electropolymerization of a novel methyl substituted unsymmetrical nitrogen analog of 3,4-ethylenedioxythiophene (EDOT), N-methyl-3,4-dihydrothieno[3,4-b][1,4]oxazine (MDTO) in air and moisture stable ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) was reported. Electrochemical study demonstrated that MDTO exhibited a significantly lowered oxidation potential (0.51 V) and the resultant PMDTO films possessed favorable electroactivity and excellent electrochemical stability and could be further doped by cyclic voltammetry to substantially improve its doping level. The polymers also provided an optical band gap of about 1.6 eV, switching from slight blue in the oxidized form to dark blue in the reduced form with good optical contrast (24.0%), moderate response time (6.8 s) and excellent switching stability and color persistence ability.