Novel core-substituted naphthalene diimide-based conjugated polymers for electrochromic applications

A novel core-substituted naphthalene diimide derivative (DPyNDI-TPA) capped with electroactive triphenylamine was employed as an electroactive precursor to prepare p(DPyNDI-TPA) polymer films through in situ electropolymerization on FTO substrates. In contrast to the non-core-substituted NDI-TPA, the introduction of pyrrolidine groups endows the p(DPyNDI-TPA) films with a distinct morphology and a capability of ionization. Under an electric field, the pyrrolidine group could release an electron and combine with counterions in the electrolyte solution. Moreover, compared with the p(NDI-TPA) films, the wrapped counter anions in the p(DPyNDI-TPA) films could serve as balancing charges in electrochromic processes, which provide the film with a much better electrochromic performance ( e.g. , switching stability, coloring-bleaching speed and coloration efficiency). This meaningful design provides new concepts for the design of organic electrochromic materials and shows great prospects in optoelectrical materials. The strategic implementation of using a core-substituted naphthalene diimide derivative to electropolymerize an ionized polymer for a better electrochromic performance is proposed.