Novel poly(2,5-dithienylpyrrole) (PSNS) derivatives functionalized with azobenzene, coumarin and fluorescein chromophore units: spectroelectrochemical properties and electrochromic device applications

摘要

Three novel 2,5-dithienylpyrrole (SNS) derivatives containing strong chromophore units such as azobenzene, coumarin and fluorescein were synthesized to investigate the effects of chromophore substituents on the electrochemical and spectroelectrochemical properties of resulting polymers. Electrochemical and optoelectronic characteristics of the homopolymers, poly(1-(2-(4-(phenyldiazenyl)phenoxy)ethyl)-2,5di(thiophen-2-yl)-1H-pyrrole) (PTPTAz), poly(4-(2-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)ethoxy)-2H-chromen-2-one) (PTPTCo) and poly(methyl 2-(6-(2-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) ethoxy)-3-oxo-3H-xanthen-9-yl) benzoate) (PTPTFlo), were investigated in detail. The combination of a strong chromophore pendant group with a poly(2,5-dithienylpyrrole) (PSNS) backbone significantly influences the electronic and optoelectronic behaviors of conducting polymers. PTPTAz and PTPTCo exhibited different colors in their neutral and oxidized states while PTPTFlo showed a yellow color in all states. The optical band gap (E-g) values of PTPTAz, PTPTCo and PTPTFlo films were calculated as 2.81 eV, 2.44 eV and 2.31 eV respectively. Moreover, a PTPTFlo/PEDOT based dual type solid state electrochromic device (ECD) was constructed. The ECD exhibited quite good long-term stability with reasonable optical memory performance under ambient conditions.