Synthesis and multi-electrochromic properties of asymmetric structure polymers based on carbazole-EDOT and 2, 5–dithienylpyrrole derivatives

Two novel asymmetric structure monomers , 3,6-Bis-(2,3-dihydro-thieno[3,4- b][1,4]dioxin-5-yl)-9-[4-(2,5-di-thiophen-2-yl-pyrrol-1-yl)-phenyl]-9H-carbazole (BDTC) and 2,7-Bis-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-5-yl)-9-[4-(2,5-di-thio phen-2-yl-pyrrol-1-yl)-phenyl]-9H-carbazole (BDDC), were designed and synthesized. Both the monomers could be electropolymerized to form the related polymer films. The electrochemical and electrochromic properties of polymer films were different from that of their homopolymers , which could be attributed to the similar copolymerization effect of asymmetric structure. Different linked positions also led to different features, PBDDC film showed more colors (orange, yellow green, green and blue) than that of PBDTC film (yellow, green and purple blue). However, after the introduction of 2, 2′-Bi(3,4-ethoxylene dioxy thiophene)(BIEDOT), the resulting copolymers exhibited similar electrochromic features(red, brown yellow, green and blue) due to the leading effect of EDOT units. Moreover, all the polymer films displayed fast switching time, reasonable optical contrast and good coloration efficiency, which made them have potential application in electrochromic devices.