Two novel carbazole-3, 4-ethoxylenedioxythiophene (EDOT) derivatives containing acceptor groups such as benzonitrile and phthalonitrile were synthesized and characterized. Both the monomers could be electrochemically polymerized and form stable electroactive polymer films. Spectroelectrochemical technique were performed to investigate the electrochemical and optical changes of the resulting polymer films, multi-electrochromic properties upon different applied potentials suggested the effect of the benzonitrile and phthalonitrile units and their potential applications in electrochromic device. Furthermore, scanning electron micrographs (SEM) were used to study the microstructure morphology of polymer films. Conjugated polymers have potential applications in the fields of field effect transistors (FETs), 1,2 electrochromic devices (ECDs), 3,4 organic light emitting diodes (OLEDs) 5,6 and supercapacitors 7,8 due to their low cost synthesis, ease in tuning the electronic and optical properties and good electrochemical stability. Particularly, electrochromic polymer materials have attracted great interest thanks to their various colors with the same materials, high optical contrast ratios, fast switching ability and outstanding coloration efficiency (CE). [9][10][11][12] Recently, design and synthesis of new electrochromic polymers with better electrochromic properties and exploring the relationship between polymer structure and their performance are still the focus of this area. 13,14 Among conjugated polymers, much attention is paid to carbazole and its derivatives due to their easily modified by introduction of new groups to many sites such as (2,7-), (3,6-), and N-positions.
15-18Comparing with poly(2,7-carbazole)s, poly(3,6-carbazole)s show potential multi-color properties because of the conjugation breaks. 19,20 poly(3,6-carbazole)s based on the donor groups (thiophene, furan, selenophene) of the conjugated main chain have been investigated and show good electrochromic properties. [21][22][23][24][25] However, for almost all the reported studies, alkyl groups are introduced into the Nposition of poly(3,6-carbazole)s, few papers are about importing the acceptor units into the N-position and exploring the effects on the performance. [26][27][28] In our previous works, 29,30 D-A structure based on the 3, 6-carbazole and thiophene were studied, and the results showed that the electrochromic properties can be tuned by changing the acceptor group at N-position of carbazole. What's more, electrochromic performance can be enhanced by introducing the EDOT into the conjugated chain of polymer, implying that polymers based on 3, 6-carbazole and EDOT with D-A structure may have some specific features.In this context, two novel monomers based on 3, 6-carbazole and EDOT functionalized with benzonitrile and phthalonitrile units were synthesized and characterized. Both polymers could be electrochemically prepared on the surface of ITO / glass electrode, and their electrochemical and electrochromic properties were investigated ...