Electrochemical synthesis, characterization and electrochromic properties of indan and 1,3-benzodioxole-based poly(2,5-dithienylpyrrole) derivatives

Indan and 1,3-benzodioxole groups were introduced to the central pyrrole ring of the dithienylpyrrole-based conducting polymers backbone, which are denominated as PIND and PMDOB, respectively. The two series of dithienylpyrrole-based polymers were electrochemically synthesized, and the cyclic voltammograms showed the redox properties of electrochemically prepared films deposited at various scan rates. Spectroelectrochemical investigations conducted in this study showed that PIND and PMDOB films are yellowish-green and yellow color, respectively, in the neutral state; they can be reversibly oxidized and reduced and this is accompanied by obvious color changes. Maximum optical contrast (ΔTmax) of the P(IND-co-perylene) s and P(MDOB-co-perylene) s films were measured as 60.7 % at 932 nm and 64.8 % at 962 nm, respectively, in an ionic liquid solution, and the maximum coloration efficiency (η) of P(IND-co-perylene)s and P(MDOB-co-perylene)s films were calculated to be 199.2 and 209.7 cm2 C−1, respectively, in an ionic liquid solution. Electrochromic devices (ECD) based on PIND and PMDOB as anodic polymers and poly(3,4-(2,2-diethylpropylenedioxy) thiophene) (PProDOT-Et2) as cathodic polymer were constructed. PIND/PProDOT-Et2 ECD showed a high ΔTmax (33.1%) at 582 nm and satisfactory redox stability, whereas PMDOB/PProDOT-Et2 ECD showed a high coloration efficiency (375.9 cm2 C−1) and satisfactory optical memories.