New, Highly Stable Electrochromic Polymers from 3,4-Ethylenedioxythiophene−Bis-Substituted Quinoxalines toward Green Polymeric Materials

Two new highly stable electrochromic polymers, poly(5,8-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2,3-di(thiophen-2-yl)quinoxaline) (PDETQ) and poly(5,8-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)quinoxaline) (PDEQ) were synthesized, and their potential use as neutral state green polymeric materials was investigated. Spectroelectrochemistry showed that both polymers reveal two distinct absorption bands as expected for this type of donor–acceptor polymer, at 410 and 660 nm for PDEQ and 405 and 780 nm for PDETQ. The colorimetry analysis revealed that while PDEQ has a green-blue color, PDETQ showed a saturated green color in the neutral state which is a unique property of conjugated polymers for the completion of the RGB color system. Both polymers have excellent switching properties with satisfactory optical contrasts and very fast switching times. In addition, via both electrochemical and spectral analyses PDETQ was proven to be an n-type dopable polymer. Outstanding optical contrasts in the NIR region, perfect stability, and fast switching times make these polymers excellent candidates for many applications like smart windows and data storage technologies. It should be noted that PDETQ is one of the few examples of neutral state green polymeric materials in literature with a relatively transmissive oxidized state, high stability, and superior switching properties. Hence, PDETQ can be a paramount choice as a green polymeric material for display applications.