Effect of Dithienopyrrole Unit on Electrochromic and Optical Properties of Benzotriazole‐Based Conjugated Polymers

Abstract

AbstractA series of benzotriazole (BTz)‐ and dithienopyrrole (DTP)‐based three polymers; poly[2‐(2‐dodecyl‐2H‐benzo[d][1,2,3]triazol‐4‐yl)‐4‐hexyl‐4H‐dithieno[3,2‐b:2′,3′‐d]pyrrole] (P1), poly[2‐ (5‐(2‐dodecyl‐7‐(thiophen‐2‐yl)‐2H‐benzo[d][1,2,3]triazol‐4‐yl)thiophen‐2‐yl)‐4‐hexyl‐4H‐dithieno[3,2‐b:2′,3′‐d]pyrrole] (P2), and poly[2‐(5‐(2‐dodecyl‐7‐(4‐hexylthiophen‐2‐yl)‐2H‐benzo[d][1,2,3]triazol‐4‐yl)‐3‐hexylthiophen‐2‐yl)‐4‐hexyl‐4H‐dithieno[3,2‐b:2′,3′‐d]pyrrole] (P3) was synthesized via Stille coupling. To investigate the effect of the π‐bridges on the electrochromic properties of BTz‐based polymers, thiophene and 3‐ hexylthiophene was incorporated between BTz and DTP moiety. Different π‐bridges affected the HOMO and LUMO energy levels, coloration efficiency, switching time, and optical contrast.