Molecular engineering of D–A–D type thiophene-based polymers consisting of quinoline moieties for electrochromic and energy storage applications

Abstract

Three D–A–D type thiophene-based monomers (HDMQT, HDPQT and HPAQT) with different quinoline-based acceptors were prepared and further electrochemically polymerized to deposit on ITO substrates as electrodes. The conjugated polymer thin films PHDMQT, PHDPQT and PHPAQT showed efficient electrochromic and energy storage performance. Among them, PHDMQT exhibited a fast electrochromic switch with a short response time of less than 0.5 s, an optical contrast of 39%, and a high coloration efficiency of over 259 cm² C⁻¹, as well as good cycling stability. Moreover, quasi-solid state electrochromic storage devices based on the present polymers employing gel-type electrolytes were fabricated, and they exhibited distinct color-changing effects during charging and discharging cycles, which suggested their potential applications in energy saving smart windows.