A 2,5-di(2-thienyl)thieno[3,2-b]thiophene (dTT)-containing homopolymer (PdTT) and four dTT-containing copolymers (P(dTT-co-bTp (2,2′-bithiophene)), P(dTT-co-TF), P(dTT-co-CPdT) and P(dTT-co-CPdTK)) were polymerized using electrochemical method and their electrochromic switching properties were explored. dTT shows lower onset oxidized potential (E_onset) than that of bTp, conjecturing that dTT displays more extended conjugated degree than that of bTp ring. PdTT film presents camel, olive green, and dark blue at 0.0, 0.8 and 1.0 V, respectively. Colorful-to-colorless switching investigations of polymeric films display that P(dTT-co-bTp) has high △T (41.3% at 1070 nm) and η (149.4 cm²/C at 1070 nm) in 0.2 M LiClO₄/ACN/DCM solution. Five dual-layer complementary electrochromic devices based on PdTT, P(dTT-co-bTp), P(dTT-co-TF), P(dTT-co-CPdT) or P(dTT-co-CPdTK) as the anodic layer and PEDOT-PSS as the cathodic layer are assembled. P(dTT-co-TF)/PEDOT-PSS ECD exhibits high △T (44.7% at 680 nm) and satisfactory electrochemical redox stability, while P(dTT-co-CPdT)/PEDOT-PSS ECD displays high η (656.5 cm²/C at 686 nm) and rapid switching time (≤ 0.9 s). On the basis of these findings, the present work offers new structural insights for significant design of large contrast and multicolored electrochromic electrodes.

Background: The thieno[3,2-b]thiophene (TT) unit is a fused heterocyclic ring, its coplanar structure and electron-donating ability can enhance carrier transporting properties of polymer chain. A 2,5-di(2-thienyl)thieno[3,2-b]thiophene (dTT) unit displays more extended conjugated degree than that of bTp, it is interesting to explore the multichromic behaviors of five dTT-based polymers and their corresponding ECDs upon applying various potentials.

Methods: A dTT-containing homopolymer (PdTT) and four dTT-containing copolymers (P(dTT-co-bTp), P(dTT-co-TF), P(dTT-co-CPdT) and P(dTT-co-CPdTK)) are polymerized using electrochemical method. The spectral properties, kinetic characterizations, open-circuit memory, and electrochemical redox stability of PdTT/PEDOT-PSS, P(dTT-co-bTp)/PEDOT-PSS, P(dTT-co-TF)/PEDOT-PSS, P(dTT-co-CPdT)/PEDOT-PSS and P(dTT-co-CPdTK)/PEDOT-PSS ECDs are systematically studied.

Significant Findings: The present work offers new structural insights for significant design of large contrast and multicolored electrochromic electrodes.

一种含 2,5-二（2-噻吩基）噻吩并 [3,2- b ] 噻吩 (dTT) 的均聚物 (PdTT) 和四种含 dTT 的共聚物（P(dTT- co -bTp (2,2'-bithiophene) ))、P(dTT- co- TF)、P(dTT- co- CPdT) 和 P(dTT- co- CPdTK)) 使用电化学方法聚合，并探索了它们的电致变色开关特性。dTT 显示出比 bTp更低的起始氧化电位（E _onset），推测 dTT 显示出比 bTp 环更大的共轭度。PdTT 薄膜分别在 0.0、0.8 和 1.0 V 时呈现驼色、橄榄绿和深蓝色。聚合物薄膜的有色到无色转换研究表明 P(dTT- co- bTp) 具有高 △0.2 M LiClO ₄ /ACN/DCM 溶液中的T（1070 nm 处为 41.3%）和η  （149.4 cm ² /C 处 1070 nm）。五种基于PdTT、P(dTT- co- bTp)、P(dTT- co- TF)、P(dTT- co- CPdT)或P(dTT- co- CPdTK)作为阳极层的双层互补电致变色器件和作为阴极层的 PEDOT-PSS 组装在一起。P(dTT- co -TF)/PEDOT-PSS ECD 表现出高 △ T (44.7% at 680 nm) 和令人满意的电化学氧化还原稳定性，而 P(dTT- co -CPdT)/PEDOT-PSS ECD 表现出高η (656.5 cm ²/C 在 686 nm) 和快速切换时间 (≤ 0.9 s)。基于这些发现，本工作为大对比度和多色电致变色电极的重要设计提供了新的结构见解。

背景：噻吩并[3,2- b ]噻吩(TT)单元是稠合杂环，其共面结构和给电子能力可以增强聚合物链的载流子传输性能。2,5-二（2-噻吩基）噻吩并[3,2- b ]噻吩（dTT）单元比bTp显示出更多的共轭度，探索五种基于dTT的聚合物的多色行为及其施加各种电位时对应的 ECD。

方法：含DTT-A均聚物（PDTT）和四个含DTT的共聚物（P（DTT-共-bTp），P（DTT-共-TF），P（DTT-共-CPdT）和P（DTT-共- CPdTK)) 使用电化学方法聚合。的光谱特性，动力学表征，开路存储器，和PDTT / PEDOT-PSS，P（DTT-的电化学氧化还原的稳定性共-bTp）/ PEDOT-PSS，P（DTT-共-TF）/ PEDOT-PSS，P (dTT- co -CPdT)/PEDOT-PSS 和 P(dTT- co -CPdTK)/PEDOT-PSS ECDs 被系统地研究。

重要发现：目前的工作为大对比度和多色电致变色电极的重要设计提供了新的结构见解。