Electrochromic (EC) materials with a dark-to-transmissive switch have great applications in optical communications, infrared wavelength detectors for spacecraft, and infrared camouflage coatings. However, such electroactive materials with high stability and cyclability are rare. Considering the advantages of the donor-acceptor approach (wide-range tuneable band position) and porous two-dimensional (2D) covalent organic framework (COF, well-ordered crystalline framework with stable structure and high surface area), in this work we constructed an extended delocalised π-electron layered dark purple EC-COF-1 by reacting the donor N,N,N′,N′-tetrakis(p-aminophenyl)-p-benzenediamine (TPBD) with the acceptor 2,1,3-benzothiadiazole-4,7-dicarboxaldehyde (BTDD). A sandwiched device made of EC-COF-1 exhibits the two-band bleaching (370 nm and 574 nm) in the visible region and becomes transparent under the applied potential with an induced absorption centring at 1400 nm. This discovery of a stable dark-to-transmissive switch in COF might open another door for their application in many EC devices for various purposes.

具有从暗到透射的开关的电致变色（EC）材料在光通信，航天器的红外波长检测器和红外伪装涂层中具有广泛的应用。然而，这种具有高稳定性和可循环性的电活性材料很少。考虑到施主-受主方法（宽范围可调节的带位置）和多孔二维（2D）共价有机骨架（COF，结构稳定且表面积大的有序晶体骨架）的优势，我们构建了这项工作通过使供体N，N，N'，N'-四（对氨基苯基）-p反应，扩展的散布的π电子层状深紫色EC-COF-1-苯二胺（TPBD）和受体2,1,3-苯并噻二唑-4,7-二甲醛（BTDD）。由EC-COF-1制成的夹层器件在可见光区域呈现两波段漂白（370 nm和574 nm），并且在施加的电势下变得透明，并以1400 nm为中心吸收。COF中稳定的暗-透射开关的这一发现可能为它们在各种用途的EC设备中的应用打开了另一扇门。