Structural design and enhanced electrochromic properties of thiophene-based covalent organic framework

Covalent organic framework (COF) materials are a class of porous organic polymers with crystal structures connected through strong covalent bonds. Due to the diversity as well as designability of their structural units, the framework structure can be precisely regulated at the atomic level through the combination of virus-active building units. In particular, the advantages of COF materials, such as designable space structure, regular pore structure, high specific surface area, low density, high thermal stability, and chemical stability, make it one of the ideal materials in the field of optoelectronic materials. In this paper, a series of imine-linked COF materials were synthesized by the solvothermal method via introducing functional groups to modify and construct a donor-acceptor (D-A) structure, and selecting aldehydes containing bithiophene groups as the main active monomer and three different nitrogen-containing functional monomers. Through testing, characterization, and comparison of the three materials, the effectiveness of the structural design method in improving the electrochromic and electrochemical properties of COFs has been proven. Finally, we discussed the current challenges that COF materials faced and explored their potential applications in other areas.