Enhanced electrochromic properties of 2,6-diaminoanthraquinone and 1,3,5-triformylresorcinol (DAAQ-TFP) covalent organic framework/functionalized graphene oxide composites containing anthraquinone active unit

Conjugated covalent organic frameworks (COFs) with redox properties can be considered as conductive polymers with ordered porous structures and can be designed for photoelectric materials application. In this paper, 2,6-diaminoanthraquinone and 1,3,5-triformylresorcinol (DAAQ-TFP) COF with anthraquinone active unit was synthesized by solvothermal method for electrochromic application in a Teflon-lined autoclave. Functionalized graphene oxide (FGO) was covalently bonded with COF to improve its electrical conductivity and photoelectric properties. After the addition of FGO, the impedance of COF was reduced, and the optical contrast and cyclic stability of COF were increased. At potential windows of 2.5 V to -3.8V, the COF-FGO-2% can be switched reversible from orange to dark brown. Stability test shows that the contrast retention is 109.1% after 1800s switching, which is much higher than COF (75%). Considering the abundance of COF building units with redox activity available, it is possible to develop novel COF based electrochromic materials with rich colors.