A rapid in situ synthesis of electrochromic covalent organic frameworks (EC‐COFs) was proposed by using green electrochemical interface polymerization of N,N,N’,N’‐tetrakis(p‐aminophenyl)p‐phenylenediamine (TPDA) and 2,5‐dihydroxy‐p‐phenylenedicarboxaldehyde (DHBD). The synthetized TPDA‐DHBD films exhibit stable polymorphic colour variations under different applied potentials, which can be attributed to the redox state changes of bis(triphenylamine) and imine electroactive functional groups within the COFs skeleton. TPDA‐DHBD represents markedly different electrochromisms from red to cyan due to the steric hindrance effect caused by the presence of UO22+, demonstrating the unique tunability of COFs materials. This work offers a new feasible idea for rapid EC‐COFs synthesis and tunable EC‐COFs realization.

In Situ Electrochemical Interfacial Polymerization for Covalent Organic Frameworks with Tunable Electrochromism