Detachable all-carbon-linked 3D covalent organic framework films for semiconductor/COF heterojunctions by continuous flow synthesis

New synthetic strategies are ceaselessly being explored to fabricate covalent organic frameworks (COFs) as continuous materials with controlled morphology. However, making substrate detachable thin layers of 3D COFs, which would allow for film-based applications, has turned out to be particularly difficult. Here, we developed a substrate-catalyzed synthesis in a continuous flow method that successfully realized the fabrication of crystalline detachable all-carbon-linked 3D SBFdiyne-COF films. The key element in the method is a highly controlled interfacial reaction between the Cu substrate and a base flowing over the substrate. Benefiting from the detachability and high quality of the fabricated film, an organic semiconductor/COF heterojunction was constructed, showing high current rectification performance of 104 under forward/reverse bias.