Oriented Thiophene‐Extended Benzotrithiophene Covalent Organic Framework Thin Films: Directional Electrical Conductivity

The synthesis of covalent organic frameworks (COFs) based on a novel thiophene-extended benzotrithiophene (BTT) building block is described, which in combination with triazine-based amines (1,3,5-triazine-2,4,6-triyl)trianiline (TTA) or (1,3,5-triazine-2,4,6-triyl)tris(([1,1´-biphenyl]-4-amine)) (TTTBA)) affords crystalline, and porous imine-linked COFs, BTT TTA TTTBA, surface areas as high 932 1200 m2 g−1, respectively. Oriented thin films are grown successfully different substrates, indicated by grazing incidence diffraction (GID). Room-temperature in-plane electrical conductivity up to 10−4 S m−1 measured for both COFs. Temperature-dependent measurements indicate activation energies ≈123.3 meV ≈137.5 TTTBA trap-dominated charge transport via hopping mechanism Moreover, conductive atomic force microscopy reveals directional defect-dominated the oriented COF strong preference direction within molecular 2D-planes. Quantum mechanical calculations predict conduct holes electrons effectively out-of-plane directions. In-plane, carrier character where triazine cores represent barrier. Out-of-plane, continuous charge-carrier pathway calculated that hampered an imposed structural defect simulated rotated layer.