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

Frey, Laura; Pöhls, Jonas Fredrik; Hennemann, Matthias; Mähringer, Andre; Reuter, Stephan; Clark, Timothy; Weitz, Ralf Thomas und Medina, Dana Dina (2022): Oriented Thiophene-Extended Benzotrithiophene Covalent Organic Framework Thin Films: Directional Electrical Conductivity. In: Advanced Functional Materials, Bd. 32, Nr. 47

Abstract

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 and BTT TTTBA, with surface areas as high as 932 and 1200 m(2) g(-1), respectively. Oriented thin films are grown successfully on different substrates, as indicated by grazing incidence diffraction (GID). Room-temperature in-plane electrical conductivity of up to 10(-4) S m(-1) is measured for both COFs. Temperature-dependent electrical conductivity measurements indicate activation energies of approximate to 123.3 meV for BTT TTA and approximate to 137.5 meV for BTT TTTBA and trap-dominated charge transport via a hopping mechanism for both COFs. Moreover, conductive atomic force microscopy reveals directional and defect-dominated charge transport in the oriented BTT COF films with a strong preference for the in-plane direction within the molecular 2D-planes. Quantum mechanical calculations predict BTT TTTBA to conduct holes and electrons effectively in both in-plane and out-of-plane directions. In-plane, charge carrier transport is of hopping character where the triazine cores represent the barrier. Out-of-plane, a continuous charge-carrier pathway is calculated that is hampered by an imposed structural defect simulated by a rotated molecular COF layer.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Chemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 1616-301X
• Sprache: Englisch
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 491502892