Oriented Covalent Organic Framework Film Synthesis from Azomethine Compounds

Strategies enabling solution processing of covalent organic framework (COF) thin films will become increasingly important as these versatile materials are integrated into a wide range of electronic and optical devices. This work highlights an approach to yield thin film synthesis of TAPA-PDA (TAPA: tris(4-aminophenyl)amine, PDA: terephthalaldehyde) and TAPB-PDA (TAPB: 1,3,5-tris(4-aminophenyl)benzene) imine COFs using azomethine compounds which can be drop cast onto a variety of substrates. High crystalline COF films are shown to form on various electronically-relevant substrates. Grazing incidence wide angle X-ray scattering characterization reveals COF films with a preferred horizontal orientation in the case of TAPA-PDA COF and a more mixed/vertical orientation in the TAPB-PDA COF film regardless of the substrate. As this exciting class of crystalline organic materials becomes more relevant for various device applications, solution processing techniques will be vital to take advantage of the properties of thin film COFs.

Automated summary

Strategies for solution processing of COF thin films are important for their integration into electronic and optical devices. This study demonstrates the synthesis of TAPA-PDA and TAPB-PDA imine COFs as thin films using azomethine compounds that can be deposited on a variety of substrates. The COF films exhibit high crystallinity and different orientations depending on the substrate. Solution processing techniques will be vital for utilizing the properties of thin film COFs as they become more relevant for device applications.