Crystallizing Sub 10 nm Covalent Organic Framework Thin Films via Interfacial-Residual Concomitance
Ashok Kumar Mahato1,2, Saikat Bag1,2, Himadri Sekhar Sasmal1,2
1Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur 741246, India.
Journal of the American Chemical Society
|December 2, 2021
Summary
Researchers developed residual crystallization (RC) to create ultra-thin, highly crystalline covalent organic framework (COF) films. These films exhibit excellent surface area and conductivity, paving the way for advanced material applications.
Area of Science:
- Materials Science
- Nanotechnology
- Chemistry
Background:
- High-quality covalent organic framework (COF) thin films are essential for advanced applications.
- Existing synthesis methods face challenges in achieving desired crystallinity and porosity on various supports.
- Controlling film thickness and morphology is critical for performance.
Purpose of the Study:
- To develop a novel synchronized methodology for synthesizing sub-10 nm COF thin films.
- To investigate the impact of interfacial crystallization (IC) on residual crystallization (RC) kinetics.
- To explore diverse crystallization pathways (fiber-to-film and sphere-to-film) for COF thin film fabrication.
Main Methods:
- Utilized a residual crystallization (RC) technique synchronized with interfacial crystallization (IC).
- Employed two distinct crystallization pathways: fiber-to-film (F-F) and sphere-to-film (S-F).
- Grew COF thin films (TpAzo and TpDPP) on various substrates including glass, FTO, silicon, and ITO.
Main Results:
- Achieved continuous, highly crystalline, and porous COF thin films with thicknesses down to ~1.8 nm.
- Obtained a maximum surface area of 2093 m² g⁻¹ for a TpAzo COF thin film.
- Demonstrated high room-temperature conductivity, with a TpAzo film reaching 3.7 × 10⁻² mS cm⁻¹.
- Investigated the growth mechanism on substrates with varying wettability.
Conclusions:
- The residual crystallization (RC) method enables precise control over the synthesis of defect-free, sub-10 nm COF thin films.
- The developed methodology is versatile, applicable to different COF types and various substrates.
- The synthesized COF thin films exhibit promising properties for electronic and material applications due to their high conductivity and surface area.
