Meniscus-Guided Control of Supersaturation for the Crystallization of High Quality Metal Organic Framework Thin Films

Herein, meniscus-guided crystallization is introduced as a means to grow high quality metal organic framework (MOF) thin films. A meniscus was formed between a target substrate and a coating blade, and by adjusting various parameters such as substrate temperature and coating speed, supersaturation was precisely controlled, through which the crystallization process was finely tuned. Consequently, a densely packed intergrown MOF thin film with thickness tunability down to 450 nm was demonstrated. The individual crystals exhibited monodispersity in size. Interestingly, the use of a microstructured coating blade resulted in the change of crystal shape, attributed to the supersaturation-induced kinetically driven crystallization process. Our film growth process is large-area scalable, uses a miniscule amount of solution, and has substrate versatility. Such an insight and demonstration of MOF thin-film growth via meniscus-guided crystallization will be highly useful for the development of various MOF thin-film-based devices in the future.