Layer-by-layer assembly of metal-organic framework thin films: Fabrication and advanced applications

Metal-organic frameworks (MOFs) are a class of crystalline porous coordination materials, which are assembled from inorganic nodes and organic linkers. Numerous applications, such as gas storage, molecule separation, catalysis, optical sensing, and charge transport, benefit from the outstanding properties of MOF materials. More advanced applications, e.g., in the electronics and optoelectronics area, demand homogeneous and monolithic MOF thin films. Recent studies demonstrated that surface-mounted MOFs (SURMOFs) are well suited to fulfill the requirements for the integration of MOFs into devices. As a crystalline thin-film material with tunable thickness, SURMOFs have been widely used in the optimization of chromophore stacking, electrical transport, stimuli-response, etc. The fabrication of SURMOFs is carried out employing a layer-by-layer (LbL) assembly technique, and it can yield MOF thin films with a well-defined orientation, tunable thickness, and editable crystalline heterostructure. We summarize the LbL assembly methods for SURMOF fabrication and the realization of advanced SURMOF architectures, including optical and electronic applications as well as the integration of photoactive SURMOFs and SURMOF-derived materials in technical devices. We conclude with a discussion of the challenges and prediction of the future of SURMOF materials.