Design strategies and optical applications of two-dimensional reticular framework nanosheet composites: A review

The composites of reticular framework nanosheets represent an emerging category of functional materials, which are assembled by typical reticular frameworks, metal-organic framework nanosheets (MONs) and covalent-organic framework nanosheets (CONs) with other organic/inorganic materials. The research significantly expands the scope of reticular chemistry and functional materials due to versatile physicochemical properties and promising applicability. Owing to their highly anisotropic architectures and inherent tailorable chemistry, the hybridization of 2D ultrathin reticular framework nanosheets could overcome the limitation of the 3D counterpart crystals, thereby creating new application opportunities. The development of composites based on reticular framework nanosheets with intriguing optical properties is still in its infancy. This review summarizes the recent advancements of these composites covering design strategies and multifaceted optical applications. The main strategies to construct the composites could be categorized into two routes: (I) MONs and CONs functioned as scaffolds to accommodate the nanomaterials; (II) MONs and CONs are integrated with other 1D fibers or 2D matrices to achieve the desired performance. Additionally, the representative applications of the composites were presented including the photo-sensing, lighting-emitting display and solar energy conversion. At the end of this review, the challenges and perspectives of the reticular framework nanosheet composites are proposed.