Moazzami Gudarzi Mohsen, Aboutalebi Seyed Hamed
National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK.
Department of Materials, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK.
Adv Sci (Weinh). 2022 Nov;9(33):e2204001. doi: 10.1002/advs.202204001. Epub 2022 Oct 17.
Van der Waals (vdW) integration of two dimensional (2D) crystals into functional heterostructures emerges as a powerful tool to design new materials with fine-tuned physical properties at an unprecedented precision. The intermolecular forces governing the assembly of vdW heterostructures are investigated by first-principles models, yet translating the outcome of these models to macroscopic observables in layered crystals is missing. Establishing this connection is, therefore, crucial for ultimately designing advanced materials of choice-tailoring the composition to functional device properties. Herein, components from both vdW and non-vdW forces are integrated to build a comprehensive framework that can quantitatively describe the dynamics of these forces in action. Specifically, it is shown that the optical band gap of layered crystals possesses a peculiar ionic character that works as a quantitative indicator of non-vdW forces. Using these two components, it is then described why only a narrow range of exfoliation energies for this class of materials is observed. These findings unlock the microscopic origin of universal binding energy in layered crystals and provide a general protocol to identify and synthesize new crystals to regulate vdW coupling in the next generation of heterostructures.
将二维（2D）晶体通过范德华（vdW）作用集成到功能异质结构中，已成为一种强大的工具，能够以前所未有的精度设计出具有精细调节物理性质的新型材料。通过第一性原理模型研究了控制vdW异质结构组装的分子间力，但将这些模型的结果转化为层状晶体中的宏观可观测量仍未实现。因此，建立这种联系对于最终设计出先进材料（根据功能器件特性定制成分）至关重要。在此，将vdW力和非vdW力的成分整合起来，构建一个全面的框架，该框架能够定量描述这些作用力的动态过程。具体而言，研究表明层状晶体的光学带隙具有独特的离子特性，可作为非vdW力的定量指标。利用这两个成分，进而阐述了为何仅观察到这类材料的剥离能量存在狭窄范围。这些发现揭示了层状晶体中普遍结合能的微观起源，并提供了一个通用方案，用于识别和合成新晶体，以调控下一代异质结构中的vdW耦合。
