Strong Interlayer Interaction for Engineering Two-Dimensional Materials

ConspectusTwo-dimensional (2D) layered materials have atomically thin thickness and outstanding physical properties, attracting intensive research in past years. To realize the applications in (opto)electronic devices, the strategies to engineer the properties of 2D materials have been widely explored, including defect engineering, in-plane strain engineering, surface modification, etc. Besides the in-plane bonding, the out-of-plane interlayer interaction is another unique degree of freedom to engineer the properties of 2D materials. Different from the well-accepted weak van der Waals interactions, some recently discovered 2D material systems display strong interlayer interaction with "covalent-like quasi-bonding". The unusually strong interlayer interaction gives rise to the dramatic evolution of physical properties with the layer number, including electronic band structure, carrier mobility, optical absorption, photoluminescence, and mechanical interlayer vibration. These results unambiguously demonstrate that the tuning of interlayer interaction via material/structure design is a powerful method to engineer 2D materials with desired physical properties for electronic and optoelectronic applications.In this Account, we focus on our recent progress in the discovery of 2D materials with strong interlayer interaction, the modulation of interlayer interaction, and the application of 2D materials with strong interlayer interaction in advanced (opto)electronics. We provide a quantitative criterion to determine the strength of interlayer interaction and discover several classes of 2D materials with strong interlayer interaction. By tuning the layer number, these 2D materials exhibit dramatic evolution of electronic, optical, and vibrational properties. The in-depth understanding of the physical origins of strong interlayer interaction provides a guideline to discover and design the unique interlayer properties in 2D materials. Furthermore, we discuss the strategies to modulate the interlayer interaction in 2D materials/heterostructures and demonstrate their promising applications in electronic and optoelectronic devices. The interlayer interaction in 2D materials can be a unique degree of freedom to modulate the physical properties of 2D material and promote the development of 2D (opto)electronic devices in the post-Moore era.