新型机械解理方法在二维材料研究中的应用

自从石墨烯被发现以来，机械解理技术已经成为制备高质量二维材料的重要方法之一，在二维材料本征物性的研究方面展现出了独特的优势.然而传统机械解理方法存在明显的不足，如制备效率低、样品尺寸小等，阻碍了二维材料领域的研究进展.近些年我们在机械解理技术方面取得了一系列的突破，独立发展了一套具有普适性的新型机械解理方法.这种新型机械解理方法的核心在于通过改变解理过程中的多个参数，增强层状材料与基底之间的范德瓦耳斯相互作用，从而提高单层样品的产率和面积.本文着重以石墨烯为例，介绍了该技术的过程和机理.相比于传统机械解理方法，石墨烯的尺寸从微米量级提高到毫米量级，面积提高了十万倍以上，产率大于95%，同时石墨烯依然保持着非常高的质量.这种新型机械解理方法具有良好的普适性，目前已经在包括MoS₂，WSe₂，MoTe₂，Bi2212等几十种材料体系中得到了毫米量级以上的高质量单层样品.更重要的是，在解理过程中，通过调控不同的参数，可以在层状材料中实现一些特殊结构的制备，如气泡、褶皱结构等，为研究这些特殊材料体系提供了重要的物质保障.未来机械解理技术还有很多值得深入研究的科学问题，该技术的突破将会极大地推动二维材料领域的研究进展.

Applications of new exfoliation technique in study of two-dimensional materials

Since the discovery of graphene, mechanical exfoliation technology has become one of the important methods of preparing high-quality two-dimensional (2D) materials. This technology shows some unique advantages in the study of the intrinsic properties of 2D materials. However, traditional mechanical exfoliation method also has some obvious deficiencies, such as low yield ratio and small size of the resulting single-or few-layer flakes, which hinders the research progress in the field of 2D materials. In recent years, we made a series of breakthroughs in mechanical exfoliation technology, and independently developed a new type of mechanical exfoliation method with universality. The core of this new method is to enhance the van der Waals interaction between the layered material and the substrate by changing multiple parameters in the exfoliation process, thereby increasing the yield ratio and area of the monolayer. Taking graphene for example, we can now increase the size of graphene from micron to millimeter, increase over 100000 times in area, and yield ratio more than 95%, in the meantime graphene still maintains very high quality. This new mechanical exfoliation method shows great universality, and high-quality monolayer flake with a size of millimeters or more has been obtained in dozens of layered material systems including MoS₂, WSe₂, MoTe₂, and Bi2212. More importantly, some special structures can be fabricated by optimizing exfoliation parameters, such as bubble and wrinkle structures, which paves the way for the study of these special material systems. Many scientific problems are still worth exploring in the mechanical exfoliation technology, and the breakthrough of this technology will greatly promote the research progress in the field of 2D materials.