New designing for nanostructured 2D materials and 2D superlattices

Abstract

As the most remarkable candidate for the next-generation electronics, two-dimensional (2D) materials have attracted much interest. Recently in a letter in Nature Materials, Professor David A. Muller and Lain-Jong Li and their cooperators reported the direct synthesis of one-dimensional (1D) MoS 2 channels embedded in 2D WSe 2 monolayers through a dislocation-catalyzed strategy [1]. They demonstrated that 1D MoS 2 channels of subnanometer widths were formed in the second-step of a two-step chemical vapor deposition (CVD) growth of the lateral WSe 2 /MoS 2 heterostructures. The root cause lies in the exposure of the as-generated 5|7 member ring dislocations along the sharp grain boundaries or implanted in WSe 2 to the Mo and S atmosphere. Through atomic resolution annular dark-field scanning transmission electron microscopy (ADF-STEM) and molecular dynamics (MD) simulations, a conclusion was drawn that the higher reactivity in the core of the misfit dislocations induced the insertion of Mo and S atoms and such dislocations were pushed away from the ordinary dislocations to form 1D channels (Fig. 1). Moreover, a 1D MoS 2 nanowire of~1 nm long could be obtained from the periodic dislocation along the boundary of two WSe 2 grains. The work could provide with the inspiration of the synthesis of 1D channels based on the substrate of defects. That is, different channels based on 2D materials could be fabricated through chemical methods which prevent from the impurities caused by lithography. It is essential for a device to simplify the constructing process in order to reduce the introduction of impurities. According to this work, the substrate design is critical to the material fabrication.Till now, plenty of substrate-designing strategies have been generally utilized to fabricate nanostructured 2D materials or superlattices. Here, the substrates refer not only to metals, SiO 2 /Si, mica, sapphire, but also to edges, grains or even defects of 2D materials. Thus, CVD growth for the synthesis of nanostructured 2D materials and superlattices lies most on the substrate designing. There have been a series of methods to design metal or non-

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Self-Assembly of Ultrathin Nanocrystals to Multidimensional Superstructures

“…Such superstructures behave as an outstanding medium for light propagation. , For instance, highly ordered 2D superstructures composed of gold or silver NCs have always attracted the attention of researchers for their utilization in solar energy conversion and plasmonic devices . A handful of tools and routes have been established for construction of 2D NC-based assemblies for a variety of applications, which include Langmuir–Blodgett technique (LBT), templated assembly, , solution-based synthesis of assembled structures, evaporation driven assembly, etc. The direct defectless arrangement of UTNCs on functional surfaces can be obtained by an epitaxial self-assembly method through interfacial modifications, as reported by Lin et al They used layered hybrid perovskite (LHP) materials as substrates and CTAB covered Au NCs as building blocks to construct 2D arrays on the LHP surface.…”

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