Wrap‐Around Core–Shell Heterostructures of Layered Crystals

Abstract

Engineered heterostructures create new functionality by integrating dissimilar materials. Combining different 2D crystals naturally produces two distinct classes of heterostructures, vertical van der Waals (vdW) stacks or 2D sheets bonded laterally by covalent line interfaces. When joining thicker layered crystals, the arising structural and topological conflicts can result in more complex geometries. Phase separation during one‐pot synthesis of layered tin chalcogenides spontaneously creates core–shell structures in which large orthorhombic SnS crystals are enclosed in a wrap‐around shell of trigonal SnS2, forcing the coexistence of parallel vdW layering along with unconventional, orthogonally layered core–shell interfaces. Measurements of the optoelectronic properties establish anisotropic carrier separation near type II core–shell interfaces and extended long‐wavelength light harvesting via spatially indirect interfacial absorption, making multifunctional layered core–shell structures attractive for energy‐conversion applications.

Self-organized twist-heterostructures via aligned van der Waals epitaxy and solid-state transformations

“…Figure 7d, e shows Raman linescans of as-grown few-layer and ultrathin SnS flakes on MoS 2 . Uniform modes across the SnS flakes confirm their single-crystallinity 48 . Representative spectra show the characteristic B 3g and A g modes of SnS along with intense E 1 2g and A 1g peaks of the MoS 2 substrate (Fig.…”

“…λ denotes the wavelength of the stripe moiré pattern generated between the SnS and SnS 2 lattices (see also Supplementary Fig. 1) 48 .…”

“…2). An alternative source of excess sulfur is the presence of S-rich minority phases in the nominally pure SnS precursor powder, shown in recent work to spontaneously produce layered SnS-SnS 2 core-shell heterostructures on mica vdW substrates 48 . Both the release of S from the SnS 2 substrate and the supply of excess S from the precursor are consistent with the limited T -range in which the spontaneous SnS → t-SnS 2 conversion is observed, as supported by DFT (Supplementary Fig.…”

Realization of Large Scale, 2D van der Waals Heterojunction of SnS2/SnS by Reversible Sulfurization

“…[42,47,49] The spontaneous heterostructure formation of few-layer SnS 2 over SnS was also reported. [48] However, none of these works has demonstrated a reversible transition, although one may get hints from previous works that this is possible. We have demonstrated by the experiment that such reversible transition cycles can be repeated for many times, by simply annealing with the sulfur vapor pressure ON/OFF in the same experiment.…”

Band Structure and Intersubband Transitions of Three-Layer Semiconductor Nanoplatelets

“…The use of different semiconductors and the construction of heterojunctions significantly expand the scope of nanostructure design, allowing one, for example, to localize electrons and holes in certain parts of nanostructure to enhance the quantum yield of photoluminescence [26,27] or to increase the spatial separation of charge carriers for photovoltaic applications [28,29]. The development of nanotechnology has made possible the synthesis of nanoscale heterostructures of various geometries, including chiral quantum dots, layered nanoplatelets, tetrapods, and anisotropic nanorods [30][31][32]. Core/shell nanostructures, where one material (core) is isolated while another (shell) is exposed to the environment, are of particular practical importance [33][34][35].…”