Emerging Two-Dimensional Inorganic Molecular Crystals: The Concept and Beyond

Abstract

The concept of two-dimensional (2D) inorganic molecular crystals (IMCs) was first introduced by Zhai and coauthors in 2019. In contrast to the layered structures of graphene-like 2D materials, 2D IMCs consist of tiny inorganic molecules bonded together through all-around van der Waals (vdW) interactions. Their structural peculiarities lead to some special behaviors and appealing properties in their synthesis and applications. In this Perspective, we first introduce the concept of 2D IMCs and present the very first synthesis of 2D IMCs using a surface-passivated growth approach. The special intermolecular effects between the inorganic molecules are also summarized. In addition, because of its molecular structure, a vdW film of IMCs can be facilely fabricated, which exhibits appealing potential in integrated 2D devices. More importantly, we give a general outlook for the further development of 2D IMCs with the goal of attracting more attention to this emerging research frontier.

Screening 0D Materials for 2D Nanoelectronics Applications

“…0D materials have several natural cleaving planes, that lead to 2D layers of clusters with different orientations and different lattices, depending on the symmetry of the clusters and of the 3D lattice. It is not a priori clear what will be the preferred orientation and ordering of the clusters when sputtered on top of a particular 2D material and how to control the growth mode, [ 12 ] and investigating it by first‐principles calculations is highly demanding.…”

“…[ 11 ] The authors called for theoretical studies to find more suitable 0D material candidates. [ 11,12 ]…”

“…[11] The authors called for theoretical studies to find more suitable 0D material candidates. [11,12] While 2D and 1D materials have been searched in many previous publications by screening experimental and/or computational material databases, [13][14][15][16] to the best of our knowledge, not 0D materials. While 0D materials are easily identified using the same dimensionality identification methods, many of the found materials are crystalline phases of substances that are gaseous or liquid even in atmospheric conditions, and thus not useable in the above-mentioned applications.…”

Giant Tunability of Charge Transport in 2D Inorganic Molecular Crystals by Pressure Engineering

“…It should be emphasized that here, 2DIMCs possess unique structural features and are distinct from 2D atomic crystals as well as 2D organic molecular crystals [1a, b, e] . For 2D atomic crystals, each layer is formed by atoms, which are connected by strong covalent bonds; whereas in 2DIMCs, each layer is composed of inorganic molecules, which are bonded together through weak van der Waals (vdW) force [1e] .…”

“…It should be emphasized that here, 2DIMCs possess unique structural features and are distinct from 2D atomic crystals as well as 2D organic molecular crystals [1a, b, e] . For 2D atomic crystals, each layer is formed by atoms, which are connected by strong covalent bonds; whereas in 2DIMCs, each layer is composed of inorganic molecules, which are bonded together through weak van der Waals (vdW) force [1e] . On the other hand, though 2D inorganic and organic molecular crystals are both composed of molecules, molecular volumes of inorganic molecules consisting of only a few atoms are much smaller than those of common aromatic organic molecules [7] .…”