Recent Advances in Two-Dimensional Materials beyond Graphene

Abstract

The isolation of graphene in 2004 from graphite was a defining moment for the "birth" of a field: two-dimensional (2D) materials. In recent years, there has been a rapidly increasing number of papers focusing on non-graphene layered materials, including transition-metal dichalcogenides (TMDs), because of the new properties and applications that emerge upon 2D confinement. Here, we review significant recent advances and important new developments in 2D materials "beyond graphene". We provide insight into the theoretical modeling and understanding of the van der Waals (vdW) forces that hold together the 2D layers in bulk solids, as well as their excitonic properties and growth morphologies. Additionally, we highlight recent breakthroughs in TMD synthesis and characterization and discuss the newest families of 2D materials, including monoelement 2D materials (i.e., silicene, phosphorene, etc.) and transition metal carbide- and carbon nitride-based MXenes. We then discuss the doping and functionalization of 2D materials beyond graphene that enable device applications, followed by advances in electronic, optoelectronic, and magnetic devices and theory. Finally, we provide perspectives on the future of 2D materials beyond graphene.

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…As an important group of layered materials, GIVMCs have strong covalent bonding existing in plane along the 2D direction while the weak van der Waals force dominating out of plane similar with other 2DLMs 2, 4. In general, GIVMCs have been classified into two groups according to their chemical compositions: MX (SiC,89 SiS,90 GeS,91, 92 GeSe,93, 94, 95, 96 SnS,97, 98, 99 SnSe,100, 101, 102, 103, 104, 105, 106, 107, 108 SnTe,109, 110) and MX 2 (GeS 2 ,111 GeSe 2 ,112, 113, 114, 115 SnS 2 ,72, 116, 117, 118 SnSe 2 73, 119, 120, 121, 122, 123, 124, 125).…”

“…The electronic band diagram of graphene shows a linear energy dispersion at the K point, thus resulting in a gapless band structure 1, 20, 133, 134, 135, 136, 137, 138, 139. Consequently, the gapless band structure of graphene results in the low controllability of electronics and inferior photoresponsivity,2, 5, 27, 134 which impedes the applications in electronics and optoelectronics. The electronic structures of typical GIVMCs are summarized in Table 1.…”

“…These 2DLMs possess different properties such as electronic structures, large specific surface area, and the quantum confinement of electrons due to the ultrathin thickness compared with their bulk counterparts, thus paving a new way for the next generation electronic, optical, optoelectronic, and flexible systems 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. Taking graphene, for example, the single layer of graphite has promising applications in broadband optical modulators16 and ultrafast high frequency photosensors17 due to the linear dispersion of the Dirac electrons 18.…”

Transparent, conductive solution processed spincast 2D Ti2CTx (MXene) films

“…Since the discovery of single-layered graphene and its remarkable properties, there has been a groundswell of interest in two-dimensional, 2D, materials [1][2][3][4][5][6][7][8][9][10][11]. The desirable optical and electronic behavior resulting from reduced dimensionality is even further enriched by the opportunity for co-assembly of different 2D materialtypes to form novel heterojunctions [12].…”

Photogeneration and Mobility of Charge Carriers in Atomically Thin Colloidal InSe Nanosheets Probed by Ultrafast Terahertz Spectroscopy

“…The tunability of the optical and electronic properties by variation of material thickness and composition offers promising prospects for application in optoelectronic devices [1][2][3][4] with high charge mobilities 5 and efficient charge carrier multiplication. 6 InSe is a layered 2D van der Waals structure, which has been successfully applied as highly responsive (87 µs) photodetector 7 and in field-effect transistors (FETs) with high charge mobility (µ = 1000 cm 2 /Vs).…”