Liquid Exfoliation Few-Layer SnSe Nanosheets with Tunable Band Gap

Abstract

Two-dimensional (2D) materials have recently drawn tremendous attention because of their novel properties and potential applications in high-speed transistors, solar cells, and catalysts. Few-layer SnSe is a new member of the 2D family with excellent performance in optoelectronic and thermoelectric devices. It is necessary to synthesize few-layer SnSe nanosheets in large scale for various applications. In this work, we develop a scalable liquid-phase exfoliation method to synthesize high-quality crystalline SnSe nanosheets. The morphology and microstructure of SnSe nanosheets are systematically investigated with high-resolution transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The thinnest nanosheets are bilayered. The optical absorption properties of SnSe nanosheets from near-infrared to ultraviolet light are studied. It is worth noting that the band gap of the nanosheets monotonically increases with the reduction of the nanosheet thickness. The electronic structure of SnSe nanosheets with various thicknesses is calculated by first-principles calculations, the evolution of the band gap as a function of the nanosheet thickness is confirmed, and the mechanism of the band gap evolution is discussed. Our work paves the way for the scalable synthesis of 2D SnSe with tunable optical absorption and band gap, which has potential for use in photoelectronic and photocatalytic applications.

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

“…Except directly fabricating SnSe nanosheets by the solution methods, other convenient approach to achieve SnSe nanosheets is chemical exfoliation technique taken in a solution environment 354,355,360–362. In a Teflon‐lined autoclave, the bulk SnSe is mixed with a solution containing EG and lithium hydroxide (LiOH).…”

“…Compared with the other three types of nanocrystals, SnSe nanosheets are most promising because the synthesis of SnSe nanosheets with mature techniques is much easier than the syntheses of other SnSe nanocrystals, [353] making SnSe nanosheets have full potentials as 2D/3D thermoelectric generators. [354,355] Generally, SnSe nanosheets can be described as multilayered SnSe. [356][357][358][359] Hydrothermal/Solvothermalbased solution methods are effective routes to fabricate SnSe nanosheets.…”

“…Except directly fabricating SnSe nanosheets by the solution methods, other convenient approach to achieve SnSe nanosheets is chemical exfoliation technique taken in a solution environment. [354,355,[360][361][362] In a Teflon-lined autoclave, the bulk SnSe is mixed with a solution containing EG and lithium hydroxide (LiOH). During heating the autoclave, due to the weak Van der Waals forces between SnSe layers, lithium ions (Li + ) can intercalate into these layers, separate the bulk into nanosheets with only a few layers thick.…”

Realizing High Thermoelectric Performance in n‐Type Highly Distorted Sb‐Doped SnSe Microplates via Tuning High Electron Concentration and Inducing Intensive Crystal Defects

“…[9] For the strategies of achieving high S 2 σ, resonant state doping, [10][11][12] band converging, [13][14][15][16] minority carrier blocking, [17,18] and quantum confinement [19][20][21] were designed and developed. For reducing κ, the strategies of nanostructuring, [22][23][24][25] hierarchical architecturing, [26][27][28] and nanoprecipitate inducing [29][30][31] were successfully adopted.Tin selenide (SnSe) is a typical semiconductor with a narrow bandgap of ≈0.9 eV, [32][33][34] making it a good candidate with great potentials for applications in low-cost thermoelectrics. [35][36][37] A remarkable high peak ZT of ≈2.6 at 923 K was reported in the p-type SnSe single crystals, [38] and a relative high ZT of ≈2.2 at 773 K was also achieved from the n-type Bi-doped SnSe single crystals, [39] both along their b-axes.…”

Recent advances in low‐dimensional semiconductor nanomaterials and their applications in high‐performance photodetectors

“…In addition, there are three widely studied 2D layered metal chalcogenides, 24,25,39,[51][52][53][54][55][56][57][58][59][60] including III-VI compounds (such as InSe and GaS), IV-VI compounds (such as SnS and GeSe), and V-VI compounds (such as Sb 2 S 3 , Sb 2 Se 3 , and Bi 2 S 3 ). And, IV-VII group semiconductor layered material (eg, PbI 2 and so on) also widely studied.…”