Controllable Synthesis of Atomically Thin 1T‐SnSe₂ Flakes and Its Linear Second Harmonic Generation with Layer Thickness

Abstract

As an important member of the IVA–VIA group compounds, 2D SnSe2 has emerged as a perfect platform for developing diverse applications, especially in high‐performance optoelectronic devices and data storage, etc. However, the bottom‐up synthesis of large‐area uniform, atomically thin SnSe2 crystals with controlled thicknesses has not yet been realized. Herein, we report the large‐area uniform growth of monolayer (1L), bilayer (2L), and few‐layer (FL) 1T‐SnSe2 single‐crystal flakes on mica substrates via a facile chemical vapor deposition (CVD) route. The feeding amount of Sn precursor and flow rate of hydrogen carrier are found to be the key parameters for the thickness‐controlled growth of uniform SnSe2 flakes. More intriguingly, obvious second harmonic generation (SHG) is revealed in the retained inversion symmetry structure of 1T‐SnSe2, with its intensity showing linear dependence with the thickness from monolayer to multilayers. The new findings reported herein should pave the ways for the thickness‐tunable growth of atomically thin SnSe2 crystals, and their unique optical property explorations and applications in nonlinear optics.

Achieving pH‐universal electrosynthesis of formate under industrial‐grade current density by enriched selenium vacancies

“…The existence of the E g peak demonstrated the successful synthesis of 1 T phase SnSe 2 , 28 which was consistent well with X-ray diffraction (XRD) analysis (Figure S6). 29 The HCOOH electrosynthesis performance of as-prepared SnSe 2 -180 was evaluated using a self-made three-electrode flow cell (Figure S7). Catalysts supported on a gas diffusion layer (GDL) and reacted with gas-phase CO 2 directly (Figure 2A), thus significantly improving HCOOH current density.…”

MAX‐phase Derived Tin Diselenide for 2D/2D Heterostructures with Ultralow Surface/Interface Transport Barriers toward Li‐/Na‐ions Storage

“…[ 16,17 ] As for the synthetic approaches of 2D SnSe 2 nanosheets (SSN), chemical vapor deposition (CVD) is the most widely used method due to its unique advantages on the precise control of reaction conditions, the high‐quality products, and the well‐defined layer numbers. [ 18,19 ] However, most CVD processes demand special substrates, such as SiO 2 /Si or mica, and sometimes hazardous precursors, such as tin iodide (SnI 2 ), which constrain the potentials for large‐scale production and the further design on its derived 2D heterostructures for energy storage applications.. [ 20 ]…”

“…[16,17] As for the synthetic approaches of 2D SnSe 2 nanosheets (SSN), chemical vapor deposition (CVD) is the most widely used method due to its unique advantages on the precise control of reaction conditions, the high-quality products, and the well-defined layer numbers. [18,19] However, most CVD processes demand special substrates, such as SiO 2 / Si or mica, and sometimes hazardous precursors, such as tin iodide (SnI 2 ), which constrain the potentials for large-scale production and the further design on its derived 2D heterostructures for energy storage applications.. [20] Herein, a new large-scale synthetic strategy for the growth of SnSe 2 bulk crystals is proposed by using a Sn-containing V 2 SnC carbide, a typical MAX phase (M n+1 AX n , n = 1-3, MAX), and Se powder as the starting materials, which can supply Sn atoms in a rectified way for the precise assembly of SnSe 2 with the Se vapor within the cold zone. This method is facile for massive growth of large-size SnSe 2 crystals without any special substrate.…”

Misfit Layer Compounds as Ultratunable Field Effect Transistors: From Charge Transfer Control to Emergent Superconductivity

“…We consider the layered indirect gap semiconductor 1TSnSe 2 that can be exfoliated and synthesized in single layer form . The electronic structure of single-layer SnSe 2 is shown in Figure (red line).…”

“…We consider the layered indirect gap semiconductor 1TSnSe 2 that can be exfoliated and synthesized in single layer form. 26 The electronic structure of single-layer SnSe 2 is shown in Figure 5 (red line). The conduction band is formed by an isolated band with a Van Hove singularity point at K. A maximum in the density of states occurs at the energy corresponding to the band flattening.…”