Quasi-Two-Dimensional Luminescent Silicon Nanosheets

Abstract

Although predicted to be stable under ambient conditions, the experimental synthesis of silicenethe twodimensional silicon analogue of graphenehas been a great challenge. Here, we report the preparation of scalable quantities of crystalline nanosheets of two-dimensional silicon by simple topochemical exfoliation of layered Zintl phases. The simple process leads to the formation of stacked layers of 2D Si nanosheets which are arbitrarily surface terminated with oxygen, hydrogen, hydroxide, and other ligands. The nanosheets exhibit strong room-temperature photoluminescence, and their overall spectroscopic characteristics closely resemble other forms of silicon nanocrystals. Remarkably, the pelletized nanosheets exhibit significantly high Hall mobility even in the absence of any doping or surface treatment, which is better than the reported values of doped Si nanosystems. Such ensembles of two-dimensional nanosheets of silicon bear the signature of exotic electronic properties and represent important building blocks in two-dimensional electronics along with potential applications in solar cells, next-generation thermoelectric materials, and sensors.

Silicene Quantum Dots Confined in Few-Layer Siloxene Nanosheets for Blue-Light-Emitting Diodes

“…The optical bandgap of about 3.14 eV (absorption edge at about 395 nm) is consistent with the estimated direct bandgap of 3.1 eV. 45 The optical bandgap (E g ) of the QD− siloxene based on the UV−vis absorption spectrum (Figure S4) was calculated and linearly extrapolated to zero to obtain the optical bandgap. This includes a direct transition (E d = 3.01 eV) and an indirect transition (E i = 2.37 eV), respectively, both being larger than that of bulk silicon crystal (1.1 eV).…”

Ultra‐Large Sized Siloxene Nanosheets as Bifunctional Photocatalyst for a Li‐O2 Battery with Superior Round‐Trip Efficiency and Extra‐Long Durability

“…The scanning electron microscopy (SEM) images show that the prepared siloxene NSs have loose layered structure and nanosheet characteristic with relatively uniform size (Figure S3). From the optical microscope image, the entire lateral dimension of siloxene can be clearly observed and it reaches up to about 63 mm, obviously larger than that reported analogous materials, [15] suggesting siloxene NSs with larger size can be prepared by this modified topochemical exfoliation reaction (Figure 1 d). Furthermore, the transparent and smooth morphology can be observed from transmission electron microscopy (TEM) image, indicating the prepared siloxene NSs have an ultra-thin nanosheet shape (Figure 1 e).…”

“…In the Fourier transform infrared (FT-IR) spectrum of siloxene NSs, some evident sharp and broad peaks at 459 cm À1 , 867 cm À1 , 1045 cm À1 , and 2140 cm À1 are found, they are ascribed to the vibrations of n(Si-Si), n(Si-H), n(Si-O-Si), and n(OSi 2 SiÀH) respectively, suggesting that the exfoliated siloxene NSs possesses a Kautsky-type structure (Figure 1 b). [14,15] As shown in the schematic diagram of Figure 1 c, this Kautskytype siloxene displays a graphene-like Si 6 rings structure via a closed connection of Si-O-Si bridge, and ended with -H and -OH. The scanning electron microscopy (SEM) images show that the prepared siloxene NSs have loose layered structure and nanosheet characteristic with relatively uniform size (Figure S3).…”

Silicene, Siloxene, or Silicane? Revealing the Structure and Optical Properties of Silicon Nanosheets Derived from Calcium Disilicide

“…Previous work determined a PLQY of 9%. 17 Further experimental investigations on the influence of terminal SiOH and SiCl groups are needed to gain a better understanding of the origin of emission. Figure 4c shows the band structure and projected density of states (pDOS) of silicane.…”