Quasi-Two-Dimensional Luminescent Silicon Nanosheets

Although predicted to be stable under ambient conditions, the experimental synthesis of silicene—the two-dimensional 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.