Effect of different exfoliation solvents on the saturable absorption properties of germanene and silicene nanosheets prepared by the liquid-phase exfoliation

Abstract

Germanene and silicene, as graphene analogs of germanium and silicon, have similar structures and properties to graphene, exhibiting exciting nonlinear optical absorption properties. Herein, 2D germanium nanosheets and 2D silicon nanosheets were successfully prepared by liquid-phase exfoliation method using ethanol, isopropanol, and N-methylpyrrolidone as exfoliation solvents, respectively. The dual-arm detection technique was used to systematically research the saturable absorption properties of the nanosheets prepared with different exfoliation solvents from the same material under the excitation of a picosecond pulsed laser. The nonlinear experiment results show that the saturable absorption properties of 2D germanium nanosheets and 2D silicon nanosheets are affected by different exfoliation solvents, and these influences from different exfoliation solvents have their advantages and disadvantages. In addition, the difference in saturable absorption properties of germanium nanosheets and silicon nanosheets under the same experimental conditions is compared. The saturable absorption behavior of germanium nanosheets in the near-infrared band is better than that in the visible band, while the silicon nanosheets have stronger saturable absorption behavior in the visible band. Both germanium nanosheets and silicon nanosheets exhibit superior SA properties, which have a wide range of application prospects in generating ultrashort pulses in ultrafast lasers as saturable absorbers. Our work provides a new idea for the study of nonlinear absorption properties of 2D materials and provides a reference and basis for further optimization and improvement of the properties parameters of saturable absorbers. Additionally, it inspires further research on the nonlinear absorption properties of semiconductor materials.