Dimension-Dependent\nNonlinear Optical Properties of\nStanene Nanosheets

Stanene (Sn)-based materials, with a graphene-like hexagonal\nstructure,\nare now attracting considerable interest for potential applications\nin photoelectricity. However, the nonlinear optical properties of\nstanene remain largely unexplored. In this work, we prepared different\nsizes of stanene by liquid phase exfoliation and differential centrifugation\nmethods, including two-dimensional (2D) Sn nanosheets (NSs) and zero-dimensional\n(0D) Sn nanodots (NDs). Z-scan measurements reveal that 2D Sn NSs\nexhibited high saturable absorption behavior, while the 0D Sn NDs\nled to reverse saturable absorption. Femtosecond ultrafast transient\nabsorption spectra revealed that the reverse saturable absorption\nof Sn NDs is derived from a stronger excited state absorption and\nfaster exciton relaxation dynamics. This research expands the potential\napplications of stanene in laser shielding and other ultrafast photonics\ntechnologies.