Xiao Qi, Ma Bo, Fei Xian, Liu Duan-Wu, Zhai Xin-Ping, Li Xiang-Yang, Xiao Ming-Jun, Peng Yong, Wang Qiang, Zhang Hao-Li
State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Special Function Materials and Structure Design, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.
Key Laboratory of Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, 730000, P. R. China.
Nanoscale Horiz. 2021 Oct 25;6(11):918-927. doi: 10.1039/d1nh00253h.
Low dimensional tellurium is currently of great interest for potential electronic applications due to the experimentally observed Weyl fermions and the excellent carrier mobility, on/off ratios and current-carrying capacity in devices. However, the optical properties of Te nanostructures are not well explored, especially in the field of nonlinear optics. Here, we prepared a series of Te nanostructures by electrochemical exfoliation and liquid phase exfoliation methods, including one-dimensional (1D) Te nanowires (NWs), quasi-1D Te nanorods (NRs), zero-dimensional (0D) Te nanodots (NDs) and two-dimensional (2D) Te nanosheets (NSs). Femtosecond Z-scan measurements reveal unique dimension-dependent nonlinear optical (NLO) properties. 1D Te NWs and quasi-1D Te NRs exhibited higher saturable absorption behavior than 0D Te nanostructures, while the 2D Te NSs are a high performance optical limiting material. Ultrafast transient absorption spectroscopy revealed the dimension-dependent exciton dynamics. The reverse saturable absorption of 2D Te NSs is derived from faster exciton relaxation and stronger excited state absorption. This work paves the way for the design of saturable absorbers with high performance and broadens the application of 2D Te in the field of laser protection and other novel ultrafast photonics.
由于实验观测到的外尔费米子以及器件中优异的载流子迁移率、开关比和载流能力，低维碲目前在潜在电子应用方面备受关注。然而，碲纳米结构的光学性质尚未得到充分研究，尤其是在非线性光学领域。在此，我们通过电化学剥离和液相剥离方法制备了一系列碲纳米结构，包括一维（1D）碲纳米线（NWs）、准一维碲纳米棒（NRs）、零维（0D）碲纳米点（NDs）和二维（2D）碲纳米片（NSs）。飞秒Z扫描测量揭示了独特的尺寸依赖性非线性光学（NLO）性质。一维碲纳米线和准一维碲纳米棒表现出比零维碲纳米结构更高的饱和吸收行为，而二维碲纳米片是一种高性能的光限幅材料。超快瞬态吸收光谱揭示了尺寸依赖性激子动力学。二维碲纳米片的反向饱和吸收源于更快的激子弛豫和更强的激发态吸收。这项工作为高性能饱和吸收体的设计铺平了道路，并拓宽了二维碲在激光防护和其他新型超快光子学领域的应用。
