Strain engineering of quasi-1D layered TiS₃nanosheets toward giant anisotropic Raman and piezoresistance responses

Quasi-one-dimensional layered TiS3 nanosheets possess highly anisotropic physical properties. Herein, we reported the anisotropic strain response of Raman and the piezoresistance effect in layered TiS3 nanosheets. An attractive Grüneisen parameter (γ m) of 5.82 was achieved for A g III mode in the b-axis strained TiS3 nanosheet, while a negligible value of γ m was obtained when the strain is applied along the a-axis direction. We also revealed the opposite piezoresistive effect with strains applied along the two principal axes, demonstrating a gauge factor ratio of approximately -1:3.2. The giant anisotropy is attributed to the strain modulated bandgap, which was further confirmed by density functional theory calculations.