Strain engineering of quasi-1D layered TiS3 nanosheets 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 Gruneisen parameter ( γm) of 5.82 was achieved for AgIII mode in the b-axis strained TiS3 nanosheet, while a negligible value of γm 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.