Optical anisotropy and polarization selectivity in MoS₂/Ta₂NiSe₅ van der Waals heterostructures

In-plane anisotropy induced by a low-symmetric lattice structure in two-dimensional (2D) van der Waals (vdWs) materials has significantly promoted their applications in optoelectronic devices, especially in polarization photodetection. Given the mature preparation technology of transition metal dichalcogenides (TMDCs), introducing artificial anisotropy into symmetric TMDCs becomes a promising way to trigger more excellent functionalities beyond their intrinsic properties. Herein, monolayer MoS2 in the MoS2/Ta2NiSe5 vdWs heterostructure presents obvious anisotropic optical properties confirmed by polarized Raman and photoluminescence spectra, which is mainly ascribed to the uniaxial strain via strong interlayer couplings. Moreover, the MoS2/Ta2NiSe5 heterojunction endows unique orientation-selected polarized absorbance. In the visible region, the dominant polarized orientation is along the armchair axis while rotated to the perpendicular direction in the near-infrared spectrum, which is mainly ascribed to the intrinsic linear dichroism of Ta2NiSe5. The results suggest that the MoS2/Ta2NiSe5 heterostructure provides a promising platform for artificial regulation of the optoelectronic properties of symmetric MoS2 and integrated optical applications in the polarization-sensitive photodetection.