Symmetry-Reduction Enhanced Polarization-Sensitive Photodetection in Core–Shell SbI₃/Sb₂O₃ van der Waals Heterostructure

Structural symmetry is a simple way to quantify the anisotropic properties of materials toward unique device applications including anisotropic transportation and polarization-sensitive photodetection. The enhancement of anisotropy can be achieved by artificial symmetry-reduction design. A core–shell SbI₃/Sb₂O₃ nanowire, a heterostructure bonded by van der Waals forces, is introduced as an example of enhancing the performance of polarization-sensitive photodetectors via symmetry reduction. The structural, vibrational, and optical anisotropies of such core–shell nanostructures are systematically investigated. It is found that the anisotropic absorbance of a core–shell nanowire is obviously higher than that of two single compounds from both theoretical and experimental investigations. Anisotropic photocurrents of the polarization-sensitive photodetectors based on these core–shell SbI₃/Sb₂O₃ van der Waals nanowires are measured ranging from ultraviolet (UV) to visible light (360–532 nm). Compared with other van der Waals 1D materials, low anisotropy ratio (I_max/I_min) is measured based on SbI₃ but a device based on this core–shell nanowire possesses a relatively high anisotropy ratio of ≈3.14 under 450 nm polarized light. This work shows that the low-symmetrical core–shell van der Waals heterostructure has large potential to be applied in wide range polarization-sensitive photodetectors.