Rolling up 2D WSe₂ Nanosheets to 1D Anisotropic Nanoscrolls for Polarization-Sensitive Photodetectors

The intrinsic low-symmetry crystal structures or external geometries of low-dimensional materials are crucial for polarization-sensitive photodetection. However, these inherently anisotropic materials are limited in variety, and their anisotropy is confined to specific crystal directions. Transforming 2D semiconductors, such as WSe₂, from isotropic 2D nanosheets into anisotropic 1D nanoscrolls expands their application in polarization photodetection. Despite this considerable potential, research on polarization photodetection based on nanoscrolls remains scarce. Here, the uniform crystalline orientation of WSe₂ nanoscrolls is achieved conveniently and efficiently by applying ethanol droplets to vapor deposition-grown bilayer WSe₂ nanosheets. Angle-resolved polarized Raman spectroscopy of WSe₂ nanoscrolls demonstrates vibrational anisotropy. Photodetectors based on these nanoscrolls show competitive overall performance with a broadband detection range from 405 to 808 nm, a competitive on/off ratio of ≈900, a high detectivity of 3.4 × 10⁸ Jones, and a fast response speed of ≈30 ms. Additionally, WSe₂ nanoscroll-based photodetectors exhibit strong polarization-sensitive detection with a maximum dichroic ratio of 1.5. More interestingly, due to high photosensitivity, the WSe₂ nanoscroll detectors can easily record sequential puppy images. This work reveals the potential of WSe₂ nanoscrolls as excellent polarization-sensitive photodetectors and provides new insights into the development of high-performance optoelectronic devices.