2D ternary vanadium phosphorous chalcogenide with strong in-plane optical anisotropy

Abstract

Low-symmetry 2D materials are reviving recently owing to their azimuth-angle-dependent physical properties, which can be applied in polarization-sensitive optical and photoelectric devices. In this work, layered V₂P₄S₁₃ with a novel low-symmetry porous structure was introduced as a promising highly anisotropic 2D material. We systematically investigated the structural, phonon-vibrational, and optical properties of 2D V₂P₄S₁₃ by transmission electron microscopy, angle-resolved polarized Raman spectroscopy, angle-resolved reflection, and absorption spectroscopy. We discovered that 2D V₂P₄S₁₃ shows strong crystallographic anisotropy, highly porous structure, and unique bi-vanadium atom coupling in the 2D plane. Polarized Raman spectroscopy indicated the strong phonon vibration anisotropy of 2D V₂P₄S₁₃. Additionally, angle-resolved difference reflection and absorption spectra demonstrated optical anisotropy with a high anisotropic absorption ratio of 1.55 at 468 nm. Remarkably, we discovered unusual linear dichroism conversion of V₂P₄S₁₃ from 468 nm to 600 nm. Such unique structural features of 2D V₂P₄S₁₃, in combination with high optical anisotropy, make it an ideal platform for novel polarization-sensitive devices.