2D AgVP₂Se₆ with Layer‐Independent and Strong In‐Plane Anisotropic Second Harmonic Generation

Abstract Exploring 2D nonlinear optical (NLO) materials that exhibit layer‐independence and in‐plane anisotropy of second‐harmonic generation (SHG) is of great importance to the fundamental studies and further development of polarization‐sensitive optoelectronics. However, such exploration remains challenging because it requires the corresponding bulk materials to have broken inversion symmetry as well as low‐lattice symmetry. Here, it is shown that AgVP 2 Se 6 can be a novel 2D NLO anisotropic material with the experimental demonstration of the layer‐irrelevant and in‐plane anisotropic NLO process. Nanoflakes of AgVP 2 Se 6 are successfully prepared by mechanical exfoliation method. The thickness‐ and polarization‐dependent SHG measurement reveal that as‐exfoliated AgVP 2 Se 6 nanoflakes exhibit layer‐independence and strong in‐plane anisotropy of SHG with the anisotropic factor up to 56.38. Moreover, temperature‐dependent Raman spectroscopy reveals that 2D AgVP 2 Se 6 nanoflakes exhibit interlayer interactions stronger than that of graphene, which is helpful in reducing interlayer slip and detachment. These attributes make 2D AgVP 2 Se 6 promising in polarization‐sensitive nanophotonic applications.