Carbonatoperoxovanadates with Strong Second-Harmonic Generation: Insights from First-Principles Calculations on Anisotropic Structures and Optical Parameters.

Carbonatoperoxovanadates are considered as promising functional materials in optoelectronic devices due to their excellent optical properties, particularly strong second-harmonic generation (SHG) response. However, the relationship between their geometric structures and optical properties remains unclear. Herein, the structural, electronic, and optical properties of carbonatoperoxovanadates A₃VO(O₂)₂CO₃ (A=K, Rb, and Cs) were investigated using first-principles calculation. Results suggest that high-density and parallel arrangement of nonlinear optical active [VO(O₂)₂CO₃] units are conducive to generating large SHG response in A₃[V(O₂)₂O]CO₃. Optical anisotropy was observed. Birefringence values for A₃[V(O₂)₂O]CO₃ were comparable to those of commonly used infrared nonlinear optical materials. Specifically, results of tiny optical characteristics (local dipole moments, HUMO-LUMO gap, polarizability anisotropy, and hyperpolarizability) indicate that asymmetry [VO(O₂)₂CO₃] is an excellent nonlinear optical active functional unit, owing to the synergistic effect between its non-centrosymmetric nonlinear optical elements. This study elucidates the structure-property relationship of carbonatoperoxovanadates, offering valuable insights for designing novel high-performance SHG materials.