Introduction of Li into Ag-Based Noncentrosymmetric Sulfides for High-Performance Infrared Nonlinear Optical...

The understanding of the structure-performance relationship is beneficial to establish the balance between the second-harmonic generation (SHG) response and laser-induced damage threshold (LIDT) in exploring novel nonlinear optical (NLO) materials. In this work, a facile strategy of partial Li co-occupation with Ag is employed to investigate the structures and NLO performances of the four Ag-based noncentrosymmetric chalcogenides Ag₂In₂SiS₆ (1), (Li_0.79Ag_1.21)In₂SiS₆ (2), (Li_1.12Ag_0.88)In₂SiS₆ (3), and (Li_1.44Ag_0.56)In₂SiS₆ (4). Both the SHG intensity and LIDT are improved as the Li element is introduced, among which 4 exhibits the optimal phase-matchable SHG response of ∼0.8 × AgGaS₂ (AGS) and a high LIDT of 4 × AGS. These NLO activities are explained by theoretical calculation and the dipole moment analysis.