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

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), (Li0.79Ag1.21)In2SiS6 (2), (Li1.12Ag0.88)In2SiS6 (3), and (Li1.44Ag0.56)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.