Mixed Anionic Tetrahedra Guided Design of New Infrared Nonlinear Optical Material Cs₃Ga₈S₁₃Cl with High Laser‐Induced Damage Threshold

Abstract The development of anti‐laser damage infrared (IR) nonlinear optical (NLO) materials is an urgent need but challenging due to the contradiction between wide bandgap and large NLO coefficient. Herein, by introducing a halogen into the NLO‐active tetrahedral unit, two halogenated metal chalcogenides Cs₃Ga₈S₁₃Cl and Cs₉Ga₈Se₁₂Cl₉ with unprecedented [GaQ₃Cl] (Q = S/Se) tetrahedral units are rationally designed and fabricated in experiments by the flux method, enriching the chemical and structural diversity of chalcogenides. Cs₃Ga₈S₁₃Cl shows a wide bandgap of ≈3.76 eV, resulting in a high laser‐induced damage threshold of ≈8 × AgGaS₂ (AGS) and a moderate NLO response (≈0.6 × AGS) with phase‐matching behavior. The results imply that Cs₃Ga₈S₁₃Cl is a promising IR NLO material for the high powder laser application and demonstrate the feasibility of the halogenated tetrahedron strategy in regulating the optical properties of chalcogenides.