Three-in-One Tetrahedral Functional Units Constructing Diamondlike Ag₂In₂SiS_3.06Se_2.94 with High-Performance...

Exploration of new functional materials with enhanced performance from known ones is always an attractive strategy. A new infrared (IR) nonlinear-optical (NLO) mixed chalcogenide Ag₂In₂SiS_3.06Se_2.94 (1), was obtained through partial congener substitution originated from Ag₂In₂SiS₆ (0). 1 crystallizes in the monoclinic space group Cc, and its three-dimensional (3D) polyanionic network is composed of {[In₄Si₂Se₅(S/Se)₁₁]^12-}_∞ helical chains sharing S/Se(5) corner atoms with cavities embedded with counterion Ag⁺ ions. It exhibits a much enhanced NLO response compared to that of 0, reaching 1.1 × AgGaS₂. Further theoretical analysis results indicate that the large NLO response can be attributed to the synergistic effect of AgQ₄ and InQ₄ tetrahedral functional motifs. This work not only reports a new high-performance IR NLO material but also enriches the partial ion substitution strategy to obtain new functional materials.