Mineral‐Inspired and Computation‐Assisted Rational Design of Polar Gittinsite‐Type Thiophosphates With Exceptional Nonlinear Optical Performance

Polar chalcogenides have emerged as a vibrant class of candidates for infrared nonlinear optical (NLO) applications. However, achieving a balance between large NLO response and wide bandgap within a polar structure remains a crucial challenge. Here, we present a mineral‐inspired and computation‐assisted creation strategy that integrates crystallographic intuition from natural prototypes with first‐principles screening of functional [P x S y ] motifs. Guided by this approach, 13 thiophosphates were successfully identified and synthesized, including 8 polar gittinsite‐type ones, AM III P 2 S 7 (A = K, Rb, Cs; M III = V, Cr, In, La, Bi). As a representative, the structure of RbInP 2 S 7 features [InP 2 S 11 ] six‐membered rings built by the asymmetric integration of [InS 6 ] octahedra and [P 2 S 7 ] dimers, resulting in strong local polarity and robust covalent In–P–S linkages. RbInP 2 S 7 exhibits a large NLO response (2.3 × AgGaS 2 ), wide optical bandgap (3.08 eV), and high laser‐induced damage threshold (13.9 × AgGaS 2 ), surpassing most reported NLO chalcogenides. This study not only uncovers a high‐performance NLO crystal but also establishes a generalizable design paradigm that integrates mineral‐inspired chemistry with theoretical screening—offering valuable guidance for the rational discovery of future functional chalcogenides.