Chiral (R/S‐MPz)Ge ₄ I ₁₀ With Unique 2D [Ge ₄ I ₁₀ ] Layered Structure and Large Chirality‐Induced Nonlinear Optical Effect

ABSTRACT Chiral organic–inorganic hybrid metal halides (OIMHs) with intrinsic non‐centrosymmetric structures have attracted considerable attention for their potential nonlinear optical (NLO) applications. However, compared to their achiral counterparts, the chirality‐induced mechanism underlying their NLO effects remains unclear. This study reports for the first time a pair of Ge‐based chiral OIMHs (R/S‐MPz)Ge 4 I 10 with a unique 2D [Ge 4 I 10 ] 2− layers, exhibiting a second‐harmonic effect approximately five times greater than that of benchmark K 2 HPO 4 (KDP). This represents the highest value achieved to date among reported chiral Ge‐based OIMHs and far exceeds those observed in the organic R/S‐MPz. First‐principles calculations reveal that the unique [Ge 4 I 10 ] 2− layer, constructed by edge‐shared [GeI 6 ] 4− octahedra induced by chirality, is crucial for the dominate NLO effect. By further enhancing the polarity of the organic component, this material achieves a gain record of ∼15×KDP. Our study not only expands the family of chiral Ge‐based OIMHs but also elucidates the relationship between chiral motif and NLO property, providing a rational design strategy for chiral NLO materials.