Cooperative Enhancement of Second Harmonic Generation in an Organic–Inorganic Hybrid Antimony Halide

Exploration of nonlinear optical (NLO) crystalline materials is a hot and continuing research topic in modern optoelectronics and laser technology. Within this portfolio, the emerging organic–inorganic hybrid metal halides provide infinite opportunities due to their fascinating advantages of inorganic metal frameworks and organic molecules. Herein, by cooperatively combining the inorganic second-order Jahn–Teller distorted octahedron [SbCl6] and the organic π-conjugated aromatic amine (N,N,4-trimethylaniline, C9H13N), a non-centrosymmetric (NCS) organic–inorganic hybrid antimony halide, (C9H14N)SbCl4, has been developed. Meanwhile, the bulky colorless single crystals of (C9H14N)SbCl4 with dimensions of 10 × 3 × 0.5 mm3 are grown by the temperature-lowering crystallization process. Further optical property investigations reveal that the crystals possess a remarkable second harmonic generation (SHG) response (2.1 × KDP, KH2PO4) and a moderate birefringence (0.095@546 nm) to achieve phase-matching behavior, and they demonstrate promising prospects for application in the NLO field. Furthermore, the crystal structure analysis and theoretical calculations demonstrate that the large SHG response primarily originates from the cooperative coupling between the highly asymmetric distorted [SbCl6] octahedron (3.649 × 10–3) and the π-conjugated aromatic amine. This work points out an efficient route for the future exploration of new quadratic NLO materials with excellent optical performance in hybrid metal halides.