Anisotropic Second‐Harmonic Generation in Chiral Hybrid Palladium Halides

Abstract Chiral hybrid metal halides (HMHs) have attracted considerable attention due to their promising application in various optoelectronic devices. In this work, one kind of zero‐dimensional (0D) R/S‐methylbenzylammonium) 2 PdCl 4 [(R/S‐MBA) 2 PdCl 4 ] single crystals have been synthesized, which possess an indirect bandgap and exhibit energy band splitting at the valence band maximum (VBM) due to the distortion in the [PdCl 4 ] 2− square‐planar structure. Notably, the chiral single crystals demonstrate a significant second‐order nonlinear optical (NLO) coefficient i.e., 15 times that of Y‐cut quartz and second‐harmonic generation‐circular dichroism (SHG‐CD) with an anisotropy factor (g SHG‐CD ) of 0.54. Interestingly, circularly polarized‐SHG (CP‐SHG) with an anisotropy factor ( g CP‐SHG ) up to 0.88 is observed in the lead‐free HMHs. These findings highlight the potential of chiral hybrid palladium (Pd) halides for applications in nonlinear optoelectronic devices.