Enhanced Nonlinear Optical Response and Self‐Powered CPL Detection in Unique Triangular–Tetrahedral Chiral Copper(I) Halides

The (R/S)-MPZCu₂Cl₄ halides exhibit a unique triangular–tetrahedral polyhedral configuration and enhanced nonlinear susceptibility. This kind of Cu(I)-based halide exhibits efficient second-harmonic generation (SHG), third-harmonic generation, and excellent circularly polarized light (CPL) detection performance. The (R/S)-MPZCu₂Cl₄ could be applied in self-powered CPL photodetection and X-ray detection with high sensitivity and radiation resistance.

Abstract

The low-coordination polyhedral architecture of Cu(I)-based chiral metal halides induces significant structural distortions, endowing these materials with remarkable circularly polarized light (CPL) activity and exceptional nonlinear optical (NLO) performance. However, achieving highly selective CPL detection with large dissymmetry factors (g _lum) in Cu(I)-based chiral metal halides remains a significant challenge. Herein, we prepared 1D chiral (R/S)-MPZCu₂Cl₄ (where MPZ is 2-methylpiperazine) halides with the unique triangular–tetrahedral configuration in the noncentrosymmetric cubic P1₂11 space group, resulting in substantial structural distortions, which significantly impact nonlinear susceptibility. Consequently, (R)-MPZCu₂Cl₄ halide exhibits efficient second harmonic generation (SHG), which is 7.29 times as high as that of KH₂PO₄. Additionally, (R)-MPZCu₂Cl₄ halide also exhibits remarkable third harmonic generation (THG) response, and g _THG-CD is as high as +0.309, which is the first demonstration of THG-based CPL detection in Cu(I)-based metal halides. The self-powered CPL photodetectors based on (R/S)-MPZCu₂Cl₄ show high CPL distinguishability at 0 V and further achieve self-powered X-ray detection with excellent low-dose detection and radiation resistance. Our study provides valuable insights into the structure–performance relationship in chiral organic–inorganic hybrid Cu(I) halides, paving the way for next-generation multifunctional optoelectronic devices.

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