Yi Chang Wu, Panyun Song, Xunpeng Li, Xiao Wei Sun, Wenjing Guo, Zhenhong Wei, Hu Cai
Second-order nonlinear optical (NLO) switches are highly promising for next-generation intelligent optoelectronic devices. Herein, a zero-dimensional organic–inorganic hybrid ferroelectric, [Me 3 NEt][FeCl 4 ] ( 1 ), was designed and synthesized via a quasi-spherical molecular strategy. Concurrent endothermic/exothermic peaks in differential scanning calorimetry (DSC) and step-like dielectric anomalies jointly corroborate the fully reversible structural transition. Strikingly, it exhibits a strong second-order NLO response with a second harmonic generation (SHG) intensity approximately 10 times greater than that of the benchmark KDP (KH 2 PO 4 ). Its ferroelectric properties were further confirmed through piezoresistive force microscopy (PFM) observations and polarization–electric field ( P – E ) hysteresis loop testing. This study not only presents a high-performance NLO switch but also offers a viable design strategy for advanced ferroelectric and photonic materials.