High-Tc Quadratic Nonlinear Optical and Dielectric Switchings in Fe-Based Plastic Crystalline Ferroelectric

Plastic crystals, as a molecular material with multiple functions, have become a research hotspot in the exploration of new ferroelectric crystal compounds, especially due to their unique solid–solid phase transition properties. Based on this, we synthesized a new 0D organic–inorganic hybrid Fe-based plastic ferroelectric [(CH3)3NCH2CHCH2]FeCl4 (1), which has a high-temperature phase transition point of 393 K, obvious ferroelectric domains, and spontaneous polarization and has been tested by dielectric and piezoelectric power microscopy (PFM) and ultraviolet absorption (UV–vis). At room temperature, it crystallizes in the space group Cmc21 and has an obvious SHG switch. In addition, compound 1 also has an optical narrow band gap of 2.45 eV, indicating that compound 1 is a high-quality semiconductor material. This work advances the development of plastic ferroelectrics and provides an avenue for exploring the frequency-doubling response and optoelectronic properties of high-temperature plastic ferroelectrics.