A multifunctional molecular ferroelectric with chiral features, a high Curie temperature, large spontaneous polarization and photoluminescence: (C9H14N)2CdBr4

Abstract

Low-dimensional chiral organic–inorganic hybrid metal halides have attracted a lot of attention in recent years due to their unique intrinsic properties, including having potential applications in optoelectronic and spintronic devices. However, low-dimensional chiral molecular ferroelectrics are very rare. In this paper, we report a novel zero-dimensional molecular ferroelectric (C₉H₁₄N)₂CdBr₄ (C₉H₁₄N⁺ = protonated 3-phenylpropylamine), which has obvious dielectric and thermal anomalies and shows a high Curie temperature at 395 K. It crystallizes in the P2₁ space group at room temperature, showing a strong CD signal, large spontaneous polarization (P_s = 13.5 μC cm⁻²), and a clear ferroelectric domain. In addition, it also exhibits a flexible SHG response. The photoluminescence spectrum shows that 1 has broadband luminescence. At the same time, compound 1 has a wide band gap, which is mainly contributed to by the inorganic CdBr₄ tetrahedron. The high tunability of low-dimensional chiral molecular ferroelectrics also opens up a way to explore multifunctional chiral materials.