A Quasi‐Two‐Dimensional Copper Based Organic‐Inorganic Hybrid Perovskite with Reversible Thermochromism and Ferromagnetism

Abstract Two‐dimensional (2D) organic‐inorganic hybrid perovskites (OHPs) have been gaining more and more attention for their unique optical, electrical and magnetic behaviors. Herein, we report a multifunctional quasi‐2D hybrid perovskite, 1, 6‐hexanediammonium tetrachlorocuprate ((1, 6‐HDA)CuCl 4 ), which exhibit reversible thermochromic behavior, temperature‐dependent conductivity and ferromagnetism. Changing temperature results in the reversible color change of (1, 6‐HDA)CuCl 4 between yellow and brown. A screen‐printing ink is prepared by using (1, 6‐HDA)CuCl 4 and used to print thermochromic patterns. The reversible thermochromism originates from the CuCl 6 octahedron distortions and lattice expansion in the crystal structure. The conductivity varies more than two orders of magnitude upon temperature change. (1, 6‐HDA)CuCl 4 also shows ferromagnetic property with Curie temperatures around 12 K.