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

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)CuCl₄), which exhibit reversible thermochromic behavior, temperature-dependent conductivity and ferromagnetism. Changing temperature results in the reversible color change of (1, 6-HDA)CuCl₄ between yellow and brown. A screen-printing ink is prepared by using (1, 6-HDA)CuCl₄ and used to print thermochromic patterns. The reversible thermochromism originates from the CuCl₆ octahedron distortions and lattice expansion in the crystal structure. The conductivity varies more than two orders of magnitude upon temperature change. (1, 6-HDA)CuCl₄ also shows ferromagnetic property with Curie temperatures around 12 K.