A Luminescent Hybrid Bimetallic Halide Family with Solvent‐Coordinated Rare Earth and Alkaline Earth Metals

Abstract Hybrid metal halides are an extraordinary class of optoelectronic materials with extensive applications. To further diversify and study the in‐depth structure‐property relations, we report here a new family of 21 zero‐dimensional hybrid bimetallic chlorides with the general formula A ( L ) n [ B Cl m ] ( A =rare earth ( RE ), alkaline earth metals and Mn; L =solvent ligand; and B =Sb, Bi and Te). The RE (DMSO) 8 [ B Cl 6 ] ( RE =La, Ce, Sm, Eu, Tb, and Dy; DMSO=dimethyl sulfoxide) series shows broadband emission attributed to triplet radiative recombination from Sb and Bi, incorporating the characteristic emission of RE metals, where Eu(DMSO) 8 [BiCl 6 ] shows a staggering PL quantum yield of 94 %. The pseudo‐octahedral [SbCl 5 ] with Cl vacancy in A II (DMSO) 6 [SbCl 5 ] ( A II =Mg, Ca and Mn) and the square pyramidal [SbCl 5 ] in A II (TMSO) 6 [SbCl 5 ] (TMSO=tetramethylene sulfoxide) enhance the stereoactive expression of the 5 s 2 lone pairs of Sb 3+ , giving rise to the observation of dual‐band emission of singlet and triplet emission, respectively. A series of Te(IV) analogues have been characterized, showing blue‐light‐excitable single‐band emission. This work expands the materials space for hybrid bimetallic halides with an emphasis on harnessing the RE elements, and provides important insights into designing new emitters and regulating their properties.