The Rb(7)Bi(3−3x)Sb(3x)Cl(16) Family: A Fully Inorganic Solid Solution with Room‐Temperature Luminescent Members

Low‐dimensional ns(2)‐metal halide compounds have received immense attention for applications in solid‐state lighting, optical thermometry and thermography, and scintillation. However, these are based primarily on the combination of organic cations with toxic Pb(2+) or unstable Sn(2+), and a stable inorganic luminescent material has yet to be found. Here, the zero‐dimensional Rb(7)Sb(3)Cl(16) phase, comprised of isolated [SbCl(6)](3−) octahedra and edge‐sharing [Sb(2)Cl(10)](4−) dimers, shows room‐temperature photoluminescence (RT PL) centered at 560 nm with a quantum yield of 3.8±0.2 % at 296 K (99.4 % at 77 K). The temperature‐dependent PL lifetime rivals that of previous low‐dimensional materials with a specific temperature sensitivity above 0.06 K(−1) at RT, making it an excellent thermometric material. Utilizing both DFT and chemical substitution with Bi(3+) in the Rb(7)Bi(3−3x)Sb(3x)Cl(16) (x≤1) family, we present the edge‐shared [Sb(2)Cl(10)](4−) dimer as a design principle for Sb‐based luminescent materials.