Expanding the 0D Rb7M3X16 (M=Sb, Bi; X=Br, I) Family: Dual‐Band Luminescence in Rb7Sb3Br16

Inorganic, lead‐free metal halides are widely sought after following the rise of the halide perovskites as outstanding optoelectronic materials, due to their enhanced stability and reduced toxicity. Herein, we report on the solvothermal synthesis of Rb7Sb3Br16, which exhibits a 0D structure comprised of [SbBr6]3− octahedra and edge‐sharing bioctahedra [Sb2Br10]4− dimers that order into layers along the c‐axis. This all‐inorganic material is air‐stable and exhibits weak orange photoluminescence (PL) at room temperature. Low‐temperature PL and PL excitation (PLE) measurements reveal the presence of two distinct emission bands that originate from these structural units, with the high‐energy emission quenching as temperature rises beyond 150 K. We are also able to obtain Rb7Bi3Br16 and Rb7Bi3I16 which both crystallize in orthorhombic symmetry, with Rb7Bi3Br16 presenting weak low‐temperature luminescence while Rb7Bi3I16 is non‐luminescent. This work expands the library of emissive inorganic metal halides and provides further evidence for the efficacy of low‐dimensional Sb−X luminescent centers based on octahedral and edge‐sharing [Sb2X10]4− dimers.ISSN:0018-019XISSN:1522-267

The Rb7Bi3−3xSb3xCl16 Family: A Fully Inorganic Solid Solution with Room‐Temperature Luminescent Members

Low‐dimensional ns2‐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 Pb2+ or unstable Sn2+, and a stable inorganic luminescent material has yet to be found. Here, the zero‐dimensional Rb7Sb3Cl16 phase, comprised of isolated [SbCl6]3− octahedra and edge‐sharing [Sb2Cl10]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 Bi3+ in the Rb7Bi3−3x Sb3x Cl16 (x ≤1) family, we present the edge‐shared [Sb2Cl10]4− dimer as a design principle for Sb‐based luminescent materials.ISSN:1433-7851ISSN:1521-3773ISSN:0570-083

The Rb 7

Low‐dimensional ns2‐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 Pb2+ or unstable Sn2+, and a stable inorganic luminescent material has yet to be found. Here, the zero‐dimensional Rb7Sb3Cl16 phase, comprised of isolated [SbCl6]3− octahedra and edge‐sharing [Sb2Cl10]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 Bi3+ in the Rb7Bi3−3x Sb3x Cl16 (x ≤1) family, we present the edge‐shared [Sb2Cl10]4− dimer as a design principle for Sb‐based luminescent materials.ISSN:1433-7851ISSN:1521-3773ISSN:0570-083

Lone-Pair-Induced Structural Ordering in the Mixed-Valent 0D Metal-Halides Rb23BiIIIxSbIII7–xSbV2Cl54 (0 ≤ x ≤ 7)

Mixed-valent metal-halides containing ns2 lone pairs may exhibit intense visible absorption, while zero-dimensional (0D) ns2-based metal-chlorides are generally colorless but have demonstrated promising optoelectronic properties suitable for thermometry and radiation detection. Here, we report solvothermally synthesized mixed-valent 0D metal-halides Rb23BiIIIxSbIII7-xSbV2Cl54 (0 ≤ x ≤ 7). Rb23SbIII7SbV2Cl54 crystallizes in an orthorhombic space group (Cmcm) with a unique, layered 0D structure driven by the arrangement of the 5s2 lone pairs of the SbIIICl6 octahedra. This red material is likely the true structure of a previously reported monoclinic "Rb2.67SbCl6"phase, the structure of which was not determined. Partially or fully substituting SbIII with isoelectronic BiIII yields the series Rb23BiIIIxSbIII7-xSbV2Cl54 (0 < x ≤ 7), which exhibits a similar layered 0D structure but with additional disorder that yields a trigonal crystal system with an enantiomorphic space group (R32). Second harmonic generation of 532 nm light from a 1064 nm laser using Rb23BiIII7SbV2Cl54 powder confirms the noncentrosymmetry of this space group. As with the prototypical mixed-valent pnictogen halides, the visible absorption bands of the Rb23BiIIIxSbIII7-xSbV2Cl54 family are the result of intervalent SbIII-SbV and mixed-valent BiIII-SbV charge transfer bands (CTB), with a blueshift of the absorption edge as BiIII substitution increases. No PL is observed from this family of semiconductors, but a crystal of Rb23BiIII7SbV2Cl54 exhibits a high resistivity of 1.0 × 1010 ω·cm and X-ray photoconductivity with a promising μτ product of 8.0 × 10-5 cm2 s-1 V-1. The unique 0D layered structures of the Rb23BiIIIxSbIII7-xSbV2Cl54 family highlight the versatility of the ns2 lone pair in semiconducting metal-halides, pointing the way toward new functional 0D metal-halide compounds.ISSN:0897-475