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.

Automated summary

This study presents the successful synthesis of Rb7Sb3Br16 with a 0D structure and weak orange photoluminescence at room temperature. Experimental results revealed two distinct emission bands in the material, with the higher energy emission quenching as temperature increases. Additionally, Rb7Bi3Br16 and Rb7Bi3I16 were obtained, with the former showing weak low-temperature luminescence and the latter being non-luminescent, expanding the library of emissive inorganic metal halides.