Lone-Pair-Induced Structural Ordering in the Mixed-Valent 0D Metal-Halides Rb₂₃Bi^III_xSb^III_7–xSb^V₂Cl₅₄ (0 ≤ x ≤ 7)

Abstract

Mixed-valent metal-halides containing n s 2 lone pairs may exhibit intense visible absorption, while zero-dimensional (0D) n s 2 -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 Rb 23 Bi III x Sb III 7– x Sb V 2 Cl 54 (0 ≤ x ≤ 7). Rb 23 Sb III 7 Sb V 2 Cl 54 crystallizes in an orthorhombic space group ( Cmcm ) with a unique, layered 0D structure driven by the arrangement of the 5s 2 lone pairs of the Sb III Cl 6 octahedra. This red material is likely the true structure of a previously reported monoclinic “Rb 2.67 SbCl 6 ” phase, the structure of which was not determined. Partially or fully substituting Sb III with isoelectronic Bi III yields the series Rb 23 Bi III x Sb III 7– x Sb V 2 Cl 54 (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 ( R 32). Second harmonic generation of 532 nm light from a 1064 nm laser using Rb 23 Bi III 7 Sb V 2 Cl 54 powder confirms the noncentrosymmetry of this space group. As with the prototypical mixed-valent pnictogen halides, the visible absorption bands of the Rb 23 Bi III x Sb III 7– x Sb V 2 Cl 54 family are the result of intervalent Sb III –Sb V and mixed-valent Bi III –Sb V charge transfer bands (CTB), with a blueshift of the absorption edge as Bi III substitution increases. No PL is observed from this family of semiconductors, but a crystal of Rb 23 Bi III 7 Sb V 2 Cl 54 exhibits a high resistivity of 1.0 × 10 10 Ω·cm and X-ray photoconductivity wi...

Enhanced visible light absorption in layered Cs3Bi2Br9 through mixed-valence Sn(ii)/Sn(iv) doping

“… 34 Lastly, very recently Benin et al reported a series of mixed valence Sb compounds with formula Rb 23 Bi x Sb 9– x Cl 54 (0 ≤ x ≤ 7), which can be described as Bi doped Rb 2 SbCl 6 , although the structure is significantly more complex than the parent cubic phase. 81 The Bi doping led to lower resistivity than corresponding mixed valence A 2 BX 6 compounds.…”

Zero-Dimensional Halides with ns2 Electron (Sb3+) Activation to Generate Broad Photoluminescence

“…Sb-doped OIMHs have been reported to emit blue, orange, or white light, with many applications for near-infrared emission. These findings indicate that appropriate ion doping can break the parity prohibition and induce carrier-absorption transitions, thereby generating colored luminescence. ,− Noculak et al synthesized Cs 2 MInCl 6 : x Sb (M = Na, K, x = 0–100%) with efficient broadband blue emission (Na, PLQY = 82%) and green emission (K, PLQY = 93%) . Kshirsagar et al reported that Sb 3+ -doped Cs 2 InCl 5 ·H 2 O exhibits highly efficient and strong temperature-dependent green luminescence .…”

Enhanced visible light absorption in layered Cs3Bi2Br9 through mixed-valence Sn(II) / Sn(IV) doping

“…34 Lastly, very recently Benin et al reported a series of mixed valence Sb compounds with formula Rb 23 Bi x Sb 9-x Cl 54 (0 # x # 7), which can be described as Bi doped Rb 2 SbCl 6 , although the structure is signicantly more complex than the parent cubic phase. 81 The Bi doping led to lower resistivity than corresponding mixed valence A 2 BX 6 compounds.…”