Supramolecular Approach for Fine-Tuning of the Bright Luminescence from Zero-Dimensional Antimony(III) Halides

Abstract

Halides of ns 2 metal ions have recently regained broad research interest as bright narrowband and broadband emitters. Sb(III) is particularly appealing for its oxidative stability (compared to Ge 2+ and Sn 2+ ) and low toxicity (compared to Pb 2+ ). Square pyramidal SbX 5 anion had thus far been the most common structural motif for realizing high luminescence efficiency, typically when cocrystallized with an organic cation. Luminescent hybrid organic–inorganic halides with octahedral coordination of Sb(III) remain understudied, whereas fully inorganic compounds show very limited structural engineerability. We show that the host–guest complexation of alkali metal cations with crown ethers fosters the formation of zero-dimensional Sb(III) halides and allows for adjusting the coordination number (5 or 6). The obtained compounds exhibit bright photoluminescence with quantum yields of up to 89% originating from self-trapped excitons, with emission energies, Stokes shifts, and luminescence lifetimes finely-adjustable by structural engineering. A combination of environmental stability and strong, intrinsic temperature-dependence of the luminescence lifetimes in the nanosecond-to-microsecond range nominate these compounds as highly potent luminophores for remote thermometry and thermography owing to their sensitivity range of 200–450 K and high specific sensitivities of 0.04 °C –1 .

Efficient Lone-Pair-Driven Luminescence: Structure–Property Relationships in Emissive 5s2 Metal Halides

“…(E) PL and PLE spectra of Cs 4 SnBr 6 , 37 (C 4 N 2 H 14 Br) 4 SnBr 6 , 19 and [18-crown-6] 2 Cs 3 SbBr 6 . 118 …”

“…This is best illustrated by comparing three 5s 2 bromides: Cs 4 SnBr 6 , (C 4 N 2 H 14 Br) 4 SnBr 6 , and [18-crown-6] 2 Cs 3 SbBr 6 ( Figure 4 E). 19 , 37 , 118 Although these three materials have different metal centers and different degrees of distortion or lone pair expression, the PL spectra appear to be triplet ( 3 P 0,1,2 )-dominated with one broad, featureless emission peak. This can be understood in terms of the higher degeneracy of the regular octahedral environment: while the trigonally distorted octahedron would have fully distinct singlet and triplet states, the regular octahedron does not fully separate these levels, and therefore, the singlet remains unobserved.…”

Hybrid 0D Antimony Halides as Air‐Stable Luminophores for High‐Spatial‐Resolution Remote Thermography

“…The use of encapsulating coating layers atop the luminophores is then required, which is orthogonal to the purpose of faithful retention of the thermal gradients and can be prohibitively laborious. Therefore, air‐durable alternatives, such as the Sb(III)‐halides, [ 47,52 ] are required. Such materials usually comprise isolated SbX 5 2− anions separated by bulky organic cations (Figure 1c).…”

“…The vast library of 0D Sb(III)‐halides allows the T q to be adjusted from below 200 K (iodides), to around RT (bromides), and above 400 K (chlorides). [ 45,52–70 ]…”

Mn2+‐Doped Metal Halide Perovskites: Structure, Photoluminescence, and Application

“…[ 47–57 ] The toxic‐lead existence is a bottleneck of metal halide perovskites for extending their applications, and thus plentiful elements (e.g., Cu + , Cu 2+ , Sn 2+ , Sn 4+ , Sb 3+ , Bi 3+ , In 3+ ) act as Pb 2+ ‐free candidates to form various perovskite structures. [ 16,58–71 ] Although composition engineering enables the appearance of metal halide perovskite with different structures and dimensions, lead‐free perovskite‐type compounds still exhibit some disadvantages, which include relatively low photoluminescence quantum yields (PLQY), poor stability against high temperature and moisture, enabling poor device performance. As an example, lead‐free CsSnBr 3 perovskites nanocrystals (NCs) show the low PLQY and bad stability, the oxidation of Sn 2+ to Sn 4+ greatly impedes their development.…”